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Specification (Technical Standard) General Contractor Deep Foundation Concrete Construction Aggregate

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GOVERNMENT OF THE FEDERAL REPUBLIC OF NIGERIA GENERAL SPECIFICATIONS (ROADS AND BRIDGES) VOLUME II REVISED 1997 DIRECTOR OF FEDERAL HIGHWAYS FEDERAL MINISTRY OF WORKS & HOUSING HEADQUARTERS ABUJA, NIGERIA INDEX TO SPECIFICATION Pages Clauses: INDEX……………………………………….. (i) – (xv) SPECIFICATIONS:SECTION I – GENERAL ……………………………………………. 1 – 23 SECTION II –CONCRETE: MASS AND REINFORCED.…………. 24 -55 SECTION III – PRESTRESSED CONCRETE………………………..56 –72 SECTION IV – PILING…. ……………………………………………73–84 SECTION V – BRIDGEWORKS………………………………………85–109 SECTION VI – ROADWORKS..………………………………….….110 –226 SECTION I - GENERAL PART (A) ADMINISTRATION CLAUSES 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 PRELIMINARY……………………………………………………………………….. DEFINITIONS………………………………………………………………………… DESCRIPTION OF WORKS…………………………………………………………. LIAISON WITH ADJACENT WORKS……………………………………………….. AVOIDANCE OF DAMAGE TO WORKS……………………………………………. DATUM…………………………………………………………………………………… SURVEYS AND LEVELS TO BE AGREED AS BASIS FOR MEASUREMENT….. DIMENSIONS AND LEVELS………………………………………………………….. PARTICULARS OF EXISTING WORK………………………………………………. WORKING DRAWINGS………………………………………………………………. ALTERATIONS OF DRAWINGS………………………………………………………. DRAWINGS OF TEMPORARY WORKS TO BE SUBMITTED…………… SETTING OUT……………………………………………………………………………. NOTICE OF OPERATION………………………………………………………………. EXISTING SERVICES……………………………………………………………………. DAMAGE TO SERVICES………………………………………………………………… FILLING HOLES AND TRENCHES……………………………………………… JOINT MEASUREMENT OF MEASUREMENT OF EXTRAS………………………. PROTECTION FROM WEATHER…………………………………………… WORKS TO BE KEPT FREEE FROM WATER……………………………………… STAFF ETC. ACCOMODATION………………………………………………………. SUPPLY OF WATER AND ELECTRICITY…………………………………………… RETURNS OF LABOUR……………………………………………………………….. PHOTOGRAPHS………………………………………………………………………… REPORTS OF ACCIDENTS OR UNUSUAL OCCURANCE…………………………. MAINTENANCE OF WORKS…………………………………………………………. AS-MADE DRAWINGS………………………………………………………………… TRAFFIC ROUTES TO BE MAINTAINED AND WORKS TRAFFIC CONTROLLED……………………………………………………………………. BARRICADES, WARNING AND DEVIATION SIGNS………………………………. WEATHER CONDITIONS……………………………………………………………… OTHER WORKS AND SERVICES…………………………………………………….. (CLAUSE 1032-1039 INCLUSIVE NOT USED)……………………………………… PART (B) MATERIALS AND TESTING MATERIALS TESTING LABORATORIES AND STAFF………………………….. TESTING OF MATERIALS…………………………………………………………….. INDEPENDENT TESTS………………………………………………………………… INSPECTION ENGINEER……………………………………………………………… MATERIALS SPECIFIED FOR B.S.S………………………………………………….. APPARATUS REQUIRED FOR TESTING……………………………………………. NOTICE OF TESTS…………………………………………………………………….. SAMPLING……………………………………………………………………………… SAMPLING OF MATERIALS FROM BORROW PITS……………………………….. SAMPLING OF MATERIALS FROM STOCKPILES…………………………………. TEST TO BE CARRIED OUT………………………………………………………….. i PAGES 1 1 2 2 2 2 2 2 2 3 3 3 3 4 4 4 4 4 5 5 5 5 5 5 6 6 6 6 7 7 7 8 8 10 11 11 13 13 13 13 13 14 14 1051 1052 1053 1060 1061 1062 1063 1064 1065 UNSATISFACTORY TEST RESULT………………………………………………….. TRIAL SECTIONS OF ROAD…………………………………………………………. HANDLING AND STORAGE OF MATERIALS……………………………………… (CLAUSES 1054 - 1059 INCLUSIVE NOT USED)…………………………………… PART (C) MISCELLANOUS ASSISTANCE FOR ENGINEER’S REPRESENTATIVE……………………………... OFFICE ACCOMODATION…………………………………………………………… FENCING………………………………………………………………………………. COMPLIANCE WITH REGULATIONS OF THE NIGERIAN RAILWAY CORPORATION, AND GOVERNMENT INSPECTOR OF RAILWAYS……………… COMPLIANCE WITH REGULATIONS OF THE NIGERIAN PORTS AUTHORITY TAKING OVER OF SITE BY CONTRACTORS………………………………………. (CLAUSES 1069 - 1099 INCLUSIVE NOT USED)……………………………………. 18 18 20 20 20 21 22 22 23 23 23 SECTION II CONCRETE: MASS AND REINFORCED 2000 CLAUSES GENERAL…………………………………………………………………………………. 2001 2002 PART (A): MATERIALS CEMENT……………………………………………………………………………. WATER ……………………………………………………………………………………. 2003 2004 2005 2006 2007 2008 AGGREGATES…………………………………………………………………………….. FINE AGGREGATES……………………………………………………………………… COARSE AGGREGATES…………………………………………………………….. STEEL REINFORCEMENT………………………………………………………………. WATERPROOF BUILDING PAPER……………………………………………………. JOINT SEALING COMPOUND AND PRIMER……………………………………….. 26 26 29 30 31 32 32 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 PART (B): WORKMANSHIP PROPORTIONS OF CONCRETE: MIXES………………………………………. CONCRETE: MIX DESIGN………………………………………………………… TRIAL MIXES……………………………………………………………………….. MIXING OF CONCRETE ………………………………………………………….. QUALITY CONTROL OF CONCRETE…………………………………………… TRANSPORTATION OF CONCRETE……………………………………………. PLACING AND COMPACTION OF CONCRETE……………………………….. CONRETE: PLACED UNDER WATER………………………………………….. PROTECTION AGAINST CHEMICAL ACTION…………………………………. ATTENDANCE OF JOINER AND STEEL FIXER………………………………. CONSTRUCTION JOINT…………………………………………………………… JOINTS TO PREVENT BONDING OF ADJACENT SURFACES…………….. SURFACE FINISHES……………………………………………………………….. CURING OF CONCRETE…………………………………………………………… FORMWORK………………………………………………………………………. REINFORCEMENT SCHEDULES………………………………………………….. 32 32 33 35 36 41 41 42 43 43 43 44 44 44 45 48 ii 24 24 2025 BENDING AND FIXING OF REINFORCEMENT………………………………… 48 2026 PART (C): PRECAST CONRETE UNITS PRECAST CONCRETE UNITS……………………………………………………… 50 2027 2028 2029 PART (D); CEMENT MORTARS AND GROUTS CEMENT MORTARS AND GROUTS………………………………………………. BUILDING IN FOUNDATION BOLTS, FITTINGS, KERBS ETC……………… EMPLOYMENT OF CONCRETE, MORTARS AND GROUTS……………………… 52 53 53 PART (E); GRANOLITHIC CONCRETE FLOOR FINISHES CEMENT………………………………………………………………………………. AGGREGATES………………………………………………………………………. GRANOLITHIC TOPPING…………………………………………………………… THE SUB-FLOOR…………………………………………………………………… LAYING………………………………………………………………………………. CURING………………………………………………………………………………. RETARDATION OF DUSTING……………………………………………………… CARBORUNDUM FINISH………………………………………………………….. GRANOLITHIC MONOLITHIC TOPPING………………………………………….. DAMP PROOFING……………………………………………………………………… (CLAUSES 2040 - 2999 INCLUSIVE NOT USED) 53 54 54 54 54 54 54 54 54 55 55 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 SECTION III PRESTRESSED CONCRETE SPECIFICATION 3000 CLAUSES GENERAL…………………………………………………………………………….. 56 3001 3002 3003 3004 3005 3006 PART (A) MATERIALS CEMENT……………………………………………………………………………… AGGREGATES………………………………………………………………………. WATER……………………………………………………………………………….. UNTENSIONED REINFORCEMENT………………………………………………. PRE-STRESSING STEEL………………………………………………………….. SHEATHING………………………………………………………………………….. 57 57 58 58 58 60 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 PART (B); WORKMANSHIP CONCRETE PROPORTIONS………………………………………………………. FIELD TESTS………………………………………………………………………… BATCHING AND MIXING……………………………………………………………. PLACING OF CONCRETE…………………………………………………………. CURING………………………………………………………………………………. FORMWORK………………………………………………………………………… SURFACE FINISH………………………………………………………………….. TOLERANCE………………………………………………………………………… PRE-STRESSING…………………………………………………………………… ADDITIONAL REQUIREMENT…………………………………………………….. LIFTING AND HANDLING………………………………………………………….. QUANTITY AND PAYMENT……………………………………………………….. 61 62 63 63 64 64 64 65 65 70 71 71 iii (CLAUSES 3019 - 3999 INCLUSIVE NOT USED) 72 SECTION IV PILING 4000 4001 4002 4003 4004 4005 4006 4007 4008 4009 4010 4011 4012 4013 4014 4015 4016 4017 4018 4019 4020 4021 CLAUSES GENERAL---------------------------------------------------------------------------------------------- 72 PART (A); GENERAL TYPES OF PILES………………………………………………………………….. APPROVAL OF TYPES OF PILES…………………………………………….... CONTRACTOR TO DRIVE OR BORE PILES……………………………………. SUB-CONTRACTOR TO DRIVE OR BORE PILES…………………………….. MANUFACTURE OF REINFORCED AND PRESTRESSED………………….. CEMENT…………………………………………………………………………….. SETTING OUT OF PILES………………………………………………………….. ALIGNMENT…………………………………………………………………………. DRIVING WITH DROP HAMMERS OR SINGLE ACTING STEAM HAMMERS.. DRIVING WITH DOUBLE ACTION STEAM HAMMERS………………………… PROTECTION OF PILE BUTTS……………………………………………………. LEADS AND FRAMES……………………………………………………………… DRIVING TO BE CONTINOUS TO FINAL SET OR LEVEL…………………….. JETTING………………………………………………………………………………. DRIVING TO FINAL SET AND RECORD OF DRIVING…………………………. RE-DRIVING HEAVED PILES……………………………………………………… DAMAGED AND MIS-DRIVEN PILES…………………………………………….. OBTRUCTIONS………………………………………………………………………. CUTTING OF PILES HEADS ETC…………………………………………………. BORED PILES OR CASINGS……………………………………………………… PAYMENT…………………………………………………………………………….. (CLAUSES 4022 - 4029 INCLUSIVE NOT USED)………………………………….. 72 72 72 72 72 72 72 72 73 73 73 73 73 73 73 73 74 74 74 74 74 74 PART (B); TEST DRIVING AND TEST LOADING OF PILES 4030 4031 4032 4033 4034 4035 4036 GENERAL…………………………………………………………………………….. RECORDING OF TESTS RESULTS…………………………………………………… PROCEDURE FOR TESTING PILES OF TYPES A, B, C AND D……………… PROCEDURE FOR TESTING PILES OF TYPES ''E'' AND ''F'' ….……………… LATERAL DISPLACEMENT TESTS………………………………………………… ASSESMENT OF RESULTS OF PILE LOADING AND DRIVING TESTS……… PAYMENT FOR TEST PILES AND LOAD TESTS……………………………….. (CLAUSES 4037 - 4049 INCLUSIVE NOT USED)…………………………………. 74 74 75 75 75 75 76 76 PART (C) PRECAST REINFORCED CONCRETE BEARING AND SHEET PILES TYPE ''A'' 4050 4051 GENERAL…………………………………………………………………………….. MOULDS AND CONCRETING……………………………………………………… iv 76 76 4052 4053 4054 4055 STRIPPING AND HANDLING……………………………………………………….. LENTHENING OF PILES…………………………………………………...……….. STRIPPING HEADS OF PILES…………………………………………………….. PAYMENT FOR PRECAST REINFORCED CONCRETE BEARING AND SHEET PILES…………………………………………………………………………………. (CLAUSES 4056 - 4059 INCLUSIVE NOT USED)…………………………….. 76 77 77 77 77 PART (D) CAST-IN-PLACE REINFORCED CONCRETE PILES TYPES "B" and "C" 4060 4061 4062 4063 4064 4065 4066 CAST-IN-PLACE REINFORCED CONCRETE PILES TYPE "B"…………. CAST-IN-PLACE REINFORCED CONCRETE PILES TYPE "C"………….. EQUIPMENT………………………………………………………………. CONTROL OF INTERNAL PRESSURES……………………………… CONCRETE……………………………………………………………….. STEEL REINFORCEMENT………………………………………………. 78 78 78 78 78 79 PAYMENT FOR CAST-IN-PLACE REINFORCED CONCRETE PILES TYPES "B" and "C"…………………………………………………………………………………………... (CLAUSES 4067 - 4069 INCLUSIVE NOT USED)………………………… 79 79 PART (E) CAST-IN-PLACE REINFORCED CONCRETE PILES TYPE "D" 4070 4071 4072 GENERAL…………………………………………………………………………….. DETAILED METHOD OF CONSTRUCTION………………………………………. PAYMENT FOR CAST-IN-PLACE REINFORCED CONCRETE PILES OF TYPE "D"……………………………………………………………………………………… (CLAUSES 4073-4079 INCLUSIVE NOT USED)……………………………………. 79 79 79 79 PART (F) PRESTRESSED CONCRETE CYLINDER PILES TYPE "E" 4080 4081 4082 4083 4084 4085 4086 4087 4088 4089 4090 4091 4092 4093 4094 4095 GENERAL…………………………………………………………………………………… MANUFACTURE…………………………………………………………………………. HANDLING……………………………………………………………………………….. EQUIPMENT……………………………………………………………………………… REINFORCING STEEL………………………………………………………………….. CONCRETE……………………………………………………………………………….. CASTING…………………………………………………………………………………. CURING…………………………………………………………………………………… METHOD OF HANDLING…………………………………………………………….. ASSEMBLY OF SECTIONS…………………………………………………………… STRESSING OF PILES………………………………………………………………….. GROUTING OF CABLES……………………………………………………………….. DRIVING RESISTANCE…………………………………………………………………. TENSION FORCES DURING DRIVING………………………………………………… CONTROL OF INTERNAL PRESSURES………………………………………………. PRE-EXCAVATION………………………………………………………………………. v 80 80 80 80 80 80 80 81 81 81 81 81 81 81 81 82 4096 4097 4098 4099 4100 TOLERANCE…………………………………………………………………………….. CUT-OFF………………………………………………………………………………… PILE SPLICES OF BUILD UPS………………………………………………………… DEFLECTIVE PILES………………………………………….…………………………. PAYMENT………………………………………………………………………………. 82 82 82 82 82 (CLAUSES 4101-4109 INCLUSIVE NOT USED)……………………………………… 82 PART (G) PRESTRESSED CONCRETE PILES TYPE "F" 4110 4111 4112 GENERAL…………………………………………………….. METHOD OF MANUFACTURE ETC………………………… PAYMENT……………………………………………………….. (CLAUSES 4113-4119 INCLUSIVE NOT USED) 82 82 83 83 PART (H) STEEL SHEET PILES 4120 4121 4122 4123 4124 4125 STEEL SHEET PILES………………………………………….. WELDING ELECTRODES……….…………………………….. PROTECTIVE PAINTING…………..………………………….. DRIVING ETC……………………………………………………….. THE RODS AND ROPES...…………………………………….. PAYMENT………………………………………………………….. (CLAUSES 4126-4999 INCLUSIVE NOT USED) 83 83 83 83 84 84 84 SECTION V: BRIDGEWORKS PART (A) PRELIMINARIES, EXCAVATIONS, FOUNDATIONS, DEMOLITIONS, TEST LOAD ETC. 5000 5001 5002 5003 5004 5005 5006 5007 5008 5009 5010 5011 GENERAL………………………………………………………… GENERAL………………………………………………………… TRAFFIC DIVERSIONS………………………………………………………… CLEARING OF SITE……………………………………………………… WATER TRAINING AND PROTECTION WORKS……………………… EXCAVATION AND BACKFILLING…………………………..…………… PAYMENT FOR EXCAVATIONS FOR FOUNDATIONS…………… EXCAVATIONS FOR FOUNDATIONS BELOW WATER LEVEL……… PREPARATION FOR FOUNDATIONS: NORMAL……………………… REMOVAL OF EXISTING STRUCTURES: GENERAL………………… EXPLOSIVES……………………...……………………………………… REMOVAL OF EXISTING SUPERSTRUCTURES AND SUBSTRUCTURES: STEEL AND CONCRETE………………………………………………………………….. vi 85 85 85 85 85 85 87 87 88 88 89 89 5012 5013 5014 5015 5016 5017 5018 5019 5020 5021 5022 5023 REMOVAL OF EXISTING SUPERSTRUCTURES AND SUBSTRUCTURES: TIMBER…………………………………………………………………………. TOTAL DEMOLITION OF EXISTING ABUTMENTS, PIERS AND LANDINGS………………………………..……………………………………… PARTIAL DEMOLITION OF EXISTING ABUTMENTS, PIERS AND LANDINGS………………………………..…………………………………………. DISPOSAL AND RE-USE OF RUBBLE RESULTING FROM DEMOLITION………………………………..……………………………………….. PREPARATION OF SURFACES OF EXISTING ABUTMENTS, PIERS, ETC. PRIOR TO PLACING CONCRETE IN CONTRACT…………………………………………… PREPARATION OF SURFACES OF EXISTING ABUTMENTS, PIERS, ETC. PRIOR TO CONSTRUCTION OF NON-BONDING JOINT…………………………………….. TEST ON COMPLETED STRUCTURES……………………….... LOADING OF STRUCTURES: CONSTRUCTIONS, BACKFILLING, TRAFFIC ETC…………………………………………………..…………………………………… AS-MADE DRAWINGS…………………………………………………….. SETTLEMENT OF BRIDGE AND APPROACHES…………………… BEARINGS…………….………………………………………………….. ELASTOMERIC BEARING PADS…………………………………….. (CLAUSES 5024-5029 INCLUSIVE NOT USED) 92 92 92 92 92 93 93 94 95 95 95 95 96 97 PART (B) STRUCTURAL STEELWORK 5030 5031 5032 5033 5034 5035 5036 5037 5038 5039 5040 5041 5042 5043 5044 5045 5046 5047 5048 5049 5050 5051 5052 5053 5054 GENERAL: MATERIALS AND WORKMANSHIP……………………… WORKING DRAWINGS...………………………………………………… SCHEDULE OF PARTS………………………………………………… MILD STEEL FOR STRUCTURAL MEMBERS ETC…………………… ROLLED STEEL PINS, KNUCKLE PINS, ROLLERS………………… STEEL CASTINGS FOR BEARINGS……………………..…………… PATTERNS OF CASTINGS…………………………………….………… GUNMETAL FOR BEARINGS…………………………………….……… FORGINGS…………………………………………...……………………… RIVETS……………………………………………………..………………… BOLTS…………...…………………...……………………………………… HAND-RAILING AND GUARD-RAILING…...…………………...……….. HIGH TENSILE STEEL FOR WELDING…...…………………...……….. HIGH TENSILE STEEL NOT TO BE FOR WELDED………...……….. HIGH TENSILE STEEL MARKING…………………...………...……….. CAST STEEL ……………………...…………………...………...……….. CAST IRON ……………………...…………………...………...……….. ELECTRODES…………………...…………………...………...……….. GREASE FOR BEARINGS….....…………………...………...……….. PAINT AND PAINTING…...….....…………………...………...……….. INTERCHANGEABILITY OF PARTS……...………………………………….. PREPARATION EDGES AND ENDS………………..…………………… HOLES FOR BOLTS AND RIVETS…………………..…………………… RIVETS AND RIVETING…………….…………………………………….. WASHERS……………….…………….…………………………………….. vii 97 97 98 98 98 98 98 98 98 98 98 99 99 99 100 100 100 100 100 100 101 101 101 102 102 5055 5056 5057 5058 5059 5060 5061 5062 5063 5064 5065 5066 5067 5068 5069 5070 5071 5072 5073 WELDING………………..…………….…………………………………….. JOINTS……………………..………….…………………………………….. NOTCHING OF FLANGES AND WEBS...……………………………….. BENDING AND PRESSING…...…….…………………………………….. SHOP ASSEMBLY………….……….…………………………………….. MACHINING…………..…………….…………………………………….. ERECTION AT MANUFACTURERS WORKS AND MARKING UP FOR REERECTION…………….…………………………………………………………………….. SHOP PAINTING AND PROTECTIVE COATINGS…………………….. GALVANIZING…………….………….…………………………………….. DRIFTS, SPANNERS ETC…...…….…………………………………….. NUMBERS OF SITE RIVETS, BOLTS, NUTS SERVICE BOLTS ETC… MEASUREMENT FOR PAYMENT OF STEEL WORK…………………… PACKING AND MARKING FOR SHIPMENT…..………………………….. ERECTION AT SITE…………...……….…………………………………….. SITE PLANNING…………….………….…………………………………….. ADDITIONAL STEEL WORK INVOLVED IN THE STRENGTHENING OF EXISTING BRIDGES…………….……………………………………………………………………. RE-USE OF GIRDERS, JOINTS ETC: OBTAINED FROM DISMANTLED STRUCTURES…………….…………………………………………………………….. GROUTING BASE PLATES, ETC: OF BEARING………..…………….. EXPANSION JOINTS………….…………………………………….. 102 103 103 103 103 103 (CLAUSES 5074-5099 INCLUSIVE NOT USED) 109 103 104 104 104 105 105 106 106 106 107 108 108 109 SECTION VI - ROADWORKS CLAUSES 6000 GENERAL……………………………………………………………………… 110 PART A DESIGN AND CONSTRUCTION STANDARDS 6001 6002 6003 6004 6005 HORIZONTAL ALIGNMENT………………………………………………………….. VERTICAL ALIGNMENT……………………………………………………………… ROLL-OVER…………………………………………………………………………… CONTRACTOR TO CALCULATE LEVELS………………………………………… CONSTRUCTION STANDARDS…………………………………………………….. (CLAUSES 6006-6099 INCLUSIVE NOT USED)…………………………………. 110 111 112 112 112 114 PART B EARTHWORKS, DRAINAGE, ETC. (I) MATERIAL 6100 6101 6102 6103 6104 GENERAL……………………………………………………………………………… UNSUITABLE MATERIAL……………………………………………………………. FILLING MATERIAL…………………………………………………………………… SELECTED LATERITIC MATERIAL FOR SOFT SHOULDERS…………………. GRASS OR GRASS SEED………………………………………………………….. viii 114 115 115 115 115 6105 6120 6121 6122 6123 6124 6125 6126 6127 6128 6129 6130 6131 6132 6133 6134 6135 6136 6137 6138 6139 6140 6141 6142 6143 6144 6145 6146 6147 6148 6149 6150 6151 6152 6153 6154 6155 6156 6157 6158 6159 6160 6161 6162 6163 6164 6165 RUBBLE AND PITCHING STONES…………………………………………………. (CLAUSES 6106-6119 INCLUSIVE NOT USED)…………………………………… 115 115 (II) WORKMANSHIP SITE CLEARANCE……………………………………………………………………. SCARIFYING EXISTING SURFACE………………………………………………… EARTHWORKS……………………………………………………………………….. PAYMENT FOR EARTHWORKS…………………………………………………… SELECTION OF SOIL FOR FILL……………………………………………………. COMPACTION…………………………………………………………………………. BORROW PITS……………………………………………………………………….. SAND FILL…………………………………………………………………………….. EXCAVATION TO BE KEPT FREE FROM WATER………………………………. SLIPS…………………………………………………………………………………… SUITABLE MATERIAL BELOW FORMATION LEVEL……………………………. SWAMP AREAS……………………………………………………………………… FORMATION OF LEVEL …………………………………………………………….. PREPARATION OF FORMATION…………………………………………………. TRIMMING OF SLOPES…………………………………………………………….. EXCAVATION IN ROCK……………………………………………………………… BACKFILLING OF EXISTING BORROW PITS…………………………………….. EMBANKMENT IN BAD GROUNG…………………………………………………. BACKFILLING ………………………………….…………………………………….. GRASSING OF EMBANKMENTS, CUTTINGS, VERGES ETC…………………. ROADSIDE DRAINAGE DITCHING…………………………………………………. CONCRETE DRAINS…………………………………………………………………. SUB-SOIL DRAINS……………………………………………………………………. CUT-OFF DITCHING………………………………………………………………….. EXCAVATION FOR CULVERTS…………………………………………………….. DEMOLITION OF EXISTING CULVERTS…………………………………………… NEW PIPE CULVERTS………………………………………………………………. EXTENSION OF EXISTING PIPE CULVERTS…………………………………….. ACCESS CULVERTS………………………………………………………………… BOX CULVERTS………………………………………………………………………. EXTENSION TO EXISTING BOX CULVERTS…………………………………….. CORRUGATED METAL OR "ARMCO" CULVERTS………………………………. INLETS AND OUTLETS OF CULVERTS…………………………………………… CLEARING DRAINS AND CULVERTS……………………………………………… PITCHING………………………………………………………………………………. APPROVAL OF METHOD…………………………………………………………… PREVENTION OF DAMAGE TO COMPLETED PAVEMENT…………………… WATER FOR CONSTRUCTION…………………………………………………… ROLLERS……………………………………………………………………………… VIBRATORY COMPACTORS……………………………………………………….. TRENCH EXCAVATION FOR WIDENING OF EXISTING PAVEMENT…………. PREPARTION OF SUB-GRADE……………………………………………………. COMPLETION AND SHAPING OF SUB-GRADE…………………………………. COMPLETION OF VERGES AND MEDIANS……………………………………… STRIPPING TOPSOIL………………………………………………………………… CATCHPITS AND CASCADES……………………………………………………… (CLAUSES 6166-6179 INCLUSIVE NOT USED)………………………………… 116 118 118 120 121 122 125 125 127 127 128 128 130 130 130 130 131 131 131 132 132 132 133 134 134 135 135 137 138 138 138 138 139 140 140 140 141 141 141 141 141 142 142 143 143 143 143 ix (III) TESTS 6180 6181 6182 6200 6201 6202 6205 6206 6207 6208 6209 6210 6211 TESTS FOR THE SELECTION OF FILLING MATERIAL…………………………. 143 TESTS FOR THE CLASSIFICATION AND CONTROL OF COMPACTED SUBGRADE AND FILLING…………………………………………………… TRIAL SECTIONS TO DETERMINE TECHNIQUE………………………………… (CLAUSES 6183-6199 INCLUSIVE NOT USED)………………………………… 144 144 144 PART C SUB-BASE COURSE, BASE COURSE ETC (1) LATERITE GENERAL……………………………………………………………………… MATERIALS FOR COMPACTED SUB-BASE COURSE AND BASE COURSE………………………………………………………………. ROCK LATERITE FOR SUB-BASE COURSE AND BASE COURSE…………………………………………………………………… (CLAUSES 6203-6204 INCLUSIVE NOT USED)………………………………. WORKMANSHIP SEQUENCE OF OPERATIONS…………………………………………………….. BORROW PITS FOR SUB-BASE, BASE COURSE AND HARD-SHOULDER MATERIALS………………………………………………………… COMPLETION OF SUB-BASE COURSE COMPLETION OF BASE COURSE………………………………………………… ROCK LATERITE FOR BASE COURSE SURFACING OF BASE COURSE………………………………………………….. PREPARATION OF BASE COURSE TO RECEIVE BITUMEN PRIME COAT…………………………………………………………………. (CLAUSES 6212-6214 INCLUSIVE NOT USED)……………………………. 145 145 147 147 147 147 148 149 149 150 150 150 TESTS 6215 6216 6217 TESTS FOR THE SELECTION OF LATERITE SUB-BASE COURSE AND BASE COURSE MATERIALS…………………………………………… TESTS FOR CLASSIFICATION AND CONTROL OF COMPACTED LATERITIC SUB-BASE COURSE AND BASE COURSE……………………………. TRIAL SECTIONS OF LATERITE SUB-BASE COURSE AND BASE COURSE………………………………………………………………………. (CLAUSE 6218-6219 INCLUSIVE NOT USED)……………………………………. 150 150 152 152 (II) SOIL CEMENT SPECIFICATION 6220 6221 6222 6223 6224 6225 DESCRIPTION………………………………………………………………………. MATERILAS FOR SOIL CEMENT STABILIZATION………………………………. APPROVAL……………………………………………………………………………. SAMPLING OF MATERIALS GENERAL…………………………………………… SAMPLING OF MATERIALS TO BE STABILISED BORROW PITS……………………………………………………………………….. SAMPLING OF MATERIALS - STOCKPILES……………………………………… x 152 155 155 155 155 155 6226 6227 6228 6229 6230 6231 6232 6233 6234 6235 6236 6237 6238 6239 6240 6241 6242 6243 6244 6245 6246 6247 SAMPLING OF MATERIALS - EXISTING MATERIAL ALREADY IN PLACE………………………………………………………………… TESTS FOR THE SELECTION OF SOIL TO BE STABILISED………………….. DESIGN CRITERIA……………………………………………………………………. PROCEDURE FOR ESTIMATION OF CEMENT CONTENT…………………….. CONSTRUCTION…………………………………………………………………….. MULTIPASS - MIX- IN - PLACE METHOD…………………………………………. TRAVELLING MIXING MACHINE METHOD……………………………………….. COMPACTION…………………………………………………………………………. GENERAL REQUIREMENT FOR PLANT MIX PROCESS………………………. BATCH MIXING………………………………………………………………………… WEIGHT PROPOTIONING…………………………………………………………… VOLUMETRIC PROPORTIONING…………………………………………………… CONTINUOUS MIXING……………………………………………………………….. SPREADING…………………………………………………………………………… COMPACTION…………………………………………………………………………. FINISHINGS……………………………………………………………………………. CONSTRUCTION JOINTS……………………………………………………………. CURING………………………………………………………………………………… FIELD CONTROL TESTS…………………………………………………………… TEST RECORDS……………………………………………………………………… ADDITIONAL CONSTRUCTION RECORDS……………………………………… SUPERVISION………………………………………………………………………… (CLAUSES 6248-6249 INCLUSIVE NOT USED)……………………………………. 155 155 156 156 157 157 158 158 158 159 159 159 159 160 161 162 162 162 163 164 164 164 164 6259 (III) CRUSHED STONE GENERAL……………………………………………………………………………… MATERIALS…………………………………………………………………………… GRADING OF CRUSHED STONE………………………………………………….. PREPARATION OF SUBGRADE…………………………………………………… FORMS………………………………………………………………………………… CRUSHED STONE TO BE LAID AND COMPACTED IN LAYERS……………… LAYING AND COMPACTION CRUSHED STONE-DRY PROCESS…………… CRUSHED STONE BASE COURSE LAID BY THE WET PROCESS……….. PREPARATION OF CRUSHED STONE BASE COURSE TO RECEIVE BITUMENINUOS SURFACING………………………………………………………….. COMPACTION…………………………………………………………………………. 6260 (IV) CONCRETE CARRIAGEWAY CONSTRUCTION GENERAL……………………………………………………………………………… 169 6261 6262 6263 6264 6265 6266 6267 6268 6269 MATERIALS CEMENT……………………………………………………………………………….. AGGREGATE…………………………………………………………………………. REINFORCING STEEL……………………………………………………………….. DOWEL BARS AND TIE BARS…………………………………………………….. SIDE FORMS………………………………………………………………………….. RAILS FOR MACHINE FINISHED CONCRETE CARRIAGEWAY………………. PREFORMED JOINT FILLER……………………………………………………….. JOINT PRIMER………………………………………………………………………… JOINT SEALING COMPOUND………………………………………………………. 169 169 169 169 170 170 170 170 170 6250 6251 6252 6253 6254 6255 6256 6257 6258 xi 165 165 166 167 167 168 168 168 169 169 6270 6271 6272 6273 6274 6275 6276 6277 6278 6279 6280 6281 6282 6283 6284 6285 6286 6287 6288 6289 6290 6291 6292 6293 6294 6295 WORKMANSHIP GENERAL……………………………………………………………………………… THICKNESS OF SLABS……………………………………………………………… CONCRETE DISTRIBUTOR………………………………………………………….. COMPACTING AND FINISHING MACHINE……………………………………… WATERPROOF UNDERLAY……………………………………………………….. SETTING, CHEKING, AND STRIKING OF SIDE FORMS……………………….. SETTING, CHEKING, AND STRIKING OF RAILS FOR MACHING-LAID CONCRETE………………………………………………….. QUANTITY AND DISTRIBUTION OF STEEL REINFORCEMENTS…………….. PLACING OF STEEL REINFORCEMENT FOR CARRIAGEWAY………………. TREATMENT AT MANHOLES……………………………………………………… JOINTS IN CONCRETE CARRIAGEWAYS GENERAL REQUIREMENTS…….. TRANVERSE JOINTS………………………………………………………………… LONGITUDINAL JOINTS……………………………………………………………… SAWING JOINTS……...……………………………………………………………… SEALING OF JOINTS………………………………………………………………… COMPRESSIVE STRENGHT OF CONCERETE………………………………….. TRAIL MIXES AND TRIAL SLABS………………………………………………….. PLACING CONCRETE……………………………………………………………….. SPREADING AND COMPACTION WITH A FINISHING MACHINED OF REINFORCED CONCRETE ROADS SLABS………………………… SPREADING AND COMPACTION WITH VIBRATING SCREED OF REINFORCED CONCRETE ROADS SLABS……………………………… SPREADING AND COMPACTION WITH A FINISHING MACHINED OR VIBRATING SCREED ON CONCRETE ROADS SLABS OR HAUNCHES AS ROAD BASES……………………………………………………………. CURING CONCRETE…………………………………………………………………. ACCURACY OF CONCRETE SURFACE USING FINISHING OR VIBRATING SCREED…………………………………………………………………….. TRAFFIC OVER FINISHED WORK…………………………………………………. TESTS SELECTION AND CONTROL TESTS……………………………………………… TRIAL SECTIONS…………………………………………………………………….. (CLAUSES 6296-6299 INCLUSIVE NOT USED)……………………………………. 171 171 171 171 171 171 172 173 173 173 173 173 174 174 174 175 175 176 176 177 177 177 177 178 178 178 178 PART D SURFACING (I)TWO COAT BITUMINOUS SURFACING DRESSING 6300 GENERAL……………………………………………………………………………… 179 MATERIALS 6301 6302 MATERIALS FOR SURFACE DRESSING…………………………………………. BITUMINOUS EMULSION……………………………………………………………. (CLAUSES 6303-6309 INCLUSIVE NOT USED)…………………………………. WORKMANSHIP xii 179 180 180 6310 6311 6312 6313 6314 6315 6316 HEATING OF CUT BACK BITUMEN………………………………………………. CUT-BACK BITUMEN PRIME COAT……………………………………………… SPRAYING OF CUT-BACK BITUMEN PRIME COAT…………………………… FIRST COAT SURFACE DRESSING……………………………………………….. FINAL SURFACE OF CARRIAGEWAY……………………………………………. WET WEATHER………………………………………………………………………. REGULATION OF TRAFFIC OVER PRIME COAT AND SURFACE DRESSING…………………………………………………………….. (CLAUSE 6317-6319 INCLUSIVE NOT USED)……………………………………. 180 180 181 182 183 183 183 183 TESTS 6320 6321 6322 6323 TESTS FOR BITUMEN……………………………………………………………….. TESTS FOR AGGREGATES, ROADSTONE AND CHIPPINGS………………… TESTS FOR BINDER DISTRIBUTORS……………………………………….…….. TESTS FOR RATE APPLICATION………………………………………………….. (CLAUSES 6324-6329 INCLUSIVE NOT USED)……………………………………. 183 184 184 184 184 6330 GENERAL……………………………………………………………………………… MATERIALS 184 6331 6332 6333 6334 BITUMEN MACADAM GENERAL…………………………………………………… BITUMEN MACADAM MATERIALS………………………………………………… BITUMEN MACADAM APPROVAL OF MATERIALS……………………………. BITUMEN MACADAM COMPOSITION OF MIXES……………………………… (CLAUSE 6335-6339 INCLUSIVE NOT USED)……………………………………. 184 185 185 185 186 WORKMANSHIP 6340 6341 6342 6343 6344 6345 6346 6347 6348 6349 6350 6351 6352 MACADAM MIXING PLANT………………………………………………………….. BITUMEN MACADAM MIXING………………………………………………………. BITUMEN MACADAM TRANSPORTATING MIXED MATERIAL…………………. 186 186 186 BITUMEN MACADAM PREPARATION OF SURFACE PRIOR TO LAYING……………………………………………………. BITUMEN MACADAM LAYING……………………………………………………… BITUMEN MACADAM SPREADER OR FINISHER………………………………. HAND SPREADING NOT ALLOWED………………………………………………. BITUMEN MACADAM ROLLING……………………………………………………. FIELD DENSITY OF COMPACTED BITUMEN MACADAM……………………… TRIAL AREAS…………………………………………………………………………. BITUMEN MACADAM FINISHED LEVELS………………………………………… BITUMEN MACADAM JOINTS………………………………………………………. BITUMEN MACADAM DAMAGED WORK………………………………………… (CLAUSES 6353-6359 INCLUSIVE NOT USED)……………………………………. 186 187 187 187 187 188 189 189 189 189 190 TESTS 6360 6361 6362 BITUMEN MACADAM TESTS………………………………………………………. PREQUENCY OF TESTS: BITUMEN MACADAM………………………………… INDEPENDENT TESTS: BITUMEN MACADAM…………………………………… xiii 190 190 190 6363 6364 6365 6366 6367 MANUFACTURER'S CERTIFICATE FOR BITUMEN …………………………….. CONTRACTOR TO TEST MATERIALS:BITUMEN MACADAM…………………. NOTICE OF TEST:BITUMEN MACADAM………………………………………….. SAMPLES TO BE IN DUPLICATE………………………………………………….. COST OF TESTS BITUMEN MACADAM………………………………………….. (CLAUSES 6368-6369 INCLUSIVE NOT USED)……………………………………. 191 191 191 191 191 191 (III) ASPHALTIC CONCRETE 6370 6371 6372 6373 6374 6375 6376 6377 6378 6379 6380 6381 6382 6383 6384 6385 GENERAL……………………………………………………………………………… MATERIAL……………………………………………………………………………… APPROVAL OF MATERIAL…………………………………………………………. SAMPLES ………………………...………………………………………………….. COMPOSITION OF MIXES…………………………………………………………… PREPARATION …………………..………………………………………………….. TRANSPORTING MIXED MATERIALS……………………………………………. PREPARATION OF AREA TO BE PAVED……………………………………….. TRIAL AREAS…………………………………………………………………………. COMPACTION………………………………………………………………………… JOINTS…………………………………………………………………………………. FIELD DENSITY OF ROLLED ASPHALT………………………………………….. FINISHED LEVELS…………………………………………………………………… ASPHALTIC CONCRETE MIXING PLANT…………………………………………. ASPHALTIC CONCRETE PAVERS………………………………………………… INSPECTION AND CONTROL OF ASPHALT MIXING PLANT…………………… (CLAUSES 6386-6399 INCLUSIVE NOT USED)……………………………………. 191 192 193 194 195 197 198 199 199 201 202 202 203 203 210 211 213 PART E MISCELLANEOUS 6400 6401 6402 6403 6404 6405 6406 6407 6408 6409 6410 6411 6412 6413 6414 6415 6416 6417 MILE POSTS………………………………………………………………………….. CULVERT BEACONS………………………………………………………………… ROAD WARNING SIGNS…………………………………………………………….. ADVANCE DIRECTION SIGNS……………………………………………………… CARRIAGEWAY MARKINGS……………………………………………………….. PRECAST CONCRETE KERBS…………………………………………………….. PRECAST CONCRETE EDGING BLOCKS……………………………………….. PRECAST CONCRETE PAVING SLABS………………………………………….. GULLEY KERBS…………………………………………………………………….. GULLEY PIPES…………………………………………………………………….. PRECAST CONCRETE CHANNELS…...………………………………………….. CAT'S EYES…………………………………………………………………………… STREET LIGHTING……………………………………………………………………. TRAFFIC LIGHTS……………………………………………………………………… ILLUMINATED GUARD POSTS……………………………………………………… GUARDS RAILS………………………………………………………………………. DELINEATORS………………………………………………………………………… TELEPHONE POLES………………………………………………………………… (CLAUSES 6418-6499 INCLUSIVE NOT USED)……………………………………. ANNEXURE TO THE GENERAL SPECIFICATION xiv 214 214 215 215 215 216 216 216 217 217 217 218 218 218 218 219 220 222 223 (ROAD AND BRIDGES) PENETRATION (GROUTED) MACADAM 6500 6501 6502 6503 6504 GENERAL……………………………………………………………………………… MATERIALS…………………………………………………………………………… WORKMANSHIP……………………………………………………………………… TRIAL SECTIONS ……………………………………………………………………. TESTS………………………………………………………………………………….. xv 223 223 224 225 225 SPECIFICATION SECTION 1 - GENERAL SECTION I - GENERAL PART (A): ADMINISTRATION ETC. PRELIMINARY 1001. The conditions of contract and the drawings shall be read in conjunction with this specification and matters referred to, shown or described in any one of them are not necessarily repeated in the other two. The drawings and specifications are intended to complement and supplement each other. Any work required by either of them and not by the other shall be performed as if denoted by each. Should any work be required which is not denoted in the specifications or on the drawings because of an inadvertent obvious omission, but which is nevertheless necessary for the proper performance of the Project, such work shall be performed as if it were described and delineated subject to the approval of the Engineer. The Contractor shall call to the attention of the Engineer's Representative, any perceived errors or omissions that occur on the drawings and/or specifications. On the drawings, figured dimensions shall govern in case of discrepancy between scaled and figured dimensions. If any discrepancy be found between the drawings and specifications, in so far as dimensions are concerned, the requirements of the drawings shall govern. If there be a discrepancy between the General Specifications and the Supplementary Specifications, the requirements of the latter shall govern. The Engineer shall have the right to correct apparent errors and omissions in the drawings and specifications and to make such interpretation as he deem necessary for the proper implementation of the intent and purpose of the drawings and specifications. DEFINITIONS 1002. The terms "Approved", "Directed" and "Required" shall mean to the approval, direction or requirement of the Engineer or, his duly authorized representative. The letters B.S. refer to the latest British Standards published by the British Standards Institution. The British Standards mentioned in the specification are particularly described in Schedule VII of Volume III of these Specifications bound together with the Bill of Quantities. Where no particular direction is given, the letters B.S. refer to the latest British Standards including any amendments in force at the time of the tendering. Materials specified to be in accordance with the British Standards are to be branded or a certificate provided where and as described in the particular Standard. Where applicable the abbreviations used in the Specification and Bill of Quantities are in accordance with the recommendations contained in B.S. l991, Parts 1 and 4, are as follows: "A.A.S.H.T.O." or "A.A.S.H.O." refer to the Specifications used by the American Association of State Highway & Transportation Officials, current edition. "A.S.T.M." refer to the American Society of Testing Materials. "C.P." or "B.S.C.P." refer to the latest (unless otherwise stated) British Standard Code of Practice, including any amendments. "DOE" refer to Department of Environment, United Kingdom "F.M.W." refer to "The Federal Ministry of Works of the Government of the Federal Republic of Nigeria. "NIS" refer to the Nigerian Industrial Standards "SON" refer to the Standard Organization of Nigeria "W.A.S.C." refer to the West African Standard Compaction. DESCRIPTION OF WORKS 1003. The works comprised in this Contract are described in Schedule V of Volume III of these specifications bound together with the Bills of Quantities. 1 The drawings showing the dimensions and layouts of the works are listed in Schedule IV appended to Volume III of these specifications bound together with the Bills of Quantities. The scope of the contract covers the supply of materials, plant, equipment, labour and supervision necessary for the complete works all as specified together with all temporary works and traffic diversions required during the construction of the works. Where called for, the contract also includes the maintenance of a diversion for traffic during construction, and the maintenance of the works in terms of Clause 49 of the conditions of contract for a period after completion as stated in the appendix to Tender. LIAISON WITH ADJACENT WORKS 1004. In the event of other works being in progress concurrently with and adjacent to the works specified in this contract, liaison shall be maintained with such other works to ensure that the several works being undertaken shall not cause any mutual interference with progress and shall culminate in the integrated improvement as a whole. If so required by the Engineer, the Contractor shall vary his programme of work in accordance with Clauses 14 and 90 of the Conditions of Contract, to coordinate the works with any other works on or adjacent to the site of the works, whether being carried out by contract or by direct labour of the Ministry. 1005. The Contractor shall arrange his programme of works and control of traffic in AVOIDANCE OF DAMAGE TO WORKS such a way as to avoid damage to the works at any stage of their construction. DATUM 1006. The datum to which the various levels have been reduced for the purposes of the contract are as stated on the respective drawings. Where these datums are likely to be covered by the new works, the Contractor shall transfer the levels to such fixed points or beacons, to be provided by the Contractor at his own cost, as shall be required and specified by the Engineer's Representative. The positions of such transferred datums shall be accurately surveyed and shown on the working and as-made drawings. SURVEYS AND LEVELS TO BE AGREED AS BASIS FOR MEASUREMENT 1007. Before the works or any part thereof are begun the Contractor and the Engineer's Representative shall together survey and take levels of the site of the works and agree all particulars on which measurements of works are to be based. Such surveys shall be recorded and signed as agreed by the Engineer's Representative and the Contractor and shall form basis of the measurements for the Engineer's Certificates. Failing such surveys and agreements being signed by the Contractor the surveys of the Engineer's Representative shall be final and binding on the Contractor. DIMENSIONS AND LEVELS 1008. The dimensions and levels shown on the drawings are believed to be correct but the Contractor must verify the same on the ground, as well as all other particular of the contract and he will be held responsible for the consequences of any error contained therein or omission therefrom. Levels on existing roads will depend upon the amount of wear and maintenance which has taken place between the time of survey and the time of construction and similarly the levels of river beds and banks will be affected by the amount of erosion and repair which has taken place in the same interval. Should any discrepancy be discovered between the levels shown on the drawings and those found on the site, which may affect the levels and dimensions of any part of the works, the Contractor shall notify the Engineer's Representative in sufficient time to enable the Engineer to prepare drawings showing the amended levels and dimensions. The attention of the Contractor in this respect is particularly directed to the extent of wing walls (also see Clause 1010). PARTICULARS OF EXISTING WORK 1009. Such information as may be given on the drawings or in the specification or in the Bill of Quantities as to the present condition, character, position and size of existing structures, roadways, rivers, pipes, cables and other services are given without guarantee of accuracy or completeness, and neither the employer nor the Engineer will be liable for the consequences of any discrepancy therein or omission therefrom. Where existing works are required to be removed completely or in part or otherwise modified, it will be the responsibility of the Contractor to satisfy himself absolutely in all respects in all matters pertaining to the carrying out and completion of the works and the rates given in the priced 2 Bill of Quantities for the carrying out and completion of the work shall be deemed to be fully inclusive and no extras will be allowed to the Contractor on the said rates. WORKING DRAWINGS 1010. Before any part of the works is put in hand the Contractor must prepare and submit for the approval of the Engineer's Representative copies in duplicate (in the first instance) of any further detailed working drawings which may be required for that part of the work and at the same time call the attention of the Engineer's Representative to any differences between these and the contract drawings. The Engineer's Representative will, after the Contractor has made any alterations which he may require, record on the copies, as amended, his approval and will return one copy to the Contractor who shall carry out the work in accordance there-with. The Contractor shall forward to the Engineer's Representative four additional copies of the working drawings as approved. In addition, working drawings are also to be submitted (the same procedure being followed as above described) in respect of any work proposed to be executed by Sub-Contractors, the distribution of drawings being as directed by the Engineer's Representative. The approval by the Engineer's Representative of all or any of the drawings shall not relieve the Contractor of his responsibility. ALTERATIONS OF DRAWINGS 1011. In any cases where drawings are specified or required to be supplied by the Contractor for the approval of the Engineer any alteration to such drawings which the Engineer may require shall be made by the Contractor without extra charge. DRAWINGS OF TEMPORARY WORKS TO BE SUBMITTED 1012. The Contractor shall submit to the Engineers Representative for his approval, complete drawings of all temporary works, stagings, required for carrying out the work, together with the calculations relating to their strength and anticipated deflections. The drawings shall show the method proposed for the erection of the various parts of the temporary works and their application to the carrying out of the permanent works. All temporary works shall be properly designed and substantially constructed to carry the loads to which they will be subjected and all drawings and calculations pertaining thereto shall be forwarded to the Engineer's Representative sufficiently in advance of the intention to proceed as will allow for their proper study and the incorporation of any modification which the Engineer's Representative may require notwithstanding the approval or modification by the Engineer's Representative of any submitted design for any of the temporary works, stagings, etc., the Contractor shall remain wholly and entirely responsible until the removal of such works for their efficiency security and maintenance and for all obligations and risks in regard to such works specified or implied in the contract and he shall reinstate the same at his own entire cost should any mishap or accident occur causing damage or injury thereto subject however to such provisions of the conditions of contract as may be applicable in the case of such damage or injury. Two copies of each drawing shall be submitted to the Engineer's Representative in the first instance and he will record on these copies, amended and modified as required, his approval and will return one copy to the Contractor who may then proceed in accordance therewith. The Contractor shall forward to the Engineer's Representative four additional copies of the drawings as approved. The cost of complying with all the requirements of this clause shall be borne by the Contractor. SETTING-OUT 1013. The attention of the Contractor is directed to Clause 17 of the Conditions of Contract. The Contractor shall give the Engineer's Representative not less than 24 hours notice of his intention to set out or give levels for any part of the work in order that arrangements may be made for checking. To enable the Engineer's Representative to check the accuracy of the Contractor's setting-out, the Contractor shall provide for the use of the Engineer's Representative approved theodolites, levels, staves, bands, pegs, labour and all things necessary as may be particularly specified in the respective clause. Any approval or collaboration in respect of setting-out by the Engineer's Representative shall not in any way affect the Contractor's sole responsibility for the accuracy of the setting-out and the consequent construction. 3 NOTICE OF OPERATION 1014. No important operation and in particular no blocking or cutting of any road, water pipe or other service shall be carried out without the consent in writing of the Engineer's Representative nor without full and complete notice being given to him also in writing sufficiently in advance of the time of the operation and will enable him to make such arrangements as may be deemed necessary for its inspection and the provision of all relevant safety precautions. EXISTING SERVICES 1015. The Contractor shall satisfy himself entirely as to the location of all existing drains, pipes, cables and similar services whether above or below ground level. Drains, pipes, cables and similar services encountered in the course of the works shall be guarded from injury by the Contractor at his own cost so that they may continue in full and uninterrupted use to the satisfaction of the owners thereof and the Contractor shall not store materials or otherwise occupy any part of the site in a manner likely to hinder the operations of such owners. If the interests of the work shall in the opinion of the Engineer so require, the Contractor shall on his direction arrange for the construction by the respective departments, bodies, corporations or authorities of permanent protective works or permanent or temporary diversions of the said drains etc., (afterwards reinstating if temporary) and the cost of such works or diversions including reinstatement shall be charged against the appropriate provisional sum provided in the Bill of Quantities. The Contractor shall be at liberty subject to the approval of the owners and the requirements of Clause 90 of the Conditions of Contract to make any further diversions he may consider necessary. The cost of these additional diversions including the cost of reinstatement shall be borne by the Contractor. No services may be tampered with by the Contractor and all works in connection with any services shall be carried out by their respective owners. DAMAGE TO SERVICES 1016. The Contractor shall be held liable for damage and interference to mains and pipes, to electric cables or services of any kind either above or below ground caused by him or his Sub-Contractors in the execution of the works. Should any damage be done to mains, pipes, wires, telecommunications or electrical apparatus or any other service, whether shown on the drawings or not, the Contractor must make good the same without delay and do any further work considered necessary by the Engineer or the owners all at his own cost or pay the costs to the owner in so doing. The Contractor will be deemed to have provided for these contingencies in fixing the rates, etc., inserted in the Bill of Quantities. FILLING IN HOLES AND TRENCHES 1017. The Contractor shall take all precautions and provide any temporary fences necessary to protect the public from accidents which may be caused by the presence of any excavations, mounds, heaps or earth or any other materials or stores connected with the works. The Contractor shall, at his own expense, and immediately upon completion of any part of the work, fill up all holes and trenches and level all mounds and heaps of earth which have been excavated or made in connection with the works. The Contractor shall bear and pay all costs, charges, damages and expenses incurred or sustained on account of or in consequence of any accident which may happen by reason of holes and trenches being dug and left unprotected, or materials being left or placed in unprotected or improper situations. JOINT MEASUREMENT OF EXTRAS 1018. In the event of the Contractor having to execute any work or provide any material in regard to which he may propose to claim extras, he shall first obtain a written order from the Engineer's Representative and shall at once make arrangements to take the measurements of the said work or materials with the Engineer's Representative. If these measurements are not taken jointly and booked and agreed at the time the work is being executed the Contractor's measurements will not afterwards be recognized by the Engineer. The fact of such joint measurements having being made will in no way commit the Engineer to a recognition of the claim if he considers such a claim without foundation. The Engineer's Representative shall at all times have full access to the Contractor's time book and may daily check the time of any extra works with the Contractor's time-keeper or otherwise, but the fact of his agreeing upon any time shall in no way bind the Engineer to value the work other than by measurement if he thinks fit so to do. 4 PROTECTION FROM WEATHER 1019. All materials shall be stored on the site in a manner approved by the Engineer and the Contractor shall carefully protect from weather all work and materials which may be affected thereby. WORKS TO BE KEPT FREE FROM WATER 1020. All those parts of the works required to be carried out in the dry, whether within any part specified to be enclosed or not, shall be kept free at all times from water from whatever source it may come to the satisfaction of the Engineer's Representative. The costs of complying with the provisions of this clause shall be borne by the Contractor. STAFF ACCOMMODATION ETC. 1021. The Contractor shall at his own expense provide for himself suitable offices and housing for his staff and labour. If required by the Engineer, the Contractor shall supply, erect and maintain suitable furnished offices and Residential quarters for the Engineer's Representative and his assistants, inspectors and staff on a site or sites to be selected, together with all proper lighting, heating, water, sanitary arrangements and attendance. SUPPLY OF WATER AND ELECTRICITY 1022. The Contractor shall make his own arrangements for the provision of water and electricity, whether for use in the execution and construction of permanent works or otherwise. In the event of the source of water being from any existing piped supply, the Contractor shall comply with any regulation laid down by the water authority and shall pay for such supply, standpipes, connections, meter rent and all other charges as required all at his own expense. The same conditions apply for the temporary supply of electrical power. RETURNS OF LABOUR 1023. Every working day, the Contractor shall supply the Engineers Representative with a return of the men employed the previous day and of the work on which they were engaged, specifying also the number employed in each trade. He shall also supply any other returns, which may be required from time to time, as to the number of men and plant employed and the nature, quality and quantity of the work done. PHOTOGRAPHS 1024. The Contractor, shall, if required, supply to the Engineer monthly, or at such other periods as he may direct, well executed and mounted photographs showing the progress of the works and also such particular sections of the works, site, plant, machinery or materials as the Engineer may direct. The cost of such photographs will be charged against the appropriate provisional sum. The copyright of the photographs shall be held by the Employers. The Contractor shall provide the Engineer's Representative (within 5 days of the photographs having been taken) with the negative and three prints of each photograph which shall be I.O. , standard size A4 or a minimum of 200mm x 300mm. On the reverse side of each print the following information shall be shown: (1) Date photograph was taken. (2) A brief description of the location illustrated or the name of the structure. (3) The negative number of the photograph. (4) The name and address of the photographer. The prints of each approved photograph shall be signed and dated by the Contractor and the Engineer's Representative. REPORTS OF ACCIDENTS OR UNUSUAL OCCURRENCE 5 1025. Notwithstanding the submission of the normal and regular monthly progress reports the Contractor shall report to the Engineer's Representative promptly and in writing the particulars of any accident or unusual or unforeseen occurrence on the site whether likely to affect the progress of the work or not - stating also the steps he has taken or is arranging to take in the matter. MAINTENANCE OF WORKS 1026. (A) During the period of maintenance as defined in Clause 48 and 49 of the Conditions of Contract, the Contractor shall maintain the works, or such part of the works as are involved, for the period named in the tender to the entire satisfaction of the Engineer. Such maintenance shall include repairs to the superstructures and sub-structures of the bridges; defects in the subgrade, base-course and bituminous surfacing of the roadways; landslips and failures of culverts, but shall not include grass cutting brushing or the cleaning of drains. (B) The Contractor will be responsible for the maintenance other than grass cutting, of all verges, margins and side-slopes, including stone pitching, for the period of maintenance and shall make good all erosions during such period whether attributable to defects in workmanship or not. (C) Before the commencement of the period of maintenance the Contractor shall remove all his buildings and plant from the whole of the site and shall clear and regrade the areas to the satisfaction of the Engineer. AS-MADE DRAWINGS 1027. On completion of the works, the Contractor shall prepare as-made drawings giving complete details of the entire works as constructed, including all work carried out by Sub-Contractors. The as-made drawings shall be prepared in accordance with the requirements of the respective clauses in the specifications and all costs arising out of their preparation, supply and distribution etc., shall be deemed to be included in the tendered rates for the work to which they refer. TRAFFIC ROUTES TO BE MAINTAINED AND WORKS TRAFFIC CONTROLLED 1028. There shall be no unnecessary obstruction of roads, railways, footpaths, waterways, electrical installations etc., during the course of the work and in no circumstances shall closure, in whole or in part, of these or any other "Right of Way be permitted except with the prior permission of the Engineer in writing. Before granting such permission the Engineer shall consult with the authorities, government departments and/or persons concerned and when desirable shall publish due notice of the proposed action in the government gazette. The Contractor shall maintain adequate through safe traffic routes for vehicles and pedestrians throughout the whole length of the public highways within and adjacent to the site of the works, including such diversion of highways as may be required, and make arrangements for watching, signalling and control of traffic by day and by night and for adequate lighting all to the satisfaction of the Engineer. The Contractor shall without extra charge if instructed to do so by the Engineer install, make use of, adequately maintain automatic "Stop and Go" signals, traffic lights or other special method or methods of traffic control and direction as the Engineer may consider necessary, and the Contractor shall carry out all such instructions to the satisfaction of the Engineer. Where directed by the Engineer, temporary single or double tracks shall be constructed and maintained in a safe and satisfactory condition for the use of all traffic during the construction of the works. The temporary tracks shall be removed and all reinstatement made to the satisfaction of the Engineer when no longer required. 6 The Contractor shall, at his own expense, and during the period of this Contract, maintain in a safe condition and adequately protect any work executed by him which is exposed to traffic. The Contractor shall supply adequate advance warning signs of reflecting type with letters not less than 150mm high and such warning signs shall be placed in positions approved by the Engineer and shall be left in such positions as long as traffic is still utilizing any such temporary running surface. The Contractor shall make arrangements and cooperate with all other contractors working in the area for directing, routing, marshalling, controlling and circulating the traffic connected with the works under this contract in accordance with the Engineer's Requirements, in order that the flow of all traffic may be facilitated, that all obstruction, inconvenience and delay may be minimized, and that the interests of all concerned, including the general public, may be protected. The Contractor shall allow in his tender for complying with the requirements of this clause and for any directions in connection therewith which the Engineer may issue from time to time. The Contractor will be deemed to have allowed for additional expense he may incur on account of extra running or kilometre covered by his vehicle or labour or material involved in compliance with these requirements. The Contractor shall be responsible for ensuring that the highways in the vicinity of the works are kept clean of mud and other debris falling from vehicles connected with the works or spreading on to the highways as a result of the works in any way. BARRICADES, WARNING AND DEVIATION SIGNS 1029. The Contractor will at all times during the contract, provide, erect and maintain such barricades, warning lights, dangers signals, reflectors, signs and watchmen as may be necessary to the satisfaction of the Engineer's Representative. Any such warning signs etc., shall be left in position as long as traffic is utilizing any temporary running surface and/or until such time as their removal is sanctioned by the Engineer's Representative. Barricades and signs shall be constructed and used in accordance with the requirements of the Engineer's Representative. All barricades, obstructions and such other conveniences as are necessary to protect the travelling public, or as required by the Engineer's Representative shall be illuminated at night by reflectors or red lanterns. The cost of barricades, danger, warning and deviation signs and providing watchmen, shall be deemed to be included in the tendered rates and prices. WEATHER CONDITIONS 1030. The Contractors shall be deemed to have taken all possible weather conditions into account when preparing their tender and they shall not be entitled to extra payment by reason of the occurrence or effect of high winds, tornadoes, excessive rainfall, temperature or humidity or any other meteorological phenomena. OTHER WORKS AND SERVICES 1031. During the continuance of the contract the employer may cause other works such as the installation of services to be carried out on, through or adjacent to the site. The Contractor shall at all times comply with the requirements of the general conditions of contract in respect of these and any other works not included in the Contract and shall allow reasonable access as approved by the Engineer on and through the site of the works to any other Contractors or workmen who may be working on or near the site. 7 The Contractor shall make adequate arrangements to the satisfaction of the Engineer's Representative for the disposal of all sewage, rubbish and all other waste materials arising from or connected with the execution of the works. The Contractor shall make his own arrangements for and shall provide any service (including telephone and radio communications) which he may require in addition to the foregoing. In the programme and particulars required under Clause 14 of the Conditions of Contract the Contractor shall: (i) provide details of the sequence he proposes for carrying out the works, (ii) state and allow a reasonable margin of time for contingencies and (iii) state his intentions regarding shift work. The Contractor's programme shall make due allowance for requirements specified in all clauses of the Specification. The Contractor shall report monthly progress to the Engineer on charts submitted in triplicate and showing actual work done superimposed upon copies of the programme. He shall furnish an explanation of any deviation from the programme and shall state proposals for improving progress should this be lacking in any respect. (CLAUSES 1032 - 1039 INCLUSIVE NOT USED) PART (B): MATERIALS AND TESTING MATERIALS TESTING LABORATORIES AND STAFF 1040. The Contractor shall provide and maintain materials laboratories, equipment and staff as directed by the Engineer and more particularly described in Schedule No. VI of the Bills of Quantities. The Contractor shall provide, maintain and staff laboratories at his own expense throughout the Contract. The said laboratories shall be in a waterproof building or rooms designated and used exclusively for the purpose and shall be maintained in a clean and tidy fashion to the satisfaction of the Engineer's Representative. The laboratories shall have an adequate water and electricity supply. The laboratories shall be staffed with Engineers well experienced in materials testing and approved by the Engineer. The laboratories shall be located within 50 Km. of all works in the field requiring sampling and testing. Work will not be permitted to begin until laboratories and staff have been provided within this distance. The Contractor shall provide all the testing equipment, tools, etc., and shall carry out tests on materials as directed and shall supply the Engineer's Representative with two copies of the results of each test on approved printed forms. A third copy of the results shall be retained in the laboratories. Without limiting the Contractor's responsibility as stipulated above, the facilities of the laboratories shall be available for the use of the Engineer's Representative and his assistants to perform control tests on workmanship and materials as provided for in the Specification. 8 Notwithstanding the results of tests carried out by the Contractor, approval of workmanship and materials shall be based on the results of these control tests. It is the responsibility of the Contractor to notify the Engineer's Representative when any items of the works scheduled below are completed and ready for approval and the Contractor shall give sufficient notice to allow control tests to be performed. Generally the time required to perform control tests by the Engineer's Representative after the receipt of the Contractor's notification shall be as follows: All filling and subgrade Unstabilized sub-base and 3 days base course 3 days Crushed stone base 3 days Surfacing materials 7 days Structural concrete 30 days Asphalt concrete 10 days Note: Where construction is carried out in arid region where moisture of finished fill, subbase base or stone base can dry out from the surface rapidly, the time of notification may be reduced at the request of the Contractor making representation to the Engineer's Representative on same. Unless otherwise specified, the cost of carrying out all tests shall be deemed to be included in the tendered rates and prices and the Contractor shall be deemed to have allowed for the costs of providing all facilities necessary. No claim for delay of any kind shall be entertained by the Engineer in this respect if the stipulations of the foregoing have not been observed. All samples and records shall be preserved as long as the Engineer's Representative may direct and they shall be kept and labelled in an orderly fashion. The laboratories, equipment, all records and samples shall be open to inspection and use by the Engineer or his Representative during all normal work hours. The laboratory building shall be in accordance with the standards specified for the office of the Engineer's Representative. Concrete floors shall be provided throughout. The Contractor also shall provide air conditioning throughout the laboratory and shall service, clean and light the building to the standards specified for the Office of the Engineer's Representative. As specified elsewhere in the Contract documents, the Contractor shall supply suitable vehicles equipped and reserved exclusively for the use at all times of the laboratory staff to permit the carrying out of control tests in the field. Where directed by the Engineer the Contractor shall remove and dispose of the building and unserviceable vehicles make good any damage to the site and leave it clean and neat. 9 The facilities of the testing laboratory shall be made available for use by the Engineer's Representative at all times for the purpose of the works. TESTING OF MATERIALS 1041. The Contractor shall arrange for the testing of all materials used throughout the contract, to ensure that they are up to the standards specified. The Contractor shall carry out such laboratory and field tests (including tests to check the accuracy of testing equipment and methods but excluding tests specified to be carried out in an independent testing laboratory) as specified and as may be necessary to ensure and satisfy the Engineer that the requirements of the Specifications are met. The type and frequency of testing shall be in accordance with the relevant Nigerian Industrial Standards or British Standards except as otherwise specified herein or directed by the Engineer. The frequencies of testing specified in the relevant clauses are intended to represent only a general guide. The Engineer's Representative shall be empowered to vary the frequencies at which tests are conducted should he deem this necessary for the proper control of the quality of the Works. Should the Engineer's Representative vary the frequencies stated in the relevant clauses of the Specification, the Contractor will not be entitled to extra payment. Unless otherwise agreed or directed by the Engineer, methods of sampling and test procedures shall be in accordance with the relevant Nigerian Industrial Standards/ British Standards, British Standard Codes of Practice, Standard Methods of the Institute of Petroleum and the American Society for Testing Materials, the Asphalt Institute, Building Research Station Digests and published recommendations of the Transport and Road Research Laboratory. Samples will be selected by the Engineer's Representative. Where tests are specified or directed by the Engineer's Representative to be carried out in an independent testing laboratory, the Contractor shall supply and deliver the samples and shall arrange for the relevant tests to be carried out. The independent testing laboratory shall be nominated by the Contractor and shall be acceptable to the Engineer's Representative. Unless otherwise specified the Contractor shall arrange for one copy of the independent testing laboratory's test certificates to be delivered to the Engineer's Representative not less than 7 working days before the materials covered by the relevant test certificate are incorporated in the Works. Each test certificate shall be relatable to the materials from which the sample was taken. When any material or article is required to comply with a British Standard or any other Standard specified herein such material or article or its container shall bear the stamp of the registered certificate trade mark of the British Standards Institution or the certification of the applicable standard. Alternatively, the Contractor shall submit to the Engineer certified test certificates furnished by the supplier or manufacturer of the material or article indicating compliance with the relevant British Standards or a copy of the manufacturer's or supplier's test certificate showing that the material has been tested and found to comply in all respects with the relevant standard. Notwithstanding the above, the Engineer's Representative may require additional tests to be carried out by an approved local testing establishment and the material shall be supplied by the Contractor. In such cases a copy of the test result shall be submitted to the Engineer's Representative in lieu of the Manufacturer's/Supplier's certificate. All testing carried out by the Contractor shall be undertaken by approved qualified staff who shall be nominated by the Contractor and sufficient notice of the 10 intention to carry out such tests shall be given to the Engineer's Representative to enable him to be present during the tests should he so desire. The Contractor shall arrange and the Engineer shall have power to send inspectors to the premises of the manufacturers and suppliers to inspect the manufacture and testing of the materials intended for use in the works. Materials tested before leaving the manufacturer's or supplier's premises may be tested again after delivery at the site, at the discretion of the Engineer's Representative. Notwithstanding the results of the tests at the supplier's or manufacturer's premises, the production of a test certificate or the results of any tests carried out by an approved testing establishment or by the Contractor, the Engineer's Representative shall have power to reject after delivery at the site any materials found to be not in accordance with the requirements of this specification. The Contractor shall be deemed to have included in his tendered rates and prices all costs arising out of compliance with the requirements of this clause. INDEPENDENT TESTS 1042. Notwithstanding successful t test results being submitted for any material, and in addition to the tests required under other clauses of this specification, the Engineer may order further tests of any material to be carried out by his own central laboratory or by an independent tester at such places as he may determine. The Contractor shall provide the samples for such tests free of charge, but payment for the tests shall be the employer's responsibility and charged against the appropriate provisional sum except as detailed in Clause 36 (4) of the Conditions of Contract. INSPECTION ENGINEER 1043. For the purposes of this contract and in accordance with Clause 36 of the Conditions of Contract, the Engineer may appoint one or more Inspection Engineers for all imported materials to be used in connection with the contract. If any Inspection Engineer is to be appointed for the inspection of imported materials the Engineer shall select the Inspection Engineer and inform the Contractor accordingly. For all materials of Nigerian origin the Inspection Engineer shall be the Engineer's duly Authorized Representative in Nigeria. Where an Inspection Engineer has been appointed for imported materials the Contractor shall before he enters into any arrangement for the supply or manufacture of materials, submit for the approval of the Inspection Engineer, the names of the manufacturers or merchants he proposes to employ. Should the Inspection Engineer at any time be dissatisfied with any of the methods or operations carried out at the manufacturer's works or place of business, he shall be empowered to cancel his previous consent for materials to be obtained from such manufacturer or merchant. Should the Contractor fail to submit for the approval of the Inspection Engineer samples of material of satisfactory quality or workmanship, the Inspection Engineer shall have the power to specify any particular manufacturer or merchant for the supply of the materials and the Contractor shall obtain such materials from the said manufacturers or merchants without additional charge. The Inspection Engineer shall examine and test and if necessary analyze all materials and test the fabrication of any structures or structural components to be used in the 11 permanent works. The Inspection Engineer and his Representatives shall have free access at all reasonable times to the manufacturer's or merchant's premises and shall be afforded every facility for making inspections and for taking of samples for testing and analyses. The manufacturers or merchants shall provide free of charge and to the satisfaction of the Inspection Engineer all appliances required for the testing of the materials at the manufacturer's or merchant's premises and they shall supply samples and meet the costs of transport thereof to enable tests and analyses to be made at a laboratory if and when directed by the Inspection Engineer. All materials to be provided by the Contractor shall be submitted for the approval of the Inspection Engineer before removal from the place of manufacture and under no circumstances shall materials be shipped without the approval certificate issued by the Inspection Engineer. The Contractor shall give twenty-one days' notice in writing to the Inspection Engineer of his intention to remove materials from the place of manufacture or fabrication. If in the opinion of the Inspection Engineer the despatch of any materials or things have been unduly delayed after they have been inspected and approval certificates issued, the Inspection Engineer may issue an order in writing that the materials or things shall be reinspected. Invoices or shipping lists in triplicate showing in detail the net weights and quantities of all materials for the permanent work despatched to the site shall be forwarded to the Inspection Engineer directly when the materials are despatched. In the case of steel and iron work such invoices or shipping lists shall show separately the net weight of articles under each item in the schedule of prices included in the invoice or shipping lists. All materials and any iron or steel articles supplied by the Contractor for use in the permanent works or any materials for fabricating permanent steel or iron structures and other articles shall be subjected from time to time before the issue of the approval certificate to such tests and inspections as may be required or directed by the Inspection Engineer. All the tests shall be carried out in the presence of the Inspection Engineer or his Representative and shall be performed in such a manner and by such processes at such premises and at such times as he may consider desirable. Notwithstanding any examination or tests that the Inspection Engineer may wish to be carried out on any perishable materials prior to their despatch to the site, the Engineer shall be at liberty to carry out any further tests that he may consider desirable after delivery of such perishable materials at the site and to reject such materials which fail to comply with the required quality or conditions, notwithstanding any provisional approval before despatch to the site. The Engineer shall arrange for the inspection on site of all materials and fabricated components to ascertain whether these materials and fabricated components have in any way become damaged in transit to site. The Engineer and the Inspection Engineer shall be kept properly informed as to the progress of any work in hand or materials being prepared and supplied by the Contractor in order that they shall be able to make such arrangements for examination, testing and analysis as they may desire. 12 The Contractor shall weigh without any extra charge any materials, articles or things supplied for the execution of the permanent work that the Engineer or the Inspection Engineer may require and such weighing shall be carried out in their presence or in the presence of their representatives. When the Inspection Engineer is satisfied in all respects with the inspection, regarding samples and test results of materials and fabrication of structures, he shall issue to the Contractor an approval certificate thereof. Where the Contractor/Manufacturer could not agree with the inspection Engineer the Contractor may request with the permission of the Engineer that such materials be tested by an independent testing body as may be agreed by both parties in dispute, and cost of such test shall be borne by the Contractor. MATERIALS SPECIFIED TO B.S. 1044. As provided in Clause 36 of the General Condition of Contract and in accordance with the Standard Organization of Nigeria or British Standard Specifications quoted for any materials used on the works of this Contract, tests may be called for by the Engineer to be carried out at the place of manufacture, fabrication, on the site, or at any of such places. The Contractor shall arrange for the testing of all materials used throughout the contract to ensure that they are up to the standard specified, i.e., aggregates, sand, cement, water, reinforcement, concrete, blinding materials as specified or decided by the Engineer. The tests to be carried out on any material except as detailed hereafter, shall be those specified, implied or intended in the appropriate N.I.S or B.S. APPARATUS REQUIRED FOR TESTING 1045. Notwithstanding that any test, piece of equipment or apparatus is not specifically mentioned or described in the various pages hereof, nevertheless if directed by the Engineer the Contractor is to supply at his own expense all apparatus and equipment of whatever kind necessary to carry out any test mentioned in or required by the provisions of the various clauses in this specification and the British Standard Specifications incorporated in this Specification. The Engineer shall be the final arbitrator on which tests are necessary for the proper execution of the works. NOTICE OF TESTS 1046. Where the Contractor is responsible for the carrying out of any control test, he shall first give notice of his intention to carry out such a test to the Engineer's Representative to enable him to be present during the test. Where the Engineer or his Representative conducts any control test, he shall give the Contractor sufficient notice to enable him, should he so wish, to be present during the test. Should the Contractor not wish to witness any control tests conducted by the Engineer or his Representative, the Contractor shall be deemed to accept the validity of the results of such tests. SAMPLING 1047. All samples of materials to be tested shall be selected according to the method laid down in the appropriate Nigerian Industrial Standards or British Standard Specification or where there is no such standard it shall be by the method to be mutually agreed between the Engineer's Representative and the Contractor in so far as the selection has not been prescribed below. 13 SAMPLING OF MATERIALS FROM BORROW PIT 1048. Trial pits in proposed borrow pit areas shall be dug from original ground level. Trial pits shall be at least one metre by one metre in size, dug to such a depth that the full extent of the material intended for incorporation in the works is exposed. Materials for testing shall not be taken from the spoil of the trial pit but shall be made up of increments taken from each face of the pit, each increment to be a representative sample of the entire depth of a horizon. The four increments shall be mixed three times and quartered or riffled down to the size required for testing. Visual examination will be made to ensure that sampling more than one horizon in any sample is avoided. SAMPLING OF MATERIALS FROM STOCK PILES 1049. The surface material of a stock pile shall be removed before sampling. At least twelve samples shall be taken from different parts of the stockpile, avoiding segregated material, and thoroughly mixed by hand before quartering down to required size. TEST TO BE CARRIED OUT 1050. In addition to the specific requirement of the various clauses of this specification, the Engineer may direct that any or all of the following procedures and tests be carried out. (A) The following tests and procedures as described in B.S.1377 "Methods of Tests for Soils for Civil Engineering Purposes":- (1975) Item 1.5 Preparation of disturbed soil samples for Testing. Test 1 (A) Item 2.1.1 Determination of moisture content (Standard Method). Test 2 (A) Item 2.2.1 Determination of Liquid Limit (CONE Penetrometer method) Test 2 (B) Item 2.2.2 Casagrande apparatus method Item 2.3 Test 3 Determination of Plastic Limit, using the following modifications:- (1) Materials for testing shall be moisturized, mixed for 15 minutes and sealed in an approved air-tight container for a minimum period of 24 hours before testing. (2) After the above period of curing, the material shall be removed from the container and remixed with 10mm spatula for an exact period of fifteen minutes. (3) For the method of determining the liquid limit as laid down in B.S. 1377 at least five points in the range 10-60 blows, evenly distributed when plotted on a logarithm scale, shall be made. Consecutive tests with respect to moisture content shall form a wetting and not a drying curve. (4) Alternatively the one point method of determining the liquid limit may be used. LL = W (N/25) tan 14 LL = W (N/25) 0.10 Where W is the moisture content %, N number of blows and tan  = 0.10 this is the slope of the calculated flow line. The value of N shall lie in range 20-30. The liquid limit shall be taken as the mean of at least two such tests. (5) The plastic limit of material shall be taken as the mean of at least three tests. 2.6.1 Test 6 (A) : Determination of the specific gravity of soil particles suitable or fine, medium and coarse grained soils 2.6.2 Test 6 (B) : Suitable for fine grained soils 2.7.1 Test 7A Determination of particle size distribution in soils, using the wet method with following modifications:- WET SIEVE ANALYSIS All materials passing 5mm sieve shall be sampled for moisture to determine the natural moisture content of the sample for wet sieving. For different sizes of materials the weight of soil sample to be used is as listed in Table I-1:TABLE I-1 WEIGHT OF SAMPLE FOR WET SIEVING Maximum Size of Particle present in substantial proportion (more than 10%) retained on Standard Test Sieves mm Minimum weight of Sample to be taken for Testing kg 63 50 50 35 37.5 15 28 5 20 2 14 1 10 0.5 6.3 0.2 passing 2mm to 63m 0.1 (A) All material passing the 5mm sieve shall be sampled for moisture content, weighed, wet sieved through the No. 75 m sieve oven dried, and sieved through the full nest of sieves. The portion retained on each sieve shall be weighed. The weight of the original sample shall be adjusted for moisture content. (B) Material retained on the 5mm sieve if it is porous or tends to retain fine particles on the surface shall be wet sieved as described in the paragraph above full allowance being made for the air dry moisture content. 15 (C) If the material retained on the 5mm sieve is clean of clay and contains no pores or adhesions, the coarse fraction may be dry sieved. (D) Pre-treatment and the analysis of the fraction passing 75m sieve may be Item 4.1.12: Determination of Density/Moisture Content Relation of Soil (B.S. Compaction Test) Item 4.4.1, 4.4.2, 4.4.3:15 A, B & C Field Density by Sand & Item 15 D Determination of Dry Density by Core-Cutter Method (for fine-grained soils). omitted. (B) Replacement Method. THE WEST AFRICAN COMPACTION TEST:- This test is identical with Test 13 in B.S.1377, (1975) except as follows: (I) The size of the mould shall be, 150mm internal diameter, and 125mm internal effective height and a volume of 2210cm3. (II) The weight of the metal rammer shall be 4.5kg instead of 2.5kg (the diameter of bottom face remaining at 50mm (III) The drop of the rammer shall be 450mm instead of 300mm (IV) The moist soil shall be compacted in the mould in five equal layers each layer being given twenty-five blows. (V) The percentage moisture content corresponding to the maximum density on the moisture content dry soil density curve shall be reported as the optimum moisture content for West African Compaction. (VI) Separate materials shall be used for each compaction point, i.e. materials only air dried previously and not oven dried, mixed with water and allowed to moisturize for 12 hours before compaction. (C) THE MODIFIED A.A.S.H.O. (AMERICAN ASSOCIATION OF STATE HIGHWAY OFFICIALS) COMPACTION TEST:This test is identical with Test 13 in B.S.1377, except as follows: (I) The size of the mould shall be 150mm internal diameter, and 125mm internal effective height and a volume of 2210 cm². (II) The weight of the metal rammer shall be 4.5kg instead of 2.5kg (the diameter of bottom face remaining at 50mm (III) The drop of the rammer shall be 450mm instead of 300mm 16 (IV) The moist soil shall be compacted in the mould in 5 equal layers, each layer being given 61 blows from the rammer dropped from a height of 450mm above the soil. (V) The percentage moisture content corresponding to the maximum density on the moisture content dry soil density curve shall be reported as the "Optimum Moisture Content for Modified A.A.S.H.O. Compaction". (VI) Separate materials shall be used for each compaction point, i.e. materials only air dried previously and not oven dried, mixed with water and allowed to moisturize for 12 hours before compaction. (D) LABORATORY C.B.R. TEST: To be carried out in accordance with the method laid down by "The Materials Testing Conference, February 1961" as follows: (I) Different samples of materials shall be used for each point in the compaction for C.B.R. Test. (II) The materials for testing shall be moisturized and sealed in an airtight container for a minimum period of 12 hours before testing. (III) The Standard Compaction used for C.B.R. Tests shall be as follows: (a) Sub-Grade Materials and all Filings:- The British Standard (b) Sub-Base Compaction. Course Material: The West African Standard Compaction. (c) Base Course Material: The West African Standard or Mod. A.A.S.H.O. Standard as directed by the Engineer may be used for laterite, stone or Mechanically Stabilized Base Course and the B.S. Compaction for Cement Stabilized Base Course. For other type of Base-Course Compaction shall be decided by the Engineer. (E) SAMPLING AND TESTING OF MINERAL AGGREGATES The following procedures and tests shall be as described in B.S. 812 "Sampling and Testing of Mineral Aggregates, Sands and Fillers":Section One: Sampling and Submission of Samples. Section Three: Determination of Particle Size and Shape. Section Four: Determination of Specific Gravity, Density, Voids and Absorption. Section Five: Organic Impurities. (F) METHOD OF TESTING CONCRETE 17 The following procedures and tests as described in B.S. 1881 - "Method of Testing Concrete":- UNSATISFACTORY TEST RESULTS Part 1. Sampling Fresh Concrete in the Field. Part 2. Slump Test. Part 3. Compacting Factor Test Part 6. Making and Curing of Compression Test Cubes in the Laboratory. Part 7. Making and Curing of Compression Test Cubes in the Field. 1051. Should in the opinion of the Engineer's Representative any of the results of the specified tests on materials be unsatisfactory, the Engineer's Representative may order the work to be stopped pending his further instruction. Executed work for which test results are unsatisfactory shall be liable to be rejected, and, if so directed by the Engineer, the work represented by the tests shall be cut out and re-executed at Contractor's Expense. The cost of all such cutting, preparation of specimens, testing, and of making good the portions of the works affected shall be borne by the Contractor. TRIAL SECTIONS OF ROAD 1052. One or more trial stretches as directed by the Engineer's Representative shall be constructed with the proposed materials prior to the start of the main construction to determine the most efficient compaction technique, the suitability of the proposed materials and of the plant. Each of these trial sections shall be at least 30 metres in length, at a site and in the alignment as directed by the Engineer's Representative. The results obtained from these trial rolling stretches shall be used as guide and complement with laboratory test results for subsequent construction and control. It is likely that these stretches will be incorporated in the works. Should one or all of these stretches or a part thereof be rejected the Contractor will be reimbursed for the rejected work in accordance with the rates at which the relevant items have been priced in the Bill of Quantities. ROLLING TEST 1052A. DEFINITION Rolling Test shall be used to establish the optimum moisture and maximum dry density of the proposed plant for a particular type of soil material. In addition it shall be used to determine the economic number of passes of the plant that may be required to achieve the maximum dry density at a known moisture. This test is a corollary to laboratory tests already carried out using CBR mould and specified compactive effort. 1052B. TEST PROCEDURE (a) Prepare a formation of a reasonable length (about 48m) adequately compacted to serve as a good platform for the rolling test. 18 (b) Spread the loose material on the prepared platform to a desired loose depth. (Between 200mm to 300mm for laterite) (c) Divide the test section into at least five bays (each bay not less than 8m) and leaving a gap of two metres between bays to avoid intermixing of materials from adjacent bays. Determine the moisture of the material in each bay. This may be done by using the speedy method and sampling in various points, taking the mean result of four as the moisture content. (d) Adjust the moisture content in each bay with a view to straddling the optimum moisture content. This could be achieved by progressively increasing the passes of the water tank in different bays as shown in the Table 1.2 TABLE I-2 SHOWING THE NUMBER OF PASSES OF WATER TANK Bay 1 Bay 2 Bay 3 Bay 4 Bay 5 4 passes 6 passes 8 passes 10 passes 12 passes (e) Mix the loose soil and water to ensure thorough moisturization using either hand, pulvimixer or rotovator. (To ensure uniform moisturization the watered material could be left over night before mixing). (f) Compact to refusal the loose material whose OMC and MDD is required with the available plant. For practical purposes fifteen to twenty passes of 10 to 15 tonnes of a three wheel roller or ten or fifteen passes of a vibrating roller will be adequate for a lateritic material. For the three wheel roller the rear wheel is the compacting wheel while the front is the compacting wheel for he vibrating roller. (g) Determine the insitu dry density and moisture content of each bay based on the mean of four tests. Concentrating the measurement on the wheel path of the rear or front wheel as the case may be. (h) Plot results of the dry density and moisture content and determine the optimum moisture content and dry density appropriate to the plant. 1052C DETERMINATION OF ECONOMIC PASSES (a) Prepare another test section as in clause 1052B and bring the moisture content to the optimum moisture content earlier determined. (b) Divide the section into bays and vary the number of passes of the roller on each bay as shown in Table 1.3 TABLE I-3 NUMBER OF PASSES OF THE ROLLER Bay 1 Bay 2 Bay 3 Bay 4 Bay 5 4 passes 6 passes 8 passes 10 passes 12 passes (c) After rolling determine the dry density of each bay (based on mean of four tests) 19 (d) Plot the dry density and number of passes relationship to determine the minimum number of passes that will achieve the maximum density. TABLE I-4 RELATIONSHIP BETWEEN COMPACTION PLANT AND LABORATORY TEST: MDD AND OMC SOIL TYPE COMPACTION HEAVY CLAY SILTY CLAY MD D OM C MDD B. S. 2.5kg 1554 26 B. S. (Heavy) 4.5kg 1810 2800KG S. W. ROLLER OM C 1666 17 522 8000 kg S. W. ROLLER SANDY CLAY SAND GRAVELLY SANDY CLAY MDD om c MDD OMC MDD OM C 21 1842 14 1938 11 2067 9 1922 14 2051 11 2083 9 2211 7 21 1762 17 1826 16 2034 10 2147 8 1666 20 1778 16 1858 14 2115 8 2211 7 PNEUMATIC TYRED ROLLER 1570 25 1666 20 1730 19 2034 11 2018 7 SHEEPSFOOT (TAPPERFOOT) ROLLER 1714 15 1842 14 1927 12 2051 5 HANDLING AND STORAGE OF MATERIALS 1053. All materials to be used in the works shall be handled with due care and whenever not in immediate use shall be adequately stored and protected having particular regard in all cases and throughout to the nature of the material and its susceptibility to damage, breakage, deterioration, attack by weather or any act of abuse. (CLAUSES 1054 - 1059 NOT USED) PART (C) MISCELLANEOUS: ASSISTANCE FOR ENGINEER'S REPRESENTATIVE 1060. The Contractor shall provide at all times during the continuance of the contract all equipment and instruments for the exclusive use of the Engineer's Representative on the scale as set out in detail in Schedule No. VI. The Contractor-shall be solely responsible for all such instruments and shall ensure that they are at all times in good repair and adjustment. The Contractor also shall supply such workmen as may be deemed necessary by the Engineer's Representative, from time to time during the continuance of the contract, to 20 assist the Engineer's Representative in carrying out his duties. These workmen shall be selected for their intelligence and knowledge of the English language, and where possible the same men shall be provided throughout the period of the Contract. Payment for furnishing workmen and instruments, etc. to assist the Engineer's Representative shall be charged against provisional sum item "Payment of Wages to Engineer's Daily Paid Staff". All instruments and equipment so furnished become the property of the Federal Ministry of Works on the completion of the Works. OFFICE ACCOMMODATION 1061. The Contractor shall provide air-conditioned office accommodations and equipment for the sole use of the Engineer's Representative and his assistants. The extent of the office accommodation and equipment to be provided as set down below unless specified in Schedule No. VI. The offices shall be 28.95 metres long by 5.55 metres wide with 2.45 metres headroom all measured internally complete with ceiling and smooth concrete or wooden floor, and a 2.02 metres wide covered veranda on all sides. The office shall be divided into three rooms each 3.6 metres long. The rooms shall be adequately ventilated and lighted and through ventilation shall be provided in the roof space. The walls must be constructed of either prefabricated timber sections or sand-cement blocks. All doors and windows shall be arranged so that they can be securely fastened on the inside. All doors shall be provided with cylinder locks with two keys. The following furnishings shall be supplied for each site office:6 6 1 1 1 3 1 3 2 2 2 2 3 1 2 1 1 4 1 1 1 1 1 1 1 Desks 1.5 metres x 0.75 metres with 2 chests of drawers Chairs with arms Table 1.5 metres x 0.75 metres with two drawers and chairs Typist's table with one chest of drawers and chair Typewriter, standard office size 3 Draughtsman's tables and stools Sets of Normal Equipment for a Draughtsman Six-drawer steel filing cabinet Four-drawer steel filing cabinets Cupboards 2.0 x 1.0 x 0.5 metres with 4 shelves Clerk's tables 1.2m x 0.75m with 12 chairs Pairs of set squares 600 and 450 Planimeters Sets of Engineer's scales, metric Set of shelves and hooks as required Stainless Steel straight edges 1 metre long Refrigerator Conference Table with 8 chairs Small Tables with chairs Set of Applicable British Standards, Current Edition Copy of AASHTO Standard Specifications for Highway Materials and Method of Sampling and Testing Volumes 1 & II, Current Edition. Civil Engineer's Radius Guide Set of transparent plastic railroad curves Electronic calculator Electric adding machine Electric erasing machine 21 1 Photocopy machine with accessories and supplies. Adjacent to the two ends of the building the Contractor shall erect a board 750mm x 600mm bearing the following inscriptions. Principal Resident's Engineer's Office (Project Designation) Section No. or Description In addition each door of the building shall be lettered in accordance with the instructions of the Engineer's Representative. These building(s) shall be erected at locations as directed by the Engineer's Representative. The offices shall be separate from those of the Contractor and shall be fenced off and provided with a separate entrance. The Contractor shall provide two water closets and two wash hand basins with mirrors in rooms attached to the use of the Engineer's Representative. The Contractor shall keep clean and maintain this lavatory accommodation. He shall also provide soap, towels and all necessary fittings and cleaning materials. The Contractor shall arrange for the offices to be connected to a water and electricity supply. The Contractor shall provide a roofed shelter for six cars which shall be built adjoining the offices. The cost of providing the offices, water, electricity supply and maintenance during the whole period of the contract shall be deemed to be included in the price inserted under the appropriate item in the Bill of Quantities. The buildings and equipment shall be for the sole use of the Engineer's Representative during the period of the Contract and shall remain the property of the Employer after the completion of the Contract. FENCING 1062. The Contractor shall provide and erect fencing or walls complete with access gates along the land acquisition boundaries during the period of construction as and where directed by the Engineer's Representative. Payment for fencing and walling will be made from the appropriate item in the Bill of Quantities. No payment will be made for fencing or walls erected by the Contractor for the purpose of making secure his own working areas, yards, stores, as this will be deemed included in this pricing. COMPLIANCE WITH THE REGULATIONS OF THE NIGERIA RAILWAY CORPORATION, ANDGOVERNMENT INSPECTOR OF RAILWAYS 1063. Where the works abut, enter into or pass over property or properties belonging to the Nigerian Railway Corporation, the Contractor shall comply with all the regulations laid down and give all notices required by the Nigerian Railways Corporation and the Government Inspector of Railways. 22 COMPLIANCE WITH THE REGULATIONS OF THE NIGERIAN PORTS AUTHORITY 1064. Where the works are sited in, or operations connected with the works in any way whatsoever pass through, waters controlled by the Nigerian Ports Authority the Contractor shall abide by all the regulations laid down, and give all notices required, by the Nigerian Ports Authority. TAKING OVER OF SITE BY CONTRACTOR 1065. The site shall be handed over to the Contractor in minimum lengthsof sixteen kilometres. The date on which each portion is taken over shall be recorded and certified in writing by both the Engineer's Representative and the Contractor's Agent and from the date on which each portion is taken over the Contractor shall be responsible for maintaining that portion of road in good condition and for repairing damage of any kind to the road culverts or bridges arising from whatever cause save and except the excepted risks as defined in Clause 20 of the "General Conditions". (CLAUSES 1066 - 1099 INCLUSIVE NOT USED) 23 SPECIFICATION SECTION II - CONCRETE: MASS AND REINFORCED 1 SECTION II MASS AND REINFORCED CONCRETE GENERAL 2000. In addition to any other relevant clause of this specification, the following shall be deemed to apply in particular to mass and reinforced concrete work, and shall be read in conjunction with all other relevant clauses of the conditions of Contract and this Specification. PART A - MATERIALS CEMENT 2001. (1) GENERAL The Cement shall be ordinary or rapid hardening portland cement and shall conform to the requirements of NIS 11 or B.S. No. 12 portland cement (ordinary and rapid hardening) and B.S.C.P.114 and shall be supplied by manufacturers of good repute to be approved by the Engineer. (2) SULPHATE RESISTING CEMENT Where the use of a sulphate resisting cement is indicated as specified or in the bills it shall be a sulphate resisting portland cement of approved type and manufacture complying with B.S. 4027. (3) COLOURED CEMENT White or coloured cement shall be of approved quality and chemical composition and shall comply with the physical requirements of NIS 11 or B.S. No. 12 (4) BLENDING There shall be no blending or mixing of cements, and the use of any air-entraining, wetting agents, or accelerators such as calcium chloride will only be permitted if called for by the Engineer. (5) EXTRA PAYMENT The Contractors shall not receive extra payment for using rapid hardening portland cement unless they do so under the specific instructions of the Engineer. (6) TEST CERTIFICATE FOR CEMENT Each consignment of cement intended for use in the works shall be accompanied by a manufacturer's test certificate showing that the cement offered has been tested and analysed, the date and results of such tests and analyses, and that the cement conforms in all respects with NlS 11 or B.S.12. Where such a certificate is not available due to exceptional circumstances which, in the opinion of the Engineer are acceptable, then the Contractor shall arrange for each consignment of cement to be tested and analyzed strictly in accordance with NIS 11 or B.S.12 by a tester to be selected by the Engineer and the tester shall supply a certificate satisfying all the requirements laid down for the manufacturer's test certificate. Irrespective of the results of these tests, the Contractor shall bear all costs in connection with or arising out of them. (7) INDEPENDENT TESTS ON CEMENT In addition to any tests mentioned elsewhere in this specification, the Engineer's Representative may require cement to be sampled at the manufacturer's works and subsequently tested by an independent tester. No cement shall be despatched until the results of such tests and analyses are known and have been approved in writing by the Engineer's 24 Representative. Payment for these tests shall be the employer's responsibility and charged against the appropriate provisional sum, except as detailed in Clause 36 (4) of the Conditions of Contract. (8) PACKING AND MARKING OF BAGS FOR CEMENT After each consignment of cement has been tested and approved as complying with B.S. No. 12 and unless approval is given by the Engineer's Representative for the handling of cement in bulk, all cement shall be packed into bags of an approved type. The bags of each consignment shall be given a distinctive mark, to be agreed between the Contractor and the Engineer's Representative, also a consignment number, so that each consignment can be easily identified on being delivered to the site and when being used subsequently in the works. (9) NOTICE OF DESPATCH AND DELIVERY OF CEMENT Before ordering the despatch from the manufacturer of a consignment of cement for use in the works,the Contractor shall give notice in writing to the Engineer's Representative of the number of the consignment, the name of the manufacturer and the number of tonnes in the consignment. When each consignment is delivered to the site, the Contractor shall issue to the Engineer's Representative a written statement showing the number of the consignment, the name of the manufacturer,the number of tonnes in the consignment, the number of bags and enclosing the respective test certificates. The statement shall also show where the consignment is stored. Cement may be shipped in bulk or in 50 Kg bags subject to approval of the Engineer and subject to such requirements as he may deem necessary. Railroad cars or trucks in which cement is shipped shall be loaded under the supervision of and sealed by the Engineer. Cars or trucks with broken seals may be unloaded, but the cement shall not be used until retested and approved. (10) STORAGE OF CEMENT ON SITE On delivery at the site, the cement shall be stored in suitable, thoroughly dry and well-ventilated lock-up sheds to be erected by the Contractor and approved by the Engineer's Representative. Great care must be taken to provide a perfectly dry floor of timber or concrete for each shed so as to prevent damp rising to the cement. Small quantities left at the site shall be stored on suitable platforms and protected with waterproof covering to the satisfaction of the Engineer. Each consignment, brand and type of cement shall be kept separate in the sheds and suitable labels are to be provided for each consignment, brand and type, on which shall be entered the consignment number, date of despatch, date of delivery at the site, the number of bags, the date when using commenced and the date when using finished. All these labels shall be handed to the Engineer's Representative when the cement has been used and will be retained by him. No cement shall be used without the permission of the Engineer's Representative and each consignment must be used singly and in order of delivery at the site, or as may be directed by the Engineer's Representative. (11) STOCK OF CEMENT AND MONTHLY RETURNS 25 The Contractor shall at all times maintain at the site such a stock of cement as will ensure due and proper progress of the works. Each month, on the date corresponding to the interim certificate date, the Contractor shall forward to the Engineer's Representative, a return of the various consignments in store, giving the total tonnage at site, the quantity received during the month, from whom it was obtained and in what sheds it has been deposited. Also the quantity issued during the month, from what consignment and sheds it was issued and in what portions of the works it was used. (12) TESTS ON CEMENT AFTER DELIVERY After delivery on the site the Engineer's Representative may require each consignment of cement to be subjected to any or all of the tests and analyses required by B.S.12 Payment for these tests shall be the Contractor's responsibility and deemed to be included in the tendered rates and prices. (13) REJECTION OF CEMENT Notwithstanding the production of test certificates whether from manufacturer tester or independent tester, the Engineer's Representative shall reject any cement found not to comply with this specification, at any time. He shall also reject any cement which has been damaged or which has deteriorated owing to inadequate protection during storage or transport or any other cause. Cement containing lumps of hardened cement or which has been stored for more than 6 months shall not be used. The Contractor shall remove all rejected cement from the site without delay and at his own expense. (14) ADMIXTURES Admixtures for accelerating or retarding the setting of the cement, etc., shall not be used in any circumstances except with the written permission of the Engineer. When such permission is sought, the Contractor must supply full details of the admixture he wishes to use. WATER 2002. Water used for mixing and curing concrete shall be clean, fresh water from an approved source and it shall be free from injurious oils, chemicals, vegetable matter, organic and other impurities and shall comply with the requirements of B.S.3148 The Contractor shall ensure that all pipes, tanks and other receptacles for the storage of water intended for use in the makings of concrete are kept in a clean condition. AGGREGATES 2003. (1) GENERAL The aggregates (fine, coarse and all-in) for all grades of concrete and mortar shall comply in all respects with B.S.882 (1973) and the Contractor shall test all samples as described therein and in B.S.812 (1967) as often as the Engineer's Representative may require,to ensure that they are continuously up to these standards. All aggregates shall be hard, strong, durable, perfectly clean and free from organic matter and deleterious coatings 26 such as clay. They shall contain no harmful material in such quantities as to affect adversely the strength or durability of the concrete, or attack the reinforcement as ascertained by tests on concrete cubes as described hereafter and by tests as described in B.S.882 (1973). (2) THE SOURCES OF ALL AGGREGATES SHALL BE APPROVED BY THE ENGINEER'S REPRESENTATIVE All aggregates whether fine or coarse if considered unsuitable by the Engineer's Representative shall be removed from the site by the Contractor at his own expense. (3) TESTING As soon as possible after receiving the Engineer's Authority to commence the works (and before commencing any concreting) the Contractor shall have delivered upon the site sample loads of aggregate representative, of those proposed for the works, and shall forward samples prepared in accordance with the method laid down in B.S. 812. The moisture content of aggregates shall be determined using the siphon can procedure notwithstanding the foregoing, Speedy Moisture Content Apparatus may be used for measuring the water content of fine aggregates. Each sample shall consist of not less than 45 Kg weight of fine aggregate and 90 Kg of coarse aggregate in accordance with the specification. No aggregate shall be used in the works until the results of these tests shall have been submitted to the Engineer's Representative and his approval in writing obtained. The minimum frequency of testing at each concrete mixing plant shall not be less than the following: (I) TESTS OF COARSE AGGREGATES (i) Sieve analysis 7 weeks (ii) Determination of clay, fine silt and fine dust (Method B - Determination of amount of aggregate passing a 75 microns 3 days (iii) Determination of flakiness index 2 weeks (iv) Moisture Content Immediately prior to commencement of mixing of concrete for each cast, and thereafter every half hour during which concrete is being mixed. (v) Determination of "ten per cent fine value" 2 weeks (II) TESTS OF FINE AGGREGATES (i) Sieve analysis 2 weeks (ii) Determination of fine silt and fine dust (Method C - Field settling test 3 days Estimation of organic impurities 3 days (iii) 27 (iv) (III) Moisture content Immediately prior to commencement of mixing concrete for each cast thereafter every half hour during which concrete is being mixed. TESTING DRYING SHRINKAGE (i) Drying shrinkage 8 weeks Notwithstanding the foregoing additional tests shall be carried out as and when directed by the Engineer's Representative (4) WASHING Washing of aggregate may only be carried out using clean fresh water obtained from an approved source. The Contractor is to provide adequate storage facilities and arrange to obtain this water at times chosen so as to cause the minimum of inconvenience to other consumers. (5) STORAGE OF AGGREGATES The Contractor shall provide proper means of storing the aggregates at each point where concrete is made and in such a manner that there is no possibility of the various aggregates mixing one with the other. Effective precautions shall be taken to prevent the aggregates segregating in the storage heaps and from being contaminated by the ground and other foreign matter. Storage heaps shall be capable of draining freely. Wet aggregates shall not be used until, in the Engineer's Representative's opinion, they have completely drained. Where aggregates are damp, the Contractor must measure the moisture contents of the aggregates continuously and adjust the amounts of aggregates and added water in each batch of concrete mixed to allow for the water contained in the aggregates. If necessary, to meet the requirements of this Clause, the Contractor shall protect the heaps of aggregates from inclement weather. (6) METHOD OF CALIBRATING SPEEDY MOISTURE TESTER (a) Procedure Sufficient fine aggregate passing sieve 1.25mm and retained on pan shall be prepared and dried to constant weight. Weigh 3 kg to make 20 separate number of specimen. (b) Air-tight moisture content tins shall be weighed empty and to each shall be placed 200 g of the dried soil and weighed again. (c) Varying quantity of water as indicated in the table below shall be added to each pair of container and allowed self moisturization for 24 hours and weighed thereafter before placing in the oven or for speedy tester method. TABLE II-1 OVEN METHOD 28 Tin Number a b c d e No. of Specimen 2 2 2 2 2 Weight of dry soil, g 200 200 200 200 200 Volume of water cc 100 120 140 160 200 Note: After weighing, place all oven method tins into a standard oven with temperature not greater than 105oC and dry the specimen to constant weight and thereafter determine the moisture contents. TABLE II-1A SPEEDY TESTER METHOD Tin Number a b c d e No. of Specimen 2 2 2 2 2 Weight of dry soil, g 200 200 200 200 200 Volume of water cc 100 120 140 160 200 Note: For the speedy tester, use the apparatus to determine the moisture content of each pair of specimen to constant moisture reading. The average reading of each pair shall be the moisture of the specimen. Same holds for the oven method. (d) Calibration Plot a straight line graph of oven moisture against speedy tester results. By using the plotted graph, speedy test results can be converted to oven method results. FINE AGGREGATES 2004. (1) GENERAL Fine Aggregate shall either comprise natural quartz sand or be obtained by crushing clean granite or shall consist of naturally occurring sand obtained from fresh water river deposits or a combination thereof and shall comply with Grading Zone 1 or Grading Zone 2 of B.S.882 or such other grading as may be approved by the Engineer. (see Table II-2) (2) FINE DUST The total quantity of fine dust passing through a 75 m mesh sieve in fine aggregate derived by crushing rock shall be determined 29 by the method described in B.S.812. and shall not exceed 8% by weight. (3) QUANTITY OF CLAY AND SILT The total quantity of clay and silt in natural sand shall not exceed 4% by weight when determined by the field settling test decantation method described in B.S.812. The quantity of organic impurities present in natural sand shall not be such as to produce a reaction as dark as the standard solution when the organic impurities are determined by the method described in B.S.812 (1975). TABLE II - 2 FINE AGGREGATE GRADING ENVELOPES. BS 410 Percentage by weight passing B.S. sieves. Test sieve Grading ZONE 1 10.00mm 100 5.00mm 90 - 100 2.36mm 60 - 95 1.18mm Grading ZONE 2 100 Grading ZONE 3 Grading ZONE 4 100 100 90 - 100 95 - 100 75 - 100 85 - 100 95 - 100 30 - 70 55 - 90 75 - 100 90 -100 600m 15 - 34 35 - 59 60 - 79 80 - 100 300m 5 - 20 8 - 30 12 - 40 15 - 50 150m 0 - 10* 0 - 10* 0 - 10* 0 - 15* 90 - 100 * For crushed stone sands, the permissible limit is increased to 20% because of its non clay nature of the fine materials. The 5% tolerance permitted may be applied to the percentages. In the last three sets of sieves, it can be applied as follows: 1% on the first of the three sieves and 2% on the others or 4% on one sieve and 1% on others. The application of tolerance will depend upon the shape of the grading graph. COARSE AGGREGATE 2005. (1) GENERAL Coarse Aggregate shall comprise natural gravel or crushed granite obtained by crushing sound hard granite taken from a source approved by the Engineer's Representative and shall contain no harmful material in sufficient quantity to adversely affect the strength or durability of the concrete or in the case of reinforced concrete to attack the reinforcement. All coarse aggregate shall be washed after crushing if necessary to comply with the specification. The flakiness index when determined by the method described in B.S.812 30 (1975) shall not exceed 30 per cent. The individual pieces shall be roughly cubical or spherical in shape and have neither glassy nor powdery surfaces. (2) CRUSHING VALUE The aggregate crushing value of coarse aggregate shall not exceed 45 per cent when determined by the method described in B.S.812. (3) THE GRADING The grading of coarse aggregate particles is required to satisfy strictly the percentages,stated for 20mm nominal sizes stated in the B.S.82 with a content not exceeding 1% passing the B.S. 2.4mm sieve size. The percentage passing through 75 m sieve shall be determined by the method described in B.S.812. Sieves shall comply to the requirements of B.S.410. STEEL REINFORCEMENT 2006. (1) GENERAL The reinforcement shall be one of the following:- (I) Rolled steel bars or hard drawn steel wire complying with the requirements of B.S.785 "Rolled steel bars and hard drawn steel wire for concrete reinforcement" and B.S.4449 (1969) Hot-rolled steel bars for the reinforcement of Concrete. (II) Cold twisted steel bars complying with the requirement of B.S.114 "Cold twisted steel bars for concrete reinforcement and B.S. 4461 (1969) Cold works steel bars for the reinforcement of concrete. (III) Such other reinforcement as may be suitable having regard to the yield stress, ductility tensile strength and other essential properties. (2) DIAMETER OF BAR The Diameter of any Bar for the purposes of this code should be taken as that of a circle having an area equal to the cross-sectional area of the bar. At the option of the Contractor, the reinforcing bars can be purchased from the manufacturer using metric units provided that the area of required steel will not be rounded downwards. When the diameters of the reinforcing bars are given in one system on the contract drawings, and they do not have exact equivalent of the bar in another system, the basic dimension must be converted to the nearest higher cross section area. The cost arising from additional weight of the reinforcing steel shall be borne by the Contractor. (3) TEST CERTIFICATES For each consignment of steel reinforcement used in the works, the Contractor shall supply a certificate giving the ultimate strength, yield stress, elongation and result of the cold bend test described in B.S.4449 and B.S. 4461. The Engineer's Representative shall have power to select pieces of steel for testing if no test data are supplied by the Contractor and the costs arising out of such tests shall be borne by the Contractor. 31 Reinforcement obtained from re-rolling scrap metal shall not be used. (4) DELIVERY When each consignment is delivered to the site, the Contractor shall issue to the Engineer's Representative a written statement showing the number of the consignment, the name of the manufacturer, the number of tonnes in the consignment. (5) STORAGE Reinforcement shall be stored on site in racks off the ground and shall be protected from rusting, damage, oil or other deleterious matter and shall be clean and free from all such matter before concrete is placed. (6) MEASUREMENT AND PRICES FOR STEEL REINFORCEMENT The prices inserted in the Bill of Quantities for steel reinforcement shall include for supplying, handling, bending, wiring, placing, cutting, cleaning, supporting and every other expenses necessary to complete the works as shown on the drawings or as may be directed by the Engineer. The Contractor shall be paid for the net calculated weight of reinforcement, excluding binding wire used in the work, in accordance with the drawings, or as may be directed by the Engineer's Representative and no allowance will be made for margins or otherwise. WATERPROOF BUILDING PAPER 2007. Waterproof Building Paper used as an underlay to concrete to prevent the loss of cement or as a means of providing a non-bonding joint between two parts of any structure shall comply with the requirements of B.S.1521 (1949) with the extra provision that the material shall not become sticky in the roll under any of the climatic conditions encountered in Nigeria. JOINT SEALING COMPOUND AND PRIMER 2008. (1) JOINT COMPOUND The joint sealing compound shall be hot poured material approved by the Engineer. The material shall adhere readily to the concrete and to the primer. It shall be ductile, not excessively soft or tacky at a temperature of 82 0C nor brittle at a temperature of 20C. (2) PRIMING PAINT A priming paint suitable for the joint sealing compound used, shall be applied to the concrete surfaces prior to the pouring of the sealing compound with the object of improving the adhesion. PART B - WORKMANSHIP PROPORTIONS OF CONCRETE MIXES 2009. Concrete to be used in the works shall be a mixture of cement, fine aggregate, coarse aggregate and water and the various grades of concrete to be used shall be in accordance with Table II -3. CONCRETE MIX DESIGN 2010. At the commencement of the works, the Contractor shall indicate the type of compaction which he intends to use in the various parts of the works and obtain the approval of the Engineer's Representative thereto. The Contractor shall then design mixes for concretes of grade as required, each design fulfilling the following requirements:- 32 (A) The cement, the aggregates and the water shall all comply with the appropriate clauses of this specification. (B) specification. The cement shall not be less than that shown in Table II-3 of this (C) The water content for each mix shall be in accordance with Clause 2013 (2) of this specification and shall be such as to give the required compacting factor and/or slump: where different methods of compaction are to be employed for the same grade of concrete, involving different compacting factors and/or slump, then a separate design mix shall be prepared for each case, to satisfy the requirements of the appropriate clause of this specification. TRIAL MIXES 2011. Following the Engineer's Representative's approval of the mix designs, the Contractor shall prepare, in the presence of the Engineer's Representative, a trial mix of each design grade of concrete. The mixes shall be prepared as follows: Before mixing, a sieve analysis of the aggregate shall be made by the method described in B.S.812 (1975) and the weight and volume of the cement, fine aggregate, coarse aggregate and water comprising the mix carefully determined. Each trial mix shall be not less than half a cubic meter in bulk before mixing and shall be mixed as specified in Clause 2012 of this specification in a mechanical mixer of the type approved for use in the works. The compacting factor and slump of each trial mix shall be determined immediately after mixing as directed in NIS 12 B.S.1881 (1970)and shall not exceed the maximum value obtained in the mix design. Each trial mix shall be handled and compacted by the methods which the Contractor proposes to use for that mix in the works, and the mixes shall show no tendency of inadequate compaction by the methods proposed. Six cubes of 150mm compression test cubes shall be made from each trial mix. The cubes shall be made, cured, stored and tested in accordance with the requirements of B.S.1881 (1971). 33 TABLE II - 3 REQUIREMENTS FOR CONCRETE FOR STRUCTURES AND GENERAL CONSTRUCTION 1 PURPOSE 2 GRADE OF CONCRETE 3 MAXIMUM SIZE OF AGGREGATE mm 4 5 MINIMUM CEMENT CONTENT PER M3 OF FINISHED CONCRETE WORK - Kg. WATER CEMENT RATIO 6 7 WORKS TEST MINIMUM COMPRESSIVE STRENGTH IN N/mm2 CEMENT N/mm2 7 DAYS 28 DAYS PRESTRESSED CONCRETE 50 45 20 20 500 450 0.35 - 0.45 0.35 - 0.45 40 35 50 45 -do- 40 20 425 0.35 - 0.45 30 40 -do- 35 20 400 0.45 - 0.55 25 35 REINFORCED CONCRETE 30 20 350 0.45 - 0.55 20 30 -do- 25 20 295 0.45 - 0.55 15 25 -do- 20 20 235 0.45 - 0.55 12 20 -do- 15 20 205 0.55 - 0.65 10 15 MASS CONCRETE 12 40 175 0.55 - 0.65 7 10 BLINDING CONCRETE 10 40 150 0.65 - 0.75 7 10 34 Rapid hardening Portland cement Ordinary Portland Cement Three cubes shall be tested 7 days after manufacture and three 28 days after manufacture. The strength requirements of the cubes at each age shall be considered to be satisfied if none of the strengths of the three cubes tested at each age falls below the appropriate design strength or if the average strength of the three cubes is not less than the strength and the difference between the greatest and least strengths is not more than 20 per cent of that average. Failing this, the Contractor shall re-design the mix and make such further trial mixes and test such further cubes as the Engineer's Representative may direct until the requirements of this specification are satisfied. The design mixes which fulfill the requirements of this specification for a particular grade of concrete shall be called the approved mixes for that grade of concrete and the Contractor shall only use the approved mixes where that grade of concrete is specified, and shall not depart therefrom without the written permission of the Engineer's Representative. The Engineer's Representative may require further trial mixes and further cube tests to be made before such permission is given. The Contractor shall allow ample time in his programme for designing and making trial mixes and for the preparation and testing of compression test cubes obtained therefrom. Should any design mix fail to satisfy the requirements of this specification and should the Engineer consider that it is essential to commence the production of that grade of concrete before the results of the cube tests of a further design mix are available, he will consult with the Contractor and decide on an interim mix for use until such time as the results of the cube tests have become known, any extra cost involved being borne by the Contractor. The Contractor shall be deemed to have satisfied himself that the materials on which he has quoted will produce a concrete which, with the specified nominal proportions and subsequent adjustments as indicated by trial mixes, will develop the cube strengths specified and at same time have the desired workability in the work itself. The cost of all trial mixes, test cubes and their testing shall be deemed to be included in the tendered rates for concrete. MIXING OF CONCRETE 2012. (1) GENERAL Concrete shall be mixed in mechanical mixers of the weigh-batch type as stated in the Contractor's mix design proposal, complying with the requirements of B.S. 1305 (1967) and fitted with an approved weight measuring device. No hand-mixing will be permitted. Mixing shall continue until there is a thorough distribution of the materials, and the mass is of uniform colour and consistency. The period of mixing, judged from the time that all materials including the water are in mixer, shall be not less than that or should not be more than 2 minutes per m3 or as recommended by the manufacturer. The concrete mixer shall revolve at the speed recommended by the manufacturer, or as ordered by the Engineer's Representative. The entire contents of the drum shall be discharged before materials for the next batch are fed in. Should there, for any reason, be a stoppage of greater than 30 minutes duration, the drum of the mixer shall be thoroughly washed out with clean fresh water before mixing is resumed. Stationary mixers shall be equipped with an acceptable timing device that will not permit the batch to be discharged until the specified mixing time has elapsed. 35 (2) RE-MIXING OF CONCRETE No partly set concrete shall be placed in the works. Concrete which has commenced to set shall not be remixed either with or without additional water and in no case shall such concrete be used in the works. QUALITY OF CONCRETE 2013. (1) APPROVAL OF MATERIALS ETC. Before their use in the works, the Contractor shall show, to the satisfaction of the Engineer's Representative that all materials and methods of storage and mixing to be employed in the production of concrete, conform in every way with the requirements of this specification. Such deliveries of materials to the site as the Engineer's Representative may designate shall be tested and analyzed to ensure that they do so comply and the tests shall be carried out sufficiently in advance of their intended use in the works to allow the results to be studied and the materials approved, modified or rejected by the Engineer's Representative as the case may be. The Contractor shall remove all rejected materials from the site without delay and at his own cost. Permission to use any material shall not be construed as an approval of its source, nor any acceptance as continued acceptance. (2) COMPACTING FACTOR Workability of concrete shall be measured by compacting factor. The Contractor shall provide a compacting factor apparatus conveniently accessible to each concrete mixer and shall measure the compacting factor by the method described in B.S.1881 at frequent intervals or as frequently as the Engineer's Representative may direct, but in any case, tests shall be carried out at least once every half-an-hour during which concrete is being mixed. Whenever the compacting factor varies from that of the approved mix the quantity of water added to the mix shall be immediately adjusted to counteract the variation. The successive values of the compacting factor and the quantity of water added shall be recorded on a suitable quality control chart, which shall be kept near the mixer and submitted to the Engineer's Representative for his inspection as he may direct. Notwithstanding the foregoing, the "V-B" consistometer test may be used in place of the compacting factor test and in such cases tests shall be carried out in accordance with the recommendations of the manufacturer of the "V-B" Consistometer; see B.S 882 part 19. The Contractor shall ensure that all their concrete mixer operators are aware of the importance of maintaining uniform controlled quality of the concrete and that they are experienced in detecting variations in concrete quality and workability and in rapidly correcting the same. (4) TESTS ON AGGREGATES In addition to the tests mentioned above, as frequently as the Engineer's Representative may decide and at least once each day when concreting is in progress, the Contractor shall sample and test the aggregates due shortly for incorporation into the works as follows:- the tests being carried out in accordance with B.S. 812 (1975). (I) SIEVE ANALYSIS OF BOTH COARSE AND FINE AGGREGATE 36 The gradings of all aggregates must be within the respective limits specified in Clause 2004; failing which the Engineer or his Representative shall instruct the Contractor to make such modifications to the proportions of aggregate in the mix as will allow for such difference, and the Contractor shall immediately do so. (II) DETERMINATION OF CLAY, FINE SILT AND FINE DUST IN THE FINE AGGREGATE - FIELD SETTLING TEST Should the amount of clay, fine silt and fine dust exceed 4% by volume, then the Contractor shall refrain from using the aggregate until he satisfies the Engineer's Representative of its suitability for making concrete of the quality required. (III) DETERMINATION OF ORGANIC IMPURITIES Should the colour produced by the test be as dark as the standard solution, the aggregate shall not be used until further comparative compression tests specified in B.S.882 (1973) have been carried out and given satisfactory results. (5) PROTECTION OF CEMENT During windy weather, effective precautions shall be taken to prevent the cement from being blown away during the process of apportioning and mixing. One method of checking this, is by use of wide planks as wind breakers in the direction of the wind, During wet weather both cement and concrete shall he adequately protected either by covering with polythene or tarpaulin. (6) PRELIMINARY CUBE STRENGTH TESTS (I) Prior to the commencement of any concreting work and subsequently whenever a change is intended in the materials or in the proportions of the materials to be used, preliminary cube strength tests shall be made in accordance with B.S.1881, "Methods of Testing Concrete", to establish that the mean strength of the mix conforms with the design requirement. Reliance shall not be placed on the strength obtained from only one set of three test specimens, but separate samples of the material to be used, taken on three occasions at intervals of not less than one day, shall be forwarded to the testing authority for preliminary cube strength tests. From each sample of material, six cubes shall be made, three for test at seven days and three for test at twenty-eight days. (II) WORKS CUBE STRENGTH TESTS Works Cubes, whether required for the normal method or for the special method of quality control described respectively hereunder,shall be made and cured in the manner described in B.S.1881. Where the concrete is vibrated, the cubes shall be compacted by similar means in such a way that full compaction of the concrete with neither segregation nor excessive latex is obtained. Samples of concrete from which works test cubes shall be made shall be taken in accordance with B.S.1881 and in particular at the time and place of deposition of the concrete and at such other times and places as the Engineer's Representative will direct. 37 (III) The frequency of sampling for each concrete mixing plant used for the Contract shall be as follows:(1) When each mix is first made for use in the works, batches shall be sampled at the rate of 8 batches per day for the first 5 days of using that mix or at such other times as directed by the Engineer's Representative until a total of 40 batches have been sampled, with a minimum requirement that (i) one batch shall be sampled each day particularly when any concrete of a particular mix is made. (ii) one batch shall be sampled for each cast of concrete to be post tensioned. (2) concrete is made. Thereafter one sample shall be taken on each day any grade of Notwithstanding the foregoing, additional samples shall be taken by the Contractor as and when directed by the Engineer's Representative. From each sample of concrete and at the place where the sample was taken six test cubes shall be made; 3 shall be tested at an age of 7 days and 3 at an age of 28 days. The test cubes shall be made cured and tested in accordance with B.S.1881. If cured at a mid-point temperature of 270C, then the 200C strengths will be assumed to be 0.80 times the 270C strength. For the strength of concrete to be acceptable to the Engineer, the following shall be achieved:- (1) Each test cube shall have compressive strength of not less than that specified on the drawings. (2) Notwithstanding the provision of sub-clause (1) above, should the 200C compressive strength of a test cube or cubes tested at an age of 7 days be below the minimum specified strength, then if the other test cubes of the set tested at 28 days comply with the Specification, the concrete shall be deemed to have passed the tests. (3) Notwithstanding the foregoing provisions of the Clause, the quality control exercised at each mixing plant and for each mix shall be such that the overall average 200C compressive strength achieved (measured in N/mm2) minus 1.64 multiplied by the standard deviation achieved (measured in N/mm2) shall be more than or equal to the specified minimum 28 days 200C compressive strength. Overall average compressive strength and standard deviation shall be calculated from the results obtained from the latest forty consecutive sets of 3 test cubes of any one mix and from any one mixing plant. S ( x ) 2 ( x)  N N 1 38 (x) 2 N N 1 ( x ) 2  S where N = Number of cubes tested x = 28 day compressive strength of 150mm cube in N/mm2 S= Standard deviation in N/mm2 Notwithstanding the foregoing, the standard deviation shall not be calculated for a mix until there are at least 40 sets of 3 test cube results available. Test reports shall include the following information:(1) Reference number of test cubes (2) Class of concrete (3) Location of concrete in works from which the sample was taken (4) Time and date test cubes were taken (5) Age of test cubes at test and curing conditions (6) Workability (7) Cement/fine aggregate/coarse aggregate ratio by weight (8) Water/cement ratio by weight (9) Individual and average compression strengths of the 3 test cubes and assumed 200C values if different (10) Individual and average densities of the 3 test cubes (11) Average compressive strength and standard deviation for which the mix has been designed (12) Overall average 200C compressive strength and standard deviation achieved using the results obtained from the latest forty consecutive sets of 3 test cubes made from the same mix and the same mixing plant. (13) Overall average compressive strength from (12) minus 1.64 multiplied by deviation from (12). If results of the cube tests do not comply with-the Specification, such remedial works as the Engineer may accept or direct shall be carried out. 39 If results of cube tests do not comply with the Specification and/or if the figure from item (13) of the test report is less than the specified minimum 28 day compressive strength, then either the quality control at the relevant mixing plant shall be improved to the satisfaction of the Engineer's Representative or the mix shall be redesigned to the satisfaction of the Engineer's Representative. If directed by the Engineer, redesign of the mix shall include carrying out further preliminary laboratory tests in accordance with the Specification with the redesigned mix. (IV) INDEPENDENT TEST CUBES The Contractor shall arrange for the Engineer's Representative to be present during the sampling of the concrete and the manufacture, storing and curing of the cubes to ensure that there is complete agreement between himself and the Engineer's Representative that the said cubes are entirely acceptable as test cubes. Should the Contractor fail to arrange for the Engineer's Representative to be present when required, or decline to do so, the cubes so manufactured will not be accepted as test cubes. Should the Contractor wish to make independent test cubes he may do so at his own expense, but the results will not be valid unless the cubes are manufactured in the presence of the Engineer's Representative and tested by an approved Agency, all in accordance with B.S. 1881.The approved form, giving the reference number of the cube, its size and weight, the grade of concrete from which it was made, the compaction factor, the date on which it was made, the date on which it was tested, the total load in kN at which it failed, the stress in N/mm² and the location of structure at which the sample of concrete was taken. Two copies of each test certificate, containing all the information mentioned above, shall be forwarded to the Engineer's Representative for his retention and a third copy retained in the Contractor's laboratory. (V) FAILURE OF TEST CUBES FOR STRENGTH REQUIREMENT Should either the test cubes crushed at 7 days or those crushed at 28 days or both, fail to satisfy the specified requirements, the Contractor shall, on the Engineer's Representative instructions, take one or more of the following steps:(A) He shall alter the design of the mix to increase its average compressive strength (B) He shall alter the method of making the concrete and controlling its quality to reduce the variability of the concrete. (C) He shall cut out and replace concrete placed in the works on any day in which a cube (was made and failed if, in the opinion of the Engineer's Representative, such concrete is likely to be incapable of fulfilling its purpose. The Engineer may require the Contractor to cut out defective concrete from the works even though test cubes made from that concrete have not failed. This may arise if the concrete failed to meet other salient features and quality standard like the following: (i) (ii) Honey combing Cold joint (7) CORRELATION OF TESTS 40 Tests on concrete materials and concrete shall be made as often as directed by the Engineer's Representative and at instances such that the test results can be directly correlated to the works test cubes for a particular batch of concrete. (8) COST OF TESTS The Contractor shall bear the cost of carrying out and supplying all labour, materials and equipment for the sieve, silt, organic impurities, bulking, compacting factor and slump tests mentioned above and any other tests required by the Engineer or the Engineer's Representative to ensure proper quality control of the concrete. He shall also bear the cost of supplying all labour, materials and equipment necessary for the preparation of the compression test cubes and their subsequent storing, curing, packing, transportation and testing. All costs arising out of modifications to the concrete mixes, cutting out and replacing of defective concrete and all other work carried out in accordance with this Clause shall be borne by the Contractor. TRANSPORTATION OF CONCRETE 2014. Concrete shall be taken from the place of mixing to the place of deposition by methods which will prevent the drying-out and consolidation of the concrete, the segregation and loss of the ingredients, and which are sufficiently rapid to ensure that the concrete does not commence to set before it is finally compacted in position. During transportation, the concrete shall be protected from all adverse effects of sun, wind and rain. The concrete shall be deposited as near as possible to its final position in the works, and no concrete shall be dropped freely or deposited by means of chutes through a depth exceeding 3 metres. All mixers, barrows, spades and other mixing and distributing equipment will be thoroughly clean before commencing each period of use and shall be kept free of partly set concrete which shall not be used in the works. No concrete shall be transported over or near to new work that has insufficiently hardened, in order to prevent harmful vibration of the new work and no planks or ways for skips, etc., shall be supported on either formwork or reinforcement for the same reason. PLACING AND COMPACTION 2015. No concrete shall be placed in any part of the works until written permission to do so has been obtained from the Engineer's Representative. Well in advance of the intention to place concrete, the Contractor shall forward to the Engineer's Representative for his approval full information about the order in which he proposes to place concrete in the various parts of the works, the height of each lift of concrete, details of the shuttering which he proposes to employ with relevant calculations, and positions of all construction joints. All construction joints shall be formed as specified in Clause 2019 and there shall be no stoppage of the placing of concrete except at such proper construction joints. The Contractor will be required to furnish the Engineer's Representative with satisfactory evidence that all preparations, precautions and provisions have been made to ensure that the concrete shall be placed and compacted in accordance with this specification before the Engineer's Representative will give his permission for concreting to proceed. For members involving "vertical" placing of the concrete, (e.g. piers) each lift shall be deposited in layers extending for the full width between shuttering and of such depth that each layer can be easily and effectively incorporated with the layer below by the means of compaction being employed. The layers shall be placed horizontally, sloping beds not being permitted unless particularly so specified. 41 For members involving "horizontal" placing of the concrete (e.g. deck slabs), the concrete shall be placed along the line of the starting point, in such quantities as will allow the member to be cast to its full depth along the full width between side shuttering and then gradually brought towards the finishing point along its entire front, parallel to the starting line, the tampers for giving the required surface and compaction following as closely behind as practicable. All members shall be concreted at such a rate as will eliminate any possibility of fresh batches of concrete being deposited immediately adjacent to batches which have commenced to set, and all members shall be poured in one continuous operation until completed, no interval being allowed to lapse while the work is in hand. Care shall be taken to ensure that the process of placing concrete does not cause any harmful vibration to adjacent work that has insufficiently hardened. Should any unforeseen occurrence result in a stoppage of concreting for such a time as might allow the concrete already placed to begin to set before the next batches can be compacted into place, the Contractor shall immediately insert, at his own cost, a proper end-shutter to form a proper tongue and groove construction joint as specified in Clause 2019 normal to the work at that point which will ensure that the section already cast is formed complete in accordance with this specification. Any additional reinforcement required as a result of the joint shall be provided by the Contractor at his own expense. No concrete for work which will present a large exposed surface (e.g. deck slab) shall be placed in the direct rays of the sun and the Contractor shall erect shades to protect such work therefrom. Compaction of the concrete shall be effected by either hand or mechanical means and all compacting tools must be approved by the Engineer's Representative before being used in the works. The concrete shall be worked well up against whatever surface it adjoins and compacted to such a degree that it reaches its maximum density as a homogeneous mass, free from air and water holes, and penetrates to all corners of the moulds and shuttering and completely surrounds the reinforcement. Care shall be taken to ensure that neither hand pounders nor mechanical vibrators come into contact with the formwork, reinforcement, or any embedded fittings and to prevent the operation of compaction from transmitting any harmful vibrations or shocks to concrete which has not yet hardened sufficiently. Compliance with the conditions of this clause may require working longer hours than usual and the Contractor must allow for this in his schemes for concreting and in the rates for the work inserted by him in the Bill of Quantities. CONCRETE PLACED UNDER WATER 2016. Concrete shall be placed under water only where particularly so specified and approved by the Engineer's Representative. The quantity of cement in any concrete placed under water shall be increased by at least 25 per cent above the cement content of the appropriate approved mix. Concrete shall be placed in still water only and every precaution shall be taken to prevent the cement and fine materials from being washed out of the concrete. Concrete shall be placed either with a tremie or a bottom opening box of a type approved by the Engineer's Representative. Bottom opening boxes shall not be opened until they are resting on the work and the lower ends of tremie pipes shall always be kept below the surface of the wet concrete already deposited. No concrete shall be allowed to fall through water at any time. Concrete shall be placed evenly over the whole area enclosed by the shuttering and must not be raked over, only the minimum of screeding being allowed once the concrete has been replaced. 42 Concrete under water shall be placed in accordance with the provisions of the British Standards Code of Practice 2004 (8.2.2.3 or 8.2.2.3.4). PROTECTION AGAINST CHEMICAL ACTION 2017. In cases where concrete is to be deposited against ground known or suspected to contain sulphate salts or other deleterious chemical agents, sulphate resisting portland cement shall be used instead of ordinary portland cement. The sulphate resisting portland cement shall be of approved manufacture and in accordance with B.S.12 (1958) and in such situations where its use is required, particular care shall be taken to keep the ground water level below the level of the concrete being placed until that concrete has hardened and has been cured as specified in Clause 2022. ATTENDANCE OF JOINER AND STEEL FIXER 2018. During all concreting operations, the Contractor that a competent joiner and a competent shall ensure steel fixer (in the case of reinforced work most especially in work in which fittings are embedded) are in attendance on each concreting operation. It shall be their duty to ensure that the formwork is maintained in accordance with the specification, temporary construction joints inserted as necessary, and reinforcement and fittings maintained in place as the work proceeds. CONSTRUCTION JOINTS 2019. All construction joints in all classes of work shall be formed by inserting stopping-off boards normal to the work to form a tongue and groove joint as detailed on the drawings and against which the concrete can be properly compacted. They shall be formed in the position shown on the drawings or as directed and approved by the Engineer's Representative. There shall be no construction joints in precast members nor in the reinforced concrete deck slabs of minor spans. In the case of tee beams the rib and slab shall be cast together in one continuous operation. In other work, construction joints shall be located at points where shear stresses or tensile concrete stresses are a minimum and at place where they will least affect the appearance and properties of the finished works, but no construction joint may be inserted without the written approval of the Engineer's Representative. All reinforcement required by the Engineer's Representative as a consequence of the position selected for any proposed construction joint shall be provided by the Contractor at his own cost, unless, in the opinion of the Engineer's Representative, the joint is absolutely necessary and there is no alternative position for such joint. When work is resumed against a horizontal surface which has hardened or recently set, the surface of the concrete shall be roughened by hacking and all laitance, loose and porous material and poorly compacted concrete shall be removed from it. When reinforcement or fittings project from the older concrete, these shall be carefully cleaned, utmost care being taken not to break the bond, and freed from all adherent coatings of concrete and other matter likely to reduce the bond between the steel and the concrete about to be poured. The surface of the concrete (and steel if applicable) shall then be swept clean, brushed with a steel wire brush to remove all loose material, saturated with water, thoroughly cleaned and all surplus water removed. A 12mm layer of stiff, freshly mixed mortar containing the same proportions of cement and fine aggregates as the grade of concrete used, shall be applied to the damp surface of the concrete immediately before concreting commences and the fresh concrete carefully pounded into it without delay. When work is to be resumed against a vertical face which has hardened or recently set, the surface of the concrete (and projecting steel and fittings if any) shall be treated exactly as described above for horizontal surfaces, but the application of the 12mm layer or mortar shall be omitted and the fresh concrete shall be thoroughly compacted against the damp vertical surfaces after the final saturation with water and the final thorough cleaning. 43 All costs incurred in complying with the requirements of this clause shall be deemed to be included in the tendered rates for concrete. JOINTS TO PREVENT BONDING OF ADJACENT SURFACES 2020. Where it is specified on the drawings that a joint is to inserted to prevent bonding between two adjacent parts of the structure, the Contractor shall insert two layers of approved building paper between those parts as specified. The paper shall be tailored to fit the surfaces of the structure in the positions accurately without any folding or wrinkling, and cut overlapping edges shall be covered with adhesive tape to prevent any turning or movement during concreting operations. Throughout the area of the joint, there must be not less than two thicknesses of approved waterproof building paper. Concreting operations and pounding etc., shall be carried out carefully to ensure that no damage shall be done to the paper. SURFACE FINISHES 2021. All concrete surfaces not requiring shuttering shall be smooth finished with approved floats to give a dense surface with a minimum of cement and fine materials being brought to the surface. The top surface of deck slabs shall be tamped to a smooth finish, aided by floats if necessary, to the levels, falls and cambers shown on the drawings or as instructed. The tamping shall not be done to the extent of bringing an excess of fine materials to the surface. Shuttered surfaces of work in mass concrete which will always be in contact with the ground and more than 0.5 meter below finished ground level on the external surfaces of abutments and piers may be cast against sawn timber shuttering. All other surfaces, including all reinforced work and all precast and prestressed, shall be cast against steel or planed timber formwork. Any surfaces, irrespective of the shuttering employed, which show honeycombing or voids shall be made good by cutting back the concrete to behind the reinforcement in the case of reinforced work or to such depth as the Engineer's Representative may specify in the case of mass work, and in either case to sufficient depth to remove all defective concrete, but no repair work shall be started until after the defective surfaces have been inspected by the Engineer's Representative. The cut shall be slightly belled to ensure that the new surface will be keyed to the sound concrete, and the new surface will be cast in accordance with the requirements of this specification and against shuttering which has been carefully aligned with the sound concrete on either side and tightly secured in position by wedging etc. All exposed concrete surfaces shall be fair finished to the entire satisfaction of the Engineer's Representative. All concrete surfaces shall be protected from damage and disfigurement due to the subsequent pouring of concrete or the carrying out of other work in the vicinity or any cause whatsoever, and the Contractor shall remove all blemishes and repair all such damage to the satisfaction of the Engineer's Representative. All costs for making good honeycombed and defective concrete and repairing damaged surfaces shall be deemed to be included in the rates for concrete and shuttering inserted in the Bill of Quantities. CURING OF CONCRETE 2022. (1) GENERAL During curing of the concrete, all precautions shall be taken to ensure a slow heat evolution and the absence of cracks. The temperature of the hot concrete surfaces should not be subjected to sudden changes by spraying of cold water and the concrete must be protected from sunshine and wind. Freshly placed concrete must be protected from rain. 44 If low heat portland cement is preferred, the cement shall conform to the requirements of B.S.1370. (2) WATER CURING Very great importance is attached to the proper curing of the freshly placed concrete and the Contractor must ensure that is effectively done. All newly placed concrete shall be protected from the effects of rain, drying winds and the sun by suitable screens of damp hessian, or damp sand after the concrete has hardened sufficiently to support them directly without marking. The ends and sides of the screens shall be held down at the edges to prevent draughts from getting underneath. As soon as the concrete has hardened sufficiently to support the coverings without marking. It shall be covered with clean sacks, hessians, or a 50mm thick layer of clean sand or other approved material which shall be kept continuously in a wet condition by frequent spraying with fresh clean water. Where the concrete to be cured is enclosed by shuttering, the shuttering shall be covered with clean sacks or hessian which must be kept continuously in a wet condition When the shuttering is removed, the damp hessian or sacks shall be hung directly around the concrete member and kept continuously wet by spraying with clean fresh water. Providing that the shuttering has been covered with approved mould oil which will prevent the timber from absorbing water from the concrete, the time that the concrete remains in formwork under the conditions herein specified shall count as part of the curing period. Curing of all concrete shall continue for at least 7 days, or as directed by the Engineer's Representative, or as otherwise specified. On no account must the surrounding sacks, hessian, etc., be allowed to dry out during the curing period. The cost of curing shall be deemed to be included in the tendered rates for concrete (3) RESINOUS CURING As an alternatived method of curing, the surface may be protected, where approved by the Engineer's Representative by treating with an approved resinous curing compound, mechanically sprayed on the surface of the finished concrete at a rate approved by the Engineer's Representative as soon as it is possible to produce a membrane of uniform thickness. Unless otherwise directed by the Engineer's Representative, the compound shall be applied immediately after completion of the laying and finishing of the concrete. Any groove over a joint shall be protected from the entry of curing liquid. FORMWORK 2023. (1) GENERAL All Formwork shall be adapted in every respect to the structure and to the required surface finish for the concrete. It shall be fixed in perfect alignment and securely propped and braced so as to withstand without displacement, distortion or movement of any kind the weight of construction and the movement of persons, materials and plant. It shall be sufficiently watertight to prevent any loss of liquid from the concrete and shall be capable of being removed without shock, vibration or damage to the concrete. Where wrot shuttering is specified, the faces to be in contact with the concrete shall be planed perfectly smooth and true, to form in all the surfaces, curves or shapes specified and joints shall be planed and perfectly watertight. Where rough shuttering is specified the faces to be in contacted with concrete shall be planed smooth and true to form. All joints must be true and perfectly tight. 45 All Formwork for new lifts of concrete shall be tightly and accurately fitted against the concrete already cast to ensure that the surface of the new work will be quite flush and in line with that of the old. Wedges and clamps shall be used wherever practicable instead of nails and where it is proposed to employ mechanical vibration the formwork shall be strengthened accordingly by increasing the number of bracing and props, nailing wedges in position and using screws instead of nails where necessary. Particular care shall be taken to ensure that joints remain tight during the process of vibration. All forms for beams and kindred members shall be designed and constructed so that the sides may be removed without disturbing the bottom boards or supports thereto. The bottom of each form shall be set with a camber of l/300th of the span or as otherwise specified or required according to the dimensions of the beams. The supporting struts shall be adjusted and securely fixed in position by approved means. Formwork for encasing steel joists shall be suspended from the joists to relieve the concrete of dead-load stresses. Unless otherwise specified, fillet strips shall be fixed in the shuttering to form a chamfer 12mm by 12mm on all external corners of the finished work. Should the Contractor wish to erect the formwork by passing ties through the work, or embedding bolts therein, he must first obtain the approval of the Engineer's Representative and when seeking such approval, shall forward full details of the type of fitting proposed for use, and show how it will be employed in the work. No type of fitting will be permitted which cannot be removed easily after use or which does not allow easy and effective making good of the concrete surface. The use of wires, etc., requiring subsequent cutting into, and plastering over, of the concrete will not be permitted. Where steel shuttering is to be used, it shall be of approved manufacture and panels shall fit tightly and accurately to form a true surface and joints which will not allow the escape of liquid from the concrete. All rivet and bolt heads must be countersunk on the inside face and finished flush so as to leave no mark on the resulting concrete surface. The provisions for timber shuttering specified above shall also apply to steel shuttering as applicable. If metal forms are used, the metal shall conform to the provisions of the B.S.4360. For prestressed units the additional 10KN/m² shall be added to the weight of the wet concrete in the design of horizontal areas of the formwork. All side forms for the prestressed units shall be eased as early as possible and the soffit forms shall permit deformation of the member when the prestress is applied. The formwork should be designed to withstand the additional forces due to the vibrations during concrete placing. The soffit shutter should be adequately supported to prevent any settlement which might cause cracking of the concrete. On the soffit shutter, provision should be made for the elastic shortening of the concrete under prestress. An upward camber shall be given to ensure that the girders do not sag under working loads. The Contractor shall make measurement before and after concreting each section, and submit the results to the Engineer. 46 The Contractor shall notify the Engineer in advance of the time he proposes any adjustments to the forms prior to concreting next section, should any adjustments be needed. All surfaces of the formwork which will come into contact with the wet concrete shall be painted with an approved non-staining mould oil, to prevent adhesion between concrete and formwork. The mould oil shall be insoluble in water, unharmful to the concrete, non-flaking and shall not be removable by rain or wash-water. The Contractor shall ensure that the oil shall be kept from contact with the reinforcement or embedded fittings. Before placing any concrete, all shavings, loose binding wires, soil, rubbish and all foreign matter shall be removed from the formwork and the formwork shall be carefully and thoroughly washed with water. Loose planks shall be incorporated in the bottom of panels of shuttering to facilitate the removal of rubbish from the section to be concreted, as necessary. No concrete shall be placed until the Engineer's Representative has inspected the formwork and props and given his approval to do so. (2) STRIPPING No formwork shall be removed without the prior approval of the Engineer's Representative and in no case shall any shuttering or props be removed before the periods mentioned in Table II-4 have elapsed after placing the concrete:TABLE II-4 FORMWORK MINIMUM STRIPPING TIME TYPE OF WORK PART OF WORK ORDINARY PORTLAND CEMENT CONCRETE SLABS SOFFIT BOARDS PROPS 5 DAYS 14 DAYS BEAMS SIDE BOARDS BOTTOM BOARDS PROPS 3 DAYS 14 DAYS 28 DAYS COLUMNS WALLS, PIERS AND ABUTMENTS 7 DAYS MASS CONCRETE REINFORCED CONCRETE 3 DAYS 7 DAYS Where props are to be left in position under slabs and beams the formwork shall have been made in such a fashion that it can be removed without disturbing the props in any way, otherwise it must be left in position for the full period that the props are left in position. The formwork shall be removed by gradual easing without jarring and only under competent supervision. Before removal of the shuttering, the concrete shall be examined and removal shall only be proceeded with if the concrete has attained sufficient strength to 47 sustain all the loads to which it will be subjected. The Contractor shall be responsible for any injury or damage to the work caused by or arising out of the removal of formwork and props and any advice, permission or approval given by the Engineer's Representative, relative to the removal of formwork and props shall not relieve the Contractor of this responsibility. (3) MEASUREMENT AND PRICES FOR FORMWORK All timber or metal moulds inclusive of all necessary supports and stagings (unless billed separately), bolts, nuts, straps, clamps, wedges and other fixings also all cutting and waste and cost of all labour and materials in making, erecting and removing the formwork and for any other work required to construct the forms to shapes and dimensions shown on the drawings or as directed by the Engineer, shall be included in the rate for formwork. Formwork shall be measured as the nett area in contact with the finished concrete surface. No measurement will be allowed for formwork for temporary construction or daywork joints. REINFORCEMENT SCHEDULES 2024. Schedules of steel reinforcement giving the location, bending, diameter, length and number of the various bars may be incorporated in the drawings or prepared on separate sheets. These schedule have been prepared for the convenience of the Contractor, but their accuracy is not guaranteed. It will be the Contractor's responsibility to check all the schedule against the drawings and to satisfy himself as to errors, omissions and all other things regarding their suitability for the work before such work is put into operation. All discrepancies shall be brought to the notice of the Engineer's Representative immediately and well in advance of placing the reinforcement in the works. Where new schedules are required or existing ones require to be amended, the Contractor shall prepare such new or amended schedules in accordance with B.S.4466 (1969) and forward three copies of each to the Engineer's Representative well in advance of placing reinforcement in the works. The Contractor shall be responsible for his own ordering sheets. The cost of checking all new and amended schedules as specified above shall be deemed to be included in the tendered rates for reinforcement. BENDING AND FIXING OF REINFORCEMENT 2025. (1) GENERAL All reinforcing bars shall be carefully bent with an even and gradual motion to the correct dimensions by experienced steel benders and in a manner which will not injure the material. In particular, no reinforcement shall be heated before bending. Unless stated to be otherwise in the schedules, all bends and bending shall be in accordance with B.S. 4466. Unless otherwise directed or authorized by the Engineer, the number, size, form and disposition of all reinforcing bars shall be strictly in accordance with the drawings. Bars generally must be of the required lengths and lapping and welding of main bars will not be permitted unless so indicated on the drawings. All reinforcements shall be rigidly in position. To prevent displacement before and during concreting the bars shall be bound together at all intersections with annealed soft black iron wire of 1.5mm diameter and the ends of the wire shall be turned inwards, away from the surface of the member. 48 Where necessary, upper layers of reinforcement shall be maintained in position by "chairs" made from bars of suitable size and supported on the lower layers of reinforcement. The chairs shall be securely tied to both upper and lower layers of reinforcement and shall be of such shape as will produce a frame of sufficient stiffness. Details of the chairs showing their size, bending and disposition in the work shall be forwarded to the Engineer's Representative for his approval before incorporation into the work. The use of temporary supports will not be permitted. Any parts of metal supports that are left in place within 50mm of an exposed surface of the concrete shall be non-rusting metal or coated with non-rusting metal. Galvanizing of such parts will be acceptable provided the weight of the zinc coating per 1000cm² of actual surface shall average not less than 56 grams and no individual specimen shall show less than 50 grams. Splicing of reinforcement steel, except where shown on the drawings or approved by the Engineer, will not be permitted. Splices shall have a length sufficient to develop the full strength in bond of the bar, and shall not be made at points where the section is insufficient to provide at least 50mm between the splices and the nearest adjacent bar or the surface of the concrete. At splices, the bars shall be rigidly clamped or wired together in a manner acceptable to the Engineer. Where practicable, reinforcement shall be assembled as rigid cases before placing in the formwork. Concrete blocks shall be used to maintain the correct distance between the reinforcement and the formwork i.e. to maintain the correct concrete cover to the reinforcement. Such blocks shall not exceed 50mm in width nor 50mm in length and their thickness shall be exactly that required to give the cover specified on the drawings. Binding wires shall be securely embedded into each block to permit adequate fastening to the reinforcing bars. The number and location of the blocks used in the work shall be to the satisfaction of the Engineer's Representative. All reinforcement shall be perfectly clean and free from loose scale, rust, oil, grease and any other matter which might reduce the bond between the steel and the concrete. Loose pieces of binding wire and other foreign matter shall be removed. The Contractor shall provide adequate scaffolding, boards, runways, etc., to ensure that the reinforcement is not displaced during concreting by being walked upon. No runways, etc., shall be supported on the reinforcement. The ends of bars which will project beyond the limits of the section being concreted shall be adequately supported and protected to prevent them from being damaged or,removed by collision, wind, or any other cause which might result in a reduction of the bond between the steel and concrete or any movement of those portions of the bars lying within the freshly poured concrete. No concrete shall be poured until the Engineer's Representative has inspected and approved the reinforcement and the arrangements for placing the concrete and the Contractor has ensured that competent steel-fixers and carpenters are in attendance See Clause 2015. (2) ELECTRIC ARC WELDING Electric Arc Welding may be permitted for joining bars, provided the approval of the Engineer has been obtained, and for work of this type the use of electrodes of the covered alloy or shielded arc type will be permitted, provided that they conform to the requirements for Class A electrodes, as described in B.S.639 "C"Covered Electrodes for Metal Arc 49 Welding Wrought Iron and Mild Steel". Workmanship shall conform to the general requirements of B.S.693 (1960), 1856 (1964) and 2642 (1965) as applied to general building construction. All such connections shall be butt-welded with standard Double V or Double U welds. PART C - PRECAST CONCRETE UNITS (NOT TO BE PRESTRESSED) PRECAST CONCRETE UNITS 2026. GENERAL The requirements of the foregoing clauses for concrete will apply to all precast work where applicable and in addition the following special clauses are to be observed. Rapid hardening portland cement shall conform to the requirements of B.S.12 and may only be used with the approval of the Engineer or his Representative. (1) FORMWORK All formwork is to be such as to ensure true arris and sound surfaces and metal lining formwork will generally be required by the Engineer. (2) DIMENSIONS Units are to be formed to the dimensions and tolerances shown on the drawings. (3) MOULDS Units are to be made in strongly constructed moulds which are closely jointed, perfectly smooth and true in alignment. The moulds must be constructed so that no bulging or distortion can occur during consolidation of the concrete, and should be fitted with suitable fastenings to facilitate easy removal without injury to the units. (4) MANUFACTURE The Contractor shall provide facility for the Engineer or his Representative to carry out any tests or inspection during all stages of manufacture as may be required to ensure the quality and soundness of the units. The proposed method of manufacture is to be approved by the Engineer before production of the units commences. All units shall have impressed upon them in some convenient position the date of manufacture and such distinguishing letters as the Engineer may direct. (5) CURING The moulds will be struck at such a time so that the units are not subject to risk or damage or distortion. All concrete shall be kept damp for seven days and protected from the direct rays of the sun for a further period of 14 days. This can be achieved by covering roof or tent. (6) CURING AND LIFTING OFF MOULDS 50 Concrete surfaces and moulds shall be protected during casting and for 14 days thereafter from the effects of sun, wind and rain etc., and the concrete shall be cured for a period of 7 days after casting, all to the satisfaction of the Engineer's Representative. The striking of moulds shall be without damage to or distortion of the concrete surfaces. (7) REJECTED UNITS Units which show signs of honeycombing or are badly pitted on any of the faces or are otherwise defective will be rejected and must be immediately broken up. (8) STACKING Units are to be stacked to the approval of the Engineer's Representative and arranged so that they are available for use in order of age. (9) TRANSPORT AND DELIVERY The methods of transporting and delivery of the units to site must be such that the units are protected from severe shock and any damage whatsoever. The proposed methods of loading, transporting and off loading must be approved by the Engineer or his Representative before delivery commences. (10) STANDARD FOR PRECAST CONCRETE WORK Precast concrete goods, whether they have been purchased for use in the works, or manufactured by the Contractor shall be in accordance with the requirements of the following British Standards, as applicable: B.S.340: Precast Concrete Kerbs, Channels, Edgings and Quadrants B.S.368: Precast Concrete Flags B.S.556: Concrete Cylindrical Pipes and Fittings B.S.1194: Concrete Porous Pipes B.S.2028: Precast Concrete Blocks (11) RECONSTRUCTION OF FAULTY WORK Should any portion of the work give evidence, in the opinion of the Engineer or his Representative that the concrete is of inferior quality, insufficiently compacted, segregated or improperly deposited and rammed in the forms or that any of the reinforcement or fittings has been omitted, incorrectly placed or subsequently displaced or that it suffers from any defect, omission or injury from any cause whatsoever which may adversely affect the strength or durability of the construction, the Contractor shall, on the written instructions of the Engineer, remove and reconstruct that portion of the work in such manner as the Engineer shall direct or approve to ensure that the requirements of this specification are fulfilled. No repairs shall be made to any faulty work until it has been inspected by the Engineer's Representative and his permission to proceed obtained. All costs involved in the reconstruction of faulty work shall be borne by the Contractor. 51 PART D - CEMENT MORTARS AND GROUTS CEMENT MORTARS AND GROUTS 2027. Mortar and Grouts shall be composed of portland cement, sand and water satisfying the requirements of this specification and mixed together in the proportions indicated in Tables II-5 and II-6. The cement and sand shall be measured by volume in gauge boxes of approved size. The common size is 0.03m³. The gauge boxes shall be filled with the respective materials without compaction, and struck level, proper allowance being made for any bulking of the sand due to moisture content. Mixing shall be done in an approved mechanical mixer, the amount of water added being just sufficient to give the consistency and workability desired by the Engineer's Representative for the use to which the mortar is to be put. Mixing shall be carried out as specified for concrete. Hand-mixing of mortar will only be permitted where very small quantities are required and the approval of the Engineer's Representative has been obtained. In such cases, the dry sand and cement shall first be mixed together by turning over with a clean shovel or trowel on a clean steel platform or other approved surface until a mixture of uniform colour has been-obtained. Water shall then be added, a little at a time, the mixture being turned over after each addition, until a homogeneous paste has been obtained. This process shall be repeated until the required consistency has been obtained. Only perfectly clean implements and surfaces shall be used in hand-mixing and care shall be exercised to ensure that no cement is washed away during the addition of the mixing water. All mortar must be in its final position in the works within 30 minutes of the initial mixing together of the sand, cement and water. TABLE II - 5 MORTAR - CEMENT/SAND MIXING PROPORTIONS PROPORTIONS BY VOLUME MORTAR QUALITY NOMINALMI X PORTLAND CEMENT SAND M1 1:1 1 1 M2 1:2 1 2 M3 1:3 1 3 M4 1:4 1 4 NOTE: Allowance should be made for moisture content of sand. BUILDING IN FOUNDATION BOLTS,FITTINGS KERBS ETC. 2028. All foundations, bolts, fittings, kerbs, etc., are to be built into the work as concreting proceeds by supporting them either from the formwork in their correct position or grouted into recesses cast in the work as specified or directed by the Engineer or his Representative. Recesses to accommodate such item shall be cast against properly constructed formwork and in no circumstances shall they be formed by cutting out green concrete. Similarly, no fittings shall be positioned in the works by inserting into concrete which has commenced to set. 52 The Contractor shall set the metal work which is to be embedded into position before concreting. All items shall be carefully cleaned, placed and firmly secured to ensure that it will not be displaced during concreting operations. Anchor bolts shall be placed by means of templates supplied by the Contractor. All threads shall be carefully greased after the bolts are firmly in position, but prior to concreting. The position of all embedded items shall be carefully observed during and at the completion of concreting operations to ensure they are in the proper position upon completion of the work. EMPLOYMENT OF CONCRETE MORTARS AND GROUTS 2029. The grade of concrete, mortar or grout to be used in the various parts of the work shall be as specified on the drawings. Where no specification is given on the drawings as to the grade of concrete, motar or grout to be used, it shall then be as given in the following Table II-6 below. TABLE II-6 MORTAR FOR GROUTING MIX PROPORTIONS GRADE MIX USE M1. 1:1 GROUTING IN HOLDING DOWN BOLTS, BEDDING GIRDER BEARINGS; PACKING BETWEEN STEEL JOISTS AND EXISTING DECKS, MAKING GOOD CONCRETE SURFACES, PIPE JOINTING ETC M3 M4 1:3 1:4 BEDDING & JOINTING PRECAST KERBS STONE PITCHING The materials shall be mixed to a consistency suitable for the purpose intended. All mortar shall be used within 30 minutes after the mixing water has been added. Admixtures of hydrated lime, fire clay, diatomaceous earth or other approved inert material may be used in the mortar to facilitate workability if the Contractor elects. The amount of admixture to be added shall be of the quantity permitted by the Engineer. PART E - GRANOLITHIC CONCRETE FLOOR FINISHED CEMENT 2030. All cement used in the works shall be from an approved source, and shall comply with the latest appropriate Nigerian Industrial Standards or British Standards. The type of cement to be used in portland high alumina cement: is to comply with the latest revision of B.S. 915. The provisions of foregoing clauses relating to ordinary portland cement shall apply to high alumina cement where applicable. AGGREGATES 2031. Concrete shall be made with specially selected aggregates of a hardness surface texture and particle shape suitable for use as a wearing finish to floors, all to be to the latest B.S.1201. All aggregates fine and coarse shall comply with the requirements for aggregates for concrete work and shall be subject to the approval of the Engineer's Representative. GRANOLITHIC TOPPING 53 2032. Granolithic Topping shall be composed of portland high alumina cement, fine aggregate as specified and granite chippings as specified. The water/cement ratio shall not exceed 0.45 and shall be kept as low as possible compatible with workability. Typical mixes are: 2 parts of portland high alumina cement to 5 parts of fine granite chippings by volume, graded as to B.S.1201 (1954). Or 1 part of portland high alumina cement to 1 part of sand, to 2 parts of fine aggregate, the aggregate passing a 150 microns (100 mesh) sieve but free from dust. THE SUB-FLOOR 2033. The Granolithic Topping shall be laid and floated on a new concrete sub-floor within 12 hours of laying the latter. Where the sub-floor consists of an existing concrete surface, this shall be hacked, thoroughly cleaned, wetted and brushed over with cement grout prior to laying granolithic topping. LAYING 2034. The Contractor shall ensure that successive trowellings are applied at appropriate times by skilled workmen. The topping shall be rendered with a wood float and struck off with a steel trowel after the set has commenced. The topping shall be laid to a thickness of 25mm to 40mm Slightly increased thicknesses are necessary when the topping is laid on matured concrete sub-floors. The toppings shall be divided into bays not larger than about 3.5m. x 3.5m. laid alternately or as directed. CURING 2035. Granolithic topping shall be cured for a period of seven days after laying all as for normal concrete. RETARDATION OF DUSTING 2036. A solution of calcium chloride added integrally or a solution of sodium silicate or other surface hardener as approved by the Engineer's Representative shall be used to retard dusting. The amount of solution added shall be as specified by the respective manufacturers or as directed by the Engineer's Representative. CARBORUNDUM FINISH 2037. For non-slip finish to treads of stairs and to landing surfaces, carborundum thickly sprinkled in the proportion of 1.50Kg. per square meter of paving shall be used, being well trowelled in before the granolithic sets. GRANOLITHIC MONOLITHIC TOPPING 2038. Where granolithic monolithic topping is ordered, it shall be applied in the following manner: Concrete shall be laid to finished level and while it is still wet and soft shall be sprinkled with a mixture of 1 part of chippings to 1 part of high alumina portland cement mixed together in a dry state and applied at a rate of spread of 8Kg/m² of surface. The chippings shall consist of a suitably graded material 6mm to dust with not more than 20% content of fine material. This mixture shall be tamped-in with a wooden float and twice trowelled with a steel trowel to a smooth and fine finish. After the topping is dry it shall be treated with one application of 10% solution of silicate of soda. DAMP PROOFING 54 2039. MISCELLANEOUS The surface to be damp proofed shall be primed and then thoroughly mopped with waterproofing asphalt. The mastic asphalt shall be laid in two courses in the manner described in British Standard Code of Practice CP 144 Part 2. Joints shall be staggered at least 150mm between courses. When the first mopping of asphalt has set sufficiently, the entire surface shall then be mopped with a second coating of hot asphalt. Special care shall be taken to see that there are no skips in the coatings and that all surfaces are thoroughly covered. The two sides of all joints shall be intimately bonded. The surfaces of any gullies and other features with which the waterproofing will be in contact shall be clean and painted with bitumen. The cost of all materials, labour, tools, equipment and incidentals, and for doing all the work involved in applying the damp proofing, complete in place as shown on the drawings or as directed by the Engineer, shall be deemed to be included in the tendered rates for concrete. (Clauses 2040 – 2999 inclusive not used) 55 SPECIFICATION SECTION III - CONCRETE: PRESTRESSED 1 SECTION III - PRESTRESSED CONCRETE GENERAL 3000. In addition to any other relevant clause of this Specification, the following shall be deemed to apply in particular to prestressed concrete work, and shall be read in conjunction with all other relevant clauses (especially those referring to mass and reinforced concrete) of the conditions of Contract and this Specification. This work shall consist of prestressing precast concrete by furnishing, placing and tensioning of prestressing steel in accordance with details shown on the drawings, and as specified in the specifications. This work shall include the furnishing and installation of any appurtenant items necessary for the particular prestressing system to be used, including but not limited to sheaths, anchorage assemblies and grout used for pressure grouting sheaths. The Contractor shall submit to the Engineer for his approval plans and working drawings. The working drawings, of the prestressing system shall contain details and substantiating calculations of method and materials the Contractor proposes to use, in the prestressing operations including any additions or rearrangement of reinforcing steel from that shown on the drawings. Such details shall outline the method and sequence of stressing and shall include complete specifications and details of the prestressing steel and anchoring devices, working stresses, anchoring stresses, type of sheaths, and all other data pertaining to the prestressing operation, including the proposed arrangement of the prestressing steel in the member. Working drawings shall not exceed 594mm x 841mm in size and each drawing and calculation sheet shall include the job site, name of the structure as shown on the contract drawings. Working drawings shall be submitted sufficiently in advance of the start of the affected work to allow time for review by the Engineer's Representative and correction by the Contractor of the drawings without delaying the work. In no case shall such time be less than six weeks. Throughout the prestressing work the Contractor shall employ on the works at least one suitably qualified engineer who shall be experienced in the systems of prestressing being used. His duties shall be as follows: (1) Supervision of the storage and fixing of prestressing components (2) Calibration of prestressing equipment (3) Supervision of tensioning operations (4) Supervision of grouting operations (5) Compilation of tensioning records (6) Such other duties as the Engineer's Representative may direct. All personnel operating the stressing equipment shall have been properly trained in its use. In addition to the normal precautions against accident which should be taken at all times for the whole of the Works, special precautions shall be taken when working with the tendons which have been tensioned or are in the process of being tensioned. The personnel should not stand in line with the tendons, their anchorages or jacking equipment. Simple protective measures such as stout timber shields sheathed with steel should be placed in line with tendons and behind the jacks to protect personnel passing in the usual course of their duties, if applicable. 56 PART (A) - MATERIALS CEMENT 3001. The Cement shall be rapid-hardening portland cement in accordance with the latest B.S. 12 with all latest amendments or portland blast furnace cement conforming to the requirements of B.S.146 with all latest amendments. The use of high alumina cement will not be permitted. The cement is to be packed in waterproof bags or steel drums and delivered to the site in first class condition. Each consignment is to be clearly marked with the date of manufacture and the date of arrival. The drums of cement are to be lifted and handled with care so as to avoid damage; and stored in a damp free location ready for use. The consignment is to be used in the order of arrival to the site. Cement is to be stored on site under cover from the weather and is to be protected from deterioration. Each drum is to be fully used once opened, and no cement is to be stored in drums which have previously been opened. AGGREGATES 3002. All concrete aggregates to be used for prestressed concrete work shall be properly cleaned and graded strictly to the requirements of the latest B.S. No. 882 to which end the Contractor shall provide washing and grading equipment on the site. Materials which are rejected from the grading process may be used up in 10 N/mm2 grade concrete in other parts of the works at the discretion of the Engineer's Representative. Any rejected material is to be removed forthwith from the site by the Contractor at his own expense. (1) FINE AGGREGATE Fine Aggregates shall consist of naturally occurring sand obtained from fresh water river deposits approved by the Engineer's Representative. The grading of sand particles shall satisfy the percentages stated for Zones 1 or 2 in B.S. 882, and as given in Table III-1 (2) COARSE AGGREGATE Coarse Aggregate shall consist of natural gravel or crushed granite rock obtained from a source to be approved by the Engineer or his Representative. The grading of coarse aggregate particles shall strictly satisfy the percentages for l9.0mm - 4.76mm nominal size stated in B.S. 882 as given in Table III-1 with a content not exceeding 1% passing the 2.36mm sieve size. 57 TABLE III-1 GRADING OF FINE AND COARSE AGGREGATES PERCENTAGE PASSING AGGREGATE FINE AGGREGATE ZONE 1 SIEVE SIZES 150 m 300 m 600 m 1.2 mm 2.4 mm 4.76 mm 9.5 mm 19.0 mm 0-10 5-20 15-34 30-70 60-95 90100 100 - - 8-30 35-59 55-90 75-100 100 - - 25-55 95-100 100 FINE AGGREGATE ZONE 2 COARSE AGGREGATE 0-10 38.1 mm 90100 - - - - 0-1 0-10 (3) TESTS Samples of the chosen aggregates shall be delivered to site and prepared by the Contractor at his own expense. Methods of testing shall be in accordance with Clause 2003 (3) of these specifications. Samples of each aggregate are to be submitted by the Contractor to a testing authority approved by the Engineer or his Representative. The Contractor shall obtain from the Engineer or his Representative written approval of the tests and types of aggregate chosen, together with the proposed arrangement for use on the works. WATER UNTENSIONED REINFORCEMENT 3003. The Water to be used for concrete manufacture shall be clean water free from chemical or organic impurities and dissolved salt solutions, which may have a harmful effect on the concrete. The Ph value shall range from 6.8 - 7.5. Periodic test on water used for concrete should be carried out on site in accordance with B.S. 3148. 3004. Such reinforcement is to be of mild steel or high yield steel as specified in the drawings. Mild steel reinforcement shall be rolled mild steel bars as for reinforced concrete works and shall comply in all respects with the latest B.S. 4449. Untensioned high-tensile steel reinforcement shall be hard drawn pre-stressing wires as specified hereunder, hot rolled high yield deformed bars complying with B.S. 4449 or cold worked deformed bars complying with B.S. 4461. PRE-STRESSING STEEL 3005. For the purpose of this specification the term "Pre-Stressing Tendon" or "Tendons" shall mean a single wire, bar or strand or a number of wires or strands grouped into a cable or a group of bars. (1) The prestressing steel should be one of the following: (I) Plain hard-drawn steel wire complying with the requirements of B.S.2691, "Steel for prestressed concrete, Part 1 Plain hard-drawn steel wire". (II) Indented or crimped hard-drawn steel wire complying with the requirements of B.S.2691 in all respects except that for the bend test. 58 (III) High tensile steel bars of open hearth steel with sulphur and phosphorus contents each below 0.05 per cent. Bars whether plain or deformed should have a tensile strength of not less than 926 N/mm2 with a 0.2 per cent proof stress of not less than 75 per cent or more than 92 per cent of the actual ultimate strength. For methods of testing see B.S. 18, "Tensile testing of metals". (IV) Such other wires, strand, or bars having properties not inferior to those laid down in B.S. 2691 or Sub-Clause (III) above respectively. Seven wire steel strand for prestressed concrete shall comply with B.S. 3617. Notwithstanding the foregoing strand shall comply with the following: (1) It shall contain no welds (2) It shall be at least low relaxation strands complying with Section 3 of B.S. 3617. TABLE III-2 PHYSICAL PROPERTIES OF PRESTRESSING STEEL PRESTRESSED STEEL Wire NOMINAL DIAMETER mm BREAKING LOAD KN (1000kgf) MINIMUM ELONGATION TO FRACTURE IN GAUGE LENGTH 7 65 (6.63) to 69 (7.038) 6% 5 35 (3.57) to 38 (3.876) 6% 4 25 (2.55) 6% Strands 8 10 13 22 67 94 160 480 (6.834) (9.588) (16.320) (48.960) 10% 10% 10% 10% Bars 25 28 650 800 (66.30) (81.60) 12% 12% REMARKS Tensile Testing is to be carried out as per * BS 5896 Mechanical Testing of Steel Wires. Additional Mechanical Properties which are not specified in this Table shall be subject to the approval of the Engineer. All bars in any individual member shall be of the same grade. When bars are to be extended by use of couplers, the assembled units shall have a tensile strength, of not less than manufacturer's minimum guaranteed ultimate tensile strength, when tested in accordance with Test Method No. California 641, or equal. Failure of any sample to meet this requirement will cause for rejection of the heap of bars and lot of couplers. The location of couplers in the member shall be subject to approval by the Engineer. 59 (V) The Engineer may permit the use of prestressing steel manufactured to standards equivalent to those mentioned above provided that minimum strength requirements are complied with, as indicated in this specification. (2) CERTIFICATES Copies of Manufacturer's Test Certificates and stress/strain diagrams shall be furnished by the Contractor and given to the Engineer or his Representative for each consignment of prestressing steel reinforcement. These certificates must be submitted to and approved by the Engineer or his Representative before the prestressing steel reinforcement is used in the works. (3) DELIVERY All prestressing steel shall be protected against physical damage and rust or other exposures that will result to corrosion at all times from manufacture, to grouting or encasing in concrete. Prestressing steel that has sustained physical damage at any time shall be rejected. The development of visible rust or other results of corrosion shall be cause for rejection, when ordered by the Engineer. Prestressing steel shall be packaged in containers or shipping forms for the protection of the steel against physical damage and corrosion during shipping and storage. A corrosion inhibitor which prevents rust or other results of corrosion shall be placed in the package or form, or shall be incorporated in a corrosion inhibitor, carrier packaging material type, or when permitted by the Engineer, may be applied directly to the steel. The corrosion inhibitor shall have no deleterious effect on the steel or concrete or bond strength of steel to concrete. Packaging or forms damaged from any cause shall be immediately replaced or restored to original condition. The shipping package and the form shall be clearly marked with a statement that "PACKAGE CONTAINS HIGH-STENGTH PRESTRESSING STELL, PLEASE HANDLE WITH CARE." The type, kind and amount of corrosion inhibitor used, including the date when placed, safety orders and instructions for use shall be indicated. (4) STORAGE Coils and bundles of prestressing steel shall be stored flat on a floor raised off the ground and under full cover from the weather. They shall be protected from damage, oil, corrosion or any deleterious matter, and shall not be opened until required. Before being manufactured into prestressing cables, the wire shall be cleaned free from loose rust and any deleterious matter, and inspected by the Engineer's Representative for approval. Prestressing steel reinforcement which shows signs of pitting or has any surface defects such as splits, roughness or necking is not to be used, and any lengths of wire or strand so affected are to be cut out of the coil and rejected. (5) TESTS Tests on prestressing steel in addition to those of the manufacturer, may be required by the Engineer and the Contractor is to make all arrangements to supply samples for testing to a nominated testing authority. SHEATHING 3006. Sheathing to prestressing tendons is to be of corrugated type such as "hydrarigid" or similar, approved by the Engineer. Sheathing enclosures for prestressing steel shall be mortar-tight, and accurately placed at the locations shown on the drawings or approved by the Engineer. All sheathings or anchorage assemblies shall be provided with pipes or other suitable connections for the injection of grout after prestressing. Sheathings for prestressing steel shall be securely fastened in place to prevent movement. 60 After installation of the forms, the ends of sheathings shall at all times be covered as necessary to prevent the entry of water or debris. The Contractor shall demonstrate to the satisfaction of the Engineer that the sheathings are free of water and debris immediately prior to installation of the steel. All sheathing for continuous structures, shall be vented over each intermediate support, and at additional locations as shown on the drawings. Vents shall be 12.5mm minimum diameter standard pipe. Connections to sheathings shall be made with metallic structural fasteners. The vents shall be mortar tight, taped as necessary, and shall provide means for injection of grout throughout the vents and for sealing the vents. Ends of vents shall be removed 25mm below the roadway surface after grouting has been completed. Grout vents shall be provided at crests and valleys in the duct profile and at intervals of not more than 15 metres in straight ducts. All sheathings for continuous structures, except sheathings in bent or pier caps, shall consist of rigid galvanized ferrous metal. Transition couplings connecting the rigid sheathings to anchoring devices need not be galvanized. At the Contractor's option, such rigid sheathings may be used in simple spans prestressed members. Rigid sheathings may be fabricated with either welded or interlocked seams. Galvanizing of the welded seam will not be required. Rigid sheathings shall have sufficient strength to maintain their correct alignment during placing of concrete. Joints between sections of rigid sheathings shall be positive metallic connections, which do not result in angle changes at the joints. Waterproof tape shall be used at the connections. Corrugated sheathing is to be delivered to the site coiled on to large diameter wooden drums, securely fastened and protected from damage, or stored straight in containers. Corrugated sheathing is to be stored on site under cover from the weather, and shall be protected from rusting, damage, oil or any other deleterious matter and shall be clean and free from all such matter before being used in the works. PART B - WORKMANSHIP CONCRETE PROPORTIONS 3007. (1) PRELIMINARY TESTS Preliminary Tests to determine the grade 50 N/mm², 45 N/mm² or 35 N/mm2 concrete mix proportions for prestressed work shall be undertaken as soon as the sources and qualities of cement, water and aggregate have been chosen. (2) PROPORTIONS The Contractor shall deliver, to a testing authority to be approved by the Engineer, sufficient quantity of cement and prepared aggregates to enable concrete cubes to be made. Such cubes shall be manufactured under laboratory conditions, using dry aggregates and proportions calculated to give the desired workability and 10% more than the average 28 days works cube strength given in Table II-3 Clause 2009. At the same time the Contractor shall arrange to make two concrete mixes on site using the same proportions of cement, water and aggregates as used in laboratory tests, with the methods to be adopted for the whole of the works. Six cubes shall be made from the second batch of concrete out of the mixer, and subsequently tested by the approved testing authority. The amount of water used for mixing under site conditions shall take into account the weight of water contained in the wet aggregates stored at the mixer and the weights of aggregates used shall be adjusted accordingly. (3) PROCEDURE The results of these preliminary tests shall give cube strengths of not less than 10% more than those stated in Table II-3 Clause 2009 in the case of cubes made under laboratory and at least the values stated in Table II-3 Clause 2009 in the case of cubes made under site conditions. 61 All cubes shall be 150mm x 150mm x 150mm and made in standard steel moulds according to the procedures described in B.S. 1881 and shall be vibrated. As a result of these tests, the mix proportions for the prestressed concrete work shall be chosen and approved by the Engineer. Thereafter these proportions shall be adhered to throughout the works and may be varied only on instructions given by the Engineer's Representative. (4) WATER CEMENT RATIO The Water-Cement Ratio shall be chosen from the laboratory tests, and shall be taken as the total weight of water added to the mix using completely dry aggregates, divided by the total weight of cement. The amount of water to be added to each batch of concrete under site conditions, shall be calculated from the results of moisture tests on the aggregates and the weight of cement used for each batch, using the same total water-cement ratio as used in the laboratory tests. No deviation from this water cement ratio shall be made except with written approval of the Engineer's Representative. Strict adherence to established water cement ratio can be maintained during the manufacture and placing of concrete by using slump value established during mix design exercise. FIELD TESTS 3008. The Contractor is to provide the following apparatus on site for the testing of aggregates and concrete mixes which, where applicable, shall comply with the requirements of B.S. 1881 and 812. 1. Sampling pans for aggregate moisture tests. 2. Electric ovens for drying out samples of wet aggregates. 3. Accurate compensating balance weighing up to 10 Kilograms with weights. 4. 12 No. steel moulds for 150mm cubes, with base plates. 5. Kango hammer vibrator for making cubes. 6. 2 No. slump cones with base plates and tamping rods. 7. 1 compacting factor apparatus. 8. Water tank for curing concrete cubes. 9. Concrete cube testing apparatus 10. Check weights for mixer weigh batchers. 11. Copper sampling tube for extracting cement samples. 12. Apparatus for testing contents of silt, clay, organic impurities in fine aggregates. 13. Airtight tins or jars for dispatch of cement samples. 14. Two sets of B.S. 410 test sieve listed below. Size mm 25 62 12.5 10 5 mm 28 37.5 600 m 300 m 150 m 15. Complete apparatus for gamma-ray inspection of grout in ducts for pre-stressing tendons. 16. 17. Cover-meter for inspection of concrete cover to reinforcement pre-stressing steel or ducts. Load cell for directly reading tension in prestressing tendons during stressing. All the equipment listed as above shall be supplied and maintained in perfect condition by the Contractor at his own expense for the duration of the works. After completion of the works all equipment shall remain the property of the Contractor. BATCHING AND MIXING 3009. All materials used for concrete manufacture shall be batched by weight. Before the casting of each prestressed beam the quantity of aggregates to be used shall be separated from the stockpiles at the mixer and thoroughly turned over by hand, to produce uniformly moist aggregate. Samples shall then be taken of each aggregate and moisture contents tests carried out to determine the percentage of water content of each aggregate by dry weight method. From these results the weights of wet aggregates and water to be used in mixing shall be calculated for the chosen quantity of cement to be used for each mix, using the dry weights proportions determined from the preliminary concrete mix design. During the casting of each beam strict control shall be maintained at the mixer to ensure that the correct weights of materials are consistently used for each mix of concrete. The workability of the concrete shall be frequently checked using the compacting factor test so that the consistency of the concrete is kept uniform. Mixes which show large variation from the workability aimed at, due to varying aggregate conditions or errors in batching, will be rejected and the necessary corrections are to be made to the mix immediately after this is observed. Stockpiles of aggregates at the mixer must always be maintained so that no fresh aggregates are fed in while casting of the beam is taking place. The mixer and adjacent aggregate stockpiles shall be placed under temporary roofing so as to be fully protected from the direct rays of the sun and rain. Where compacting factor test apparatus is not available, slump test may be used to control the consistency of the concrete being produced and placed. PLACING OF CONCRETE 3010. Casting of prestressed beams shall be carried out on specially prepared casting beds, which are to be constructed under a temporary roofing so as to be fully protected especially from the direct rays of the sun and rain. (1) VIBRATION The methods of vibration to be used shall be carefully designed to ensure full compaction of the concrete, thus producing first class appearance without subsequent patching of concrete faces. Full details of the Contractor's proposed methods of manufacturing the beams shall be submitted to the Engineer's Representative for approval. 63 (2) PRELIMINARY TESTS When a design mix has been approved by the Engineer's Representative, the Contractor is to allow for a preliminary casting of a short length of beam complete with prestressing cables and reinforcement, using the proposed methods of vibration for the whole works. (3) CASTING Each prestressed component shall be cast in one continuous operation and no construction joints will be allowed. CURING 3011. Curing of the prestressed components shall ensure a slow heat evolution in the concrete so that shrinkage cracks may be avoided. Prestressed components shall be completely covered with hessian, which shall be kept continuously wet for a period of seven days. If tensioning of the prestressing tendons takes place before this time, the hessian shall be retained in position until the period of seven days has expired. The prestressed components shall then be cured in air for a further period of seven days or enough time to achieve the necessary strength before being erected into position on the bridge. FORMWORK 3012. Formwork shall be of purpose made steel moulds or plywood panels, and shall be rigidly fastened together so that no displacement can take place during casting. Formwork shall be designed so that it can be removed without shock or damage to concrete, and must be braced and held in position so as to avoid any holes or fastenings through the prestressed component. Moulds shall be of such a nature as not to allow the concrete member to deform when the prestress is applied. The bottom portions of the moulds shall be prevented from adhering to the concrete. Subject to the approval of the Engineer's Representative, stripping of side formwork may take place 24 hours after casting or as soon as is convenient after the concrete has reached its final set. Stripping of bottom formwork shall not be carried out until after transfer of prestress to the prestressed component. SURFACE FINISH TOLERANCE 3013. Prestressed concrete work shall, unless otherwise specified, have a smooth finish on all surfaces exposed in the completed work. Surfaces which will be in contact with concrete cast in place to form a composite construction shall be purposely left very rough, in order to provide an adequate key. The valleys and ridges of any roughening system shall be transverse to the direction of stressing. 3014. The Contractor shall provide continuous, experienced supervision during all mould-assembly and concreting operations, in order to ensure that the tolerance in longitudinal dimensions for all concrete work shall remain within the following limits: (1) For Component about 9m Long ± 6mm (2) For Component about 18m Long ± 10mm (3) For Component about 36m Long ± 13mm 64 The tolerance for lack of straightness on plan or variation in camber shall also be of the same order as shown above for the respective lengths of the components. The dimensional tolerances on web steel shall be of the order of 3mm. PRESTRESSING 3015. (1) GENERAL Wires shall be straightened if necessary to produce equal stress in all wires or wire groups or parallel lay cables that are to be stressed simultaneously or when necessary to insure proper positioning in the sheathings. When wires are to be button-headed, the buttons shall be cold formed symmetrically about the axes of the wires. The buttons shall develop the minimum guaranteed ultimate tensile strength of the wire. No cold forming process shall be used that causes indentations in the wire. At transfer of the prestress the concrete shall have a minimum cube-strength of 30 N/mm2. In order that any applied force may be maintained after the tensioned tendons have been anchored, an allowance must be made in assessing the value of the applied force for loss of stress due to the yield in the anchorages and for slip when the tendon is wedged after tensioning. At transfer of the prestress, the concrete shall have the cube strengths as shown on the drawings, or as specified. These requirements shall be ascertained from works tests on three cubes manufactured and cured under the same conditions as the concrete member. Sufficient cubes shall be made so that if the stipulated strength is not achieved, further cubes will be available for such additional testing as may be required. At transfer of prestress, the measured deflection of the beam shall not exceed the limits given on the drawings, or as specified. (1) POST TENSIONING (I) The system of prestressing and the magnitude of the post tension in a structural component shall be as shown on the drawings. (II) MANUFACTURE OF CABLES Prestressing cables shall be preassembled in the factory or manufactured on site from coils of wires or strands. The cable consisting of a number of high tensile steel wires or strands shall be formed in the manner as directed by the Engineer or his Representative. In estimating the length of all cables, extra allowance must be made for attaching either one or two tensioning jacks as instructed by the Engineer. The method of measurement for the purpose of payment shall be the length of the finished cable placed, positioned, tensioned, anchored, cut and grouted complete as in the finished structure. (III) SHEATHING Sheathing shall be carefully examined prior to use and any damaged lengths shall be cut away and rejected. Joints in corrugated sheathing shall be formed by the use of couplers and/or by wrapping the joints with tape. They shall be so designed as to prevent the ingress of cement, concrete or other material during casting. All joints in sheathing shall be approved by the Engineer's Representative. (IV) PLACING OF PRESTRESSING TENDONS AND SHEATHING Tendons shall be carefully handled so as to avoid sudden bends or kinks, and threaded into the flexible sheathing before being placed into the beam formwork. The 65 sheathing and the prestressing tendon shall be rigidly supported in the exact positions as shown on the drawings so that no movement can take place during casting of the beams. (V) PLACING OF ANCHORAGES The anchorages shall be placed accurately in accordance with the drawings and firmly fixed to resist displacement during vibration of the concrete. The anchorages shall be fixed so as to be perfectly collinear with the axis of the tendons and to remain so throughout the casting of the component. (VI) SYSTEM OF POST TENSIONING All post-tensioned prestressing steel shall be secured at the ends by means of approved permanent type anchoring devices. All anchorage devices for post- tensioning shall hold the prestressing steel at a load producing a stress of not less than 95 percent of the guarantee minimum tensile strength of the prestressing steel, when tested in accordance with Test Method No. California 641 or equal. When headed wires are used, the outside edge of any hole for prestressing wire through a stressing washer or through an unthreaded bearing ring or plate shall not be less than 5mm from the roof of the thread of the washer or from the edge of the ring or plate. The load from the anchoring device shall be distributed to the concrete by means of approved devices that will effectively distribute the load to the concrete. Such approved devices shall conform to the following requirement: (a) Bending stresses in the plates or assemblies induced by the pull of the prestressing steel shall not exceed the yield point of the material or cause visible distortion in the anchorage plate when 100 percent of the ultimate load is applied as determined by the Engineer. (b) Materials and workmanship shall conform to the requirements in Section V Bridgeworks, Part (B) Structural Steelwork. (VII) JOINTS Joints in the spaces between a series of precast elements which are to be prestressed together shall be made precisely in accordance with the requirements shown on the drawings. Suitable extensions or connections of the ducts through the gaps shall be provided and steps taken to ensure that the jointing material does not enter the duct or press against the prestressing steel. The holes for the prestressing steel shall be accurately made and meet one another in true alignment at the ends and shall permit unobstructed passage of the grout. The stressing operation shall not take place until the filling material in the joint has attained a strength equal to at least 1½ times the stress at transfer of prestress. The time lag is to be established during design process. 66 (VIII) TENSIONING (1) No post-tensioning of pre-stressing tendons shall take place until the concrete has attained the specified stress as ascertained from tests on cubes cured and hardened under the same conditions as the concrete of the member. Before the stressing, single wires or strands, the wires or strands in each cable shall be of equal length in tension. (2) Tensioning shall be carried out with the approved type of jacks. (3) Before tensioning the anchorages shall be carefully cleaned on all surfaces, removing heavy dirt. (4) The amount of tension given to the tendons shall conform to a schedule of tendon tensions, to be supplied by the Engineer, and will be based on the test data for prestressing steel. (5) Measurement of the force shall be by an accurate gauge indicating the force on the hydraulic jack and also by the elongation of the steel after allowing for any initial slip in the wedges or jaws of the grips. The Engineer may also specify the use of a load cell to determine the tendon tension directly. (6) Approval shall be obtained from the Engineer's Representative before each tendon is anchored. The contractor shall provide printed sheets and supply the Engineer's Representative with a record of all extension and pressure readings for each tendon in every prestressed structural component. (7) No tensioning of tendons can commence until permission is obtained to do so from the Engineer's Representative. (8) The order and sequence of tensioning shall be as specified on the drawings or as instructed by the Engineer's Representative. (9) The prestressing force should be applied from one or both ends as specified on the drawings. (10) Each wire, pair of wires, cables, strand, or bar shall be attached in such a manner as to ensure that the elongation is uniform throughout its length. Should any tensioned steel or anchorage break or be damaged, it should be replaced if so ordered. Throughout all tensioning operations a spare jack capable of maintaining the designated load should be available. (11) All tensioning shall be carried out in the order specified or approved. After tensioning, the wires, strands or bars shall be secured in position and cut off as directed. (12) Immediately before tensioning, the Contractor shall prove that all tendons are free to move between jacking points and that members are free to accommodate the horizontal and vertical movements due to the application of prestress. (13) The Contractor shall establish the datum point for measuring extension and jack pressure to the satisfaction of the Engineer. 67 (14) The tendons shall be stressed at a gradual and steady rate until they attain the force described in the Contract. (15) The Contractor shall keep full record of all measured tensioning operations, including the extensions, pressure gauge or load cell readings and the amount of pull-in at each anchorage. Copies of records shall be supplied to the Engineer within 24 hours of each tensioning operation. (IX) GROUTING (1) After tendons have been tensioned and anchored they shall be grouted up solid throughout. Suitable outlet with plugs being provided to prevent air locks unless otherwise specified. Grouting trials shall be undertaken when required by the Engineer. The method of mixing and injecting the grout shall be approved by the Engineer before grouting is commenced. The pressure at which the grout is to be pumped into the duct shall be approved by the Engineer and shall not normally exceed 552 kN/m². (2) Grout shall be either a neat cement grout with a water cement ratio not exceeding 0.4 or cement mortar (1:1 by weight). An expanding plasticizing admixture should be used. All ducts and holes shall be thoroughly washed out with water, immediately before grouting and after the stressing operation has been completed. Grouting is to be carried out continuously, the discharge from consecutive air holes being observed throughout. The mixer shall be thoroughly cleaned before grouting is commenced. A complete spare grouting plant for immediate use in case of emergency or breakdown of the equipment operation shall be available. (3) Care shall be taken to avoid lumps in the cement, and sieving shall be carried out before mixing the grout. It is essential to mix up a quantity of grout sufficient for a particular duct immediately prior to its injection and to use only this batch on the duct. (4) During the grouting operation grout shall be continuously added to the bucket from which the grout is being pumped and the bucket shall not be changed otherwise air may enter the sheathing with the grout. (5) Before the commencement of grouting and after the completion of it, reports shall be made to the Engineer's Representative in writing. The duct shall be plugged when grout is issued freely from the outlet end, and once plugged the pressure shall be gradually reduced to prevent blow backs or air pockets. The Contractor shall keep full records of grouting including the date each duct was grouted, the proportion of the grout and any admixtures used, the pressure, details of any interruption and tapping up required. Copies of these records shall be supplied to the Engineer within 3 days of grouting. Where required by the Engineer, the Contractor shall provide facilities and attendance for the radio- graphic testing of ducts. (6) The grout mixer shall produce a grout of colloidal consistency. The grout injector shall be capable of continuous operation with sensibly constant pressure up to 690 kN/m² and shall include a system of circulating or agitating the grout whilst actual grouting is not in process. All baffles to the pump shall be fitted with sieve strainers size 1.2mm. 68 (7) The equipment shall be capable of maintaining pressure on completely grouted ducts. It shall be fitted with a nozzle which can be locked off without loss of pressure in the duct. (8) The pressure gauges shall be calibrated before they are first used in the works and thereafter as required by the Engineer. All equipment shall be thoroughly washed with clean water at least every 3 hours during the grouting operations and at the end of use for each day. (X) FINISHING OFF TENDONS After grouting, the ends of the anchorages and any protecting ends of cut-off tendons shall be covered over by a 1:1 mix mortar packed hard into the recesses on the beam. (2) PRE-TENSIONING (I) In long line beds for pre-tensioning, due consideration shall be given to the friction caused by the varying shape and number of diaphragms which will affect the magnitude of the applied pre-stressing force. (II) In order to obtain concrete of uniform strength, where members are cast in a long line bed, the difference in strength at transfer between components of the same type cast in the same line shall not exceed 15 per cent. The Contractor shall satisfy the Engineer's Representative by tests on special cubes cured under the same conditions, as the members that this condition is complied with. (III) With pre-tensioning, the specified force shall be maintained by the use of approved fixing devices, at the ends of the tensioned steel during concreting and curing, until the concrete has attained the strength specified. The tensioned steel shall then be released gradually and uniformly. (3) TRANSVERSE PRE-STRESSING (I) GENERAL Transverse pre-stress shall be as specified and shown on the drawings. (II) JOINTING Joints between precast concrete units are to be made in accordance with the drawings or instructions from the Engineer's Representative. They shall consist of dry or wet joints. In the case of dry joints they shall be filled with dry concrete quality 50 N/mm² which shall be mechanically rammed into position and in the case of wet joints they shall be filled with wet concrete quality 50 N/mm² and fully vibrated into position. In both cases joints shall be finished flush with, the pre-cast concrete faces. During jointing, protection and continuation shall be given to the transverse cable holes, using a method to be approved by the Engineer's Representative. (III) TRANSVERSE CABLES Transverse pre-stressing tendons, shall be as indicated on the respective drawings and threaded through the transverse holes after the structural components are in position. 69 Tensioning will be carried out to a schedule of tendon tensions, to be supplied by the Engineer, and must be commenced at the centre working towards the ends symmetrically. The tendons are to be grouted in the same way as for the longitudinal pre-stressing. Permission shall be obtained from the Engineer's Representative prior to the commencement of stressing and grouting and the completion of stressing and grouting shall be reported to the Engineer's Representative all as for the longitudinal pre-stressing. ADDITIONAL REQUIREMENTS 3016. The following additional requirements shall be complied with: No cracks will be permitted due to: (1) Shrinkage, settlement of formwork, or damage in handling before application of pre-stress. (2) Local weakness of concrete at or immediately following pre-stressing or (3) Improper handling and transporting after application of pre-stress. Where grooves are provided in which tendons have been placed, they shall be cleaned before the mortar is inserted. Mortar shall consist of one part by weight of cement to three parts of sand with a water-cement ratio not exceeding 0.4 and shall be thoroughly compacted in the grooves, preferably by the use of vibrators, and subsequently cured. Alternatively, mortar comprising one part of cement to one part by weight of sand together with an approved expanding plasticizing agent and less water may be used. External cables shall be embedded in mortar of these proportions, an upper cover being placed over the cables after vibration is completed to ensure that expansion occurs uniformly within the original profile. Any tension and retensioning procedure when allowed for offsetting losses shall be strictly in accordance with the instructions of the Engineer's Representative. The procedure to be adopted for all operations, using large diameter single strands used as prestressing tendon shall be specially approved by the Engineer. LIFTING AND HANDLING 3017 The Contractor shall furnish the Engineer's Representative with full details of the proposed method of transporting and erecting, prestressed beam for his approval, before commencing this work. Should any cracking or other damage to components during transport or erection render the components unfit for use the Contractor shall replace the same at his own expense. The method of lifting and handling prestressed beams is to ensure that the design dead weight bending moment is not exceeded at any point in the beam throughout the whole operation. Lifting from casting beds shall not take place until grouting is completed and at least 24 hours old. Erection of the beams on to the bridge spans shall not take place until the concrete has attained a cube strength as specified on the respective drawings. The lifting of the beams shall be made using temporary lifting devices provided by the Contractor to the 70 Engineer's Representative's approval. Initial lifting from casting beds and final lowering on to bearings shall be carried out using hand operated chain blocks so as to avoid sudden shock in the beam. (2) STORAGE Beams shall only be stored on specially prepared temporary bearings, which must be such that the design dead weight bending moment is not exceeded at any point. Beams shall only be stored singly, and not on top of each other. (3) TRANSPORTING OF BEAMS Transporting of beams from place of storage to point of erection shall be carried out using a purpose-made conveyance which will ensure that the design dead weight, bending moment is not exceeded at any point over the length of the beam, this can be done by in-built pad into the vehicle which actually come into contact with and support the structural units. Frame may be introduced into the vehicles to support particular structural units. All units must be coupled directly to the frame to eliminate movement of units in transit and shall be designed so as to avoid winching or dragging the beams in a horizontal direction over rough ground. The transporting of other structural components shall be as approved by the Engineer. QUANTITY AND PAYMENT 3018. No separate payment will be made for prestressing precast concrete members. Payment for prestressing precast members shall be considered as included in the contract price for furnishing precast members. The contract lump sum price paid for prestressing precast members shall include full compensation for furnishing all labour, materials, tools, equipment and incidentals and for placing and tensioning the prestressing steel in precast concrete structures, complete in place, as shown on the drawings, as specified in these and the special provisions and as directed by the Engineer. Full compensation for furnishing and placing additional deformed bar reinforcing steel required by the particular system used, ducts, anchoring devices, distribution plates or assemblies and incidental parts, for furnishing samples for testing, working drawings and microfilms, and for pressure grouting ducts shall be considered as included in the Contract Lump Sum Price paid for in prestressing cast-in-place concrete or in the contract price for furnishing precast members, and no additional compensation will be allowed therefore. (CLAUSES 3019 - 3999 INCLUSIVE NOT USED) 71 SPECIFICATION SECTION IV - PILING 102 SECTION IV - PILING GENERAL 4000. In addition to any other relevant clause of this specification, the following shall be deemed to apply in particular to piling works, and shall be read in conjunction with all other relevant Clauses of the Conditions of Contract and this Specification. PART (A) - GENERAL TYPES OF PILES 4001. Piles used in the works shall be one of the following types:(I) Type "A": Precast reinforced concrete bearing and sheet piles. (II) Type "B": Cast-in-place reinforced concrete bearing piles formed by driving a steel shell which is filled with concrete and left in place. (III) Type "C": Cast-in-place reinforced concrete bearing piles formed by driving a steel pipe casing, inserting a permanent steel shell, filling it with concrete and then withdrawing the driving casing. (IV) Type "D": Cast-in-place reinforced concrete bearing piles formed by driving a heavy steel pipe casing, filling the casing with concrete and withdrawing the casing during or after concreting. (V) Type "E": Prestressed concrete cylinder bearing piles driven in. (VI) Type "F": Prestressed concrete cylinder bearing piles bored in. (VII) Type "G": Steel sheet piles. APPROVAL OF TYPE 4002. The Contractor shall submit to the Engineer for his approval, details of all the types of piles intended for use in the works. These details shall comprise complete detailed drawings and specifications, a comprehensive list of the equipment to be used and a full description of the methods to the employed. The Contractor's attention is drawn to the fact that no equipment or material intended for use in the construction or driving and/or boring of piles shall be imported on to the site until the Engineer's approval has been obtained. CONTRACTOR TO DRIVE OR BORE PILES 4003. Should the Contractor elect to carry out the pile drive or boring from his own resources he will be required to satisfy the Engineer that the personnel he intends to employ in the operation have had sufficient experience in similar installations under like sub-surface conditions. SUB- CONTRACTOR 4004. Should the Contractor elect to employ a Sub-Contractor for the piling, he shall satisfy the Engineer that the Sub-Contractor is sufficiently experienced in similar operations under like sub-surface conditions. MANUFACTURE OF REINFORCED AND PRE-STRESSED CONCRETE PILES 4005. In addition to the particular requirements of this part of the specification, all the relevant clauses of the specification shall apply to the manufacture of reinforced or prestressed concrete piles. CEMENT 4006. The Cement used in the manufacture of all reinforced or prestressed concrete piles shall be sulphate resisting portland cement in accordance with B.S. 4027 unless otherwise shown on the drawings. SETTING OUT OF PILES 4007. The Contractor shall be responsible for the correct location of all piles and the establishment of all lines and levels. ALIGNMENT 4008. Piles shall be driven or bored as accurately as possible to the vertical or to the specified batter. Any pile deviating from its proper alignment to such an extent that its load carrying capacity cannot, in the opinion of the Engineer, be corrected by the strengthening of the foundations, pile-cap or pile ties, shall be replaced or supplemented by an additional pile at the Contractor's expense. In general the allowable tolerances will be in the case of piles type "A" - "D" within 75mm of the position shown on the drawings and within 1½ of the inclination shown on the drawings, and in the case of piles type "E" and "F" within 150mm. 72 of the position shown on the drawings. No wedging or drawing into line of piles that have wandered will be allowed. DRIVING WITH DROP HAMMERS OR SINGLE ACTING STEAM HAMMERS 4009. Piles shall be driven with a drop hammer or with a single acting steam hammer. The weight of the hammer and the drop to be used shall be subject to the approval of the Engineer and shall conform to the recommendations of CP 2004 and will depend on the type of pile to be used. In general the energy per blow will be of the order as follows:(I) For piles types "A", "B", "C" and "D" - at least 26,500 Joules or 35,000 Joules depending upon cross-sectional dimensions of the piles, the lighter hammer being used up to 300mm diameter piles and the heavier from 300mm diameter to 400mm diameter. (II) Kg. For piles of type "E" at least 54,300 Joules with a ram weight of not less than 6,800 DRIVING WITH DOUBLE ACTION STEAM HAMMERS 4010. Double-Acting steam hammers may be used when driving piles to refusal but shall not be used for other piles except with specific permission of the Engineer. PROTECTION OF PILE BUTTS 4011. Suitable anvils or cushions, depending on the type of the pile, shall be used to prevent damage to the pile butts. LEADS AND FRAMES 4012. Unless otherwise specified or directed driving shall be done using fixed leads which will hold the pile firmly in position in axial alignment with the hammer. Raking piles shall be held in position during driving right down to the level at which the piles enter reasonably solid ground and to the satisfaction of the Engineer's Representative. Piles shall be driven from an approved type frame. DRIVING TO BE CONTINUOUS TO FINAL SET OR LEVEL 4013. When the driving of any pile commences it shall be continued without cessation for any avoidable cause until the pile has been driven to the required set or level as directed by the Engineer's Representative. Where levels or sets are indicated on the drawings these may be varied, at the Engineer's discretion, in accordance with the results of test piles driven in representative areas. JETTING 4014. Where water or air jetting is contemplated to assist the driving of the piles, the permission of the Engineer must be obtained. The jetting shall be carried out in a manner to the satisfaction of the Engineer's Representative and must be discontinued when the toe of the pile is 3 metres short of the estimated final depth of penetration. Driving shall be completed by hammer only, without jetting, to the required set or as indicated by the Engineer's Representative. Where it is intended to employ water or air jetting to assist the driving of a number of piles in a group, the jetting of piles in the group must be completed before the driving of any pile to its final penetration is commenced. DRIVING TO FINAL SET AND RECORD OF DRIVING 4015. All piles shall be driven to the specified final set in the presence of Engineer's Representative. A record of the driving of each pile shall be kept in the form of the "Daily Pile-Driving Record" as set out in the British Standard Code of Practice No. 8004. Four copies of each of these records shall be forwarded to the Engineer's Representative for his retention. RE-DRIVING HEAVED PILES 4016. Observations and measurements shall be made in the field during the process of driving piles, by any suitable method satisfactory to both the Contractor and the Engineer to determine whether a driven pile has been lifted from its original seat during the operation of driving adjacent piles. The Contractor shall provide the necessary tools such as tell-tale pipes and instruments, to make these measurements. Such measurements shall be properly corrected for any temperature variations that might exist in the case of the pile shell or instrumentation. Where such observations or measurements indicate that a pile has been unseated, it shall be driven to the resistance specified. 73 DAMAGED AND MISDRIVEN PILES 4017. Broken or shattered piles will not be accepted. Should any pile be damaged by over-driving or not conform to the tolerances of the specification, an extra pile or piles shall be driven in its place, at the Contractor's expense unless in the opinion of the Engineer the pile is out of place or plumb as the result of an underground obstruction. Piles rejected after driving may remain in the ground at the descretion of the Engineer, in case of shell piles the shell shall be filled with concrete, and be cut off as directed. When rejected piling is withdrawn, the space, if another pile is not driving into it, shall be filled solid with gravel or broken stone without payment thereof. OBSTRUCTIONS 4018. Where boulders or other obstructions make it impossible to drive certain piles in the location shown and to the proper bearing strata, the Contractor shall resort to all usual methods to install the pile or steel pipes as required, including spudding, jetting, or other feasible means. If, in the judgement of the Engineer, the Contractor is unable to complete the pile driving properly by resorting to such methods, the Engineer may order an additional pile or piles driven for which the Contractor will be paid in accordance with the tendered rates. Piles abandoned because of obstructions encountered before reaching the accepted bearing strata shall be left in position or shells filled with concrete and be paid for as a complete pile for the length driven. Where directed by the Engineer, excavation operations shall be carried out to remove obstructions and the Contractor shall be reimbursed for such operations at rates and prices to be agreed between the Contractor and the Engineer. CUTTING OFF PILE HEADS ETC 4019. The tops of piles shall be cut off true and level at the elevations indicated on the drawings, all to the satisfaction of the Engineer's Representative. All portions which are battered, split, wrapped or buckled, or damaged or imperfect in any way shall be removed. Shells and casings shall have sufficient excess length to allow the complete removal of working tops. BORED PILES OR CASINGS 4020. The method of boring steel casing or pipes into the ground shall be subject to the approval of the Engineer. PAYMENT 4021. Payment for piling shall be made as detailed hereunder in the parts of this section of the specification dealing with the particular types of piles. (CLAUSES 4022 - 4029 INCLUSIVE NOT USED.) PART (B) - TEST DRIVING AND TEST LOADING OF PILES GENERAL 4030 (i) Test piles shall be driven or bored as appropriate and loaded in the manner detailed hereunder in the numbers and locations indicated on the drawings and/or in the contract documents and/or as directed by the Engineer. (ii) Unless otherwise directed the test piles shall remain as working piles under the completed foundations. (iii) Test piles shall be driven or bored using the equipment and methods approved by the Engineer for the remaining working piles. (iv) Before any load test is made, the proposed apparatus, structure and method to be used, in making the load test, shall be approved by the Engineer. All load tests shall be made under the supervision of the Engineer's Representative. RECORDING OF TESTS RESULTS 4031. The results of all piles loading tests shall be set out in a report the form of which shall be as directed by the Engineer. This report shall include a description of the pile and its driving record; type and size of hammer used, a tabulation of the load time, settlement and rebound data; and remarks concerning unusual circumstances during the driving or boring or loading of the pile and any other information which the Engineer or his Representative may require. PROCEDURE FOR TESTING PILES OF TYPES A,B,C AND D 4032. The following procedure shall be adopted for the testing of piles referred to above as types "A", "B", "C" and "D" 74 (i) Piles shall be load tested to twice the design load with the test load applied in seven increments equal to 0.5, 0.75, 1.0, 1.25, 1.5, 1.75 and 2.0 times the design load with a minimum of two hours between the addition of load increments. Increments shall not be added until the rate of settlement is less than .25mm per hour, or if each increment thereafter for the test load shall remain in place until there is no settlement in a 2-hr. period. (ii) If the full test load can be applied without failure of the pile, this load shall remain on the pile for 48 hours, after which the test load shall be removed in four equal decrements with a minimum of one hour between decrements. (iii) Readings of settlements and rebounds shall be made with a minimum of two dial gauges mounted on an independent framework and positioned on opposite corners of the test plate. Readings shall be recorded to the nearest 250 m and shall be made every 30 minutes during the loading cycle and every hour during the application of the full test load. Readings of rebound shall be made before and after each decrement and 24 hours after the entire load has been removed. (iv) The load test shall be considered satisfactory provided that the net settlement (after rebound) does not exceed 10% of the pile diameter. (v) Piles to be load tested will be contract piles driven in their proper location. During the load testing of piles, the driving of contract piles may be continued at the Contractor's option provided the testing process is not affected by the pile driving. Should the results of the load test indicate that longer piles are necessary, the Contractor will be required to further drive piles driven during the load testing operation without additional cost to the owner except for the added pile length. Piles driven during the testing operation shall not be filled with concrete until the required length and/or resistance has been determined by load test. PROCEDURE FOR TESTING PILES OF TYPES "E" AND "F 4033. The following procedure shall be adopted for the piles referred to above as types "E" and "F":Pile driving or sinking requirement as to depth of embedment and/or requested final driving resistance shall be determined in each area of similar soil conditions by load testing at least two piles selected by the Engineer. The total applied load shall equal 150% of the design dead load, plus 200% of the design live load. The test load shall be applied in six increments equal to 25, 40, 55, 70, 85 and 100% of the total test load. Time interval between increments shall not be less than two hours and increments of load shall not be added until the rate of settlement has dropped below .25mm per hour. The full load shall remain on the pile for 48 hours, after which a test load shall be removed in four equal decrements allowing one hour between decrements. Readings on settlements and rebound shall be taken before and after each increment or decrement, every two hours during the 48 hours the full load is on the pile and 24 hours after the full load is removed from the pile. The test shall be considered satisfactory if the net settlement (after deduction of rebound) does not exceed 10% of the pile diameter. LATERAL DISPLACEMENT TESTS 4034. The Engineer may order, if he so desires, that lateral displacement tests be carried out by jacking between adjacent piles to a given lateral displacement. The method of carrying out lateral displacement test shall be as directed by the Engineer. ASSESSMENT OF RESULTS OF PILE LOADING AND DRIVING TEST 4035. The information obtained from the driving of the test piles shall be applied to a suitable dynamic pile formula or formulae. The formula or formulae to be employed shall be as selected by the Engineer. The results of this application or these applications shall be considered in conjunction with the results obtained from the loading test and lengths of the remaining piles in a particular area or group shall then be agreed between the Contractor and the Engineer. 75 PAYMENT FOR TEST PILES AND LOAD TESTS 4036. Payment for the fabrication and driving or boring of the test piles shall be made at the tendered rates and prices for working piles of the same type entered in the bills of quantities. Payment for the pile load tests shall be made at the unit price quoted for load test on the particular type of pile in the bills of quantities, except where the Contractor should have made any kind of guarantee as to safe bearing capacity of any particular type of pile in any location, payment for load test shall only be made for tests which are, in the opinion of the Engineer, successful. The price by the Contractor for the carrying out of a load test shall be deemed to be inclusive of all the cost involved in the carrying out of the load test and also of the cost of obtaining the stipulated information during the driving of the test pile. (CLAUSES 4037 - 4049 INCLUSIVE NOT USED.) PART (C) - PRECAST REINFORCED CONCRETE BEARING AND SHEET PILES TYPE "A". In addition to any other requirements of other parts of this section of the specification the following requirements shall be complied with in respect of precast reinforced concrete bearing and sheet piles. GENERAL 4050. The piles shall be manufactured at the site of the work in which they are to be used and in an area entirely free from the harmful effects of shock and vibration. They shall be cast in lengths as determined by test. MOULDS AND CONCRETING 4051. The moulds shall be so supported that the pile is not distorted during or after casting and shall be such as to ensure that the resulting pile is straight and true on each face. The sides of the moulds shall be capable of being removed without shock or jarring of the pile. Shoes, reinforcement, links, toggle-hole tubes and all other fittings shall be fixed accurately in the positions shown on the drawings. Shoes shall be of the type shown on the drawings and of approved manufacture. They shall weigh not less than as shown on the drawing, and shall have chilled-hardened cast iron bases and mild steel straps cast in, i.e. The straps shall run continuously through the cast iron bases. All castings shall be of clean, grey, tough metal, free from sand, honeycombing, porous places, air holes or other defects and shall be delivered to the site without being painted, stopped or plugged in any part, otherwise they will be rejected. Shoes shall be fixed accurately to the piles with the points truly on the longitudinal axis and the lower ends of the reinforcing bars shall bear on the top of the shoe. Forks for retaining the longitudinal reinforcing bars in position shall be of cast iron or pressed steel and of approved shape and length. Each pile shall be poured in one continuos operation. During concreting and subsequently, the pile shall be protected from the effects of sun, wind and rain by covering with screens of clean, damp sacks or hessian, care being taken to prevent contact with the wet concrete until it has hardened sufficiently to prevent marking. When so hardened, the concrete and moulds shall be intimately and completely covered with the damp sacks or hessian and these shall be kept in a continuously wet condition for a period of not less than 10 days after casting. STRIPPING AND HANDLING 4052. The sides of the moulds shall not be removed before two days after casting and the piles shall not be disturbed on the bottom boards for at least 10 days after casting. The piles shall be removed from the bottom boards only by canting sideways and shall be rolled carefully to the stacking ground for final curing. The runners and other supporters upon which the piles are canted and rolled shall not be more than 2 metres apart and shall be perfectly level one with the other so that during the operations of canting and rolling each 76 pile shall be fully supported at each interval of 2 metres along its length. Each pile shall have the date of manufacture painted on one side and this date shall determine the sequence in which the piles are driven. The piles must on no account be lifted at this stage and, until ready for driving, must be adequately supported at each 2 metres interval throughout their length. The Contractor shall keep the piles in a continuously wet condition until a period of at least 14 days has elapsed since manufacture. Otherwise than as aforesaid, the piles shall not be handled, lifted, slung, pitched or driven before 6 weeks after manufacture and then shall be slung only from the toggle-holes provided in the positions shown on the drawings or as approved by the Engineers Representative. Should the Contractor wish to use rapid hardening cement he shall first obtain the approval of the Engineer's Representative. Where approval has been given, and rapid hardening cement used in the manufacture of the piles, the sides of the moulds shall not be removed earlier than 2 days after casting, and the piles shall not be disturbed on the bottom boards for at least 4 days after casting. Curing shall continue for the full period of l4 days, and the piles shall not be driven before three weeks after manufacture. Notwithstanding the foregoing requirements, the Contractor shall be responsible for any damage done to the piles due to the sides of the moulds being removed too soon or the piles being moved from the bottom boards too soon or from any other cause and all piles damaged during manufacture, handling, driving or at any other time shall be replaced at the Contractor's expense. LENGTHENING OF PILES 4053. In every case where it is found to be necessary to increase the length of a pile after it has been driven, the head of the pile shall be cut off to expose the reinforcement for a length not less than 1.2 metres below the top of the steel reinforcement. The joint shall be made by butting the lengthening bars to the pile bars with the addition of a supplementary bar to every pile bar and of equal area. These supplementary bars shall extend at least 1.2 metres on each side of the joint and shall be secured to both pile and lengthening bars by No. 16 S.W.G. wire, links being provided as directed. The extension shall be carried out vertically so as to form a true continuation of the pile. Butt welding of reinforcement may be allowed by the Engineer's Representative and where so allowed shall be carried out in strict compliance with the instructions of the Engineer's Representative. STRIPPING HEADS OF PILES 4054. After the piles have been driven, the concrete shall be cut away from those portions of the piles extending above a level of 75mm minimum above the bottom of the pile cap, without damaging the reinforcement and leaving exposed a minimum length of 0.90m of the main bars. The binders, links, forks and toggle-hole tubes within this portion shall be removed and the main bar reinforcement shall be bent into the base of the foundation as shown on the drawings. PAYMENT FOR PRECAST REINFORCED CONCRETE 4055. Payment for precast reinforced concrete bearing and sheet piles shall be made on the basis of the length of the pile per linear metre measured from the tip to the cut-off elevation at the tendered rates and prices entered in the bills of quantities for the sheet piles particular type and dimensions of pile. The tendered rates and prices shall be deemed to include for all materials, equipment, labour and supervision involved in the completed pile driven and in place. No payment shall be made for withdrawn or ejected piles. (CLAUSES 4056 - 4059 INCLUSIVE NOT USED) PART (D) - CAST-IN-PLACE REINFORCED CONCRETE PILES. TYPES "B" AND "C" 77 ln addition to any other requirements of any other parts of this section of the specification the following requirements shall be complied with in respect of cast-in-place reinforced concrete piles of types "B" and "C". CAST-IN-PLACE REINFORCED CONCRETE PILES TYPE "B" 4060. These piles shall be formed by driving a shell to the required bearing, leaving the shell permanently in place, and filling it with concrete. Shells shall have sufficient strength and rigidity to permit their being driven and not to be distorted by soil pressure or the driving of adjacent piles; they shall be sufficiently watertight to exclude water during placing of concrete. No concrete is to be placed until all piles in a cluster have been driven and approved. CAST-IN-PLACE REINFORCED CONCRETE PILES TYPE "C" 4061. These piles shall be placed by driving a heavy steel pipe casing with an interior core or point to the required depth, removing the core and inserting a permanent steel shell, filling it with concrete, and then withdrawing the driving casing. Shells shall have sufficient strength and rigidity not to be distorted by soil pressure or the driving of adjacent piles and they shall be sufficiently watertight to exclude water during placing of concrete. Shells shall be cylindrical with a minimum diameter of 315mm.No driving casing shall be withdrawn until all piles within 3 metres centre to centre, have been driven. Pile shells may be step tapered, cylindrical or a combination of such shapes and may be plain or corrugated. Plain cylindrical shells and shells driven without an internal mandrel shall have a minimum diameter of 325mm. and a minimum wall thickness of 8mm. with steel meeting respective B.S. requirements. Piles driven with an internal mandrel shall have a minimum top diameter of 255mm. and a minimum butt diameter of 355mm. For the step taper portion of any pile, the maximum distance between changes of diameter shall be 3.6 metres for shells driven with an internal mandrel, the Contractor shall assume responsibility for providing shells of sufficient strength and thickness to withstand proper driving without injury, to obtain proper penetration and to resist harmful distortion and/or buckling due to soil pressure. The lower end of each pile shell shall be closed by a butt steel plate or shoe firmly welded to the shell. EQUIPMENT 4062. Pile driver leaders shall be of the rigid or fixed type to insure accurate alignment of the pile and hammer during driving. The use of swinging leads will not be permitted. The cushion block used shall be a one-piece hardwood block with grain parallel to the pile axis and enclosed in a close fitting steel housing, except that subject to the approval of the Engineer, a cap-block of other materials may be used providing the hammer energy transmission characteristics of the proposed capblock are equal to or greater than the wood capblock specified herein. The use of wood chips, small wood blocks, rope or other material which permits excessive loss of hammer energy shall not be permitted. The introduction of fresh capblock material just before or during the final driving of the pile shall not be permitted. CONTROL OF INTERNAL PRESSURES 4063. Observation shall be made during driving to determine whether or not the soil and/or water is rising inside the pile. If this occurs to such an extent that soil and/or water is trapped in the pile under the follower, provision shall be made for the escape or removal of such soil and/or water before driving is continued. CONCRETE 4064. No concrete shall be placed in any pile shell until the shell has been inspected and found to be free of water, debris or other foreign matter. Concrete for cast-in-situ piles shall have an ultimate compressive strength of not less than 20 N/mm² at the end of 28 days and shall be composed of approved portland sulphate 78 resisting cement, clean sharp sand and gravel or crushed stone of maximum 25mm diameter. Care shall be taken to ensure that the concrete is thoroughly compacted and that the minimum cover of 38mm to the main reinforcing bars is maintained throughout. After driven shells have been inspected and found satisfactory, approximately 0.03 cu.m. of 1:2 cement grout shall be deposited in each pile followed by concrete of 100 to 125mm slump deposited in the pile in a continuous operation through a funnel hopper having a discharge opening not greater than 200mm. in diameter. Concrete strength shall be determined from Standard Cube Test made from each day's pour as specified for reinforced concrete. STEEL REINFORCEMENT 4065. All Steel Reinforcement shall be in accordance with the drawings prepared by the Contractor or the Engineer whichever is applicable. It shall comply with the latest issue B.S.785, B.S.4449 or B.S.4461 depending on the type specified. All bars bending to be in accordance with B.S.1468. Reinforcement shall not be welded except where indicated on the drawings. PAYMENT FOR CASTIN-PLACE REINFORCED CONCRETE PILES TYPES "B" AND "C" 4066. Payment for Cast-In-Place Reinforced Concrete Piles of Types "B" and "C" shall be made on the basis of the length of the pile per linear metre, from the tip to the cut-off elevation at the tendered rates and prices entered in the Bill of Quantities for the particular type and dimension of pile. The tendered rates and prices shall be deemed to include for all materials, equipment, labour and supervision involved in the complete pile driven and in place. No payment shall be made for withdrawn or rejected piles. (CLAUSES 4067 - 4069 INCLUSIVE NOT USED) PART (E) - CAST-IN-PLACE REINFORCED CONCRETE PILES TYPE "D" In addition to the requirements of any other parts of this section of the specification the following requirements shall be complied with in respect of cast-in-place reinforced concrete piles of type "D". GENERAL 4070. Cast-in-place reinforced concrete piles of type "D" are formed by the driving of a heavy steel pipe casing closed at the lower end by a cast steel pointed shoe firmly fitted to the casing so as to provide a watertight joint. Reinforcement steel is then placed within the casing and concrete poured, the casing may be removed whilst the concrete has being poured or may be removed after the concrete has been poured. Alternatively the casing may be filled with the concrete aggregate mix and cement-sand grout injected after the casing has been removed. DETAILED METHOD OF CONSTRUCTION 4071. Where this type of piling is proposed for the works, the Contractor shall submit, in detail, his proposed method of carrying out the piling, to the Engineer for his approval, and shall carry out the work strictly in accordance with the method as approved by the Engineer. PAYMENT FOR CAST-IN-PLACE REINFORCED CONCRETE PILES OF TYPE "D" 4072. Payment for cast-in-place reinforced concrete pile of type "D" shall be made on the same basis as for piles of types "B" and "C" at the tendered rates and prices. (CLAUSES 4073 - 4079 INCLUSIVE NOT USED) 79 PART (F) - PRESTRESSED CONCRETE CYLINDER PILES TYPE "E" In addition to any other requirements of any other parts of this section of the specification the following requirements shall be complied with in respect of prestressed concrete cylinder piles of types "E" AND "F". GENERAL 4080. Prestressed concrete cylinder piles of type "E" shall have outside diameter and minimum dimensions as indicated on the drawings or as approved by the Engineer. Prestressing cables of the composition, number and type as indicated on the drawings or approved by the Engineer, shall be uniformly placed in the wall of the piles. MANUFACTURE 4081. specification. (I) All materials shall be as stated in the relevant parts of the (II) Metal forms shall be used and they must be well braced and stiffened against deformations under pressure of the wet concrete. They shall have smooth joints and inside surfaces accessible for adequate cleaning. The portions of the form which form the end surfaces of the pile (or sections) must be a true plane and perpendicular to the axis of the pile with the following tolerances: Maximum allowable deviation for abutting end surfaces 3mm, for head end surfaces, 13mm and for the point end 76mm Forming tubes for the longitudinal holes for the prestressing cables shall be 35mm nominal diameter and shall be positioned so that there will be a minimum cover of 38mm to the outside finished surface of the pile, shall be inside the spiral steel reinforcement and shall be uniformly spaced around the pile circumference. HANDLING 4082. Piles shall not be handled or moved in any manner that would result in cracking or permanent damage to the concrete or to the grout surrounding the wires. EQUIPMENT 4083. Piles shall be driven with an approved hammer which shall develop a rated energy per blow of not less than 54,300 Joules and which shall have a ram weight of not less than 6,800 Kg. A solid hardwood cushion block, at least 150mm thick, shall be used in the base of the hammer between the hammer ram and the follower. A laminated ring-shaped cushion block at least 150mm thick made up of 25mm hardwood boards and cut to fit the head of the pile, shall be used between the follower and the top of the pile. Both cushion blocks shall be inspected periodically during driving and blocks that have been unduly worn and compacted with use shall be replaced before driving is continued. Piles may be driven without guides or leaders except that the hammer shall be kept in accurate alignment with the axis of the pile. REINFORCING STEEL 4084. Each pile or pile section shall have a cage of non-prestressed reinforcing steel of the size, dimension and arrangement shown on the contract drawings or as approved by the Engineer. This reinforcing cage shall be securely held in position during the casting and spinning of the concrete. The spiral steel reinforcement shall have a minimum concrete cover of 25mm to the outside surface of the finished pile. CONCRETE 4085. Concrete used shall be not leaner than Grade 35 N/mm2 or as indicated on the Contract drawings. The concrete mix shall be such as to give the most uniform possible distribution of the aggregates across the wall of the pile. The fine and coarse aggregates shall be as nearly as possible of the same specific gravity. CASTING 4086. Piles shall be centrifugally cast and shall be cast in convenient sections as approved by the Engineer. 80 CURING 4087. Piles or pile sections may initially be steam cured. After removal of forms, membrane curing may be applied to all surfaces except abutting end surfaces and core holes. METHOD OF HANDLING 4088. The Method of Handling piles or pile sections shall be such that no permanent damage to the concrete will occur. If piles are made up of sections, any section which has more than 10% of the end surfaces spalled to a depth of more than 3mm shall be rejected. ASSEMBLY OF SECTIONS 4089. In making up the full length pile, the abutting surface of each section shall be covered by a sealing material of sufficient thickness to fill all voids (except at the cable holes) when the sections are brought together under compression as later specified. This sealing material must attain a minimum ultimate strength of at least equal to or greater than that of the concrete and must be as resistant to exposure and weathering as is the concrete. After the sealing material is applied, the pile sections shall be brought into contact and held together by a force equivalent to not less than 0.79 N/mm2 on the gross concrete area while the sealing material sets. The individual sections shall be lined up so that the maximum deviation in the alignment of the outside surfaces of two adjacent sections at the joint will not exceed 6mm and the maximum deviation in the alignment of the prestressing cable holes at the joint will not exceed 6mm STRESSING OF PILES 4090. Piles shall not be stressed until the compressive strength of the concrete is at least 30.0 N/mm2 after the prestressing cables have been threaded through the cable holes to make up cables of the required number of wires; the cables shall be tensioned to an average cable unit stress as indicated on the drawings or approved by the Engineer. This tension shall be measured by the elongation of the wires and checked by the jack pressure. The tension in the wire shall be transferred to mechanical end-locks or anchors. Aggregate stress losses through transfer of the stressing force from the jack to temporary anchorage shall not exceed an average of 10% on one cable or an average of 5% on all cables in any one pile. GROUTING OF CABLES 4091. All cables holes shall be grouted with a mixture of cement and water in such a manner that the interstices are completely filled with the grout material. The cable tension shall be maintained by the mechanical anchors while the holes are grouted and until the grout attains sufficient strength to hold permanently the tension in the cables. During this period, the piles shall not be moved or handled in any manner that would result in permanent damage to the grout. The grout curing period must be sufficient to permit the removal of the temporary anchors without slippage of the wires in the grout except that the stress loss through transfer shall not exceed an average of 10% on one cable or an average of 5% on all cables in any one pile. During removal of end anchors, if the wires do not part under stress with a "Cup and Cone" fracture, but can be burned completely through with a cutting torch, no slippage is considered to have occurred. DRIVING RESISTANCE 4092. Piles shall not be driven until the concrete has attained the minimum strength as specified on the drawings. The piles shall be driven to a resistance or tip elevation as determined by load test to be satisfactory for the required design load, but the final resistance shall not exceed 10 blows per 25mm with the approved hammer. In no case shall the stroke of the hammer exceed 1200mm. TENSION FORCES DURING DRIVING 4093. When the point of the pile is passing through soft soil so that there is little or no resistance to penetration at the bottom of the pile, the stroke of the hammer shall be reduced to approximately 600mm 81 CONTROL OF INTERNAL PRESSURES 4094. Observation shall be made during driving to determine whether or not the soil and/or water is rising inside the pile casing. If this occurs to such an extent that soil and/or water is trapped in the pile under the follower, provision shall be made for the escape or removal of such soil and or water before driving is continued. PRE-EXCAVATION 4095. The Contractor may use any combination of driving and drilling approved by the Engineer to obtain the required pile embedment. Jetting or pre-excavation shall be done below the pile tip elevation and the final seating of the pile shall be done by driving only for the last 3 metres. TOLERANCE 4096. Piles may be driven with the use of template or other method approved by the Engineer. The top of each pile shall not vary more than 150mm from the required plan location. CUT-OFF 4097. Where piles are required to be cut-off, cuttings may be performed with pneumatic tools, sawing, or other method approved by the Engineer. In no case shall explosives be used for cutting off piles. PILE SPLICES OR BUILD UPS 4098. If pile tops are driven below the established cut-off elevation, or if pile tops are damaged below the cut-off elevation, the pile shall be built up to the required elevation using a cast-in-place concrete extension of the cylinder or by use of an acceptable length of cylinder pile section. The pile splice shall consist of a poured plug or reinforced concrete extending at least l.4 metres into the original pile and, where possible, the same length into the added section as detailed on the drawings. This concrete plug may be an extension of the plug connecting the pile to the cap. DEFECTIVE PILES 4099. Piles damaged by improper driving or manipulation to force them into proper position shall be repaired at the Contractor's expense to the satisfaction of the Engineer. Any pile damaged by handling or in transit shall be repaired to the satisfaction of the Engineer or shall he replaced all at the Contractor's expense. PAYMENT 4100. Payment for prestressed concrete cylinder piles of type "E" shall be made on the same basis as for piles of types "D" or "C" at the tendered rates and prices. (CLAUSES 4101 - 4109 INCLUSIVE NOT USED) PART (G) - PRESTRESSED CONCRETE PILES OF TYPE "F" In addition to any other requirements of any other parts of this section of the specification the following requirements shall be complied with in respect of prestressed concrete cylinder piles of the types "F" GENERAL 4110. Prestressed concrete cylinder piles of type "F" are formed by the forcing into the ground of heavy steel casing and the removal of the earth from its inside. After the casing has been installed to the required depth a precast prestressed concrete cylinder pile is inserted into the casing either in sections and stressed insitu or as a complete unit. The space between the steel casing and the prestressed concrete shall be grouted with sand-cement grout as directed and approved by the Engineer. METHOD OF MANUFACTURE 4111. Where prestressed concrete cylinder piles of Type "F" are proposed for use in the works, the method of manufacture and construction shall be as approved by the Engineer and the Contractor shall comply strictly with this approved method. 82 PAYMENT 4112. The payment for prestressed concrete cylinder piles shall be made on the same basis as for piles of type "E". (CLAUSES 4113 - 4119 INCLUSIVE NOT USED) PART (H) - STEEL SHEET PILES STEEL SHEET PILES 4120. All steel sheet piles shall be of an inter-locking section as shown on the drawing and shall be a type and manufacture approved by the Engineer. Steel sheet piles, tie rods, rivets, and bolts shall conform to the minimum requirements of B.S. 4360, Parts 1 & 2 and B.S. 449. If cofferdams for foundation construction are used, the steel sheet piling for the cofferdams shall be carried well below the bottom of the footings and shall be well braced and as watertight as practicable. The interior dimensions of cofferdams shall provide sufficient clearance inside the walls for constructing forms and driving pile and to permit pumping outside the forms. For purpose of constructing the cofferdam, any enlargement in excess of 50mm outside the dimensions of the footing as shown on the drawings shall be considered as being for the sole purpose of expediting the work of the Contractor as is of no value to the F.M.W.H. and quantities of such excavation and backfill will not be included in the quantities to be paid for. In tidal waters or in streams at a time of probable flood, cofferdam walls shall be vented at low water elevation to ensure equal hydrostatic head both inside and outside of the cofferdam during the period of placing and setting of seals. No shoring will be permitted in cofferdams which will induce stress, shock, or vibration in the permanent structure. When permitted by the Engineer, cross struts or bracing may extend through foundation concrete. Such struts or bracing below low water will be permitted to remain in place, or when specified in the special provisions or shown on the drawings, to be removed. Struts or bracing above low water shall be removed and the resulting space filled with concrete of the same mix as that specified for the surrounding concrete. The Contractor shall submit to the Engineer, for approval, drawings showing his proposed method of cofferdam construction and other details left open to his choice or not fully shown on the drawings. The drawings shall be submitted at least two weeks in advance of the time the Contractor begins construction of the cofferdams. After completion of the substructure, the cofferdams with all sheeting and bracing shall be removed at least to 1 metre below the level of the stream bed, by the Contractor at his own expense, and such removal shall be performed in a manner that will not disturb or mar the finished concrete or masonry. WELDING ELECTRODES 4121. Electrodes used for welding shall comply with B.S. 639 or B.S.693 depending on the type employed. PROTECTIVE PAINTING DRIVING ETC. 4122. Where directed on the drawings or in the specifications, steel sheet piles shall be coated before driving with two coats of an approved bituminous paint, in a manner as directed by the Engineer's Representative. 4123. The piling shall be driven either singly or in pairs vertically and to true lines and even planes in the position shown on the drawings and to the levels indicated thereon. Should there be any defect in the horizontal or vertical alignment of the piling or should a break, through any cause whatsoever, occur in the continuity of the piling, the Contractor shall withdraw such defective pile or piles and drive such further piles as may be necessary to 83 remedy the defect. Should any distortion, fanning or creep occur in the alignment of the piling the Contractor shall immediately take steps to rectify the defect and shall, where necessary, supply and drive suitable tapered piles to the satisfaction of the Engineer's Representative. All costs incurred by the Contractor in carrying out the necessary remedial measures shall be at his own expense. Should any tapered piling have to be manufactured locally they shall have along the joint 22mm diameter rivets at 150mm pitch except for a length of 600mm 150mm at each end the pitch shall be 75mm All necessary holes for tie-rods shall be neatly drilled and for drains they shall be neatly burnt out, all in the positions shown on the drawings. TIE RODS AND ROPES 4124. The steel sheet piling shall be connected to the anchor piles by mild steel tie-rods or ropes as approved by the Engineer. They shall be in lengths as indicated and coupled together with forged steel coupling boxes or turnbuckles. Each end of each rod shall be threaded for a distance of 230mm with standard whitworth right and left-handed threads as the case may be. Mild steel bearing plates and washers of approved sizes shall be provided for the outer end of the tie-rods, the washers being tapered. The tie-rods and ropes coupling boxes or turn- buckles and other fittings shall be cleaned with wire brush or other approved means to remove all millscale, rust, etc., and shall then be given one coat of the bituminous solution and the tie-rods and ropes shall, after fixing in position, be wrapped in approved hessian and, with all fittings, be given a second coat of the approved solution. Where possible the coupling boxes or turnbuckles shall also be wrapped in hessian. PAYMENT 4125. The quantity of sheet piling to be paid for under this item in this section except for cofferdams, will be the number of square metres of sheet piling placed in its final position. The unit price bid for this item shall include the cost of furnishing all labour, materials and equipment necessary to complete the work, including the cost of furnishing and placing, if necessary removing, all wales and braces. No separate payment will be made for providing cofferdams unless it is called for on the drawings. When Cofferdams are called for on the drawings they shall be paid for at the contract lump sum price bid for the item COFFERDAM in the proposal. This price shall constitute full compensation for constructing cofferdams, controlling, removing water from excavation, all labour, materials, tools, equipment, and incidentals. (Clauses 4126 – 4999 inclusive not used) 84 SPECIFICATION SECTION V - BRIDGEWORKS 1 SECTION V - BRIDGE WORKS GENERAL 5000. In addition to any other relevant clause of this specification, the following shall be deemed to apply in particular to bridge works, and shall be read in conjunction with all other relevant clauses of the conditions of contract and this specification. PART (A): PRELIMINARIES. EXCAVATIONS, FOUNDATION, DEMOLITIONS, TEST LOADS ETC. GENERAL 5001. The Contractor shall himself obtain full and accurate information in connection with the existing structures, traffic, periods of flow and non-flow in the waterways, normal water levels, whether above or below ground level, flows and frequencies, floods, nature and condition of soils and sub-soils etc., And generally acquaint himself with all factors influencing the construction and maintenance of the works as shown on the drawings and specified herein, and shall be deemed to have allowed for all such conditions in the rates inserted by him in the bill of quantities. TRAFFIC DIVERSION 5002. Before commencing any operation of construction, the Contractor shall forward to the Engineer's Representative, and obtain his approval of, his proposals for avoiding interference with the existing traffic-way, rail road and water, and for providing, and maintaining alternative ways for all such traffic. All diversions shall be of dimension, capacity and standard at least equal to those of the traffic-ways which they replace when such traffic-ways are maintained in a good condition and they shall be maintained continuously to this standard during the period they are in use. Where the use of temporary bridge spans is involved the Contractor shall submit complete and detailed drawings and calculations for the scheme to the Engineer's Representative. The Engineer's decision on whether such methods may be adopted or not shall be absolutely final. Notwithstanding the approval or modification by the Engineer's Representative of any schemes, drawings or calculations, the Contractor shall remain wholly and entirely responsible for the sufficiency of all traffic diversions and temporary works and for all obligations and risks in regard to such works specified or implied in the contract and he shall reinstate the same at his own cost should any mishap or accident occur causing damage or injury thereto subject to such provisions of the conditions of contract as may be applicable. Payment for all such diversions including for temporary bridging or converting as necessary shall be deemed to be included in the tendered rates and prices, unless elsewhere expressly allowed for. CLEARING OF THE SITE 5003. The site of the works shall be cleared completely to the satisfaction of the Engineer's Representative. Generally, the waterway shall be cleared of all obstructions to the flow of water. All fallen trees, bushes and accumulations of debris shall be removed and deposited as directed. Trees which are to be retained shall be indicated by the Engineer's Representative. WATER TRAINING AND PROTECTION WORKS 5004. Such details of training works and protective works to the banks and protection beds of waterways as may be shown on the contract drawings are schematic only. Exact details of the training and protective works shall be supplied by the Engineer's Representative after consideration of the final disposition of the works, local site conditions etc. EXCAVATION AND BACK FILLING 5005 (A) GENERAL Excavations shall be of the widths and lengths necessary for the construction of the works and shall be taken down to the depths shown on the drawings. Or as otherwise specified hereafter or to such other depths as the Engineer's Representative may require. When the final level of the excavation has been reached, the Contractor shall so inform the Engineer's Representative, and together they shall inspect, measure and agree in writing all particulars on which measurements of the works are to be based. No back filling or construction shall be undertaken until after the final levels and dimensions of the excavation have been surveyed and agreed. Failing such surveys and agreements being signed by the 85 Contractor, the surveys of the Engineer's Representative, shall be final and binding on the Contractor. Any obstacle encountered in the course of excavations shall be reported to the Engineer's Representative and dealt with as directed by him. Excavations shall, where necessary, be properly shored and supported and the Contractor shall provide pumps, cofferdams, sheet piling etc., as necessary to ensure that all construction is carried out in the dry. Should any slips or falls result from the omission by the Contractor of any precaution, all loose and disturbed material shall be completely removed and the ground made up at the Contractor's own expense with approved material which shall include concrete grade 10 N/mm² should the Engineer's Representative so require. Should the material forming the bottom of any excavation, whilst acceptable at the time of excavation, become puddled, soft or loose during the progress of the works, the Contractor shall remove such damaged, softened or loosened materials and replace them with concrete grade 10 N/mm² or as directed by the Engineer's Representative, at the Contractor's own expense. Sumps dug in the bottom of excavations shall be cleaned out, all soft and puddled material removed, and the hole made up with approved material as described above. Should excavations be taken to a depth greater than that required by the Engineer's Representative such extra depth shall be made up at the Contractor,s expense with concrete grade 10 N/mm² or as directed by the Engineer's Representative. The Contractor shall not leave any item or temporary works in position in the excavations after back-filling, without the permission of the Engineer's Representative. Permission will only be given in cases where the Engineer's Representative is satisfied that no adverse effect will result to the finished works. No payment shall be made to the Contractor for any item of temporary works so left in position, unless such item was left in on the explicit instructions of the Engineer's Representative. Excavations shall be backfilled with approved materials in layers not exceeding 150mm compacted thickness, and shall be thoroughly compacted by approved methods. Where such material lies below a roadway or will form part of an embankment it shall be selected and compacted entirely in accordance with the requirements of all relevant clauses of this specification. Back-filling of excavations for reinforced concrete culverts, open drains and any other structure shall be brought up equally on either side of the structures to eliminate unbalanced earth pressures. Earth and other material taken from excavation shall be set aside for selection for re-use as filling materials, and materials unsuitable for this purpose shall be disposed of by the Contractor at his own expense, as directed by the Engineer's Representative. Selected material shall be free draining-material. The material shall have Plasticity Index (PI) of not more than 5, and shall meet the following gradation requirements when tested in accordance with B.S. 410:- Sieve Size Total Per cent Passing (by weight) 50mm 25mm 86 100 60 - 100 1.1mm 500 m 255 m 75 m 20 - 100 10 - 70 8 - 40 5 - 10 When tested for bearing capacity, selected material shall have a California Bearing Ratio (CBR) of not less than 20% when compacted to 95% of maximum density, using BS compactive effort up to a depth not more than 600mm to formation level; there after compaction shall be 100% MDD of the material using BS effort. Free draining shall be defined as a material having coefficient of permeability of not less than 1x 10-2mm/sec. Before driving piles, the common embankment material shall be placed and compacted to the top elevation of the prism of selective material. No payment for placing of selective material will be made, but the cost thereof shall be included in the price bid for the item "Excavation and Backfill" scheduled in the proposal. (B) ROCK The term "solid rock" shall mean rock found in ledges or masses in its original position, which would normally be removed by blasting and pneumatic tools or by wedges and sledge hammers if removed by hand, and all solid boulders or detached pieces of rock exceeding 0.2 Cubic metres in size trenches and 0.3 Cubic metres in size in general excavations, to the classification of which the Engineer's Representative is satisfied. Should any difference of opinion arise between the Contractor and the Engineer's Representative as to whether any material is rock, the Engineer's decision shall be final and shall be made before the material is disposed of or covered up. Should the Contractor wish to use explosives for the excavation of rock, he must obtain the permission of the Engineer's Representative. When permission is granted the Contractor shall proceed as directed in, and satisfy all the requirements of, clause 99 of the conditions of contract and clause 5010 of this specification. PAYMENT FOR EXCAVATIONS FOR FOUNDATIONS 5006. Excavations for foundations shall be paid for on the actual quantities measured on site by multiplying the horizontal area of the base of the foundations by the mean depth from surface level, and at the appropriate rates for excavation inserted in the bill of quantities. The rate shall include for all shoring, pumping, backfilling and compactions, and for all pumping, digging, backfilling of sumps and for all other things necessary to allow the proper placing of the foundations. No payment shall be made to the Contractor for any item of temporary works left in position unless it has been left on the instruction of the Engineer's Representative. No item of temporary works shall be left in position without the approval of the Engineer's Representative. EXCAVATIONS FOR FOUNDATIONS BELOW WATER LEVEL 5007. Where excavations have to be made and foundations formed below water level, suitable arrangements shall be made to exclude the water from the site, and the Contractor shall, when tendering, submit a full and clear description, supported by drawing and sketches, of the methods he proposed to use in respect of each foundation where these conditions will be encountered. The methods proposed shall be directed in all cases to permit the execution of the whole of the work in the dry unless this is shown in the method statement to be entirely impracticable or uneconomical. The Contractor must satisfy himself absolutely as to 87 what water levels may be experienced at and during the period of construction, whether such water levels be above ground level or below and as to what flows and water levels will be attained during flood and high tide periods and as to the condition of soils and subsoils and all other matters pertaining to the adequacy of the temporary works and the efficient and proper construction of the works themselves. The Contractor shall take all precautions to prevent flooding of the works and shall make good any loss or damage to the temporary works and the works themselves caused thereby at his own cost and to the satisfaction of the Engineer's Representative. If Contractor chooses to use steel cofferdams for the below water level foundation excavations, the materials shall conform to SECTION IV, Clause 4120 "STEEL SHEET PILES." No separate payment for cofferdams will be made, but the payment shall conform to the applicable portion of the SECTION IV, Clause 4125 "PAYMENT." PREPARATION FOR FOUNDATIONS: NORMAL 5008. The depths to which foundations are to be taken, and their dimensions as shown on the drawings are an indication only of the anticipated requirements. The actual depths and consequently the dimensions are to be finally determined on site by excavating through the various strata until a material is reached, which is capable, in the opinion of the Engineer's Representative, of safely sustaining the pressure exerted and of providing complete security against the effects of scour. All excavations shall be taken out as nearly as possible to exact dimensions to minimize back- filling, and in accordance with clause 5005 of this specification. No concrete shall be placed in any foundation until the Engineer's Representative has inspected and approved the excavation and the arrangements for transporting and depositing the concrete, and given permission in writing to proceed. The sides of the excavation shall be such as to eliminate any possibility of loose material falling into the work as concreting proceeds. The bottom of the excavation shall be clean and levelled off and free from all loose material. Contractor shall draw the attention of the Engineer's Representative to any soft spots which may occur and these shall be cut out as directed, measured in conjunction with the Engineer's Representative, and afterwards filled with concrete grade 10 N/mm2. No payment shall be made for cutting out and filling soft spots which have not been measured in conjunction with the Engineer's Representative. When foundations are to rest on rock, all adherent clay, etc., drummy, soft and loose rock, shall be cut away until the hard solid rock is exposed and the base left approximately horizontal or to a slight fall or stepped, as may be directed by the Engineer's Representative. Immediately before concreting is commenced, the surface of the rock shall be thoroughly cleaned and wetted and the concrete shall be poured directly on to the rock and against shaped side-shuttering. The filling of the hollows with rubble, broken rock etc., will not be permitted. It is the intention that all concrete shall be placed in the dry, and the Contractor shall direct all his efforts towards this end. REMOVAL OF EXISTING STRUCTURE: GENERAL 5009. Before any part of any existing structure is removed the Contractor shall forward to the Engineer's Representative for approval, full details of the method by which he proposes to dismantle the structure and provide an alternative way for traffic during the subsequent works. (See also clauses 90 of the conditions of contract and 5002 of this specification). Such details shall be accompanied by drawings and calculations as required by the Engineer's Representative showing that no part of the structure which may be required for re-use in another part of the works or by the Engineer elsewhere under another contract, shall be over 88 stressed or damaged in any way during the operation. Such details shall be submitted to the Engineer's Representative sufficiently in advance of the intention to commence the work as this will allow the proper study of the proposals and the incorporation of any amendments which the Engineer may require. Notwithstanding the incorporation of any such amendments or any approval given by the Engineer's Representative to any method proposed, the Contractor shall remain wholly and entirely responsible for the safety of the work and for all obligation and risk specified or implied in the contract and shall make good at his cost any damage resulting from any mishap or accident arising from the operation, subject to such provisions of the conditions of contract as may be applicable. The demolitions and dismantling shall be carried out in a workmanlike manner and the Contractor shall observe all rules, regulations and orders which may have been made or may be made by the government or any other responsible authority with regard to the safety of all persons, whether employed by him or not during such operations. Before removing any superstructure or sub-structure, the Contractor shall bring to the notice of the Engineer's Representative any existing damage to the structure and point out any missing parts and the Engineer's Representative and the Contractor shall together agree in writing that such damage did exist and that such parts were missing before the commencement of operations by the Contractor. Should the Engineer then require the Contractor to repair such damage or to replace such missing parts, the Contractor shall do so as directed and he shall be paid for the work at rates to be mutually agreed between him and the Engineer. Should the Contractor fail to bring such damage or missing parts to the notice of the Engineer's Representative it will be deemed for the purpose of subsequent payment that the Contractor accepts that the structure is complete and entirely free from damage before the commencement of dismantling operations. After dismantling, the Contractor shall spread out all the components and advise the Engineer's Representative that they are ready for inspection. Any damage or loss discovered in addition to that previously agreed shall be made good at the Contractor's own cost and to the satisfaction of the Engineer's Representative. Parts which have been lost shall be replaced by entirely new material and members which have been damaged shall be repaired or completely replaced as required by the Engineer, who shall consider the degree of damage in relation to the importance of the member, and the Engineer's decision in these matters shall be final. EXPLOSIVES 5010. Should the Contractor wish to demolish any part of the existing structure by using explosives, he must first satisfy the Engineer's Representative that this is the most economical and satisfactory way of performing the work and obtain his permission to proceed. The Contractor shall provide proper buildings or magazines in suitable positions for the storage of the explosives in a manner and in quantities to be approved. He shall also be responsible for the prevention of any un-authorized issue or improper use of any explosive brought on to the works, and shall employ experienced and responsible men by whom only shall explosives for the purpose of the works be handled, all to the satisfaction of the Engineer's Representative and in conformity with the statutory regulations. During blasting, the greatest care shall be taken by the Contractor that no injury be done to persons or property or to any finished work or any work which is to remain untouched. The shots shall be properly loaded and covered and only moderate charges shall be used, and where directed by the Engineer's Representative, the Contractor shall provide heavy mesh blasting nets. Blasting shall be restricted to whatever hours the Engineer's Representative shall prescribe. If, in the opinion of the Engineer's Representative, blasting would be dangerous to persons or adjacent structures, or is being carried on in a reckless manner he may prohibit it, and order that the demolition be carried out by other means see also clause 99 of the Conditions of Contract. 89 REMOVAL OF EXISTING SUPER STRUCTURES AND SUB-STRUCTURES STEEL AND CONCRETE 5011. Existing concrete deck, where required to be remove shall be demolished in a manner which will ensure that no damage whatever shall be caused to the supporting steel troughing joists, trusses, bracing, or any other member or part of the structure. The use of explosive is forbidden. Before dismantling any part of any structure which is to be re-used either wholly or in part either by the Contractor in another part of the works or by the Engineer elsewhere under another contract, the Contractor shall mark each part of the structure with a distinguishing mark which shall be assigned to it in a marking plan to be prepared by him, in figures or letters not less than 50 mm. high and in such a manner that the pieces may be readily identified and put together again in their proper positions when required. The figures and letters shall be painted on, in at least two places on each member, and on a surface which has first been thoroughly cleaned and freed from all rust, loose paint, grease, dirt and other deleterious coatings and given one coat of protective paint. The colour of the paint to be used for the letters and figures shall be such as to make them readily visible against the background of protective paint. Where more than one bridge is to be marked in any contract, the Contractor shall ensure that no combination of figures and letters employed in the marking of one bridge is repeated in the marking of another. All markings shall be to the approval of the Engineer's Representative and dismantling of the structure shall not be proceeded with until the Engineer's Representative has checked and approved the marking on the structure and compared them with those on the marking drawings and given his permission to proceed. The drawings showing the markings shall conform to the requirements of Clause 5020 hereinafter. The Contractor shall forward to the Engineer's Representative one set of hand-made negatives on best quality linen, one set of velograph negatives on best quality linen and one set of prints on linen showing black lines on a white ground, of the marking drawings and the cost of producing and supplying all these negatives and prints shall be deemed to be included in the rates for dismantling. Troughing, joists, trusses, trestle, piers, cylinders, etc., shall be dismantled with great care. Temporary supports, horses, jacks, wedges, stiffening, bracing, etc., being provided to ensure that there will be no overstraining or buckling of any member or connection during the operation. Bolts and other fastenings shall be removed without causing damage to or elongation of the holes from which they are withdrawn. Where required for re-use by the Engineer under another contract the Contractor shall, after dismantling and satisfying the requirements of clause 5009, scrape, clean and free all parts of the dismantled structure from all loose paint, grease and other deleterious coatings. Areas of rust should be cleaned down to the bare metal and all thick edges, fins, blistering etc., due to previous coats of paint removed. The surfaces, when thoroughly dry, shall be given one coat of protective paint, particular attention being given to surfaces which have been in contact or inaccessible whilst the structure was erected. Care shall be taken to ensure that the distinguishing marks are not obliterated during this operation. Surfaces which have been galvanized shall be examined by the Engineer's Representative who shall direct whether the whole is to be cleaned thoroughly, freed from all deleterious matter and given one coat of protective paint or whether only the bad spots are to be touched up with an approved proprietary galvanizing commodity (aluminium paint is not to be used for this purpose). All bright and machined surfaces shall be cleaned and well coated with a mixture of white lead and tallow free from acid, or with other approved coating which will not readily melt when exposed to the sun in the tropics. Exposed machined surfaces shall be further protected by timber casings or other approved means. Free ends of members shall be 90 stiffened to prevent distortion during transit, and the ends of members with turned bolts connections suitably protected. A full set of new bolts, nuts and washers, rivets and all other fastenings should be supplied together with spares in accordance with clause 5066 of this specification, and in addition a complete set of erection tools (drifts spanner, screw-drivers etc., but not riveting apparatus) in accordance with clause 5065 of this specification. Turned bolts, nuts and washers shall be covered with a mixture of white lead and tallow free from acid and black bolts, nuts and washers, and field rivets shall be thoroughly cleaned, heated to about the melting temperature of lead and whilst hot dipped into boiled linseed oil. Straight bars and plates shall be bundled and temporarily bolted together. If this is not possible they shall be bound in at least three places with annealed steel wire of not less than 6mm diameter which must be tightly fastened. All rivets, bolts, nuts, washers, screws small plates and small article generally shall be packed in bags. A separate bag being used for each diameter and length of rivet, bolt etc., and each bag having a metal label wired on indicating its contents. The bags shall be packed into strong wooden cases or casks whose gross weight shall not exceed 300 kilograms. Each case, cask etc., shall be clearly marked with its weight and an indication of its contents. Bundles shall have a metal label, stamped with similar information, attached to each end, the label being secured at each of the end by a separate wire so that it lies flat with the bundles. All marking and labellings shall be to the satisfaction of the Engineer's Representative. All parts of the structure protected, marked and packed as above specified shall then be stacked in a position indicated by the Engineer's Representative to await collection by him and transport to his store, and all operations mentioned in this clause up to and including this final stacking shall be deemed to be included in the rates for dismantling the structure. Should the Engineer require the Contractor to transport the structure to his store, the Contractor shall do so without delay and payment shall be made in accordance with the rates in the day work schedule referred to in the bill of quantities or as mutually agreed before transporting. Where the structure is to be incorporated elsewhere into the works, either wholly or in part, the Contractor shall proceed as follows. On the marking drawings specified above, he shall indicate (i) Those parts of the structure which are not required for incorporation into the works and which will be stacked in readiness for transport to the Engineer's store, and (ii) Those parts of the structure which will be required for incorporation elsewhere into the works. Those parts covered by (i) shall be treated entirely as specified above for structure required for incorporation elsewhere into the works. Those parts covered by (ii) shall be treated entirely as specified above for structures required by the Engineer for re-use under another contract, with the following amendments. After dismantling, the required items shall be spread out and the Contractor shall inform the Engineer's Representative that they are ready for inspection. The Engineer's Representative shall then examine the items with respect to length, quality weight and condition and shall pronounce upon their suitability for incorporation into the works and shall advise the Contractor as to what cuts etc., should be made to permit their proper fitting, and they shall together agree as to where such work shall be carried out. The items shall then be transported to that part of the works unto which they are to be incorporated and the Contractor shall then proceed as directed in clause 5071 of this specification. The cost of all operations involved 91 in complying with these requirements shall be deemed to be included in the rates for dismantling and re-erection. All paint and painting shall be in accordance with clause 5049 of this specification. REMOVAL OFEXISTING SUPER STRUCTURE AND SUBSTRUCTURE: ALL TIMBER 5012. Existing decks, trestles, mud sills, piles etc., in timber shall be removed as carefully as possible. The use of explosives is forbidden. Timber piles shall be withdrawn completely, or sawn off, as directed by the Engineer. All timber, fastenings etc., shall be cleaned and stacked neatly as directed in a place to be indicated by the Engineer's Representative. Unless particularly so mentioned in the drawings no distinguishing marks,making plans, painting or protective coatings will be required. TOTAL DEMOLITION OF EXISTING ABUTMENTS PIERS AND LANDINGS 5013. The demolition of existing abutments, piers and landing will be permitted only after the superstructure has been removed to the satisfaction of the Engineer's Representative. The demolition shall be carefully carried out and the use of explosives will be subject to the approval of the Engineer's Representative. Generally, abutments and piers which are specified in the drawings to be completely removed, shall be completely removed above the lowest level of the ground in contact with the abutments or piers as approximately indicated in the drawings and in the bill of quantities, or as directed by the Engineer's Representative, below this level only so much will be removed as is required for the proper construction of the new abutments and piers. Reinforced concrete piles shall be completely withdrawn or cut away above the levels stated in the drawings or as directed by the Engineer's Representative. PARTIAL DEMOLITION OF EXISTING ABUTMENTS, PIERS AND LANDINGS 5014. Abutments, piers and landings which are required to be only partially demolished in a manner which will ensure that no damage whatever will be caused to that portion or the structure which will remain. The use of explosives for this work will not be permitted. The demolitions shall be carried out to the lines and levels shown on the drawings or to such lines and levels as the Engineer's Representative may determine after examination of the material exposed. The surfaces remaining after demolition shall be freed from all loose stones, rubble, mortar or other material and left in a perfectly sound condition, to the satisfaction of the Engineer's Representative. Under no circumstances shall any new work be constructed upon or against any part of the structure that remains until the Engineer's Representative has inspected it and given his permission to proceed. DISPOSAL AND REUSE OF RUBBLE RESULTING FROM DEMOLITION 5015. All concrete and masonry rubble and all other such material resulting from demolition shall be tipped as directed. No debris shall be allowed to block, interfere with or hinder the flow of water under the new structure, or along any part of the watercourse or through any drain, gully or water course, in the vicinity of the work, nor shall any debris be allowed to obstruct the passage of traffic or cattle or other animals along recognized paths. The rubble may be re-used as plums in the construction of the new abutments and piers should these be of mass concrete, at the discretion of the Engineer's Representatives. PREPARATION OF 5016. After demolition operations have been completed the surfaces of the remaining SURFACES OF portions of the substructures which are to receive new concrete shall be thoroughly hacked EXISTING ABUTMENTS, and freed from all loose plaster, mortar and other material and random stones shall be PIERS, ETC., PRIOR TO removed in the case of masonry walls as directed by the Engineer's Representative to provide PLACING OF an efficient key between the new work and the old. Immediately before concreting begins, the CONCRETE IN CONTACT surfaces shall be thoroughly washed with clean fresh water to remove all deleterious matter, all surplus water being then removed. The wet horizontal surfaces shall be covered with a 12mm layer of stiff, freshly mixed mortar class M1 which shall be thoroughly worked into all interstices to ensure intimate contact with the old structure and the fresh concrete shall be poured and carefully pounded into it without delay. The fresh concrete shall be carefully 92 worked into all corners, crevices and interstices in the wet vertical surfaces to ensure complete bounding with the old structure. PREPARATION OF SURFACES OF EXISTING ABUTMENTS, PIERS, ETC., PRIOR TO CONSTRUCTION OF NON-BONDING JOINT 5017 Where the drawings require a non-bonding joint or a gap to be left between the surfaces of the remaining portions of the existing substructure and those of the new work, the relevant surfaces of the existing structure shall be thoroughly cleaned and freed from all loose material. Irregularities in the surfaces shall be filled in with concrete Grade 10 N/mm² or the whole rendered with a minimum 12 mm thickness of plaster of a grade to be approved by the Engineer's Representative, to give a smooth surface over the whole area of the joint. The non-bonding joint shall then be constructed as directed by the Engineer's Representative or a gap left as directed in the drawings. TEST ON COMPLETED STRUCTURES 5018 (A) CONCRETE STRUCTURES The Engineer may instruct that a loading test be made on the works or any part thereof if, in his opinion, such a test is deemed necessary for one or more of the following reasons:(a) The site made concrete tests cubes failing to reach the specified strength, (b) The shuttering being prematurely removed, (c) Overloading during construction of the works or part thereof, (d) Concrete improperly cured. (e) Any other circumstances attributable to alleged negligence on the part of the Contractor which, in the opinion of the Engineer may result in the works or part thereof being of less than the expected strength. (f) Any reason other than the foregoing. If the loading test be instructed to be made solely or in part for the reason (a) the test shall be made at the Contractor's own cost. If the test be instructed to be made for one or more of the reasons (b) to (e) inclusive, the Contractor shall be reimbursed for the cost of the test if the result thereof is satisfactory. If the test be instructed to be made for the reason (f) the Contractor shall make the test and shall be reimbursed for all costs relating thereto unless the result of the test is unsatisfactory in the opinion of the Engineer. The test load shall not be applied within eighty-four days of the completion of placing of the concrete in the part of the structure to be tested, and the latter shall not be supported during the test by the shuttering or other non-permanent support. Means shall however be taken to ensure that in the event of failure under the test, temporary support of the loaded members shall be immediately available. The test shall proceed strictly as directed by the Engineer. If the result of the loading test is not satisfactory in the opinion of the Engineer, the Engineer shall instruct that part of the works be taken down or cut out and reconstructed to comply with this specification, or that other remedial measures be taken to make the work secure. 93 All remedial measures shall be carried out expeditiously by the Contractor at his own expense. The test load to be applied shall be a series of tractors, lorries, or road rollers equivalent to the 1.10 times the design load of the particular structure, disposed of in one or more arrangement so that the maximum bending moments, thrusts, tensions and shear forces due to the test load are produced at the critical sections. During the test a record of the sequence of all cracks and deflections at mid-span will be kept together with any other observations which the Engineer may elect to record. The residual deflection if any shall be recorded and if required by the Engineer the test will be repeated. The period of loading shall be one hour in any particular case or as otherwise directed by the Engineer. (B) STEEL STRUCTURES If, through any negligence or bad workmanship or carelessness or default on the part of the Contractor or any Sub-Contractor or for any other reason whatsoever, the Engineer shall deem the strength of any steel span or any part thereof to be adversely affected, the Engineer shall order such tests to be carried out as shall indicate the real strength of the structure. The test may follow that specified above for reinforced concrete structures or any other form that the Engineer may consider desirable. If in the opinion of the Engineer, the result of the test is not satisfactory the Engineer shall order such remedial measures to be carried out as may be necessary in his opinion, and the Contractor shall carry out such remedial measures without delay and at his own expense. LOADING OF STRUCTURES: CONSTRUCTION, BACKFILLING, TRAFFIC, ETC 5019. Under no circumstances shall any part of any structure included in the works be loaded in any way until permission to do so has been obtained in writing from the Engineer's Representative. The Contractor shall arrange his programme of construction so that the loads of subsequent construction shall not be imposed upon work already completed until, in the opinion of the Engineer's Representative, that work has developed sufficient strength to withstand safely the resulting stresses. No backfilling of earth against or on top of any part of any structure shall be commenced until the Contractor has sought and obtained the written permission of the Engineer's Representative so to do. This will be given after the Engineer's Representative has inspected and measured the work to be covered and the Contractor has carried out all repairs, and all other work that the Engineer's Representative may require to ensure that the work complies with this specification. Additionally, no backfilling shall be undertaken until the requirements of the preceding paragraph of this clause are satisfied and the following conditions fulfilled:(i) No earth shall be backfilled against or on top of a mass concrete structure until at least 14 days have elapsed since the pouring of the last concrete, without the approval of the Engineer's Representative. (ii) No earth shall be backfilled against or on top of a reinforced concrete structure until at least 28 days have elapsed since the pouring of the last concrete and the results of the 28 days compression cube tests have been studied and proved acceptable (iii) No earth shall be backfilled against the walls, nor placed on top of the roof slab, of a reinforced concrete culvert until at least 28 days have elapsed since the pouring of 94 the last concrete in the complete structure, including wingwalls should these be monolithic with the barrel, and the results of the 28 days compression cube tests have been studied and proved acceptable. No earth shall be placed on to the roof slab unless this is so specified on the drawings, and then strictly within the limits shown thereon. (iv) Backfilling of all excavations for abutments, piers, culverts, etc., shall be brought up equally and simultaneously on all sides to eliminate unbalanced earth pressures, filling to open-type abutments shall likewise be brought up equally and simultaneously around supporting columns, walls, etc., to eliminate unbalanced earth pressures. All backfill shall be done in layers not exceeding 150mm compacted thickness, and in accordance with the requirements of all relevant clauses of this specification. During backfilling operations, the Contractor shall take every care to ensure that no undue loads shall be imposed upon the structure and he shall furnish the Engineer's Representative in advance with full details of his proposed method of performing the task, showing that the structure will not be overstressed in any way. In no case shall any structure be used for the passage of constructural traffic, storage of materials etc., without the written permission of the Engineer's Representative, whose decision in these matters shall be final. AS - MADE DRAWINGS 5020. On completion of the work, and after it has been approved by the Engineer's Representative, the Contractor shall prepare as-made drawings of each bridge, showing complete, fully dimensioned details of the foundations, material on which they are founded, ground levels, road levels, protection works, superstructure and all other work carried out under the Contract. The drawings shall be originals prepared from records taken as the work progresses and agreed with the Engineer's Representative, and shall not be merely amended prints of the contract drawings. Draughtsmanship shall be of a high standard, to the satisfaction of the Engineer's Representative. The drawings shall be by CAD (Computer Aided Designed) or handmade drawing ink, on best quality tracing linen and shall be 594mm by 841mm overall including a margin of 50mm on the left hand side, and a margin of 10mm on the other three sides and the title box shall follow the form shown on the contract drawings. These original tracings together with one black and white print of each on linen shall be forwarded to the Engineer for his permanent retention. The cost of preparing and supplying all these negatives, velographs, prints etc., shall be deemed to be included in the rates for carrying out the works to which they refer. SETTLEMENT OF BRIDGE AND APPROACHES 5021 The Contract shall include:(a) The return to site and carrying out of a survey of settlement of bridge and approaches at a time just prior to the completion of the maintenance period and the submission of a report of the results of this survey to the Engineer. The cost of this survey shall be deemed to be included in the tendered rates and prices. (b) The carrying out of any jacking operation or other remedial works deemed necessary by the Engineer as a result of this settlement to re-establish the bridge and approaches to the proper levels. The cost of any such operation shall be deemed to be included in the tendered rates and prices. BEARINGS 5022. Bearing devices expansion or fixed, shall be constructed in accordance with the details shown on the drawings and approved by the Engineer. 95 Metal bearing shall comply in all respects with the requirements of B.S 5400 and as specified on the drawings. The masonry plates shall be set level. The expansion devices shall be set to conform to the temperature at the time of erection or to the setting specified. When masonry plates are shown on the drawings to be placed (not embedded) directly on concrete, the concrete bearing area shall be constructed slightly above grade and shall be finished by grinding or other approved means to a true level plane which shall not vary perceptibly from straight edge placed in any direction across the area. the finished plane shall not vary more than 3mm from the elevation shown on the plan. ELASTOMERIC BEARING PADS 5023. Elastomeric bearing pads shall conform to the requirements of B.S. 1154 and the special provisions. Where elastomeric bearing pads are shown on drawings, the concrete surfaces on which pads or packing are to be placed shall be wood float finished to a level plane which shall not vary more than 1.5mm from a straight edge placed in any direction across the area. The finished plane shown on the drawings. Pads 12mm and less in thickness may be either laminated or all elastomer. Pads over 12mm in thickness shall be laminated. Laminated pads shall consist of alternate laminations of elastomers and metal or elastomer and fabric bonded together. The outside laminations shall be metal or fabric. The outside and edges of metal laminations shall be coated with elastomer not more than 3mm in thickness. Laminations of elastomer shall be 12mm ± 3mm in thickness. Variation in thickness of an individual elastomer lamination shall not exceed 3mm within the width or length of a pad and the variation in thickness of all elastomer laminations within a pad shall be such that each metal or fabric lamination will not vary by more than 3mm from a plane parallel to the top or bottom surface of the pad. The total out to out thickness of pad shall not be less than the thickness shown on the drawings nor more than 6mm greater than that thickness. Variation of total thickness within an individual pad shall not exceed 3mm. The length and width of a pad shall not vary more than 3mm from the dimensions shown on the drawings. Pads containing metal laminations shall be fully moulded. Pads of all elastomer or with fabric laminations may be cut from large sheets. Cutting shall be performed in such a manner as to avoid heating of the material and to produce a smooth edge with no tears or other jagged areas and to cause as little damage to the matter as possible. Corners and edges of moulded pads may be rounded at the option of the Contractor. Radius at corners shall not exceed 9mm and radius of edges shall not exceed 3mm. 96 The bond between elastomer and metal or fabric shall be such that, when a sample is tested for separation, failure shall occur within the elastomer and not between the elastomer and metal or fabric. Metal laminations shall be rolled mild steel sheets not less than 1.0mm. Fabric laminations shall be either (1) a long chain synthetic polymer containing at least 85 percent of polyester from ethylene glycol and terephthalic acid or (2) a long chain synthetic polymeric amide from hexamethylene diamine and adipic acid. Each ply of fabric shall have a breaking strength of not less than 12.5 N/mm². Fabric laminations shall be single ply at top and bottom surfaces of the pad and either double ply or double strength within the pad. The sole polymer in the elastomeric compound shall be neoprene and shall be not less than 60 percent by volume of the total compound. The Contractor shall furnish to the Engineer a certification by the manufacturer that the elastomer, and fabric (if used ) in the elastomeric bearing pads to be furnished conforms to all of the requirements specified in the British Standard. The certification shall be supported by a certified copy of the results of tests performed by the manufacturer upon samples of the elastomer and fabric to be used in the pads. Where elastomeric bearing pads over 12mm in thickness are shown on the drawings, such pads may be manufactured as a moulded laminated pad, or at the option of the Contractor, may be made up by stacking individual laminated pads. Individual laminated pads used for stacking shall be normally 12mm in thickness. When laminated parts are stacked, their contact surfaces shall be cleaned prior to stacking and a positive method shall be used to hold the individual parts in the stack in proper alignment. The quantity of Elastomeric Bearing pads for which payment will be made, will be the number of pads actually constructed and installed as prescribed. Payment for the Elastomeric Bearings pads shall be made for the quantities as above determine, at the unit price shown in the Bill of Quantities, which price shall include the cost of bearing pads, dowels, hardware, setting, all material, equipment, labour, and all else necessary thereof and incidental thereto. (CLAUSES 5024 - 5029 INCLUSIVE NOT USED) PART (B) - STRUCTURAL STEELWORK GENERAL: MATERIALS AND WORKMANSHIP 5030. All materials and workmanship involved in the fabrication of steelwork shall comply with the requirements of B.S. 5400 together with the additional requirements and modifications specified hereinafter. All materials and fittings shall be the best of their respective kinds and free from defects. Accurate workmanship is essential and all work shall be neatly finished. WORKING DRAWING 5031. Before any part of the work is put in hand, the Contractor shall prepare working drawings in accordance with clause 1010 of this specification. The working drawings shall be submitted as mechanically reproduced prints on medium weight paper showing either black lines on a white background, or white lines on a 97 blue background, and all costs involved in supplying them shall be deemed to be included in the rates for steelwork. SCHEDULE OF PARTS 5032 As soon as possible after the signing of the contract, the Contractor shall prepare schedules of all parts which go to make up the work, including bought-out material, and shall forward a copy, to the Engineer's Representative, the duly authorized inspector for guidance during inspection. MILD STEEL FOR STRUCTURAL MEMBERS ETC 5033. Unless otherwise specified in the contract, structural steelwork shall comply with the provisions of B.S 4360 (1990) "Weldable Structural Steels" and shall be of the grade indicated on the drawings. All sections shall conform to British Standard dimensions. ROLLED STEEL PINS, KNUCKLE PINS, ROLLERS 5034. Steel for rolled steel pins, knuckle pins, rollers etc., shall be of the minimum tensile strength as specified on the drawings and finished as indicated. (Not rivet steel) STEEL CASTINGS FOR BEARING 5035. Steel casting for bearings shall comply with the requirements for B.S. 3100: and shall be Grade A steel except where noted on the drawings. PATTERNS OF CASTINGS 5036. Patterns of all castings are to be submitted to the Inspection Engineer, and shall be approved before moulding is commenced and the casting are run. Where this cannot be done on account of their large size the pattern shall be kept available at the manufacturer's works for approval by the Inspection Engineer. Each casting shall be legibly marked with a number or identification mark by which it can be traced to the cast from which it was made. All castings shall be subject to tensile and bend tests and wherever possible the test samples shall be attached to the castings. No casting shall be repaired or welded without the previous sanction of the Engineer's Representative. If permission be given to effect repair by welding, the Engineer's Representative shall decide whether further heat treatment is necessary and such treatment shall be carried out to his satisfaction. All surfaces to be machined shall have adequate allowance left on to enable the castings to be machined to the plan dimensions but in no case shall the allowances be less than 3mm. Unless otherwise specified or shown on the drawings all holes in castings shall be boldly filiated and free of all faults affecting their strength and value for the service intended. GUNMETAL FOR BEARING 5037. Gunmetal for girder bearing strips etc., shall be made of the following mixture: Copper 88 per cent, tin 10 per cent, zinc 2 per cent, and shall show a tensile strength of not less than 215 N/mm² with 7.5% elongation on 50mm. FORGINGS 5038. Forgings shall comply with B.S.29 and the steel shall have a minimum tensile strength of 430 N/mm² or as indicated on the drawings. RIVETS 5039. Steel for high tensile steel rivets shall comply with the requirements of B.S. 548 "High Tensile Structural Steel for Bridges, etc., and General Building Construction", Amendments CE 52, May 1936; CE6854 February 1938: CG 715 June 1942 and current amendments. Steel for mild steel rivets shall comply with the requirements of B.S. 15 1948 "Structural Steel", Amendment PD 3346, April 1959 or latest edition. BOLTS 5040. All bolts must comply with the requirements of B.S. 1083: 1965 (Precision Hexagon Bolts, Screws, Nuts and Plain Washers), and of B.S. 1968: 1963 (Unified 98 Precision Hexagon Bolts, Screws, Nuts (Unc and Unf Threads) and Plain Washers Normal Series), Amendment PD5706 November 1968 and PD 6623 or latest edition. High strength bolts and nuts washers for high strength bolts shall comply with B.S. 3139 and B.S. 3294, part 1. All galvanized bolts shall conform with requirements of B.S. 729, Part 1. Minimum zinc coating shall be 90 m. HANDRAILING AND GUARD RAILING 5041. Hand-Railing and Guard-Railing shall be as shown on the drawings or as directed by the Engineer. HIGH TENSILE STEEL FOR WELDING 5042. High Tensile Steel to be used for plates and rolled sections that are specified to be welded must comply with the requirements of B.S. 4360 with the following additional requirements: (A) The chemical composition shall be as specified in tables 6, 8, 11, 13 and 16 of B.S. 4360 and upon request, the supplier shall supply details of the ladle analysis to the Engineer. (B) The steel to be used for plates shall be delivered in a normalized condition. (C) The high tensile steel (welded quality) for plates shall be subjected to the VNotch Charpy 2 millimetre impact energy test. The average of three test specimens and the average impact energy at 00C shall not be less than 35 joules (D) As a result of the V-Notch Charpy test the crystalline area in the fractures of the high tensile steel (welded quality) test pieces shall be measured. In general the average crystalline area in the fractures of the test pieces shall not be greater than 80 per cent of the original area of the test piece below the notch. (E) The high tensile steel (welded quality) for plates shall be subjected to the Vicker's test for hardness. For the hardness control test of the steel; a single welded bead shall be deposited on the outer surface on the plate with 4mm diameter welded electrode, and a cross section of the bead and the plate shall be cut and etched. The hardness in the heat affected zone shall be measured by the Vickers method and shall not exceed 350 Vickers. (F) The frequency of the tests described in (C), (D) and (E) above shall be the same as those for tests for the control of tensile strength, yield point and elongation as specified in B.S. 4360. (G) Should the results of the tests described in (C), (D) and (E) above not reach the requirements specified then the steel may be re-normalized and re-submitted for inspection. The cost of re-normalizing the steel shall be borne by the manufacturer. If the steel is re-normalized then all the tests required under this specification shall be repeated if after re-normalizing the results of the tests do not reach the requirements specified then the inspection Engineer will reject the steel and the costs of the rejected shall be borne by the manufacturer HIGH TENSILE STEEL: NOT TO BE WELDED 99 5043. High Tensile Steel to be used for plates and rolled sections and welding will not be permitted except where shown on the drawings. HIGH TENSILE STEEL: MARKING 5044. All High Tensile Steel shall be marked strictly in accordance with the requirements of B.S. 4360. All steel not correctly marked and identified may be rejected by the Inspection Engineer. CAST STEEL 5045. Steel castings are to be true and clean and shall comply as regards quality and tests with the requirements of B.S. 3100 for Steel Castings for General Engineering Purposes, 1967. The casting shall be thoroughly annealed and stress relieved and tested as per the above for cracks. They are to be well fettled and dressed where necessary to remove roughness or inequalities. All holes for bolts shall be drilled unless shown on the drawings to be cored. CAST IRON 5046. Cast Iron shall comply with the requirements of B.S. 1452: (1961) for Grey Iron Castings. All holes in cast iron for bolts shall be drilled unless shown to be cored. ELECTRODES 5047. The Electrodes to be used for welding steel must be of the best heavily coated type and of such make as the Inspection Engineer may approve. They shall be kept in a dry store in unbroken packets and shall be accompanied by the Maker's Certificate of date of manufacture and guarantee that they fulfil in all respects the requirements of B.S. 639, B.S 1856 and B.S 2642 depending upon the grade of steel employed in the Contract. 1. Electrodes shall not be used in a damp condition. The inspection Engineer shall have access at all times to inspect the store at the works and may reject electrodes which he considers unsuitable. 2. The Contractor shall submit to the inspection Engineer the name(s), and all relevant particulars of the electrodes he proposes to use. 3. The quality and type of the electrodes to be used for the submerged arc welding of high tensile steel must be approved by the Inspection Engineer and will depend on the submerged arc welding process that will be used. GREASE FOR BEARINGS 5048. Grease for bearings shall be such as will ensure adequate lubrication of the bearings under tropical conditions. The following is the approximate analysis of a suitable grease:high-class viscous mineral oil pure soap (dry) best flake graphite 78.0 Per cent 5.0 Per cent 17.0 Per cent The melting point of the grease shall be not less than 1380C The grease shall be packed for shipment in strong airtight metal drums. PAINT AND PAINTING 5049. All paint used in the works, whether applied in the shop or in the site shall be the best of its kind and all ingredients used in its manufacture shall comply with the appropriate British standards. In any paint system (viz: primer, undercoats and finishing coats) each coat of paint shall be compatible one with the other, and to ensure this, all paint shall be obtained from the same approved manufacturer with a guarantee of compatibility. The paints shall be used as specified for the various parts of the work. 100 PRIMING PAINT All priming paint shall be in accordance with B.S.2523. UNDERCOAT Exterior quality aluminium paint tinted with sufficient blue pigment to distinguish if from the finishing coat. FINISHING COAT Exterior quality aluminium paint PROTECTIVE PAINT Where steel is specified to be given one coat of protective paint, such paint shall be of priming paint, as specified by the Engineer's Representative. Where the paint has to be applied to a surface already painted with a bituminous paint, the protective coat shall be of bituminous paint of best approved quality and colour. The aluminium content of the paint used for undercoat and finishing coat shall comply with B.S 388 and shall constitute not less than 20 per cent by weight of the total paint. The approved volatile matter of the paint shall not exceed 45 per cent. The paint shall be of the type in which the aluminium paste is mixed with the vehicle immediately prior to application and the date of manufacture shall be marked on each container. Mixing of the paint and its application to the work shall be strictly in accordance with the manufacturer's instructions and this specification. During painting, the paint shall be stirred as necessary to keep the pigment in suspension. Prior to shop painting all surfaces of steelwork shall be cleaned and de-sealed to bare metal by steel grit or sand blasting. Before the application of any paint, the surfaces to be treated shall be thoroughly cleaned and freed from all scale, loose paint, grease, rust and other deleterious coatings. Surfaces shall be protected in accordance with CP 2008. The paint shall not be applied to any surface which is not thoroughly dry and shall be applied entirely by hand brush and thoroughly worked into all crevices, corners and splices and around all bolt heads, nuts, rivets, etc. Successive coats of paint shall differ in colour and each coat shall be thoroughly dry before the next is applied. All paintings shall be carried out in accordance with the standards laid down in British Standard Code of Practice C.P 231 and all testing, where directed by the Engineer shall comply with B.S 3900. Before the application of any paint, the surfaces to be treated shall be thoroughly cleaned and freed from coatings. The paint shall not be applied to any surface which is not thoroughly dry and shall be applied entirely by hand brush and thoroughly worked into all crevices, corners and splices and around all bolt heads, nuts, rivets, etc. Successive coats of paint shall differ in colour and each coat shall be thoroughly dry before the next is applied all painting shall be carried out in accordance with the standards laid down in British Standard code of practice C.P.231 (1952) INTERCHANGE ABILITY OF PARTS 5050. Corresponding parts of each unit should be Inter-changeable as far as economic manufacturing conditions permit. PREPARATION OF EDGES AND ENDS 5051. When single universal plates are used with their edges flush with heels of angles or channels, as in box girders, end posts etc. the edges shall be planed. The edges of universal plates shall also be planed when used as web plates of riveted plates girders and there are flange plates. Where two or more universal plates or flats of the same nominal width are used in tier (excluding covers to a single plate) the edges shall be machined to make them straight and flush. 101 HOLES FOR BOLTS AND RIVETS 5052. All holes for rivets and black bolts shall be 1.5mm larger than the nominal diameter of the cold rivet or bolt as manufactured and all hole shall be drilled, or drilled small and reamed. Punching and sub-punching and reaming shall be permitted only for floor plates and troughing and only when these do not exceed 12 millimetre in thickness. Holes for turned bolts shall first be drilled at least 3.0mm small in diameter and afterwards when the structure is assembled, they shall be reamed or drilled to the correct size through all thicknesses in one operation. Sub-punching will not be permitted. RIVETS AND RIVETING 5053. Rivet heads shall be of standard shape, unless otherwise specified, and of uniform size for the same diameter of rivet. They shall be full, neatly made, concentric with rivet holes, and in full contact with the surface of the member. Rivets shall be heated uniformly to "light cherry red colour" and shall be driven while hot. Any rivet whose point is heated more than the remainder shall not be driven. When a rivet is ready for driving, it shall be free from slag, scale, and other adhering matter. Any rivet which is scaled excessively, will be rejected. All rivets that are loose, burned, badly formed or otherwise defective shall be removed and replaced with satisfactory rivets. Any rivet whose head is defective, in size or whose head is driven off centre, will be considered defective and shall be removed. Where required, rivets shall be cut for examination by the Engineer's Representative and afterwards replaced free of charge. Stitch rivets that are loosened by driving of adjacent rivets shall be removed and replaced with satisfactory rivets. Caulking, recupping, or double gunning of rivet heads will not be permitted. WASHERS 5054. All bolts shall be provided with washers, those for turned bolts being bright finished. Round washers shall not be less than 6mm thick for turned bolts and not less than 3mm thick for black bolts. Tapered washers of the correct angle shall be provided under all heads and nuts bearing on bevelled surfaces and where tapered washers are required for turned bolts, round washers shall also be supplied. Tapered washers shall be not less than 5 mm mean thickness. All washers shall comply with the requirement of B.S 3410. WELDING 5055. No welding of any description will be permitted except where shown on the drawings. Unless otherwise described in the Contract, metal-arc welding shall comply with B.S 1856 and B.S.2642 as appropriate except for tack welds and temporary attachments for which the procedures laid down in B.S. 2642 shall be followed. The temperature of steels welded in accordance with B.S 2642 shall be not less than 10 C when welding is commenced. Electrodes and fluxes shall be used in accordance with the manufacturer's instructions. The use of welding processes other than those covered by B.S. 1856 and B.S. 2642 shall be subject to the approval of the Engineer. The general welding programme for shop; and site welds, including particulars of the preparation of fusion faces, the method of pre-heating where required, the methods of making the welds, and the types of electrodes shall be submitted to the Engineer for his approval before the work is put in hand. No departure from the agreed welding programme or from the details shown on the drawings shall be made without the agreement of the 102 Engineer. Electrodes and fluxes shall be so chosen that the properties of the deposited metal are not inferior to those of the parent metal. The position of welds required for temporary attachments shall be agreed by the Engineer before the work commences. Where automatic or semi-automatic processes are used back gouging of the deposited weld will not be required where the Engineer is satisfied that the root is free from imperfection. The cost of furnishing materials, labour, equipment and all else necessary thereof and incidental thereto. JOINTS 5056. Joints shall not be made in any plate or section or in any part of the bridgeworks, except where shown on the drawings. Abutting joint in compression members and girder flanges and where shown on the plans shall be faced and brought to an even bearing. NOTCHING OF FLANGES AND WEBS 5057. When the flanges or webs of any member have to be cut or notched to enable the section to be trimmed into another member,a hole of suitable diameter shall first be drilled through the flange or web so as to leave a fillet at the intersection of the cut lines. BENDING AND PRESSING 5058. Troughing up to 8 mm thick may be pressed cold. Over 8 millimetre and up to 12 mm thick cold pressing shall be subject to the approval of the Engineer's Representative. SHOP ASSEMBLY 5059. Members shall not be riveted up until the parts have been thoroughly scraped, cleaned and freed from all scale and other deleterious matter. Thereafter, surfaces which will be in permanent contact after shop assembly shall be given one coat of priming paint on each face and the parts drawn firmly together with bolts whilst the paint is still wet. All rivet holes shall be thoroughly brushed out and all burrs and exuded paint removed before rivets inserted and riveting commenced. Surfaces not in contact but which will be inaccessible after shop assembly shall receive the full protective painting treatment before assembly viz one coat of priming paint, one undercoat and assembly viz: one coat of priming paint, one undercoat and one finishing coat. All paint and painting shall be in accordance with requirements of clause 5049 of this specification. All reamering of holes shall be carried out in the manufacturer's works and the edges of all holes on the outside faces of members shall be slightly arrised. MACHINING 5060. The bearing surfaces of bearing plates etc., shall be planed level, the cut being made in the direction of expansion of the girder. Surfaces which require machining shall be indicated on the drawings. ERECTION AT MANUFACTURER'S WORKS AND MARKING UP FOR RE-ERECTION 5061. Before being despatched, all bridge spans shall be temporarily erected complete in the manufacturer's works so that the Inspection Engineer can be satisfied as to both the alignment and fit of all connections. After the work has been passed by the Inspection Engineer and before it is dismantled, each part shall be stamped with the distinguishing mark, assigned to it on the marking drawings, in figures not less than 16 mm high, in such a manner that the pieces may be readily identified on arrival at site and put together in their proper positions. The marking shall also be stencilled on each part in one or more places after it has received the coat of paint mentioned in Clause 5062 and a circle of white paint shall be placed round each stamped erection mark. No marking other than that specified shall be put on the steelwork. 103 The drawings showing the markings shall be as set forth in Clause 5020. The Manufacturer shall forward to the Engineer one set of hand made tracings on best quality polyester or tracing linen, one set of mechanical copies on tracing linen (e.g. velograph) and one set of prints showing black lines on white background of the marking drawings. The cost of producing and supplying all these tracings and prints shall be deemed to be included in the rates for steel work. SHOP PAINTING AND PROTECTIVE COATINGS 5062. After approval by the inspection Engineer but not before, the whole of the work shall be thoroughly wire brushed, scraped, cleaned and freed from all scales, grease and coatings. Areas of rust shall be cleaned down to the bare metal. The surfaces shall be thoroughly dried and given one coat of priming paint. All paint and painting shall be in accordance with requirements of clause 5949 of this specification. See also clause 5059 for the treatment of surfaces which will be in permanent contact or inaccessible after shop assembly. All machined surfaces, turned bolts, nuts and washers, and all bright surfaces shall be well coated with other approved coating which will not readily melt when exposed to the sun in the tropics. Exposed machined surfaces shall be further protected by timber casings or other approved means. Field rivets, black bolts, nuts and washers shall be thoroughly cleaned, heated to about melting temperature of lead, and whilst hot, dipped in boiled linseed oil. GALVANIZING 5063. Items which are shown on the drawings to be galvanized shall first be cleaned by pickling and then galvanized by the hot process. The smelter used in this process shall comply with B.S 222 and the manufacturer shall produce evidence to the satisfaction of the Engineer's Representative that this is so, and at his own cost. In addition, samples of metal from the batch may be taken by the Inspection Engineer for independent analysis and if found to contain less than 98.5 percent of pure zinc, the galvanized parts represented will be rejected. The cost of this independent analysis will be borne according to clause 36 (4) of the conditions of contract. The galvanized surfaces shall be evenly covered, clean and free from drops or spelter, spots and blemishes of every kind. After coating, all traces of flux shall be removed. The coating shall weigh not less than 34 grams per square metre of surface treated. All cutting, holing, threading etc. shall be carried out before galvanizing. Cutting, holing, threading etc., after galvanizing will only be permitted where the written approval of the Inspection Engineer has been first obtained. Where such permission has been given, the cut edges shall be protected by an approved proprietary galvanizing commodity, aluminium paint must not be used for this purpose. All materials shall be stored for a period of 7 days after galvanizing in such a manner that air comes freely in contact with the surfaces. At the end of this period each article will be examined by the Inspection Engineer and those showing signs of acid spot, cracks, blisters or other defects will be rejected. At the discretion of the Inspection Engineer the quality of the galvanizing may be tested by the copper sulphate test as described in B.S 729: 1961 and the ductility and adhesion of the zinc coating tested by bending or otherwise. For the purpose of these tests 104 more than 1 per cent of the articles will be selected for testing and the cost of the tests and replacement of the articles thus destroyed shall be borne by the Contractor. DRIFT, SPANNERS ETC. NUMBER OF SITE RIVETS, BOLTS, NUTS, SERVICE BOLT ETC 5064. Drifts for rivets and bolts shall be supplied to the extent of one per cent (with a minimum of six for each size) of the net number of rivets or turned bolts used in the work. Drifts for use with turned bolts shall be turned to suit the holes. Spanner, the handles of which shall be made in the form of a podger and joggled, shall be supplied in the proportion of 1 in every 500 or less for each size of bolt and nut. Where necessary, brace spanners, screw drivers etc., shall also be supplied. The Contractor shall ensure that an adequate number of all tools necessary for the proper and efficient erection of the work at site are provided; the above requirements are regarded as a minimum. 5065. The full number of rivets, bolts, nuts, washer etc., required to complete the work shall be supplied and in addition, the following spares shall be provided for each span:Black bolts, nuts and washers 10 percent of the full number of each size required. Turned bolts, nuts and washers 10 per cent of the full number of each size required. Foundation bolts 5 per cent of the full number with a minimum of 2% of each size required. Rivets 15 per cent of the full number of each size when the number is 250 or less plus 10 per cent of the number of each size in excess of 250. Service bolts complete with nuts and washers shall also be supplied equal to 25 per cent of the net number of site rivets for all girder work and 10 per cent of the net number of site rivets for trough and plated floors. There shall be no reduction in any of the above number in the case of multiple spans. The bolt lists including all lengths of rivets to be provided shall be submitted on acceptable reproduced prints, and all costs involved in suppling them shall be deemed to be included in the rates for steelwork. MEASUREMENT FOR PAYMENT OF STEELWORK 5066. Payment for steelwork shall normally be made on the computed weight of the structure as determined from the dimensions given on the drawings, on the basis given in B.S. 5400, if however the weight of any materials falls short of the calculated weight by more than 2½ per cent, but nevertheless be accepted, the actual weight of such material only shall be paid for. If there is any difficulty in obtaining the B.S. section specified or shown on the drawings, the nearest B.S. section may be submitted for approval. Should the weight of the substituted section differ from that of the specified section the weight to be taken for the purpose of payment shall be the lighter of the two. For the purposes of payment and unless otherwise shown on the drawings, castings, forgings, special alloy steels, wrought iron and all structural shapes and plates of expansion joints, pier protection, access manholes, steel deck drains and other miscellaneous steel members, shall be considered as structural steelwork except that when specific items of the 105 above are called for in the Bill of materials, the weight or unit of measurement of each selected item as specified therein, will be paid at the respective contract unit price as named in the bid schedule. PACKING AND MARKING FOR SHIPMENT 5067. All works shall be protected from damage in transit, full allowances being made for handling under difficult conditions. Particular care shall be taken to stiffen free ends and to prevent distortion and to adequately protect all machined surfaces, the ends of members with turned-bolt connections etc. Straight bars and plates, when bundled, shall be temporarily bolted together. If this is not possible they shall be bound in at least three places with annealed steel wire of not less than 6 millimetre diameter which must be tightly fastened. All rivets, bolts, nuts, washers, screws, plates and small articles generally shall be packed in bags, a separate bag being used for each diameter and length of rivet, bolt, etc., and each bag having metal label wired on indicating its contents. The bags shall be packed into strong wooden cases or casks, whose gross weight shall not exceed 300 kilograms. Each case, cask, or drum, shall be clearly marked with the shipping marks, and indication of its contents and its weight. Bundles shall have a metal label, stamped with similar information, attached to each end, the label being secure at each of its ends by a separate wire so that the label lies flat with the bundles. All marking and labelling shall be carried out to the satisfaction of the Engineer's Representative:- ERECTION AT SITE 5068. The steelwork shall be erected at site in accordance with B.S.153: with the following amendments and additional requirements. All lines and levels shall be as shown on the drawings or as specified by the Engineer's Representative. The Contractor shall be responsible for all setting out and shall give all necessary assistance and facilities for checking by the Engineer's Representative (see clause 1013). Any stakes or marks set out by the Engineer's Representative on site shall be carefully preserved. In addition to the requirements given under clause 7 of B.S. 153, the Contractor shall comply with the requirement of Clause 1012 of this specification relating to drawings and calculations for temporary works and stagings etc. The Contractor shall obtain the prior approval from the Engineer for the method of erection and he shall forward to the Engineer's Representative complete details, drawings and calculations for the proposed method of erection at the time of seeking such prior approval. SITE PAINTING 5069. Surfaces which will be in permanent contact after site assembly or erection shall be thoroughly clean and freed from all scale, loose paint, grease and other deleterious coatings. Areas of rust shall be cleaned down to the bare metal. The surfaces shall be thoroughly dried and one coat of priming paint applied to each face. The parts shall then be drawn firmly together whilst the paint is still wet. All rivet holes shall be brushed out and exuded paint removed before the rivets are inserted. Similarly for bolts and bolt holes. Surfaces which will be inaccessible after site assembly or erection shall be thoroughly cleaned and freed from all scale, loose paint, grease and other deleterious coatings. Areas of rust shall be cleaned down to bare metal. The surfaces shall be 106 thoroughly dried and then given one priming coat, one undercoat and one finishing coat of paint. Care shall be taken to ensure that no paint shall be applied to or allowed to foul any reinforcement or other steelwork which is to be embedded in concrete. In the case of steel joists which will be so embedded and steel troughing which will be concrete filled, and all other such surfaces, those surfaces which will be in contact with the concrete shall be thoroughly cleaned and freed from all rust, scale, loose paint, grease and other deleterious coatings before the concrete is poured against them. Where concreting or any other operation likely to foul the steelwork has to be carried out (e.g. pouring of concrete deck slabs supported on R.S.Js.), preparation and painting of surfaces shall not be undertaken until such time as the cause of likely fouling or damage no longer exists. All paint and painting shall be in accordance with clause 5049 of this specification. ADDITIONAL 5070. Before embarking on the strengthening of any bridge the Contractor shall forward to STEELWORK IN THE the Engineer's Representative for approval full details of the method he proposes to STRENGTHENING OF employ to carry out the work. Such details shall be accompanied by drawings and EXISTING BRIDGES calculations showing that no part of the existing structure shall be overstressed or likely to suffer any damage during the strengthening operations and to ensure that this will be so, the Contractor shall provide temporary supports, bracing, struts etc., as necessary. In no case shall any part of an existing bridge be removed to facilitate strengthening until a temporary substitute has been fixed in place to the complete satisfaction of the Engineer's Representative. The Contractor shall amend his proposals for undertaking the strengthening of the bridge as required by the Engineer's Representative and shall not commence the work until the Engineer's Representative has given his approval to the scheme and his permission to proceed. Before ordering the additional steelwork, the Contractor shall completely satisfy himself in all respect as to the dimension and positions of all fastenings and members of the existing structure and shall be responsible for ensuring that all new plates, joists etc., required for the strengthening shall avoid or accurately pick up all such existing fastenings and members as the case may require. The Contractor shall also check existing spans as indicated on the drawings to ensure that the lengths of new joists etc., are adequate for the work proposed, and before ordering any such material shall inform the Engineer's Representative of the dimensions, weights etc., which he proposes to obtain and obtain his approval therefore. Any indications of the sizes or positions of any part of any existing structure as are shown on the drawings are of a general nature only and the Contractor must on no account regard such indications as accurate. The Contractor shall be deemed to have inspected each and every structure and to have taken all necessary information and measurements required for the proper carrying out of the work, and to have allowed for such in his rates. The additional steelwork shall be manufactured, fabricated, protected, transported, fixed in position and be in all respects in accordance with requirements of this specification and the drawings. All fabrication which can be done in the shop shall be done there and only the absolutely necessary minimum, as approved by the Engineer, shall be done at the site, where the additional steelwork comes into permanent contact with the existing steelwork, the contact surfaces of both shall be thoroughly scraped and cleaned and freed from all loose paint, scale, grease and other deleterious coatings. Areas of rust shall be cleaned down to the 107 bare metal. The contact surfaces shall then be given one coat of priming paint and brought together and fastened whilst the paint is still wet. Surfaces of both existing and additional steelwork which will be inaccessible after strengthening measures are complete shall be prepared as described above and given the full protective paint treatment viz:- one priming coat, one undercoat and one finishing coat, before assembly is begun. Where site welding is to be employed, paint and other coatings shall be removed from the areas to be welded for a suitable extra distance to ensure that the quality of the welds will not be impaired. When strengthening is complete, the surfaces of all added steelwork, and those of the existing steelwork which have been damaged during the operation shall be prepared as above and given one coat of priming paint, one undercoat and one finishing coat. All paint and painting shall be in accordance with the requirements of clause 5049 of this specification. The cost of fulfilling all the requirement of this clause shall be deemed to be covered by the rates for supplying, fixing and painting additional steelwork. RE-USE OF GIRDERS, JOIST ETC., OBTAINED FROM DISMANTLED STRUCTURES 5071. Girders, joists etc., from a dismantled structure which are to be re-used in the strengthening or reconstruction of another structure are thus indicated on the drawings. The Contractor shall check the dimensions of such girders, joists etc., against those of the structure into which they are to be incorporated and obtain the approval of the Engineer's Representative as to their suitability for such use before commencing any cutting, drilling etc., that may be necessary. (See also clause 5011). All work shall be carried out strictly in accordance with the drawings or as directed by the Engineer's Representative, and in compliance with this specification. When the work on the girders, joists etc., has been completed, and before they are incorporated into the structure, they shall be submitted to the Engineer's Representative for approval and when this has been obtained and not before, the Contractor shall forthwith incorporate them into the works as directed on the drawings. The Contractor shall ensure that during fabrication, assembly and subsequent incorporation into the works, the girders, joists etc., are given the paint treatment specified in clause 5069. GROUTING OF BASE PLATES, ETC., OF BEARINGS 5072. The base plate, etc., shall first be located accurately with respect to both line and level, by careful tapping, levering, wedging etc., as approved by the Engineer's Representative. Care shall be taken to ensure that no damage is done to any item, especially machined surfaces. Immediately before the operation of grouting in, the entire area covered by the bearing, including pockets for holding down bolts, and a sufficient extra area around to prevent contamination, shall be thoroughly cleaned by washing with water from hose pipes, compressed air etc., and all dust,loose and deleterious matter shall be removed. All surplus matter shall then be dried off by mopping and the use of compressed air and the surfaces left damp. Freshly mixed mortar, as directed and of suitable consistency shall then be introduced to fill the pockets for the holding down bolts, and the space beneath the bearing plates. the mortar shall be well pounded into the space, working from one side with suitable pounders until the mortal appears on the opposite side and every care should be taken to ensure that the mortar appears on the opposite side and every care shall be taken to ensure that the entire void is filled, giving complete support to the bearing over the entire area, without air holes etc. To ensure this, wooden screed shall be introduced around the edges of the grouting space to contain the mortar during the pounding operations. Any mortar which may foul the threads of bolts, nuts, or affect their bearing on washers and plates shall be carefully removed without disturbing the mortar already placed, and on completion of the operation, the edges of the mortar shall be trimmed as shown on the 108 drawings. The whole shall then be covered with wet sacks or hessian which shall be kept continuously damp for a period of not less than 7 days, after which they shall be removed and all loose, adherent or projecting mortar liable to reduce the efficiency of the bearings carefully removed. After 28 days all holding down and other bolts shall be tightened as directed. EXPANSION JOINT 5073. Expansion joints shall be provided where shown on the drawings and be of the type specified. Detailed working drawings shall be submitted to the Engineer for approval. The drawings shall be supplemented by the materials specifications not covered in the GENERAL SPECIFICATION OF THE FEDERAL MINISTRY OF WORKS or specified on the drawings. Expansion joint sealant as shown on the drawings shall be produced from neoprene compound and conform with the requirements of ASTM Specifications D2628-67T, (see Clause 6269). Expansion joint sealant shall be placed in correct position. When nosing type construction will be used the expandite expoform or equal epoxy resin special mortar shall be used for forming the joint nosing for joint sealant. The epoxy shall comply with DOE requirements for nosing materials contained in Technical Memorandum (Bridges) BE3/72. The expansion joint sealant, shall conform to the following: Density 1350 kg/m3 Hardness 50 to 60, Shore A Tensile strength 13.8N/mm² (minimum) Elongation at break 250% (minimum) The size of the gap shall be compatible with the mean bridge temperature at the time of installation. This temperature shall be determined in accordance with arrangements agreed with the Engineers. The position of all bolts cast into concrete and holes drilled in plates shall be accurately determined from templates. The mixing, application and curing of all proprietary materials shall comply with the manufacturers requirements. During the placing and hardening of concrete or mortar under expansion joint components, relative movement shall be prevented between them and the supports to which they are being fixed. When one half of the joint is being set, the other half shall be completely free from longitudinal restraint. In particular where strongbacks or templates are used to locate the two sides of a joint, they shall not be fixed simultaneously to both sides. Screw threads shall be kept clean and free from rust. Ramps shall be provided and maintained to protect all expansion joints from vehicular loading. Vehicles shall cross the joints only by means of the ramps until the Engineer permits their removal. (CLAUSES 5074 - 5099 INCLUSIVE NOT USED) 109 SPECIFICATION SECTION VI - ROADWORKS 1 SECTION VI - ROADWORKS GENERAL 6000. In addition to any other relevant clause of this specification, the following shall be deemed to apply in particular to roadworks, and shall be read in conjunction with all other relevant clauses of the conditions of contract and this specification. PART (A): DESIGN: AND CONSTRUCTION STANDARDS HORIZONTAL ALIGNMENT 6001. For new roads, the horizontal alignment must be carefully chosen as this is cost related. A good alignment shall provide good drainage, minimum and balanced earthworks and must avoid swampy and high water table areas, where this is possible. A good horizontal alignment allows straight portions of the road on the horizontal plane to be connected with horizontal curves which may be circular or transitional. For the rehabilitation of roads in general, the proposed new alignment shall follow closely on that of the existing road, except where necessary to effect realignment to conform with the current standards of the Federal Ministry of Works and Housing or to effect the most economical sitting of new bridges. It shall consist of a series of straights joined by circular curves. All gradients, vertical and horizontal curves, sight and passing distances, rate of superelevations etc., shall conform with the accepted standards of the Ministry for the particular terrain and adopted design speed as follows:TERRAIN ADOPTED DESIGN SPEED, KM/H LEVEL 100 ROLLING 80 HILLY 60 HORIZONTAL CURVES AND SUPER-ELEVATION Radii of horizontal curves and super-elevation rates shall comply with the following formula:E = V²/2.25R Where V = design speed in km/h R = Radius of circular curve in metre E = Super-elevation, this is normally limited to an absolute maximum of 8%. DEFINITIONS:(I) TANGENT RUN-OFF That distance in which the level of the outer edge of the pavement is brought to the level of the crown of the road section. (II) SUPER-ELEVATION RUN-OFF That distance in which the super-elevation is brought from zero to its maximum value. Super-Elevation shall be achieved by rotating the pavement about the profile of the inside edge of the pavement in flat terrain where the drainage of the inside edge of the curve is likely to present a problem. In cases where the inside edge of the curve may be easily drained, then the super- elevation shall be achieved by the rotation of the pavement about the centre-line profile. The sequence of operations is as follows:- 110 (a) The outer half of the pavement width is brought to the same horizontal plane with the crown of the cross section. This is done within the distance called the tangent run-off. (b) The outer half of the pavement is then brought to the same inclined plane as the inner half of the pavement. (c) (i) For rotation about the inner edge, the pavement shall then be finally rotated about its inner edge to the required full super-elevation. No cut is involved along the inner edge in this operation. (ii) For the rotation about the centre-line, the pavement shall be rotated about its centre-line to the required full super-elevation. This operation involves "cut" along the inner edge of the pavement. TABLE VI-1 DESIGN SPEED WITH CORRESPONDING SUPER-ELEVATION AND MINIMUM LENGTH SUPER-ELEVATION RUN-OFF DESIGN SPEED KM/H 100 80 60 MAXIMUM GRADIENT OF SUPERELEVATION RUN OFF RELATIVE TO CENTRE-LINE OF ROAD (PERCENT) 0.45 0.5 0.57 MINIMUM LENGTH OF SUPER-ELEVATION RUN-OFF (METRE) 55 45 40 MAXIMUM RATE OF CHANGE OF SUPER-ELEVATION RUN-OFF LENGTH OF SUPER-ELEVATION RUN-OFF WITHIN THE CURVE (CIRCULAR) 0.05 m/m PER 30 METRE 20% The proposed Road shall be constructed in accordance with the horizontal alignment, formations and levels and other details as in the DRAWINGS or as directed by the Engineer's Representative. VERTICAL ALIGNMENT 6002. The straight portions on the vertical plane which are connected by vertical curves are called gradients. Two cases of vertical curves occur with gradients either meeting at summits or meeting at sags. The choice of gradient will affect construction costs, vehicle operation cost, road capacity and passenger's comfort. With these considerations, the vertical alignment shall conform with adopted standards of the Ministry. The finished work shall be to even gradients joined by vertical curves. The lengths of vertical curves shall be calculated using the formula:L = K(G1-G2) = KA Where L = length of vertical curve in metre, recommended minimum value of 100m for all speeds. A = (G1 - G2) = change in gradient (algebraic difference) percent. The ultimate sign of A should be ignored, i.e. A is always positive. 111 K = constant for any particular speed TABLE VI-2 DESIGN SPEED FOR VERTICAL, SUMMIT OR SAG CURVES WITH CORRESPONDING K VALUES DESIGN SPEED KM/H K SUMMIT VERTICAL CURVE SAG VERTICAL CURVE 100 80 60 100 80 60 50 26 12 35 23 13 The level of any point along the vertical curve shall be equal to the level at the tangent point plus G1X/100 + AX2/200L where X = distance of the point from the tangent point in metre. G1 = gradient of the road section (per cent). A = change in gradient (algebraic difference) i.e. (G1 - G2) per cent. L = length of the vertical curve in metre AX2 200L should be positive for a sag vertical curve and negative for a summit vertical curve. ROLL-OVER 6003. Roll-Over is the algebraic difference in cross-falls of two adjacent lanes of pavement area. The Roll-Over shall be in accordance with the details as shown on the DRAWINGS or as directed by the Engineer's Representative. CONTRACTOR TO CALCULATE LEVELS 6004. The Contractor will be responsible for working out all levels of the pavement, shoulders, ditches etc., that are necessary for the setting out of the works and will, if required to do so, furnish the Engineer's Representative with lists of these levels for his approval prior to setting-out. The Contractor shall locate and preserve where directed all concrete land markers, beacons, bench-marks etc. CONSTRUCTION STANDARD 6005. The road shall be constructed to the following standards:(I) WIDTH The formation width between drains comprising a carriageway, hard-shoulders and soft shoulders shall be constructed to the dimensions shown on the drawings or as ordered by the Engineer. (II) BASE-COURSE The base course of the carriageway, which may be continued over the hard shoulders or extended a minimum of 300mm at either side of the surfaced width as shown on the drawings or as directed by the Engineer shall be constructed of approved material having a finished compacted thickness of not less than 150mm and complying in all respects 112 with this specification. The base course to the hard-shoulders if different from that of the carriageway, shall be constructed of such other approved material as directed by the Engineer's Representative, but also having a finished compacted thickness of not less than 150mm. (III) SUBBASE COURSE The Subbase Course of the carriageway, which may be continuous over the hard shoulders as shown on the drawings or as directed by the Engineer's Representative, shall be constructed of approved material having a finished compacted thickness as shown on the drawings, or as directed by the Engineer depending on the C.B.R. value of the subbase in question. (IV) GEOMETRY The horizontal and vertical alignments, superelevations and cambers of the road shall be constructed in accordance with the DRAWINGS or as directed by the Engineer. (V) BITUMINOUS SURFACING The surfacing of the roadway shall be two-coat bituminous surface dressing or hot asphaltic concrete pavement as shown on the DRAWINGS or as directed by the Engineer. (VI) SIDE SLOPES TO EMBANKMENTS Side slopes to embankments and cuttings shall be constructed in accordance with the drawings or as directed by the Engineer's Representative. The coefficient of resistance of the material shall be the determinant factor for the embarkment slope. (VII) SIDE DRAINS Unless shown otherwise on the drawings the invert of the side drains shall be not less than 900mm below the finished level of the crown of the road. All side drains shall, where shown, be excavated to the profile and dimensions shown on the drawings, but the Engineer's Representative may direct that the side drains be constructed to such lesser profiles consistent with drainage capacity as he may think fit due to the existence of rock or other obstruction. Where the height of the embankment exceeds 900mm above the existing ground, and the natural gradient of the surrounding area is towards the roadway, then catch-water drains shall be constructed as shown on the drawings or as directed by the Engineer's Representative. (VIII) CULVERTS Generally culverts shall consist of precast concrete pipes laid either as single or multiple culverts, and where shown shall be bedded and haunched with a minimum of 150mm of concrete. In cases where sufficient cover is not available the Engineer's Representative may direct that culverts be surrounded with a minimum of 150mm of concrete. (IX) JUNCTION WITH ROADS A Minor Roads 113 At all junctions with minor roads where shown on the DRAWINGS or directed by the Engineer's Representative, bell mouth shall be constructed carrying the construction and drainage to a minimum of 15.0 metres from the edge of the proposed roadway along the minor road as shown in details on the DRAWINGS or as directed by the Engineer's Representative. B. Major Roads All junctions with major road culverts shall be constructed as shown on the DRAWINGS or as ordered by the Engineer's Representative. (X) WIDENING OF ROADWAY THROUGH VILLAGES AND AT RECOGNIZED LORRY HALTS Where the roadway passes through villages and at recognized lorry halts, the base course and the asphalt concrete pavement shall be widened. Concrete side drains shall be constructed. All as shown on the DRAWINGS or as directed by the Engineer's Representative. (XI) HARD SHOULDERS Surface dressed hard shoulders shall be constructed on both sides of the roadway as shown on the DRAWINGS or as directed by the Engineer's Representative. (XII) SOFT SHOULDERS AND EMBANKMENT SLOPES Soft shoulders and embankment slopes shall be constructed so as to have the top 75mm consisting of top soil and shall be grassed throughout unless otherwise directed. At the discretion of the Engineer's Representative, the top 75mm may consist of a compacted layer of approved lateritic material in lieu of top soil. (XIII) SUBGRADE A. Cuts The subgrade of the road shall be shaped to the dimensions, formations and levels as shown on the Drawing or as directed by the Engineer's Representative and the top 150mm subgrade shall be watered and compacted to 100% B.S. standard compaction at optimum moisture content (OMC). B. Embankments The subgrade of the roadway shall be shaped to the dimensions formations and levels as shown on the DRAWINGS or as directed by the Engineer's Representative. (CLAUSES 6006 - 6099 INCLUSIVE NOT USED) PART (B) - EARTHWORKS, DRAINAGE, ETC. (1) GENERAL MATERIAL 6100. The materials used in the works shall be new and/or of the qualities and kinds specified, and no materials shall be used in the works unless approved. Materials delivered to the works shall be equal to the approved samples. Deliveries shall be made sufficiently in advance of constructional requirements to enable samples to be selected by the Engineer's Representative for testing before using the materials in the works. 114 Materials failing to comply with the specification shall be immediately removed from the works at the Contractor's expense. These specifications on materials shall be read in conjunction with latest amended report of "the Lagos materials testing conference", a copy of which will be made available to the Contractor on request. No material shall be used until it has been approved by the Engineer or his Representative. Permission to use any material shall not be construed as an approval of its source nor any acceptance as continued acceptance. UNSUITABLE MATERIAL 6101. In no case will material which contains organic matter or other deleterious substance be used. FILLING MATERIAL 6102. Material for filling in the embankment shall be obtained from sources approved by the Engineer's Representative and no slurry, mud, soft or otherwise unsuitable materials shall on no account or under any circumstances be placed in embankments. Large pieces of rock, or other materials shall be properly broken up and beaten down and no accumulation at the foot of side slopes of embankments of boulders or lumps having no cohesion will under any circumstances be permitted. The Engineer's decision regarding the suitability of any material shall be final, and any material of which more than 35% passes the No 75 m sieve may be rejected depending on the plasticity characteristics of this material, provided good quality fill materials are available, otherwise such material may be modified for use. The material to be used for the forming of embankments shall generally be obtained from cuttings which may be widened as agreed with the Engineer's Representative. The material shall be spread evenly over the area of embankment and compacted in uniform layers to the specified density and moisture using B.S. compactive effort. Each compacted layer shall not be greater than 150mm. SELECTED LATERITIC MATERIAL FOR SOFT SHOULDERS 6103. Where directed by the Engineer's Representative under the provisions of clause 6163 the material selected for the upper 75mm of the soft shoulder shall or preferably be a well graded lateritic soil with a Plasticity Index of not less than 10 and not more than 20. GRASS OR GRASS SEED 6104. The seed, or the grass used for sowing or planting on the verges, the slopes of embankments and cuttings shall be daub grass (cynodon dactylion) or bahama grass. Tall, quick-growing or tussock grasses shall not be used without the consent of the Engineer. The Contractor must anticipate the requirements for the supply of suitable grass. RUBBLE AND PITCHING STONES 6105. Stones for filling behind retaining walls or walls of culverts shall be angular and graded from 12mm to 75mm with a fine content below 12mm not exceeding 20% stones, for pitching the inverts and sides of ditches embankment slopes and culvert inlets, and outlets, shall be of durable natural broken rock of approximate cubical shape 225mm x 225mm x 225mm or 150mm x 150mm x 150mm as appropriate. (CLAUSES 6105 - 6119 INCLUSIVE NOT USED) (II) SITE CLEARANCE WORKMANSHIP 6120. The Contractor shall fell, grub-out roots and clear from the site all trees occurring within the boundary of the works as directed. In addition all bushes, ant hills, ants' nests, 115 grass, stumps and other vegetation shall be cleared from the site and roots, grubbed up, holes made in grubbing up, removing the ant hills, roots, stumps and the like shall be backfilled and compacted to a density at least equal to that of the surrounding ground except that all holes, cavities, and wells within the road width shall be backfilled with approved soil which shall be thoroughly compacted throughout by power rammer to a density not less than the dry density of the surrounding ground. Outside the above limits, on the inside of bends, bushes and trees shall be felled and their roots grubbed up as directed to give an unobstructed sight distance of 150 metres. For purposes of measurement, the girths of the trees shall be taken 900mm above ground level except that where a tree has a buttress the girth shall be taken immediately above the buttresses. No economic trees or crops shall be removed prior to their enumeration and valuation for compensation purposes. The Contractor shall remove gates, gate posts, manhole covers, kerbs, signs, water mains and other items to the extent directed by the Engineer's Representative. Foundations shall be broken up and removed to a depth of 900mm below natural subgrade level or finished grade level, whichever is lower. Structures to be demolished shall be broken up and removed. Prior to demolition the Contractor shall ensure that services have been disconnected to the satisfaction of the appropriate authorities and/or owners. Foundations shall be broken up and removed to a depth of 900mm below Natural Subgrade Level or finished grade level, whichever is lower. Pits, tanks, underground chambers and the like shall be demolished to a depth of 900mm below Natural Subgrade Level or finished grade level, whichever is lower and the remainder shall be properly cleaned out. Clearing limits for this Contract shall be the entire length of the project within widths as hereinbelow defined. I. Buildings, walls and other man-made items Clear everything within the Right-of-Way limits. II. Compound walls - reconstruction Any and all existing compound walls located within the Right-of-Way limits shall be cleared and removed as part of the appropriate item in the Bill of Quantity. Also included as part of this item shall be the reconstruction of all such walls, equal to the removed wall, along the Right-of-Way line connecting to the points at the start and end of the removed section. The cost of such reconstruction shall be considered included in this item. Reconstruction of compound walls may be required anywhere along the alignment. III. Wells Working wells outside the limit of grading shall be maintained in a condition equal to their present condition. Working wells within the limits of grading shall be filled as herein- above required. Replacement wells equal to the existing wells shall be constructed outside the limits of grading. The cost of all replacement wells shall be considered as included in Item "Clear Site as specified..... etc;." 116 Non-working wells within the Right-of-Way lines, shall be filled as hereinbefore required. IV. Trees and All Other Erosion Resisting Vegetation All trees shall be cleared within a strip fifty (50) metres wide, (25 metres to each side of the centre line). To ensure that future falling trees do not clog road side drains, all trees outside this 50 metre strip whose height is such that, if they fell would reach to the nearest roadside drain, shall be cleared. All other erosion resisting vegetation shall be cleared only within the limits of grading. Outside the above limits and within the Right-of Way lines all vegetation shall be selectively thinned and/or trimmed. A. Selective thinning shall include the removal of live and dead trees both standing and fallen, shrubs, and other vegetation and debris in the areas shown on the Drawings and designated for removal by the Engineer. The trees, shrubs and other vegetation to be removed will be so designated by the Engineer's Representative. Trees shall be carefully felled to prevent damage to adjacent vegetation, structures and property. Trees, stumps and all debris shall be removed in a manner that will not compact or disturb the soil adjacent to trees and shrubs to remain. B. Trimming existing trees shall include the complete removal of all defective or undesirable limbs and the repair of all injuries or wounds on existing trees as directed by the Engineer's Representative. All diseased, dead, broken and seriously injured branches shall be removed. Healthy low branches shall not be removed except as otherwise directed by the Engineer's Representative. All wounds over 25mm diameter shall be painted with tree paint. The bark around all wounds and other injuries shall be traced and treated in accordance with approved arboricultural practice. All pruning tools and methods employed shall be in accordance with arboricultural practice and shall be subject to the approval of the Engineer. All trees to remain within the areas designated for selective thinning shall be trimmed to remove all dead and undesirable limbs up to a height of 5m above ground. The Engineer will determine which live limbs are undesirable. Materials designated for incorporation in the Works shall be removed, marked where necessary for future identification and stored for re-use. The Contractor shall load, transport, unload and stock materials designated for delivery to the owner's thereof. Other materials resulting from clearing operations shall become the property of the Contractor as soon as he takes possession of the land for the Works. The Contractor shall remove and dispose of such materials. Clear material shall be burnt or disposed of as directed by the Engineer's Representative. Trees to be cut down shall have all light branches trimmed off and burned 117 and useful trimmer shall be cut in suitable lengths and stacked at the roadside ready for removal as directed by the Engineer's Representative. Payment will be made under this for the net areas cleared and shall include for the satisfactory removal of anthills and ants' nests and for any backfilling and compacting required and for disposal of material, but shall not include any areas of grass on the road vergers or otherwise, which is subjected to periodic cutting and maintenance. SCARIFYING EXISTING SURFACE 6121. Unless otherwise directed by the Engineer's Representative, the existing road shall be scarified, shaped to required formation level, and compacted as specified, where the average difference between the proposed formation levels and the existing ground levels does not exceed 75mm. Payment shall be made once only under the appropriate item in the Bills of Quantities and shall include for all operations required to bring the existing road to the required formation levels. Where ordered in writing by the Engineer's Representative, existing bituminous surfaces shall be scarified, re-shaped and compacted as specified and all surplus material shall be disposed of as directed by the Engineer's Representative. Payment shall be made under the appropriate item, in the Bill of Quantities and shall include for all operations as required herein. Except as provided above, the removal of existing bituminous surfacing by scarifying and roughening of existing unsealed roads and vergers etc., shall be deemed to be included in the tendered rates and prices for earthworks. EARTHWORKS 6122. In the Contract the following words and expressions shall have the meanings hereby assigned to them except where the context otherwise requires:(1) (2) "Existing Ground Level" means the ground level shown on the Drawings as existing at the start of the Works. "Finished Ground Level" means the ground level after the completion of the Works. (3) "Natural Subgrade Level" means the level at the completion of excavation for roadworks. (4) "Formation Level" means the level at the completion of earthworks for roadworks prior to top soiling. (5) "Stripped Ground Levels" means the ground levels after the completion of clearing operations. (6) "Specified Finished Excavation Levels" means the levels of the completed excavation after trimming, compacting and preparation of the surface of the excavation as calculated from the levels shown on the Drawings, or the levels directed by the Engineer's Representative. (7) "Specified Finished Fill Levels" means the levels of fills after trimming, compacting and preparation of the surface of the fill (excluding top soiling) placed in accordance with the Drawings or as directed by the Engineer's Representative. Excavated material shall be classified by the Engineer's Representative as suitable material, or unsuitable material. 118 Unsuitable material shall include the following:(1) Material from swamps, marshes and bogs. (2) Peat, logs, stumps, roots and other perishable or combustible material. (3) Top soil and highly organic clay and silt. (4) Clay having a liquid limit exceeding 80% or plasticity index exceeding 55. (5) Highly micaceous materials. Suitable material shall exclude the foregoing unsuitable materials and shall comprise all other natural material acceptable for use in the Works, whether obtained from within or without the Site. Top soil shall mean soil which can be seen to have been broken down by agricultural cultivation and/or is seen to be capable of supporting vegetable growth. It shall include turf. Solid rock shall mean rock found in ledges or masses in its original position, which can only be loosened by blasting or by pneumatic tools, or excavated by hand, by using wedges and sledge hammers. Rock which is in a shattered condition and/or is capable of being loosened by rippers or earthmoving plant is excluded from the definition of solid rock. Boulders or detached pieces of rock each exceeding 2 cubic meter size in trenches or 6 cubic meter size in general excavation, shall be regarded as solid rock. Where embankments are to be constructed on steeply sloping ground, including the side slopes of existing embankments, existing sloping surfaces shall be excavated to form benching as shown on the Drawings or as directed by the Engineer's Representative. Materials for filling shall comprise the following:(1) General Fill General fill shall consist of suitable material as defined herein. Subject to the requirements regarding the forming of embankments isolated boulders not exceeding 3 cubic metres in size may be included in general fill. (2) Rock Fill Rock fill shall consist of sound igneous rock or other sound rock acceptable to the Engineer's Representative or such strength that when compacted an excess of fines will not be produced. It shall be free draining and reasonably well graded and shall have a maximum size of 3 cubic metres. The percentage of material by weight passing a 5mm sieve shall not exceed 30%. It shall be free from silt, clay and organic material. Such material may be deposited below water without the associated use of compaction plant. (3) Granular Fill Granular fill shall consist of an approved granular material of maximum, size not greater than 38mm which is inert in water and which on analysis by sieving complies with the following requirements. 119 Sieve Size Percentage by Weight Passing 10mm up to 100 5mm not more than 85 600m not more than 45 75m not more than 5 (4) Special Granular Fill Special granular fill shall be hard and durable and shall consist of broken rock or gravel. It shall be well graded with a maximum size of 38mm. The percentage of material by weight passing 75 m sieve shall not exceed 10. It shall be free from silt, clay and organic material. (5) Granular Bedding Granular bedding shall consist of crushed rock or gravel having a smooth grading curve within the limits specified for l9mm nominal size all in aggregate to Table 3 of B.S 882. The fraction passing the 425 m sieve shall be non-plastic when tested in accordance with B.S 1377 (1975) Sections 2, 3 and 4 unless such fraction constitutes less than 2 per cent of the whole by weight. Earthworks shall be measured by super- imposing the specified finished formation levels on initial cross sections taken by the Contractor at 30 meter intervals or closer if necessary along the centre line. The levels of such cross sections shall be agreed by the Engineer's Representative. A maximum quantity of material excavated from cuttings shall be placed to fill and the utmost advantage shall be taken of the natural moisture content of the soil in placing such fill provided the materials meet the qualities for use as such see clause 6102. Fill shall be placed and compacted in layers of a compacted thickness 150mm or such thickness that may be found necessary to achieve the required density over the full width of the formation. The Contractor shall route his earth-moving equipment in such a manner over the full width of the filling as to achieve a uniform compaction over the entire width by this method. All fill including subgrade and vergers shall then be compacted to 100 per cent of the maximum dry density obtained in the British Standard Compaction Test. In the case of extension to existing embankments benching will be required as indicated on the drawings or as directed by the Engineers's Representative and such benching shall be deemed to be included in the tendered rates for earthworks. PAYMENT FOR EARTHWORKS 6123. Payment for earthworks shall be made once on the basis of the total quantity of measured fill by the Contractors together with the quantity of unsuitable material and/or of excess cut placed to spoil, all as determined from the cross sections referred to in clause 6122. The depth of unsuitable material, if any, to the placed to spoil shall be agreed between the Contractor's Agent and Payment for this material will be on the net volume as measured in situ. The quantity of suitable excess cut placed to spoil shall be determined as follows:(i) The net volume of suitable material excavated from cuttings or side drains shall be determined by deducting the quantity of unsuitable material placed to spoil from the total quantity of cut as determined from the cross-sections. (ii) The total volume of filling placed in embankment shall be found from the cross-sections. 120 (iii) The volume of suitable excess cut placed to spoil shall be taken as the volume found in (i) above less the volume found in (ii) above with an adjustment made to the latter to allow for compaction. The adjustment which shall be made for compaction shall be based on the ratio of the maximum dry density of the filling at 100% B.S. Compaction to the in situ dry density of the material in the cutting or side drain. Haulage rates will he assessed on the basis of the use of the nearest acceptable road making materials to the section of work under construction. Stripping of topsoil will not be measured as roadway excavation. The quantity of stripping topsoil for which payment will be made will be the area stripped in accordance with the Drawings or as directed by the Engineer, measured in units as specified in the bill of quantities. SELECTION OF SOIL FOR FILL 6124. Soils shall be obtained from areas of cut including ditching or from approved borrow pits. All grass and vegetation shall be removed from the surface of the areas of cut or borrow pits before excavation of the fill material is commenced and no such grass or vegetation shall be included in the fill. In borrow pits the top soil, shall be carefully removed and stockpiled. Topsoil shall not be removed from any area until excavations or filling operations are about to start in that area. Topsoil on the sites of cuttings and embankments shall be excavated to the average depth directed by the Engineer's Representative or as specified hereinafter. The Contractor shall, at his own expense and to suit his own convenience, make arrangements for and provide such temporary storage sites as may be required for heaps of topsoil. If any materials suitable for subbase, base or aggregates as specified herein are encountered in material removed as roadway excavation, and the Contractor elects to use such material for constructing items, payment for the various items shall be as follows: If the Contractor elects to use materials removed from cuttings for constructing items of subbase, base or aggregates, payment will be made for such material excavated under the appropriate roadway excavation item and for such material so placed under the appropriate item of subbase or base, provided that the Contractor furnishes and places borrow excavation material, in embankment without cost, in an amount equal to the value of the material used in the base, subbase or as aggregate in place prior to excavation. The Contractor shall at his own expense, make arrangements for and provide such spoil dumps as may be required for the disposal of excavated materials which are not to be incorporated in the Works. The spoil dumps shall be located and shaped in accordance with the Contractor's proposals as and shall be finished with neatly trimmed slopes, adequately surface soiled, all to the satisfaction of the Engineer's Representative. During the course of the excavation from an area of cut or borrow pit or other approved source of fill material, the Contractor shall provide adequate supervision to ensure that only soil of a type approved by the Engineer's Representative is excavated. Care shall be taken during such excavations to avoid any pockets of heavy clay, vegetation or other unsuitable material and if any such unsuitable material or soil of an unapproved type is 121 included in the fill it shall be dug out and made good with approved material where directed by the Engineer's Representative and at the Contractor's own expense. Where a sandy soil is encountered in the excavation of a cut or borrow pit, the Engineer's Representative shall have the power to instruct the Contractors to place this sandy soil to the top layer of fill. Any material which in the opinion of the Engineer's Representative is not suitable for fill shall be tipped to spoil as and where directed. After removal of fill material from borrow pits etc., The area shall be levelled and top soil replaced all to the satisfaction of the Engineer's Representative. The Contractors shall arrange and pay for any compensations and other payments whatsoever required for their access to and occupation and use of the borrow areas for fill material. Payment for all arrangements, compensations and other costs, clearance, removal and replacement of topsoil, excavations and disposal of unsuitable materials and all other operations and requirements of this clause shall be deemed to be included in the tendered rates and prices for earthworks. COMPACTION 6125. Compaction shall be measured by expressing the dry density of the sample as a percentage of the maximum dry density at optimum moisture content. Compaction of all material shall be carried out at a moisture content optimum for the compaction effort of the plant used. The Engineer's Representative may, however, direct that the moisture content at compaction be further controlled in order to reduce as far as possible any subsequent consolidation or swelling. Where it is necessary to add water to the material to achieve the dry density specified, the cost of obtaining, transporting or pumping, spraying and mixing sufficient water must be allowed in the Contractor's prices for compaction. Water shall be added as and where necessary by a water carrier fitted with an approved sprinkler and the uniform wetting of the layer to be compacted shall be achieved. Under no circumstances will compaction solely by construction or other traffic be accepted. Fill materials shall be placed, spread and levelled in layer of loose depth not exceeding 230mm of general fill, 460mm of rock fill, 230mm of special and granular fill. Notwithstanding the foregoing, where rock fill or granular fill is placed below water level there shall be no restriction on the depth of layers. The material of each layer, of whatever type, shall be uniform throughout the layer. Except as otherwise necessary to conform to the zoning of the various types of materials, each layer of material shall extend over the full width of the filling. No layer of fill material shall be placed until the Engineer's Representative is satisfied that the underlying layer is properly compacted. Rock fill (including solid rock excavated from cuttings) shall be placed, spread and levelled by a track laying tractor, and large voids shall be filled with broken fragments before compaction. 122 Isolated boulders and isolated large fragments of solid rock forming part of general fill shall be evenly distributed throughout each layer, but no stone exceeding 150mm in size shall be placed within 300mm of formation level. During the construction of embankments the Contractor shall control and direct construction traffic uniformly over the full width. Unless permitted by the Engineer's Representative, fill materials shall not be stockpiled on embankments. Embankments shall be constructed in such a manner that the completed formation is not damaged by construction traffic. The Contractor may elect to construct embankments to such higher levels as may be necessary to protect the formation and in such cases shall delay removal of the surplus material until preparation of the formation can immediately proceed. The provision, placing, compaction and subsequent removal and disposal of such material shall be at the Contractor's expense. All road materials shall be incorporated in the works by an approved sequence of operations namely the dumping of materials, spreading by grader, watering and mixing as specified above and compacting by approved means. The Contractor shall keep the delays between consecutive operations to a minimum. All compaction equipment must operate over the whole area to ensure uniform compaction by it. All filling including the subbase course and base course shall be compacted in layers of a compacted thickness of 150mm or such other thickness as may be found necessary to achieve the required density. Longitudinal and transverse joints in any two successive layers shall be staggered to a minimum distance of 3 metres. At the beginning of the Works and from time to time as may be necessary in the opinion of the Engineer's Representative, the Contractor shall carry out, to the satisfaction of the Engineer's Representative, field trials, supplemented by any necessary laboratory investigations to determine types of compaction equipment, suitable layer thickness and moisture contents all within the requirements of the specification for the placing and compaction of the various materials to be used in the earthworks. The sites of trials shall be agreed between the Contractor and the Engineer's Representative. Copies of the full records of all such trials shall be provided promptly to the Engineer's Representative. If compaction trial fill is placed as part of the permanent work, such fill shall conform to the requirements of the specification and if it does not it shall be removed or reworked until it does conform. Extra work required either to rework or remove the trial section shall be at the Contractor's expense. The Contractor shall submit to the Engineer's Representative his proposals, based on the rolling test result's for the compaction of each variety of material to be used in the earthworks, including proposals in relation to types of plant, numbers of passes and loose depth of layers. Work (other than rolling test) shall not start on any particular variety of material until the Engineer's Representative has signified in writing his agreement to the Contractor's proposals for that material. 123 The Contractor shall not modify the agreed methods without the consent of the Engineer's Representative. Work in compaction of fill materials shall be carried out only when the moisture content is within the range shown by the field or by laboratory tests whichever is appropriate on that material to be suitable for the attainment of the densities specified below. (i) For material which is within 600mm Formation Level or in the filling adjacent to structures (including backfilling), not less than 100 percent of the maximum dry density for the material obtainable by B.S standard compaction. (ii) For all other material, not less than 95 per cent of the maximum dry density for the material obtainable by B.S standard compaction. The foregoing compaction requirements shall also apply to the subgrade material which is within 600mm of formation level in cuttings. The Contractor and the Engineer's Representative shall from time to time agree upon field compaction methods and relevant plant for the various materials such that by correlation using the relative density and ISO CBR control tests, the need for the extensive tests on the finished road section may be reduced. The Contractor and the Engineer's Representative shall also agree on procedures for determining the areas of fill to which particular sets of test results should be deemed to be applicable. Such areas shall include clay or peat deposit where consolidation test may be necessary. All sections of the works shall be protected from damage by plants, rainstorms or other cause. All such damage should it occur, shall be made good by the Contractor at his own expense. In particular the exposed surface of each lift of fill or sub-base course or base course material, after compaction, shall be protected by a cambered surface from excessive moisture content changes due to rainstorms until the next lift is placed. If such changes in moisture content do take place and the surface of the compacted layer softens, the Contractor shall, if required by the Engineer's Representative, remove and replace the material affected at his own expense. Should the material used for subbase or base course be prone to drying from the surface the Contractor shall from time to time keep the finished surface slightly dampened. This process will continue until another layer is placed. Should there be patches of unsound ground, excessive sand or clay, which are, in the opinion of the Engineer's Representative unsatisfactory, then such areas shall be rectified by admixture of suitable materials or by cutting out and replacement to ensure a uniformly compacted formation. Tests for the control of compaction shall be carried out at regular intervals as directed by the Engineer's Representative. If any test result from a particular area falls below the minimum specified, then the Contractor shall at his own expense scarify, water and recompact that area to the satisfaction of the Engineer's Representative, provided the constituency of the material will not be adversely affected as double compaction may 124 increase percentage passing 75 m sieve to more than 35% thus reducing the strength of the material. The Contractor shall allow in his construction programme time for such tests and for the results to be made known, before the next stage of the works. BORROW PITS 6126. The Contractor shall at his own expense clear bush, topsoil and other inferior materials from the site of borrow pits. The Contractor shall also bear the cost of compensation for borrow pits outside the area of the site. Borrow pits for road materials shall be excavated only where the natural slope of the ground is away from the road, except that where he considers it essential for the proper execution of the works the Engineer's Representative may approve the excavation of borrow pits in ground above road level. Generally in rural areas the nearest edge of the pit shall be not less than 15 metres from the centre-line of the road. The Contractor shall so plan his method of execution of the works that the haul of road materials from borrow pits is reduced to a minimum. The Contractor may be allowed to form "side-borrow-trenches" for fill material wherever it is required providing such trenches are self draining, having a minimum fall along the line of the road of 1 in 120. All other pits shall be properly drained to the satisfaction of the Engineer's Representative by the construction of turnouts or other approved methods. In build-up areas, the Contractor shall submit to the Engineer, his proposals for obtaining fill materials and shall furnish details regarding the locations, sizes and owner of all borrow areas, together with his proposed method of working and all measures proposed to eliminate damage or nuisance to persons or property. He shall be required to submit his proposed method for the reinstating such borrow areas at the same time. The Contractor shall obtain the Engineer's written approval for the above before commencing work on any borrow area. In addition the Contractor shall comply with all other relevant clauses of the conditions of contract and this specification. No borrow pit shall be abandoned until the area has been levelled, topsoil replaced and the sides battered to a slope of 1 in 1½ so that no animals may be trapped, all to the satisfaction of the Engineer's Representative. The cost of all operations detailed under this clause shall be deemed to be included in the tendered rate for earthworks. Regulations under the mineral ordinance must be observed by the Contractor. SAND FILL 6127. Where sand fill, either hydraulic or otherwise, is specified, it shall be obtained from a source or sources approved by the Engineer. Where such sources occur in waters or areas under the jurisdiction of the Nigerian ports Authority or the inland waterway department of the Federal Ministry of Transport or other appropriate authority, then the Contractor shall first obtain written permission to remove material from the authority concerned and shall comply, in all respects with all regulations laid down by such an authority. The quality of the material intended for use as sand fill shall be subject to the approval of the Engineer. For hydraulic sand fill the grading of the material shall be such that not more than 15% passes the 75 m sieve and in no-case will isolated 125 pockets or layers of silt, clay or other organic impurities be accepted. For sand fill placed by any method other than the hydraulic, the grading shall be such that not more than 15% passes the 75 m sieve, and in no case will isolated pockets or layers of silt, clay or other organic impurities be accepted. The relative density of hydraulics sand fill placed in embankment shall be as follows: (A) (B) (C) Top 600mm Next 600mm Below the Top 1200mm 90% 80% 70% Sand fill placed by any method other than the hydraulic shall be compacted in layers by a method approved by the Engineer's Representative to a density of not less than 100% of the maximum dry density obtained in the British Standard Compaction Test. Vibrative system of compaction is recommended. In the case of hydraulic sand fill the Contractor shall construct all drains, ditches, spillways, marginal bonds necessary for the proper protection of the works. Such drains, marginal bonds etc., shall be constructed sufficiently in advance of the deposit of the sand fill, so as to effectively drain and retain the sandfill and to prevent any of the material from flowing into any harbours, creeks, canals, drains etc., or from causing any damage or nuisance to persons or property. The Contractor shall be responsible for any slip or settlements which may occur during the construction of the sand fill or the bunds, drains, etc., and shall also be responsible for same during the maintenance period. The Contractor shall make good such slips and settlements to the satisfaction of the Engineer's Representative. The Contractor shall be responsible for the full and efficient drainage of water resulting from the hydraulic sand fill operation and shall construct such open drains as may be necessary to drain all surface and rainwater, so as to avoid all ponding. The Contractor shall make due allowance for settlement and drying-out of the sand-fill and for the making good of same. Before any hydraulic sand fill is commenced, the Contractor shall, in conjunction with the Engineer's Representative, survey the site and mutually agree the surface levels, and such agreement shall be recorded in writing by both parties. The levels shall be taken on a grid with points at not exceeding 15 metres centres and the Contractor shall construct concrete pilot-pillars to the satisfaction of the Engineer's Representative to enable the grid lines to be located during the filling operations. The Contractor shall construct sufficient tell-tales, consisting of 50mm x 50mm x 10mm angle of adequate length with a flange of 900mm in diameter fixed at one end, all in non-corrosive metal, to the satisfaction of the Engineer's Representative, to enable any subsidence of the original ground level to be 126 measured. The method of measurement of hydraulic sand fill shall be on the basis of the volume of material placed as determined from the area filled and the depth of fill to the finished level from the original ground level or the subsided original ground level, as applicable. Should any dispute arise as to the subsided original ground level, as indicated by the tell-tales, then the same shall be determined by the taking of borings or by the digging of trial-pits. Payment for trial pits shall be from the appropriate item, in the bills of quantities. Where no such item is included, payment will be from appropriate provisional sum. If option of trial pit is chosen shuttering shall be provided to check the collapse tendencies of sand fill. Hydraulic sand fill shall be deposited in layers as directed by the Engineer, but in any case the thickness of such layers shall not exceed the limits stipulated as follows:(A) First Layer - not exceeding 450mm in thickness (B) Second Layer - not exceeding 750mm in thickness. (C) All subsequent Layers - not exceeding 900mm in thickness The finished level shall be as shown on the drawings or as directed by the Engineer, and shall be agreed as the result of a joint survey carried out by the Contractor and the Engineer's Representative. A tolerance of 75mm above or below the finished level may be permitted during pumping operations, but the same shall be made good by subsequent grading or dozing to the satisfaction of the Engineer's Representative and to the tolerances stipulated for the sub-grade. Without limiting his commitments under the terms of the contract, the Contractor shall not be required to make good any normal expected settlement of the original ground levels after completion of the sand fill. The Contractor shall be deemed to have allowed for all the foregoing provisions in his rates and prices for sand filling. Should the Engineer so desire the Contractor shall place stock-piles of material in quantities and areas as directed. Payment for theses stock pile shall be made at the tendered rates and prices for hydraulic sand fill. EXCAVATION TO BE KEPT FREE FROM WATER 6128. The Contractors shall keep all excavations free from water and shall at their own expense construct such temporary grips and ditches and provide and maintain pumps as may be found necessary for this purpose. Excavation free from water may be possible if underground design formation level is not close to the water level. SLIPS 6129. During the carrying out of excavations the Contractors shall limit vertical and other temporary faces to such heights as are suitable to the nature of the soil exposed. If in the course of the works, any slips, slides, or subsidences occur and such slips, slides or subsidences extend beyond the lines and slopes and below the levels shown on the drawings, the excess excavation will not be paid for and the Contractors shall at their own expenses carry away such materials and make good in a manner satisfactory to the Engineer's Representative and without extra charge. UNSUITABLE MATERIAL BELOW FORMATION LEVEL 6130. Where unsuitable ground or other unsuitable material is found below formation level or below the slope of cuttings under areas of fill, this shall be excavated and disposed off as directed by the Engineer's Representative, and the space left void shall be backfilled with selected fill and compacted to at least 100% of the M.D.D. achieved in the British Standard compaction test. 127 Payment shall be made under this clause for any material removed as unsuitable soil only on the written direction of the Engineer's Representative provided such unsuitable material could not have been discovered during the tendering period. Measurement for this item shall be on the compacted backfill only and payment for this work will be at the rates entered in the bill of quantities for earthworks. SWAMP AREAS 6131. Certain existing swampy areas on the proposed line of reconstruction may have been delineated on the drawings. The attention of the Contractor is particularly drawn to the fact that, under the provisions of this specification, he is responsible for the safe passing of traffic in such areas and that the cost of any diversions which may be required for this purpose are deemed to be included in the tendered rates and prices. The Contractor shall programme and execute his earthmoving operations such as to complete the embankments in swamp areas prior to initiating work or other embankments and to allow minimum settlement periods as specified in volume III, or as agreed by the Engineer to elapse between first raising the embankments to the specified finished surface level in the area or such other level as may be required and the start of the construction of any part of the pavements, drainage or other permanent works in the area. Prior to, during and subsequent to the settlement periods specified above the Engineer's Representative will carry out investigations in filled sections of swamp areas to collect information on which to base predictions of the magnitude and rate of settlement which will occur after completion of the works. Such investigations will be undertaken, to ascertain, inter alia, the strength, compressibility of ground beneath embankment, ground water levels and vertical settlements and they will be made by means of various measuring devices. The results of such tests shall be used by the Engineer's Representative to predict the equitable surcharge to facilitate early maximum settlement. The measuring devices shall be supplied and installed by the Contractor using methods approved by the Engineer. They shall be read by the Engineer's Representative. The Contractor shall supply such skilled and unskilled assistance as the Engineer may direct. The Contractor shall take all practicable precautions to prevent damage or disturbance to measuring devices. Should any damage or disturbance occur the Contractor shall make good same at his own expense to the satisfaction of the Engineer. The Contractor shall be deemed to have allowed for any reduction in the efficiency of his operation and for any delays or stoppages caused thereto by the installation, testing and reading of the various measuring devices and the avoidance of damage or disturbance thereto. As a result of the investigations described above, The Engineer may direct the Contractor to take measures to reduce or to compensate for settlements which will occur in filled sections of swamp areas after completion of the Works. Such measures shall consist of : (i) the surcharging of filled areas so as to accelerate the consolidation of foundation materials and/or 128 (ii) providing settlement allowances in the finished levels of the pavements, drainage and other permanent works constructed in the filled sections of swamp areas. If so ordered by the Engineer, the Contractor shall construct surcharge loads of fill in such locations and to such dimensions and levels as the Engineer directs. The Contractor shall re-schedule his filling operations in other parts of the Site to compensate for the fill materials so diverted and to provide for the incorporation in the works of fill material made available on subsequent removal of the surcharge loads. Except as provided hereunder, surcharge loads shall remain in position for such periods as the Engineer directs, after which the Contractor shall remove the surcharge loads, incorporate the fill material in the works and make good to the satisfaction of the Engineer's Representative the area on which the surcharge load was formed; provided that in no case will the Engineer direct that surcharge load in any area should be left in position for a period extending beyond the end of the settlement allowed for that area in accordance with Volume III. The Contractor shall incorporate such settlement allowances as the Engineer considers necessary in the finished levels of the pavement, drainage works and other permanent works in filled sections of swamp areas. Settlement allowances shall be provided by the addition or removal of fill material and not by varying the dimensions of pavements, drainage works or other permanent works. The Contractor shall be deemed to have allowed for any reduction in the efficiency of his operations and for any delays, stoppages or inconveniences caused thereto (directly or indirectly) by the operation of this Clause. The Contractor will be required to lay a satisfactory running surface of gravel or other approved material on the completed earthworks. Further construction shall not be permitted until all settlement has effectively ceased to the satisfaction of the Engineer. Before further construction continues the road formation shall be made up to the specified levels. The extent of such areas shall be defined by the Engineer's Representative before construction starts, and the measurement of earthworks within the area declared by the Engineer's Representative to be a settlement area shall be the net cubic contents of the voids formed by the removal of the material excavated in accordance with the specification and drawings, no allowance being made for bulking. The rates entered in the Bill of Quantities under the various items for excavation shall include for the excavation of material and the loading, transport, deposition and compaction as specified, as shown on the drawings or as directed by the Engineer's Representative. FORMATION LEVEL 6132. The formation level shall be the level of the embankment or cutting in its final shape after completion of the earthworks and before the superimposition of the sub-base course, base course, or hard shoulder, and before the surface material is applied. PREPARATION OF FORMATION 6133. All earthworks shall be graded to provide the required formation profile. The Contractor may elect to leave sufficient material above formation level to protect the formation and to delay the excavation of this material until preparation of the formation can follow immediately. The subsequent removal and disposal of such material shall be at the Contractor's expense. Cuttings other than those in rock shall not be excavated to formation level in wet weather. If suitable material below formation level is damaged by any cause such material shall be removed and replaced by properly compacted general fill and such operations shall be at the expense of the Contractor. 129 Not less than 150 metres of completed subgrade shall be maintained in advance of the paving operations at all times. Failure to comply with the provisions of this paragraph will be deemed sufficient cause for stopping the paving operations until this provision is met. During the preparation of the formation, suitable motor graders shall be used and shall be operated by highly experienced operators. Payment for work done under this clause will be deemed to be included in the tendered rates for earthworks. TRIMMING OF SLOPES 6134. All slopes of cuttings and embankments shall be trimmed to the batters specified by the Engineer's Representative with a permissible tolerance of plus or minus 50mm measured at right angles to the batter. Payment shall be deemed to be included in the tendered rates for earthwork. EXCAVATION IN ROCK 6135. When solid rock is encountered in excavations, the Contractor shall excavate and dispose of such material as directed by the Engineer's Representative. The Contractor shall not use explosives for excavations in rock without the prior written approval of the Engineer. Where such approval is given, the Contractor shall provide proper magazines in suitable positions for the storage of explosives and take all necessary precautions to prevent any unauthorized issue or improper use of any explosives, to the satisfaction of the Engineer's Representative. The Contractor shall comply with any regulations regarding the times for blasting, sizes of blasts, loading of shots, provision of blasting nets, etc., that the Engineer's Representative may prescribe. Blasting may be prohibited if, in the opinion of the Engineer's Representative, it will be dangerous to persons or property or to any finished or existing work. "Solid Rock" shall mean any material having a volume greater than 0.30 cubic metres that, in the opinion of the Engineer's Representative, can only be removed by the use of sledge hammers and wedges (if removed by hand) or explosives and pneumatic tools (if removed mechanically). Soft or decomposed material or boulders in excess of 0.30 cubic metres which can be removed by dozing, pushing, rooting, ripping, scarifying or by the use of other normal earth-moving plant shall not be classified as "Solid Rock". Payment will be per cubic metre of "solid rock" excavated and disposed of as directed by the Engineer's Representative. Should any difference of opinion arise between the Contractor and the Engineer's Representative the matter shall be referred to the Engineer, whose decision shall be final and shall be obtained before the material is disposed of or covered up. If the Contractor is still not satisfied, the matter may be referred to an Arbitrator. Any material having a volume of less than 0.30 cubic metres or material, which in the opinion of the Engineer's Representative can be removed by dozing, pushing, rooting, ripping scarifying or by the use of other normal earthmoving plant shall be classified as earthworks, and the cost of such operations shall be deemed to be included in the tendered rates and prices for earthworks. BACKFILLING OF EXISTING BORROW PITS 6136. Existing borrow pits adjacent to the roadway shall be backfilled as and where directed by the Engineer's Representative. 130 Such areas shall be backfilled with approved soil which shall be thoroughly compacted throughout by power rammers or other approved methods, to a density not greater than insitu density of the soil to promote vegetation growth as obtained in the British Standard Compaction Test. Measurement for this item shall be on the compacted backfill only, based on initial and final levels, and payment under the relevant items of the bill of quantities, shall include for benching and providing, placing, watering and compacting the material to the required density as specified herein. EMBANKMENT IN BAD GROUND 6137. The Contractor shall bring to the notice of the Engineer’s Representative cases where embankments are required to be sited over swamp or unstable ground. Where such conditions exist the Engineer's Representative may direct that the first lift of fill material before compaction can be increased to 450mm in order to establish firm ground for the compacting plant. This may not be done without the written approval of the Engineer's Representative and even if such approval is given, the Contractor is not relieved of his responsibility to provide a well compacted stable embankment of the same standard as the rest of the works. BACKFILLING 6138. No backfilling shall be carried out until the Engineer's Representative has inspected and passed the culverts and other structures which will be covered up. The excavation containing culverts will be backfilled in layers not exceeding 150mm thickness with materials approved by the Engineer's Representative. When existing pipes and conduits have insufficient earth cover during embankment construction, the Contractor shall protect them against damage by his equipment and operations. The embankment above and for a distance of not less than 600mm each side of such facilities shall be compacted by such means as the Contractor may choose so as to prevent damage to such facilities. The Contractor shall repair or make good any damage to such facilities that may be caused by his operations. Embankments constructed in the vicinity of bridges and culverts prior to the completion of abutments and wing walls shall terminate temporarily on slopes 5:1 or flatter which shall be located so as to allow ample space for construction of the structure and for placing and compacting the backfill and remaining embankment adjacent thereto. Embankment around and adjacent to abutments, culverts and piers shall be placed simultaneously on both sides thereof to approximately, the same elevation. Any space over the culverts and between the sides of the culvert and the walls of the excavations shall be filled with selected material in a damp state approximating to its optimum moisture content. The material shall be thoroughly compacted by hand or power rammers to not less than the dry density specified in Clause 6125. The cost of all backfilling as specified herein shall be deemed to be included in the tendered rates and prices. GRASSING OF EMBANKMENTS CUTTINGS, VERGES, ETC 6139. On completion of the verges, margins, embankments, etc., or at such other times as may be approved for the purpose of planting, all areas specified to be grassed shall be sown with broadcast seed or individual planting at 225mm centres and running parallel to the centre line of the road. The Contractor shall be responsible for watering and maintenance and for ensuring that the grass takes root, spreads and forms a thick mat. 131 Except where otherwise directed, the Contractor shall keep grassed areas mowed or cut until the commencement of the period of maintenance. The grass shall be cut three times during the growing season, or as often as it may be necessary. The condition of grassed areas will be assessed by the Engineer's Representative immediately after the third cutting. Areas which have not become established to his satisfaction for any reason whatsoever shall be made good to the satisfaction of the Engineer's Representative. ROADSIDE DRAINAGE DITCHING 6140. Roadside drainage ditches shall be constructed to the lines, grades and levels shown on the drawings or as directed by the Engineer's Representative. Where ditches collect surface water along their length and if he considers it necessary, the side at which the water enters the ditch shall be protected by constructing a bund and by allowing the water to enter the ditch only at specific points through the bund. Where the gradient of the road is flatter than 1 in 120 the ditch shall be deepened to provide an adequate drainage slope. All ditches with a gradient steeper than 1 in 120 shall be paved in the invert with small stones embedded in the bottom of the ditch and for a height of 150mm up the sides. Pitching with small stones if ordered by the Engineer' Representative shall be paid for separately. Payment for roadside drainage ditches is covered under earthworks and shall include for all trimming, shaping and bunding required. Spoil excavated from drains shall, where suitable be incorporated in the filling, and the quantity so used shall be deducted from the quantity of fill. No spoil shall be placed within 2 metres of the drain. Use shall be made of suitable roadside ditches at the discretion of the Engineer's Representative. CONCRETE DRAINS 6141. Concrete drains shall be constructed to the lines and levels shown on the drawings, or as directed by the Engineer's Representative and shall comply in all respects with the requirements stipulated for mass and reinforced concrete. The grade of concrete and quantity and size of reinforcement to be used shall be as shown on the drawings or as directed by the Engineer. The invert of drains shall be trowelled to a smooth finish and the inside face of walls shall be left with a fair finish as obtained from wrot shuttering. Where possible, spoil excavated for the construction of the drains, if suitable, shall be incorporated in the filling and payment will be made, once only, under the appropriate item for earthworks in the Bill of Quantities. Otherwise, the material excavation shall be disposed of as directed by the Engineer's Representative, and paid for under the appropriate item in the Bill of Quantities. SUB-SOIL DRAINS 6142. All water appearing on the formation as surface water held in depressions and potholes and sub-soil water which in any way affects the stability of the formation or pavement shall be carried to the side drains in rubble or stone filled drains, to the approval of the Engineer's Representative. Graded stone filling shall be hard and durable and shall consist of broken rock or gravel. It shall be well graded with a maximum size of 75mm and the percentage passing a 38mm sieve shall not exceed 5%. Graded stone filling shall be placed 132 in layers not exceeding 225mm loose depth and shall be well rammed as filling proceeds. Stone filled drains on side slopes shall be constructed prior to any surface soiling and grassing Pipes for sub-soil drains shall be mainly slotted flexible PVC pipes or perforated concrete pipes with ogee joints or perforated corrugated metal pipes. They shall be laid with dry joints. The pipe trenches shall be filled with graded stone filling which shall be carefully placed and packed in layers not exceeding 225mm in loose depth. Stone filled pipe drains on side slopes and margins shall be constructed prior to any surface soiling and grassing. Payment for work done under this clause shall be at the rate entered in the Bill of Quantities. CONSTRUCTION IN PERCHED WATER AREA 6142A. A sure way of avoiding drainage problems of perched or spring water is to carry out a proper soil survey of the area concerned and modify or re-adjust either the vertical or horizontal alignment or (both) to make the formation level far away as much as possible from the perched water table or under ground springs. If circumstances make this impossible the following procedure may be useful: Once the formation has been prepared water should be pumped out of the section to allow perforated pipes to be laid across the section in close proximity to enable water flow into it, and get channelled out of the roadway. Thereafter the pipes are to be covered with specially selected granular materials which will serve as weep holes over and above the perched water level, before approved fill is laid and compacted to not less than 95% MDD at a moisture not less than 2% above OMC using sheepsfoot (Taper-foot) roller up to a depth of 600mm below formation level, thereafter 100% compaction at OMC of compactive effort will apply. Compaction depth shall not be greater than 150mm per layer. In the alternative water proof material of uniform thickness (gauge) polytene sheets may be used to wrap the fill placed after the application of the weep pipes and selected fill to prevent ingress of water into the pavement. This method may be necessary particularly if the crown of the road is within one metre from the level of the perched water table. CUT-OFF DITCHING 6143. Cut-off ditching, metre drains turn-outs and culvert outfalls, including bunding as and where required by the Engineer's Representative shall be constructed where shown on the drawings or as directed by the Engineer' Representative and will be paid for under the appropriate items of the bill of quantities. Payment shall include for all trimming, shaping and bunding. EXCAVATION FOR CULVERTS 6144. Excavation for drainage works shall be carried out to the lines, levels and depths shown on the drawings or as directed by the Engineer's Representative and in such a manner that the stability of the sides and bottom of the excavation is ensured. Excavation shall be kept from water until, in the opinion of the Engineer's Representative, concrete or other works therein are sufficiently set and any filling has been completed. 133 Trenches shall be excavated through natural ground, or, where pipe culvert structures are to be placed under embankment, the Contractor shall, unless otherwise directed, complete the construction of the embankment to a minimum elevation of 300mm above the elevation of the top of pipe. The pipe trench shall then be excavated and the pipe placed in the trench. The width of trenches at any point below the top of the pipe shall not be greater than the outside diameter of the pipe at the bell or bank plus 900mm to permit satisfactory jointing and thorough tamping of the bedding material under the pipe. Sheeting and bracing, where required, shall be placed within the trench width as specified. Care shall be taken not to over excavate. Where trench widths are exceeded, redesign with a resultant increase in cost of stronger pipe or special installation procedures will be necessary. Cost of this redesign and increased cost of pipe or installation shall be borne by the Contractor. The width of trench for structural concrete pipe culverts shall not exceed the widths shown on the Drawings or as specified above, and these widths shall be maintained to a height of at least 300mm above the top of the barrels of the pipes. Where directed by the Engineer's Representative soft material below the required levels of excavation shall be removed and filled to the required level with compacted granular bedding material or concrete grade 15N/mm². Where excavation is taken out to a greater depth than is necessary or there is over-excavation at the sides of the trench, the Contractor shall fill in the excess excavation at his own expense with 10 N/mm2 concrete or with compacted granular bedding as directed by the Engineer's Representative. Rock encountered in trenches for pipes shall be excavated to the depths shown on the Drawings. Where no depths are shown it shall be excavated to a depth 150mm below the intended level of the bottom of the pipes and replaced with granular bedding or concrete grade 10 N/mm2 as directed by the Engineer's Representative. For measurement purposes, depths shall be measured from formation level in the case of cuttings and from the original ground level where the new carriageway is on embankments. The rate for excavation shall include for any extra width over the net width which the Contractor may consider to be necessary. The rate for excavation shall also include for any timbering, shoring, strutting, or pumping if required, backfilling and compaction and for the disposal of surplus material as directed by the Engineer's Representative to a distance not exceeding 1.6 kilometres. Soft yielding material shall be dug out and replaced with approved selected material compacted to 100% of its maximum dry density obtained in the West African Compaction Test. All backfilling shall be compacted to 100% of its maximumdry density obtained in the West African Compaction Test. DEMOLITION OF EXISTING CULVERTS 6145. The Contractor will be required to excavate and demolish existing culverts as and where directed by the Engineer's Representative. Materials from the demolition will be disposed off as directed by the Engineer's Representative. Where the culvert has been demolished the area will be backfilled with suitable material as specified in the relevant clause of the specification. Payment will be made under the appropriate items in the Bill of Quantities, and shall include for excavation, demolition and disposal of materials and backfilling, all as specified herein. 134 NEW PIPE CULVERTS 6146. Where specified on the drawings, all pipe culverts shall be bedded on and haunched with a minimum of 150mm thickness of Grade 15 N/mm² Quality Concrete. (a) Unreinforced concrete pipes shall comply with B.S 556. They shall be unreinforced standard pipes and the following shall apply:(1) Joints shall be ogee type (2) High alumina or sulphate resisting cement will not be required. (3) Samples of aggregate will not be required. (4) required. Tests other than the manufacturer's quality control tests will not be (5) No variation will be allowed in the time of maturing. (6) Certificates in accordance with Clause 8 of Appendix A will be required. (7) Admixtures will be prohibited. Unreinforced concrete pipes shall be surrounded with concrete and the pipe trenches shall be filled to natural subgrade level with special granular fill. No concrete shall be placed around any length of pipe until the Engineer's Representative has approved the laying and jointing of same. Special granular fill shall be placed and thoroughly compacted in layers not exceeding 250mm loose depth. (b) Structural concrete pipes shall comply with B.S 556. They shall be reinforced extra strength pipes of the Class specified on the Drawings and the following shall apply:(1) Joints shall be flexible spigot and socket type with rubber gaskets and performance data will not be required. (2) High alumina or sulphate resisting cement will not be required. (3) Samples of aggregate will not be required (4) required. Tests other than the manufacturer's quality control tests will not be (5) Certificates in accordance with Clause 8 of Appendix A will be required. (6) Admixtures shall be prohibited. Pipes shall be laid true to line and level and each pipe shall be separately boned between sight rails. Immediately prior to laying, pipes shall be examined for defects and no 135 defective materials shall be incorporated in the Works. Where non-standard lengths of unreinforced concrete pipe are required at catch pits, headwalls, outfalls and the like, the pipes shall be cut and the ends made good. Where it is necessary to cut structural concrete pipes, they shall be sawn and the cut end shall be cast into the manhole catch pit headwall etc. so that at least 75mm concrete cover is provided. Ogee joints shall be thoroughly cleaned before laying and 1:2 cement sand mortar shall be evenly applied to the ends so as to completely fill the joint. The pipes shall then be properly drawn together, the outside of the joint shall be neatly pointed and any surplus mortar on the inside of the joint shall be removed. Structural concrete pipes shall be laid and joined in accordance with the manufacturer's recommendations and the methods recommended for flexible jointed pipes in National Building Studies Special Report 35 'Pipe Laying Principles'. Care shall be taken to ensure that excess cement mortar and earth or other material is thoroughly cleaned out of the pipes. Cleaning shall be carried out during the laying of the pipes by drawing a timber badger through the pipes at a distance of 2 pipes lengths from the last made joint or by other means acceptable to the Engineer's Representative. The timber badges shall be not less than 450mm long and shall have a diameter 12mm less than the internal diameter of the pipe. The badger shall only be removed from the pipe in the presence of the Engineer's Representative. If for any reason, the invert level of a pipe culvert is such that the depth of cover at the edge of the pavement is less than 600mm or the diameter of the pipe, then, on the instruction of the Engineer's Representative the culvert shall be given a complete surround 150mm thickness, of Grade 15 N/mm² quality concrete in place of a concrete haunch, and payment shall be made for same at the appropriate rates in the Bills of Quantities. The outlets of pipe culverts shall be pitched with stone to a minimum length of 2 metres from the face of the culvert or as directed, and the level of the pitching shall be at least 75mm below the culvert invert. The width of pitching shall be decided on site by the Engineer's Representative. The inlets of culverts shall be pitched only where directed by the Engineer's Representative. In cases where pitching is unobtainable the Engineer's Representative may order a 150mm thick apron of Grade 15 N/mm² concrete to be constructed. Where directed catchpits of the required internal dimensions shall be constructed at the inlets of culverts. The inverts and walls shall be of Grade 15 N/mm² quality concrete, reinforced if directed. The backfilling shall be of approved material, compacted as specified in the relevant clauses of this specification. a. Backfilling trenches: After the bedding has been prepared and the pipe installed, selected material from excavation or borrow pit, at a moisture content that will facilitate compaction, shall be placed along both sides of the pipe in layers not exceeding 150mm in compacted depth. The backfill-shall be brought up evenly on both sides of the pipe for its full length. Care shall be taken to ensure thorough compaction of the fill under the haunches of the pipe. Each layer shall be thoroughly compacted with mechanical tampers or rammers. This method of filling and compacting shall continue until the fill has reached an elevation of at least 300mm above the top of the pipe. The remainder of the trench shall be backfilled and compacted by spreading and rolling, or compacted by mechanical rammers 136 or tampers in compacted layers not exceeding 150mm. Tests for density will be made as necessary and directed by the Engineer, at no expense to the Contractor. b. Backfilling pipe in fill sections: The fill material shall be uniformly spread in layers longitudinally on both sides of the pipe, not exceeding 150mm in compacted layer and shall be compacted by rolling parallel with pipe or by mechanical tamping or ramming. Prior to commencing normal filling operations, the crown width of the fill at a height of 300mm above the top of the pipe shall extend a distance of not less than twice the outside diameter on each side of the pipe, or 4m whichever is less. After the backfill has reached at least 300mm above the top of the pipe, the remainder of the fill shall be placed and thoroughly compacted in layers not exceeding 150mm. c. Construction machinery: In compacting by rolling or operating heavy equipment parallel with the pipe, displacement of or injury to the pipe shall be avoided. Movement of construction machinery over a culvert or a storm drain at any stage of the construction shall be at the Contractor's risk. Any pipe damaged thereby shall be repaired or replaced at the option of the Engineer's Representative and at the expense of the Contractor. EXTENSION OF EXISTING PIPE CULVERTS 6147. Existing pipe culverts shall be extended to the lengths shown on the drawings or as directed by the Engineer's Representative. The extension shall be of a similar diameter to the existing culvert, and constructed in a like manner. Where existing headwalls occur within the carriageway width they shall be removed to a minimum depth of 300mm below new road level and the new road constructed to the profile shown on the drawings. The existing culvert and the new extensions shall be cleaned out and flushed as necessary on completion to clear all dirt, cement mortar and other obstruction to allow the free passage of water through its full internal area. If so directed by the Engineer, the existing culverts which are to be retained and do not already have a complete surround or haunch of concrete as required, shall be dug out and the surround or haunch completed by 150mm of concrete as specified for new culverts. ACCESS CULVERTS 6148. Access culverts shall if sufficient cover is not available for pipe culverts, be constructed in the form of a small slab or box culverts to the grade, sizes and dimensions shown on the drawings or as directed by the Engineer's Representative. The roof and floor slabs shall consist of grade 25 N/mm² concrete reinforced as shown on the drawings. The walls shall consist of grade 10 N/mm² mass concrete. Construction shall comply with all relevant clauses of the specification or such modifications as the Engineer may decide. The headwalls shall be constructed of precast concrete blocks with a 6:1 sand cement mix. BOX CULVERTS 6149. Box culverts shall be constructed to the grades, sizes and dimensions shown on the drawings, or as directed by the Engineer's Representative, and the finished surface shall be smooth and regular free from flaws, air holes and excrescences and with a constant grade. The grades of concrete and quantity and size of reinforcement to be used shall be as shown on the drawings and shall comply in all respects with the requirements stipulated for mass and reinforced concrete. Culvert construction shall comply in all respects with the requirements of this specification or such modification thereof as the Engineer may decide. 137 EXTENSIONS TO EXISTING BOX CULVERTS 6150. The Engineer shall provide the Contractor with additionaldrawings for the construction of the extensions to the existingsmall section box culverts. Measurement of the works incorporated in these extensions shall be as for new reinforced concrete box culverts. The existing culvert and the new extensions, shall be cleaned out and flushed as necessary on completion to clear all dirt, cement mortar and other obstructions to allow the free passage of water through its full internal area. CORRUGATED METAL"ARMCO" CULVERTS 6151. Where corrugated metal culverts are specified, they ORshall be of galvanized corrugated metal pipes or pipe arches of the"armco" or other approved type complying with the cross-section and gauge specified. The pipes or pipe arches shall be assembled in convenient lengths in accordance with the manufacturer's instructions or as directed by the Engineer's Representative. Before laying, care must be taken to ensure that the bottom of the trench or if laid under embankments, the prepared bed, is accurately graded and compacted to provide a solid uniform bearing for the pipes or pipe arches and to ensure this the Engineer's Representative may direct that a 300mm thick compacted layer of approved material be constructed. The width of the trench shall be such that a minimum of 300mm is left between the pipe or pipe arch and the side of the trench. Back filling shall be of approved material laid in uniform layers of 150mm in depth and compacted to 100% of its maximum dry density achieved in the West African Standard Compaction Test. For multiple structures, the minimum clearance between each pipe or pipe arch shall be not less than half of the maximum cross- sectional width of the pipe or pipe arch. The minimum depth of compacted cover (excluding the base course) over any pipe or pipe arch shall be at least 300mm. The maximum depth of fill over any pipe or pipe arch shall not exceed the manufacturer's recommendation for the particular gauge of culvert used. Corrugated metal pipes culverts and channels shall comply with the materials section Standard Specification for Corrugated Metal Culvert Pipe, Designation M36-60 of the American Association of State Highway and Transportation Officials except that:(i) The pipes culverts and channels shall be manufactured from steel complying with B.S 1449: Part Al, or Part l B with copper content when required at 0. 2 per cent minimum. (ii) The pipes culverts and channels shall be coated with spelter complying with B.S 729: Part l, alternatively the pipes may be manufactured from steel sheet complying with B.S 2989. (iii) The pipes and culverts shall be bitumen coated in the course of manufacture as specified hereinbelow. Where available, all culverts shall be factory coated with a double layer of protective bitumen. Where the culverts are not factory coated, i.e. in the case of the large diameter or multiple culverts, the Contractor shall apply two coats of approved bitumen, as a protective measure, to the satisfaction of the Engineer's Representative, and the Contractor shall be deemed to have allowed for this in his tendered rates and prices. If for any reason, such as the acidity of the sub-soil water, the Engineer considers any further protective measures to be necessary, the Contractor shall carry out same as directed and shall be paid at rates to be mutually agreed between the Engineer and the Contractor. 138 The Contractor shall take every precaution to ensure that the protective coatings, including galvanizing, are not damaged in any way during transporting, storing, assembling or laying of the culvert, and he shall make good any such damage to the satisfaction of the Engineer's Representative and at his own expense. (1) Bitumen - Bitumen for coating shall have the following properties: as in Table VI -3 below: TABLE VI-3 QUALITY OF BITUMEN COATING INLETS AND OUTLETS OF CULVERTS TEST TYPE LIMIT % TEST METHOD Bitumen soluble in cold carbon tetrachloride, not less than 99.5 Loss in weight on heating to 163 C, not more than 1 AASHTO T47 Penetration of residue after heating compared with penetration of same sample before testing for loss on heating, not less than 85 AASHTO T49 AASHTO T45 6152 The positions, lengths, dimensions and levels of all culverts including aprons shall be as shown on the drawings or as directed by the Engineer's Representative. The culvert shall be cleaned out and flushed as necessary on completion to clear all dirt, and other obstructions to allow the free flow of water through its full internal cross-sectional area. The outlets of all culverts shall be protected from erosion by stone pitching or concrete to a minimum length of 2 metres from its face. The width of the pitching or concrete shall be decided by the Engineer's Representative and a toe-wall 450mm deep shall be constructed at the edge of such pitching or concrete. The inlets to culvert shall be similarly protected, only where directed by the Engineer. Where the gradient of the roadside drainage ditch would be excessive if the ditch were graded to the invert level of culverts, catchpits or balancing ponds shall be constructed as and where directed by the Engineer's Representative. The catchpits shall be constructed of mass concrete to such dimensions as required by the Engineer's Representative. CLEARING DRAINS AND CULVERTS 6153. Before any drain or culvert is brought into use the Contractor shall ensure to the satisfaction of the Engineer's Representative that it is free from all extraneous material, all such material being completely removed from the site. During the period of maintenance the Contractor shall ensure that the drains and culverts shall be kept clear of all obstructions and before the maintenance certificate is granted all drains and culverts must be cleaned out to the satisfaction of the Engineer. All costs incurred shall be deemed to be included in the tendered rates and prices. PITCHING 6154. Pitching will be provided where shown on the drawings or as directed by the Engineer's Representative. The stone used for pitching shall comply in all respects with the requirements of this specification. The pitching shall be either 150mm or 225mm thick as appropriate and if directed or shown on the drawings shall be set in mortar comprising 1 part of cement to 4 parts of sand. The ground on which the pitching is to be placed shall be shaped and compacted to the 139 satisfaction of the Engineer's Representative before the pitching is laid. At the extremities of the pitching, toe-walls shall be formed in the same construction and they shall be carried down to a depth of 450mm, or to such greater depth as may be specified on the drawings or by the Engineer. Pitching shall be measured per square metre of complete pitching and payment will include for the supply of all materials, labour etc., and the construction of the completed pitching shall be as specified in this Clause. Catchpits where required may also be constructed in pitching stone laid in cement mortar as directed on site by the Engineer's Representative, and measurement shall be per square meter of wall. Payment for toe walls shall be based on the length of wall constructed and shall include for excavation and backfilling. APPROVAL OF METHOD 6155. The Contractor shall not commence work on the sub-grade, sub-base course, base course or surfacing until he has obtained the Engineer's Representative's approval of the plant, materials and methods that he proposes for clearance, excavation, mixing, transporting, heating, spreading, grading and compacting the same as appropriate compaction tests will be required before such approval is granted. The foregoing provisions shall not prevent the Engineer from requiring the Contractor to vary his plant, material or methods at any time during the execution of the works, should he considers this essential for carrying out the contract. The Contractor shall not vary plant, material or methods which have been approved by the Engineer's Representative without previously obtaining his approval of such variation. The Engineer or his Representative's approval of any of the Contractor's plants, material or methods shall not at any time imply responsibility for the execution of the work involved and the Contractor shall at all times be solely responsible for constructing the sub-grade, sub-base, base and pavement surfacings in accordance with the specification and drawings. PREVENTION OF DAMAGE TO COMPLETED PAVEMENT 6156. The Contractor shall ensure that the passage of any vehicle or plant over the partially completed pavement or over the sub-grade, sub-base or base does not occasion any rutting or other damage or disturbance to the partially completed works, and should such rutting or other damage or disturbance occur, the Contractor shall make the same good as directed by the Engineer's Representative at his own expense. Vehicles and plant passing repeatedly over the partially completed pavement or over the sub-grade, sub-base or base shall not be allowed to travel in a single track, but such traffic shall be spread out over as great a width as practicable. There shall be no storage or stockpiling of materials on top of partially completed pavements or on the base, sub-base or sub-grade. WATER FOR CONSTRUCTION 6157. The Contractor shall provide all water necessary for the construction of the sub-grade, sub-base, base and pavement surface. Such water shall be clean and free from organic matters, waste matter or other harmful or deleterious substances, and shall be obtained from an approved source. The Contractor shall provide all plant necessary for conveying and distributing water. Where it is necessary to increase the moisture content of materials comprising the sub-grade, sub-base or base, the water shall be evenly sprinkled on the surface of the soil by spraying machine of a type or types to be approved by the Engineer's Representative, such machines 140 being capable of uniformly distributing the water at a known predetermined and constant rate. ROLLERS 6158. Smooth-wheeled, sheepsfoot and pneumatic tyre rollers where employed for compacting soils and pavement materials as detailed in subsequent clauses shall be of a type and compacting effort approved by the Engineer's Representative and shall be capable of achieving the specified degree of compaction. The compactive effort shall be designated as the weight per centimetre width of rolling wheel, for the smooth wheeled and pneumatic type rollers. The comapctive effort of the sheepsfoot roller shall be expressed dividing the total load of the roller by the foot area (square centimetre) in contact on hard ground. The distribution of wheels on any roller shall be such that the whole of the ground surface within the width of the roller is loaded during each pass of the roller. VIBRATORY COMPACTORS 6159. Where vibratory compactors or power rammers are used on the works they shall be of the type approved by the Engineer's Representative and shall be capable of obtaining the specified degree of compaction approved. TRENCH 6160. Where the exiting carriageway is to be widened on its existing alignment, the EXCAVATION FOR Contractor shall excavate a trench with neat and vertical sides to each side of it to contain the WIDENING OF additional pavement construction required for the new carriage way width.Each edge of the EXISTING PAVEMENT existing surfacing shall be cut-back as directed by the Engineer's Representative on site, but such cut-back will be kept to the minimum compatible with the provision of a straight and clean sharp edge to the surfacing on the inside edge of the trench. Payment for the excavation of the trenches including for the trimming back of the existing surfacing and the disposal of all excavated material shall be made per cubic metre of material excavated under the appropriate item for earthworks in the Bill of Quantities. Measurement shall be based on sections taken before and after excavation of the trenches but payment shall not be made for excavation in excess of that specified and required to receive the specified pavement. The maximum amount of trench excavation shall be placed to fill and payment shall be made once only as decided above. PREPARATION OF SUB-GRADE 6161. The sub-grade whether in trench excavation or construction shall be graded and compacted to such level as will permit the works to be constructed to the required thickness and specified finished levels and tolerances. Before it is compacted, the Engineer's Representative will inspect the sub-grade and the Contractor shall notify the Engineer's Representative when each area of sub-grade is ready for inspection, and shall allow reasonable time for the inspection to be made. Wherever ordered by the Engineer's Representative, the Contractor shall excavate any unsuitable material from below the sub-grade and shall deposit the same as and where directed by the Engineer's Representative. The Contractor shall replace the void with fill material approved by the Engineer's Representative. Payment will be made in accordance with the relevant clause of this specification, excepting where the unsuitable material has been imported by the Contractors. All loose pieces of stone or other material exceeding 75mm in size in any dimension shall be removed from the surface of the sub-grade before compaction is commenced and disposed of as directed by the Engineer's Representative. 141 The Contractor shall then compact the whole of the Sub-grade by the use of approved smooth wheeled, sheepsfoot or pneumatic tyred rollers, static or vibratory type as approved by the Engineer's Representative. Final compaction shall be by smooth wheeled roller. The density required shall be 100 per cent of the maximum dry density obtained in the British Standard Compaction Test. Payment for compaction of sub-grade will be made once only either through earthworks items, or other appropriate items in the Bill of Quantities. COMPLETION AND SHAPING OF SUBGRADE 6162. Immediately before the construction of the subbase course, the upper surface of the sub-grade shall be tested for smoothness and accuracy of formation and if any areas are found to lack the required smoothness or accuracy, such areas shall be scarified, reshaped, re-compacted as specified, or otherwise treated as the Engineer's Representative may require until the required smoothness and accuracy is obtained. The finished surface of the sub-grade shall be left as smooth as possible and the accuracy of finish in the longitudinal direction shall not vary at any point by more than 12mm from a 5-0 metre straight edge, placed in any position on the finished surface parallel to the centre line. The transverse profile shall conform to the same accuracy using a correctly shaped template instead of the straight edge. The level of any point on the aforesaid surface shall not vary by more than 12mm from the finished level of the pavement less the specified thickness of the pavement construction. Payment for all of the work required by this clause shall be deemed to be included in the tendered rates and prices. The requirements of this clause shall not be held to apply to the existing bituminous surfacing scarified, shaped and recompacted on lengths of strengthening of the existing alignment. Payment for all of the operations required under this clause shall be deemed to be included in the tendered rates and prices. COMPLETION OF VERGES AND MEDIANS 6163. On completion of the carriageway and hard shoulders, the verges and medians shall be brought to finished level, shaped to the cross-falls as shown on the drawings and compacted so that the upper 150mm has a dry density of not less than 100% of the maximum dry density as determined by the West African Standard Compaction Test. Where the material forming the verges or medians is of such a nature that it is liable to erosion, the Engineer may direct that the top 75mm of the verges or medians be formed of cohesive lateritic soil, or other approved material, and the 75mm of filling material below it shall be compacted in one operation to 100% of the maximum dry density as determined by the West African Compaction Test. The selected lateritic soil for the verges or medians shall be preferably a well graded lateritic soil with a plasticity index of not less than 10 and not more than 20. Payment for this selected compacted 75mm of topping to the verges or medians shall be made under the appropriate item in the Bill of Quantities. The verges or medians shall be cleared of any windrows or heaps of material and shall be graded evenly, as directed, so that water drains in the required manner. The verges and medians shall be grassed, sealed or paved where directed by the Engineer. STRIPPING TOPSOIL 6164. Stripping topsoil shall apply only to those sections of the roadway to be realigned; that is, where the proposed roadworks will not fall within the limits of the existing roadworks. Only those areas of the new construction outside the existing roadworks will be stripped of topsoil. 142 Before grading work is commenced the vegetation and underlying topsoil within excavation and embarkment areas shall be stripped off to a depth of not less than 100mm and not more than 150mm below the existing ground surface. Stripped material which is or may be made suitable for topsoiling shall be stored and used therefore if needed. Stripped topsoil in excess of the quantity required for the Project topsoiling shall be stored at locations specified for future use of the Engineer. Topsoil shall not be stored in areas where it will interfere with surface drainage or with the conservation of trees, shrubs and other vegetation that are to remain. CATCHPITS AND CASCADES 6165. Catchpits and cascades shall be constructed of in-situ concrete Grade 15N/mm² as shown on the drawings. Unshuttered exposed concrete surfaces shall be finished with a wooden float. The ends of pipes shall be properly built into the catahpits and unreinforced concrete pipes shall be cut off flush with the inner surface of catchpits. Excavation not occupied by the catchpit cascade or by adjacent pipe drains shall be backfilled with the excavated material which shall be placed and compacted in layers not exceeding 225mm loose depth to a dry density equivalent to that of the surrounding ground. Should the excavated material become unsuitable for backfilling due to any cause, the Contractor shall provide other suitable material for filling at his own expense. (CLAUSES 6166 - 6179 INCLUSIVE NOT USED.) TESTS TESTS FOR THE SELECTION OF FILLING MATERIAL 6180. The following tests shall be carried out on all material proposed for use as fill:(I) PLASTICITY TESTS (II) GRADING TESTS (III) DENSITY/MOISTURE CONTENT COMPACTION TESTS (IV) LABORATORY C.B.R. TESTS. Unless otherwise stated to the contrary, these tests shall be carried out as described in section 1 of this specification. TESTS FOR THE 6181. The tests listed below will normally be required to be carried out for each 2 CLASSIFICATION OF kilometres of sub-grade or each layer of fill. The numbers and types of tests listed however, COMPACTED SUBare given only as a guide to the Contractor for tender purposes and the actual number and GRADE AND FILLING type of tests which will be carried out during the construction of the works will be determined entirely at the discretion of the Engineer. (I) CLASSIFICATION TESTS 2 NO. LIQUID LIMIT TESTS 2 NO. PLASTIC LIMIT TESTS 2 NO. SIEVE ANALYSIS TESTS 143 4 NO. BRITISH STANDARD COMPACTION TESTS 2 NO. LABORATORY C.B.R. TESTS AT THE SPECIFIED DENSITY AND MOISTURE CONTENT. (Il) CONTROL TESTS 20 NO. INSITU DRY DENSITY TESTS. Except where otherwise stated to the contrary, these tests shall be carried out as described in section 1 of this specification, or where no such description is given in accordance with the appropriate British Standard, AASHTO and ASTM Standards. The sieve analysis shall be carried out in accordance with the standards laid down in the latest amended report of the "Lagos materials testing Conference", a copy of which shall be made available to the Contractor on request, or as per the latest B.S 1377. TRIAL SECTIONS TO DETERMINE TECHNIQUE 6182. The Contractor's attention is particularly drawn to the necessity for carrying out trial sections with each type of proposed filling material prior to the start of the main construction for the particular type of material, to determine the most efficient technique, the most suitable compacted thickness of each layer and the suitability of the proposed materials and plant, all as described in the Clause 1052 of this specification. (CLAUSES 6183 - 6199 INCLUSIVE NOT USED) PART (C) SUB-BASE COURSE, BASE COURSE ETC. (1) GENERAL LATERITE 6200. In addition to any other clause of this specification, the following shall be deemed to apply in particular to laterite sub-base course and base course work, and shall be read in conjunction with all other relevant clauses of the conditions of contract and this specification. MATERIALS MATERIALS FOR COMPACTED SUB-BASE COURSE AND BASE COURSE 6201. All materials for the sub-base course, base course and hard shoulders shall be selected by the Contractor. Where a preliminary soil survey has been carried out by the Engineer, a copy of the report on the soil survey shall be made available to the Contractor. Where no such soil survey has been carried out the Contractor shall make his own arrangements for the location of borrow pits and sources of materials, and the cost of any survey shall be deemed to be included in the tendered rates and prices. The soil survey report of the Engineer, when available, shall be used for guidance only, and shall not relieve the Contractor of his responsibility for executing the works in accordance with the Conditions of Contract and this Specification. All selected material shall be free of roots, vegetable matter, and other deleterious material and shall be approved by the Engineer's Representative before its incorporation into the works. Normally the minimum strength of such base course material shall not be less than 80% C.B.R. value being determined at maximum dry density and optimum moisture content unsoaked with either West African or Modified A.A.S.H.T.O. compaction. However, where 144 the Engineer's Representative considers it necessary on account of perched water-table or any other reasons, he may specify that a C.B.R. value of 80% be obtained after at least 24 hours soaking. For construction on perched water area see clauses 6142 and 6142A. Base Course The requirements below in Clauses 6250, 6251, and 6252 shall apply herein. Subbase Type 1 The subbase material shall consist of pit-run laterite, sand, or screening, and soil of other similar binding or filler material and shall be obtained from approved sources. The maximum dimensions of any particle shall not be greater than two-thirds of the compacted thickness of the layer in which it is to be placed. Oversize material shall be removed by screens, grizzlies or by hand picking. The gradation and soil constants shall comply to the requirements specified herein. The material shall be free from vegetable matter, and excessive amount of lumps of clay, and other objectionable or foreign substances. Table VI-4 Gradation of Subbase Material: Sieve Percent Passing by Weight 75mm 600 m 425 m 75 m 100 25-60 10-40 5-20 The percent by weight passing the No-75 m sieve shall be less than but not greater than 35%. The material passing the 425 m sieve shall have a liquid limit of not more than 35% and a plasticity index of not more than 12, as determined by American Society for Testing Materials methods, serial designation D 432-39 and 424-39 respectively or as determined by test No 2 or 2A and test Nos 3 of B.S 1377 (1975). Prior to approval of the subbase material a test section shall be constructed to the thickness shown on the typical pavement section and compacted to 100 percent of maximum density. When the test section is compacted to 100 percent maximum density at optimum moisture content, the subbase material shall be of such quality that it shall have the minimum CBR of 30% after at least 24 hours soaking. Once established that the subbase meets the CBR quality requirement at 100 percent maximum density it shall be placed and compacted in the field to that density. Subbase course, Type 2 The minimum strength of material for Subbase Course type 2, shall not be less than 20% CBR after at least 24 hours of soaking, for light traffic. The C.B.R. values shall be assessed in the same manner as for base course, at the optimum moisture content and maximum dry density of the West African Compaction Test. At the Engineer's Representative discretion material with a liquid limit greater than 35%, and a plasticity index greater than 12 may be disallowed for use as subbase course or base course. Subbase Course Type 3 145 The use of Substandard Material for Subbase If the Engineer's Representative is satisfied that good materials for base or subbase course are not available, sub standard materials may be used adopting the following guide lines. Class A Materials These are materials rejected either due to too much fine, silt, or clay content but slightly fall short of strength specified. (i) The material may be used by compacting it to a dry density slightly less than maximum at moisture content slightly greater than OMC, to contain the tendency for such material to swell or shrink due to cycle of weather. To make up for strength deficiency, a ratio of strength proportion of the material to what is specified shall be worked out and the depth of the subbase/base course adequately increased to account for the deficiency. (ii) On the other hand, where sand is available at economical rate, mechanical stabilization shall be used to reduce the fines content thus increasing the strength of the material. It will be necessary to determine economic percentage of the sand required before the method is put into use. Subbase Course - All Types The gravels as excavated from the pits may contain oversize material and such material must be broken down so that all material used in base course shall pass a 25mm sieve; and that used in subbase shall pass a 50mm sieve. The work of breaking down or disposal of such oversize material shall be deemed to be included in the tendered rates and prices. ROCK LATERITE FOR SUBBASE COURSE AND BASE COURSE 6202. Rock Laterite for base course shall be hard and durable and shall be from a source approved by the Engineer’s Representative. Samples of the stone shall be submitted to the Engineer’s Representative for his approval and shall be tested by soaking the specimen in water for 96 hours to ensure they do not disintegrate. The stone shall not be less than 225mm deep, and shall be not less than 230 sq.cm. base area, where the thickness of the course is 225mm. The percentage of wear shall not exceed 50% as determined by ASTM C131-51 procedure. Rock Laterite for blinding shall be clean crushed laterite aggregate graded from 5mm to dust from the same source as material for pitching, free from excessive clay or silt. (CLAUSES 6203 - 6204 INCLUSIVE NOT USED) WORKMANSHIP SEQUENCE OF OPERATIONS 6205. The pavement construction for the roadway shall consist of the following as specified herein and shown on the drawings:(A) The scarifying of the subgrade where no filling is applied. (B) The compacting of the subgrade. 146 (C) The laying and compacting of the sub-base course and base course. (D) The providing of prime and first coat bituminous surface dressing to the base course of the carriageway if applicable. BORROW PITS FOR SUB-BASE, BASE COURSE AND HARD SHOULDER MATERIALS 6206. The Contractor shall arrange and pay for any compensations or other payments whatsoever required for access to and occupation and use of the borrow pits for course and selected shoulder materials. The Contractor shall clear subbase, base the areas and remove and stockpile overburden to such depths as may be required by the Engineer's Representative. Under no circumstances will payment be made for removal of overburden. Materials used which may include the incorporation of suitable overburden as directed shall be taken only from such areas and to such depths and in such a manner as the Engineer's Representative shall direct. The Contractor shall at his own expense remove and dispose of all unsuitable materials, the removal of materials may require prior rooting and scarification and the Contractor shall be deemed to have allowed for this in the tendered rates and prices. The material as excavated may not fall within the required limits of grading for the completed pavement and the Contractor shall be deemed to have included in the tendered rates and prices for any additional work which may be required to bring the material within the specified limits when laid and compacted in the road bed. Borrow pits shall be worked and drained so as to obtain the maximum quantities of available suitable materials and shall be finally drained, levelled, and topsoil replaced all as specified and to the satisfaction of the Engineer's Representative. Payment for all arrangements, compensation, operations and other requirements of this clause shall be deemed to be included in the tendered rates and prices. The width of the subbase course and base course shall be as shown on the drawings or as directed by the Engineer. The compacted thickness of the subbase course and base course is dependent on the C.B.R. values of the Sub-grade and that of the material used, and shall be as shown on the drawings or as otherwise directed by the Engineer's Representative in accordance with the following provisions:The specified combined thickness for the subbase course and the base course has been derived from the pavement design diagram, curve E(RRL.RN/2503) based on an anticipated minimum C.B.R. value (after at least 48 hours soaking) for the compacted Sub-grade. Where a C.B.R. value in excess of the anticipated value is achieved, then compacted thickness of the Sub-base course may be reduced at the discretion of the Engineer's Representative and in accordance with curve E(RRL.RN/2803). Under no circumstances shall the combined compacted thickness of the pavement be reduced to less than 150mm. Before compaction, the subbase course and base course material shall be brought to the optimum moisture content for the compaction effort of the plant to achieve the density specified. Where the existing moisture content of the material is higher than this, the soil shall be allowed to dry out by aeration; where it is lower sufficient water shall be added to the soil such that uniform wetting of the material to optimum moisture content is achieved. Compaction of the subbase course and the base course shall be carried out separately, and shall begin immediately the soil has been brought to the required moisture content and shall be carried out rapidly until completion. The compaction of the subbase 147 course and base course shall be carried out to a dry density not less than 100% of that achieved in the West African Standard Compaction Test at optimum moisture content, but the compaction of the base course may be carried out to a dry density of not less than 100% of that achieved in the Modified A.A.S.H.O. Compaction Test at optimum moisture content, if so directed by the Engineer. The base course shall be finished to camber or cross-fall as shown on the drawings or as otherwise directed by the Engineer's Representative. COMPLETION OF SUB-BASE COURSE 6207. Immediately before the construction of the base-course, the Sub-base course shall be tested for thickness, surface finish, and accuracy, and if any areas are found to lack the required thickness surface finish, or accuracy or specified density, such areas shall be scarified, recompacted to the specified density or otherwise treated as the Engineer's Representative may require until the required thickness smoothness accuracy or density is obtained. The finished surface of the Sub-base course shall be left as smooth as possible and the accuracy of finish in the longitudinal direction shall not vary at any point by more than 12mm for a 5 metre straight edge, placed in any position on the finished surface parallel to the centre line. The transverse profile shall conform to the same accuracy using a correctly shaped template instead of straight edge. The level of any point on the aforesaid surface shall not vary by more than 12mm from the finished level of the pavement less the specified thickness of the base construction. The thickness of the Sub-base course at any point shall not be less than the specified thickness by more than 12 mm The Contractor shall include in his rates the digging of trial holes, and making good same, to the satisfaction of the Engineer's Representative. COMPLETION OF BASE COURSE 6208. Immediately before the application of the surfacing the base course shall be tested for thickness, smoothness and accuracy as specified below and if any areas are found to lack the required thickness, smoothness and accuracy or the specified density, such areas shall be scarified, reshaped and recompacted with additional approved material added where necessary or otherwise treated as the Engineer's Representative may require until the required thickness smoothness, accuracy or density is obtained. The finished surface of the base shall be left as smooth as possible and the accuracy of finish in the longitudinal direction shall not vary at any point by more than 5mm from a 3.0 metre straight edge, placed in any position on the finished surface parallel to the centre line. The transverse profile shall conform to the same accuracy using a correctly shaped template instead of the straight edge. The level of any point on the aforesaid surface shall not vary by more than 5mm from the finished level of the pavement. The thickness of the base course at any point shall not be less than the specified thickness by more than 12mm and the average thickness over a length of 0.4 kilometres shall be equal to, or in excess of the specified thickness. The Contractor shall include in his rates for digging necessary trial holes, and making good same, to the satisfaction of the Engineer's Representative. In the process of completing the base course it may be necessary to place material to a greater thickness than that specified and to grade it to the specified finish. In so doing excess material will be wasted. Payment for this and for all other operations required to obtain the specified finish shall be deemed to be included in the tendered rates and prices. 148 ROCK LATERITE FOR BASE COURSE 6209. The base course for the carriageway shall consist of approved rock laterite as specified, laid to the required total thickness after compaction. The lumps of rock laterite shall be tightly wedged across the prepared formation and interstices shall be filled with approved spalls from the same source as the rock laterite before thoroughly rolling. Rolling shall be carried out with a roller weighing not less than 58 kilograms per centimetre width of roll and any depression or surface irregularity which occurs during rolling shall be corrected with approved crushed quarry fines as specified, watered and again rolled with a roller weighing not less than 58 kilograms per centimetre width of roll. No blinding shall be done until the rock laterite bottoming has been inspected and approved by the Engineer's Representative. When completed the surface of the base course shall be smooth and even, free from irregularities or loose material and true to cross section, line and level as shown on the drawings. If any clay or mud appears to the surface of the foundation, the Contractor shall without additional charge dig out the affected areas of such depth as directed and make good the foundation and finish in conformity with the adjacent surface. SURFACING OF BASE COURSE 6210. The base course of the carriageway shall, where applicable, be provided with a prime coat and other surfacing as specified in the relevant clauses of this specification. The surfacing shall be laid as soon as possible after the construction of the base course. PREPARATION OF BASE COURSE TO RECEIVE BITUMEN PRIME COAT 6211. Immediately before spraying of the prime coat, the surface of the base course shall be swept clean, and all loose dust, dirt and the like removed. The Engineer’s Representative may also direct that any very smooth surface to which the surfacing is unlikely to adhere, be roughened with wire brushes or other approved means. If any weak areas are found they shall be cut out and refilled with base course material and rolled to correct cross-section and gradient. The surface shall be slightly damped before the application of the prime coat surface. (CLAUSE 6212 - 6214 INCLUSIVE NOT USED) TESTS TESTS FOR THE SECTION OF LATERITE SUBBASE COURSE AND BASE COURSE MATERIALS 6215 The following tests shall be carried out on all material proposed for use as subbase course and base course:- 1. Plasticity Test. 2. Grading Test. 3. Density/Moisture Content Compaction Test. 4. Laboratory C.B.R. Test. 149 These tests shall be carried out as described in Section I of this specification. TEST FOR CLASSIFICATION AND CONTROL OF COMPACTED LATERITIC SUBBASE COURSE AND BASE COURSE 6216. The tests listed below will normally require to be carried out for each 2 kilometres of subbase course and base course. The numbers and types of tests listed are, however, given only as a guide to the Contractor for tender purposes and the actual number and type of tests which will be carried out during the construction of the works will be entirely at the discretion of the Engineer's Representative: CLASSIFICATION TESTS 2 No. Liquid limit tests 2 No. Plastic limit tests 2 No. Sieve Analysis Test 4 No. West African Standard compaction tests, or 4 No. MOD A.A.S.H.T.O compaction. CONTROL TESTS 4 No. Laboratory C.B.R Tests at specified conditions 20 No. Insitu dry density tests per 2 km in an alternate manner, i.e. Right, Centre, Left, Centre, Right, etc. Except where otherwise stated to the contrary these tests shall be carried out as described in Section I of this specification or where no such description is given, in accordance with the appropriate B.S. The sieve analysis shall be carried out in accordance with the standards laid down in the report of the "Material Testing Conference, February 1963" A copy of which shall be made available to the Contractor on request. 6216A INTRODUCTION OF ISO CBR ISO CBR is introduced because of the known factors that our pavement elements i.e. subgrade, subbase and base courses are usually compacted at a higher moisture content than the plant optimum moisture content (OMC). The word ISO means equal. The procedure for establishing the control data with the working system is as follows: 1. BORROW PIT FOR FILL When borrow pit is approved for fill after passing all necessary tests, as carried out in the laboratory, three sets of moisture/density CBR tests shall be performed on the specimen using the following levels of compactive efforts: (a) Sub-B.S., (b) B.S. and (c) West African Standard. Each set of tests will have a minimum of five specimens. All specimen shall be soaked ideally for 48 hours, however the following soaking periods are recommended: for the southern part of the country 96 hours soaking whilst for the north 48 hours to 24 hours soaking. 150 NOTE:- For Sub - BS compaction, the following shall apply:- Use CBR mould, number of layers shall be three using 2.5kg rammer. Height of fall = 300mm, Number of blows per layer shall be 25. After determination of the dry density, moisture and CBR of each set of tests, relevant graph of density/moisture of each shall be plotted. Thereafter the values of CBR for compacted specimen so obtained shall be plotted as individual points on the compaction curve of each set of specimen using corresponding dry density points. Typical method of plotting ISO graph is shown in Fig. VI-1 while the completed specimen of an ISO-CBR graph is show in Fig. VI-1A. 2. SUBBASE AND BASE COURSE The above test will be performed on the materials approved for use as either subbase or base course using the following compactive efforts: B.S., WAS and Modified A.A.S.H.O. The results will be treated as above and relevant graphs with ISO CBR plotted. 3. USE OF ISO CBR FOR CONTROL In our present day control system we have no method of checking whether the compacted layer meets the specified CBR criteria, we are only concerned with 100% relative density and moisture content relative to the laboratory design moisture and invariably the laboratory determined OMC do not often tally with the plant OMC. We are aware that maximum CBR can only be obtained around OMC if this moisture is not achieved on site the strength of the pavement will be less than specified, if plant OMC is less than laboratory OMC: meaning that the section is compacted to a moisture over and above the plant OMC, thus producing a compacted pavement with weak strength. When the density and moisture of compacted layer is determined, same is plotted on the control graph and the field CBR is read from the ISO CBR line, this being the CBR value of the pavement. This is a surer way of ascertaining that both the density, moisture and required CBR are obtained on site. TRIAL SECTIONS OF LATERITE SUBBASE COURSE AND BASE COURSE 6217. The Contractor shall carry out trial sections with the proposed materials prior to the start of the main construction to determine the most efficient compaction, technique, layer thickness and suitability of the proposed materials and plants, as described in the relevant clause of this specification. See clause 1052A for a rolling test method. (CLAUSES 6218 - 6219 INCLUSIVE NOT USED) (11) SOIL CEMENT SPECIFICATION DESCRIPTION 6220. Soil cement shall consist of a course or courses composed of soil stabilized with portland cement. It shall be constructed on prepared and accepted subgrade, subbase or existing pavement in accordance with these specifications and in conformity with the lines, grades and typical cross sections as shown on the drawings and compacted to a specified finished thickness to the satisfaction of the Engineer. 151 FIGURE VI-1 152 FIGURE VI-1A 153 MATERIALS FOR SOIL CEMENT STABILIZATION 6221. The materials used for soil-cement stabilization shall comply with the following specifications:(A) CEMENT The cement used shall be ordinary portland cement and shall comply with B.S 12 or with the latest British standard specification for the cement specified, or NIS 11 of 1974 or NIS 15 1980. (B) WATER: The water shall be clean and free from harmful amounts of alkalis, acids or organic matter. No water shall be used for stabilization without the approval of the Engineer's Representative. The Contractor may be required to collect samples of water in an approved manner and to arrange for an analysis of the water by an approved testing agency. (C) SOIL: The soil shall be free from roots, vegetable matter or other deleterious substances. It shall be the nearest available approved material which when stabilized with 3% - 7% cement shall meet the design criteria specified in clause 6228 of this specification. APPROVAL 6222. Representative samples of all materials proposed for use in the soil-cement shall be submitted to the Engineer by the Contractor at the Contractor's expense. The Engineer will test the proposed materials and inform the Contractor if the tests indicate compliance with the specifications. No material shall be used until it has been approved by the Engineer. Permission to use any material shall not be construed as approval of its source nor any acceptance as continued acceptance. GENERAL METHOD OF SAMPLING MATERIALS 6223. All materials to be tested shall be selected according to the method laid down in the appropriate British Standard Specification and "Amended Decisions of Material Testing Conference" or where there is no such standard by a method to be mutually agreed between the Engineer and the Contractor. SAMPLING OF MATERIALS TO BE STABILIZED FROM BORROW PITS 6224. Trial pits in a proposed borrow pit area shall be dug from original ground level and not from the bottom of any existing borrow pits. Trial pits shall be at least 1.2 x 1.2 metres in size and dug to such a depth that the full extent of the material intended for incorporation in the works is exposed. Materials for testing shall not be taken from the spoil of the trial pit but shall be made up of increments taken from each face of the pit after the overburden soil has been removed. The four increments shall be mixed three times and quartered or riffled down to the size required for testing. SAMPLING OF MATERIALS FROM STOCKPILES 6225. The surface material of a stockpile shall be removed before sampling. At least twelve samples shall be taken from different parts of the stockpile and the resulting large sample shall be thoroughly mixed by hand before being quartered for testing. SAMPLES OF MATERIALS EXISTING MATERIAL 6226. Soil samples shall be taken by digging trenches across the full width of the proposed pavement to the depth of processing so that soil sampled shall be the soil that will be actually used ins oil-cement construction. TESTS FOR THE SELECTION OF SOIL TO BE STABILIZED 6227. The following tests shall be carried out on all materials proposed for soil-cement stabilization:(i) (ii) (iii) Liquid Limit Test Plasticity Test Grading Test 154 (iv) (v) (vi) Density/Moisture Content Compaction Test Laboratory C.B.R Test Unconfined Compression Test. The tests are to be performed in accordance with the relevant B.S as modified by the latest "amended decisions of Materials Testing Conference". DESIGN CRITERIA 6228. The stabilized soil shall meet the following specification for C.B.R test results. The specimens shall be cured with a wax cover for 6 days and soaked for 24 hours before testing, after allowing the specimen to drain for 15 minutes. TABLE VI-5 DESIGN CBR VALUES FOR SOIL CEMENT MIX-IN-PLACE OR PLANT MIX METHOD OF CONSTRUCTION DESCRIPTION OF TEST LABORATORY TEST ON MATERIAL MIXED IN THE LABORATORY MIX-IN-PLACE PLANT MIX 180% 160% 100% 100% 80% 80% LABORATORY CONTROL TEST ON MATERIAL MIXED EACH DAY IN THE FIELD OR ON CORED SPECIMENS FROM COMPLETE SOIL-CEMENT PAVEMENT (AVERAGE) LABORATORY CONTROL TEST ON MATERIAL MIXED IN THE FIELD OR ON CORED SPECIMENS FROM COMPLETED SOIL-CEMENT PAVEMENT (MINIMUM) PROCEDURE FOR ESTIMATION OF CEMENT CONTENT 6229 (A) Classify the soil according to U.S public road Administration system (B) The estimated range of cement content is determined using the A.A.S.H.O soil group (shown in table VI-6 below) (C) Material requiring high cement content should be rejected as unsuitable. (D) Perform B.S. compaction on the material to establish M.D.D and O.M.C using the middle cement content e.g. (4.5)% cement for A-2 as shown in table VI-6 etc.. The C.B.R and U.C.S specimens shall be moulded to this density and moisture content. (E) Establish the relationship between cement content vs C.B.R. and U.C.S (unconfined compression shear) for soaked and unsoaked specimens. (i) Moulding 3 C.B.R specimens and 6 U.C.S. at each cement content, with a minimum of three cement contents. e.g. for A-2 3%, 4.5% and 6%. (ii) Wax and cure all specimens for 6 days (Except 3 U.C.S specimens at each cement content which should be cured for 7 days and tested without soaking). 155 (iii) Testing all C.B.R Specimen and the 3 U.C.S specimens at each cement content after 24 hours soaking by complete immersion in water and allowed to drain for 15 minutes. (iv) Plot graphs of Cement contents vs C.B.R. (soaked). Cement contents vs U.C.S.(soaked and unsoaked). Establish the required cement content at 180% C.B.R for site mix or 160% for plant mix and the corresponding U.C.S. values soaked and unsoaked for quality control in the field. TABLE VI-6 MODIFIED CEMENT CONTENT REQUIREMENTS OF A.A.S.H.O. SOIL GROUPS AASHO SOIL GROUP USUAL RANGE IN CEMENT REQUIREMENT PERCENT BY WEIGHT OF SOIL AMENDED CEMENT CONTENT BY WEIGHT OF DRY SOIL ESTIMATED PERCENT OF CEMENT USED IN MOISTURE DENSITY DETERMINATION BY WEIGHT OF DRY SOIL PERCENTAGE CEMENT CONTENT BY WEIGHT OF DRY SOIL FOR MOULDED SPECIMEN A-1-4 4-6 2-4 3.0 2-3-4 A-1-B 4-7 2-5 3.5 2-3.5-5 A-2 5-8 3-6 4.5 2-4.5-6 A-3 6-9 4-7 5.5 4-5-6 A-4 7-11 5-9 7.0 5-7-9 A-5 8-12 6-10 8.0 6-8-10 A-6 9-13 7-11 9.0 6-9-12 A-7 10-14 8-12 10.0 8-10-12 Note: practicable. CONSTRUCTION Heavy clay soils ranging from A-5 to A-7 should be avoided where 6230. The Contractor shall submit to the Engineer for approval his method of stabilization which may be based on either the mix-in place or plant mix principle. Whichever method of mixing is used the maximum period between mixing of the cement and final roll off of stabilized material shall be 2 hours. The lengths of the treated sections shall be regulated to ensure that the 2 hours time limit is not exceed. MULTIPASS-MIXIN-PLACE METHOD 6231. (A) Level pegs shall be set at 30 metres intervals and the base course material to be stabilized imported from borrow pits, spread and shaped to the required cross-section and longitudinal gradient. It may be necessary to compact the base course material to obtain a fair estimate to correct grade and cross-section. If the material of the existing roadbed is to be used the surface shall be graded to required cross-section and longitudinal gradient. The 156 cross-section and grade shall be checked by the Engineer's Representative before construction starts. (B) The material to be treated shall be scarified to the required depth and thoroughly pulverized (including pre-wetting the soil if necessary to aid pulverization). Precaution shall be taken to obtain a uniform condition of the material for the full depth and width to be treated. A pulverization of 80% (i.e. ratio of the weight of soil mixture passing the 5mm sieve to the weight of the total representative sample taken exclusive of the gravel retained on the 5mm sieve shall be achieved before the cement is spread. (C) Cement shall be spread uniformly over the pulverised soil. Cement may be supplied in bags or in bulk. If bags of cement are used, the bags shall be placed at calculated intervals along the verge, the bags opened and the cement spread evenly on the pulverized soil by shovels and rakes. If the cement is supplied in bulk, it shall be spread by an approved mechanical cement spreader and each batch in the spreading equipment shall be weighed so that the average rate of spread can be determined by the Engineer. The rate of spread per linear metre shall not vary more than 10% from the approved rate. (D) Wet Mixing is preferred to avoid (i) Loss of cement due to formation of clouds of cement dust during dry mixing (ii) evaporation Loss of time in excessive adjustment of moisture content due to rapid (iii) Variation in cement content due to segregation caused by prolonged mixing. The road mixing plant shall have provision for introducing water at the time of mixing, through a metering device or by other approved method. The water shall be applied by means of controls that will supply the correct quantity of water to produce a complete mixture with a uniform moisture content. Leakage of water from equipment will not be permitted and care shall be exercised to avoid the addition of an excessive amount of water. TRAVELLING MIXING MACHINE 6232. The procedure for construction with either mixing plant shall be as directed by the Engineer. COMPACTION 6233. Compaction shall commence as soon as an intimate mixture has been obtained and the specified degree of pulverization has been achieved. It is essential that the moisture content at the time of rolling shall be at the optimum of the compaction plant in use. GENERAL REQUIREMENT FOR PLANT MIX PROCESS 6234. windrout type or flat-type travelling The mixing equipment shall be batch type mixing plant using revolving blade, or rotating drum mixers or continuous type at the option of the Contractor. The soil, water and cement may be proportioned either by weight or by volume. In all plants cement shall be added in such a manner that it is uniformly distributed throughout the soil during the mixing operation; the charge in a batch mixer, or the rate of feed to a continuous mixer, shall not exceed that which will permit complete mixing of the 157 material. Dead areas in the mixer, in which the material does not move or is not sufficiently agitated shall be corrected either by a reduction in the volume of material or by other adjustments. The weights or rates of feeds of soil and water shall be within 5% of the amount specified by the Engineer and the weights or rates of feed of cement shall be such that the cement content in samples taken from any part of a mixed batch or from different batches or from time to time from the product of continuous mixers or from mixtures spread on the roadbed, shall not vary more than 0.4% above or below the designed cement content by weight of dry soil. BATCH MIXING 6235. The mixer shall be equipped with a sufficient number of paddles of a type and arrangement to produce a uniformly mixed batch. The mixer platform shall be of ample size to provide safe and convenient access to the mixer and other equipment. Mixer and batch box housing shall be provided with hinged gates of ample size to permit ready sampling from each of the plant bins and of the mixture from each end of the mixer. The mixer shall be equipped with a timing device which will indicate by a definite audible or visual signal the expiration of the mixing period. The device shall be accurate to within 2 seconds. The plant shall be equipped with a suitable automatic device for counting the number of batches. The time of mixing a batch shall begin after all ingredients are in the mixer and shall end when the mixer is half emptied. Mixing shall continue until a homogeneous mixture of uniformly distributed cement is produced. In general the time of mixing shall not be less than 30 seconds, except that the time may be reduced when tests indicates that the requirement for the variation of cement content (±.4%) is being consistency compiled with. WEIGHT PROPORTIONING 6236. When weight proportioning is used the discharge gate on the weight box shall be so arranged as to blend the different sizes of the soil as they enter the mixer. Cement shall be weighed on scales, separate and distinct from the soil batching scales. VOLUMETRIC PROPORTIONING 6237. Where volumetric proportioning is used for batch mixing, the volumetric proportioning device for the soil shall be equipped with separate bins, adjustable in size, for the various sizes of soil. Each bin shall have an accurately controlled gate or other device so designed that each bin shall be completely filled and accurately struck-off in measuring the volume of soil to be used in the mix. Means shall be provided for accurately calibrating the amount of material in each measuring bin. CONTINUOUS MIXING 6238. In addition to the General requirements as provided in section 15, continuous mixing of the material shall conform to the following requirements. The correct proportions of each soil size introduced into the mixer shall be drawn in from storage bins by a continuous feeder, which will supply the correct amount of aggregate in proportion to the cement, and so arranged that the proportion of each soil size can be separately adjusted. The bins shall be equipped with a vibrating unit which will effectively vibrate the side walls of the bins to prevent any "HANG UP" of material while the plant is operating. A positive signal system shall be provided to indicate the level of the material in each bin and as the level of the material in any one bin approaches the strike-off capacity of the feed gate, the device will automatically close down the plant instantly. The plant shall not be permitted to operate unless this automatic signal system is in good working order. The drive shaft on the soil feeder shall be equipped with a revolution counter reading to 1/100 of a revolution and of sufficient capacity to register the total number of revolutions 158 in a day's run. The continuous feeder for the soil may be mechanically or electrically driven. The continuous mixing plant shall be equipped with a hopper of at least 0.6 cubic metre capacity which is divided into as many compartments as there are sizes of soil being proportioned. The hopper shall be suspended under the soil feeders on a scale frame in such a manner that the discharge from each soil feeder may be diverted into separate compartments in the hopper when the feeders are in full operation. The weight of a loaded hopper shall be indicated on a springless dial scale of 2,278 kilograms maximum capacity with 2 kilogram graduations. Each compartment of the hopper shall be equipped with a gate so that each size may be withdrawn separately on a conveyor below the hopper in order that the total weight of each size of soil may be determined and representative samples obtained. The material so over withdrawn may be returned to storage. SPREADING 6239. Side forms shall be set to the lines and grade as shown on the drawings. Forms shall be of steel or stout timber and shall be of sufficient strength to resist springing out of shape during placing of soil cement. The mixed material shall be protected by covers against moisture loss while being transported to the spreading site and each layer shall be spread in one operation without segregation (not more than 30 minutes shall elapse between mixing and spreading). Immediately prior to spreading, the area to be covered shall be moistened and kept moist, but not excessively wet. The mixture shall be simultaneously deposited and spread with a self-propelled mechanical spreader ready for compaction without further shaping. The spreader shall be provided with a screed that strikes-off and distributes the material to the required width and thickness within 5% of the pre-determined rate. The screed shall be adjustable to the required cross section. Screed action includes any cutting, crowding, or other practical motion that produces a finished texture of uniform appearance. If the spreader leaves ridges, indentations or other objectionable marks in the surface that cannot be eliminated by rolling, or prevented by adjustments in operation, its use shall be discontinued. The use of motor grades, except for final trimming after compaction, will not be permitted. The mixed material shall be spread for the full planned width, either by one spreader or by several spreaders operating in a staggered pattern across the subgrade or subbase course, unless otherwise permitted by the Engineer or if traffic conditions require part width construction. Should permission be granted or part width construction be required, for the use of one spreader operating alternately on continuous lanes, not more than 30 minutes shall elapse between the time of placing material in adjacent lanes at any location. If longitudinal construction joints are necessary they shall fall on lane lines. Where the required compacted thickness is 150mm or less, the soil cement may be spread and compacted in one layer. Where the compacted thickness is more than 150mm the 159 soil cement shall be spread and compacted in 2 layers of approximately equal thickness and the maximum compacted thickness of any one layer shall not exceed 150mm or as directed. Work on each layer shall be performed in a similar manner and the surface of the compacted material shall be kept moist or prevented from drying out by a method approved by the Engineer until covered with the next layer, either by using damp sand or sacks. Soil cement base course placed in inaccessible areas may be spread by approved methods in one course. After spreading the material shall be thoroughly compacted to the required lines and grades by means of pneumatic tampers or with other compacting equipment which consistently obtains equal or better compaction than that specified. Soilcement shall not be mixed or placed during rain. COMPACTION 6240. (A) All rolling equipment shall be self-propelled and reversible and shall produce the required compaction within the operation time. e.g. from mixing, wetting, spreading and compaction. (B) Initial rolling may be performed with smooth wheel steel-tyred rollers weighing not less than 10,886 kilograms with a compression on the rear wheels of not less than 58 kilograms of the tyre width, or with other compacting equipment which consistently obtain equal or better compaction than that specified. Pneumatic tyred rollers shall be the oscillating type and having a width of not less than 1.2 metres and equipped with pneumatic tyres of equal size and diameter. Wobble wheel rollers will not be permitted. The tyres shall be inflated to 6.3 kg per sq. cm. or such lower pressure as the Engineer may direct and maintained so that the air pressure will not vary more than 0.35 kg per sq. cm. from the designated pressure. Pneumatic-tyred rollers shall be so constructed that the total weight of the roller can be varied to produce an operating weight per tyre of not less than 907 kilograms. The total operation weight of the roller shall be varied as directed by the Engineer. (C) Rolling tests shall be carried out to establish the plant maximum dry density (MDD) its optimum moisture content (OMC) and the number of economic passes to achieve the MDD see Table I-4 for guidance on performance of different plants relating to MDD, and OMC of different types of soil. (D) Rolling shall be performed in such a manner that bumps and irregularities are eliminated and the finished surface shall be true to the required grade and cross section within the tolerances specified. Rolling shall commence from the outer edge of the verge to the centre of the roadway except on super-elevated curves where rolling shall begin on the low side and progress to the high side. (E) Areas inaccessible to rollers shall be compacted to the specified density by other means, approved by the Engineer. (F) All compaction planes shall be removed. The finished surface shall be smooth, dense and free of ridges or cracks. The surface shall be kept moist at all times until the curing seal is applied. FINISHINGS 6241. The finished surface shall not deviate at any point in a longitudinal direction by more than 5mm from 3 metre straight edge laid in any position on the finished surface parallel to 160 the centre line. The transverse profile shall conform to the same accuracy when tested using a correctly shaped template. The thickness shall not vary more than ± 12mm from the design thickness of base at any point. If the finished surface exceeds the above tolerance, the excess material shall be trimmed with the least possible disturbance of the material to remain in place. The excess material shall be removed and disposed of immediately after trimming and no loose material shall be left on the base and the area shall be rolled again. Filling low spots in the cement treated base will not be permitted. CONSTRUCTION JOINTS 6242. (A) TRANSVERSE JOINTS At the end of each day's work or first thing in the morning a transverse vertical construction joint shall be formed by cutting back 600mm into the compacted soil-cement, and disposing of the material. Additional mixture shall not be placed until the construction joint is placed. When starting the work the 900mm section adjacent to the joint shall be thoroughly hand mixed. (B) Longitudinal joints shall be constructed by cutting back vertically into the existing stabilized material for approximately 75mm and the material cut away may be disposed of in the adjacent lane to be constructed. The face of the cut joints shall be moistened in advance of constructing the adjacent section. CURING 6243. The completed soil-cement shall be cured by either damp sand cover or bituminous curing seal as directed by the Engineer. (A) DAMP SAND Immediately after compaction the soil cement shall be cured for a period of 7 days by a 50mm layer of damp sand spread evenly over the surface. The Contractor shall keep the sand damp and shall close the stabilized soil to all traffic during the curing period. (B) BITUMINOUS CURING SEAL The curing seal shall consist of liquid bitumen MC-O, or MC-1 unless otherwise specified. The curing seal shall be applied at a rate between 0.68 - 1.13 litres per square meter of surface and shall provide a continuous membrane over the soil-cement pavement. The curing seal shall be applied as soon as possible, but not later than 8 hours after the completion of final rolling. The surface shall be kept moist until the seal is applied. No traffic or equipment shall be permitted on the sealed base during the first 6 days after the application of the curing seal, unless otherwise permitted by the Engineer. FIELD CONTROL TESTS 6244. In order to ensure adequate cement content, proper moisture content, adequate compaction, adequate pulverization, intimate mixing and adequate strength, the following field quality control tests shall be carried out during construction. (I) MOISTURE CONTROL TEST In each stretch, the moisture content shall be checked and adjusted to optimum moisture content of the plant in use before compaction commences. "Speedy" 161 moisture tester of any type may be approved by the Engineer for use, the speedy tester should be calibrated first before being put into use (for calibrating procedure see clause 2003(6)). (II) TEST FOR ADEQUATE PULVERIZATION Before the addition of cement 80% pulverization shall be achieved and this shall be checked for each stretch. For procedure see Clause 6231 (B). (III ) TEST FOR INTIMATE MIXING Intimate mixing shall be checked by examining the colour of exposed material from a series of holes to the full depth of mixed soil-cement made at regular intervals. Uniform colour of the exposed material indicates thorough mixing. (IV) STRENGTH Samples of mixed soil-cement shall be taken in the field prior to compaction. The samples shall be compacted into CBR and/or UCS mould to B.S. or field density and sealed with wax. In particular UCS specimens shall be statically compacted, to the same densities as those of field compacted CBR specimens. The specimens shall be cured in the laboratory and tested after 7 days ( 6 days curing and 24 hours soaking). The frequency of these tests shall be one test for every 400 square metres and part thereof of material laid in each layer. (V) IN SITU DRY DENSITY TESTS These tests shall be carried out immediately upon the completion of compaction of each section. At lease one dry density test shall be carried out for each 350 square metres of material laid in each layer, using the sand bottle or other in-situ density testing equipment or the nuclear gauge testing equipment approved by the Engineer. These tests may be located where samples for CBR and/or UCS have been taken. (VI) THICKNESS OF PROCESSED LAYER The thickness of the Soil-cement layer shall be measured using the in-situ dry density holes, the thickness of cored specimens from hardened soil-cement and any additional holes at the discretion of the Engineer. (VII) DETERMINATION OF CEMENT CONTENT The Contractor shall provide the necessary equipment and reagents to enable cement extraction tests to be carried out by the Engineer. For procedure refer to B.S 1924 (1975) test No 6. (VIII) CBR & UCS TESTS ON CORED SPECIMENS CBR and UCS tests shall be carried out on cored specimens taken from hardened soil-cement. The frequency of these tests shall be at least one test for each 400 square metres and part thereof of material laid in each layer. Sampling shall be in staggered pattern. 162 TEST RECORDS 6245. The results of all the tests mentioned in this section of the specification shall be carefully recorded in a manner approved by the Engineer. The test results shall be recorded in triplicate, one copy to be retained by the Contractor and the other two copies to be handed to the Engineer's Representative. ADDITIONAL CONSTRUCTION RECORDS 6246. In addition to these records required under the provision of clause 6245, above the Contractor shall keep a record for each individual section of soil-cement construction giving the following details:(I) Location, length and width of the section, (II) In situ moisture content on scarification, (III) Moisture content prior to addition of cement, (IV) No. of bags of cement used. (V) Time the cement was spread. (VI) Complete mixing time. (VII) Moisture content prior to compaction. (VIII) Compaction and Grading time. (IX) Total operation time from cement spreading to completion of compaction. (X) Location of borrow pit used. This record shall be prepared in triplicate, one copy to be retained by the Contractor and two copies to be handed to the Engineer's Representative. SUPERVISION 6247. The attention of the Contractor is drawn to the fact that he must provide adequate experienced supervisory staff during all the stages of soil-cement construction. (CLAUSE 6248 - 6249 INCLUSIVE NOT USED) (III) CRUSHED STONE GENERAL 6250. In addition to any other clause of this specification the following shall be deemed to apply in particular to crushed stoned base course, and shall be read in conjunction with all other relevant clauses of the conditions of contract and this specification. MATERIALS 6251. MATERIALS FOR CRUSHED STONE BASE COURSE Base course aggregate shall consist of crushed Stone. (A) PHYSICAL PROPERTIES OF AGGREGATE Materials for use as Stone base shall be classified under two categories i.e. Coarse aggregate and Fine aggregate. 1. COARSE AGGREGATE: 163 Coarse aggregate shall be granite crushed stone sourced from approved Quarry by the Engineer's Representative and shall have sizes ranging from 50mm and retained on 5mm sieve. The aggregate shall be free from clay or silty materials, and when subjected to 10% fine test or aggregate crushing value, the value of the results shall range from 7.5% to 12.5% for 10% fine and not more than 35% for aggregate crushing value. It shall also comply with other requirements under clause 2005 (1) and (2) (2) FINE AGGREGATE Fine aggregate known as binder materials shall be materials passing sieve 5mm and retained on 75 m sieve. It may be sourced from river bed at location approved by the Engineer's Representative or be fines from crushed stone. It shall be free from vegetation or other objectionable matter. Fine aggregate shall be clean without any clay content, strong and sharp. It shall be of such grading characteristic that when combined with coarse aggregate, the composite material shall conform to the gradation and other requirements specified in clause 2004 (1-3). (3) Liquid limit and Plasticity Index requirements stated herein shall apply to any aggregate component that is blended to meet the require gradation and also to the aggregate in the compacted base course. The portion of fine aggregate passing the 75 m sieve shall be either non-plastic or shall have a liquid Limit not greater than 30% and Plasticity Index not greater than 6. This index test will only be applicable to materials for wet laying. (4) COMBINATION PROCEDURE. It is easier to handle gradation size by use of two categories of materials:- Firstly, grade the gradation aggregate and plot on the stone base design envelope, next, grade the fine aggregate and plot in the design envelope. By simple proportion and physical examination of the two graphs, guided by experience ,two to three combination trials may produce the required satisfactory grading that will fall into the envelope, otherwise simple calculation may be used to achieve the required combination proportion. NOTE: Once an acceptable combination is produced, frequent grading checks on both specimens must be carried out to insure that deviation in gradation is not allowed to occur. The results of such grading test will enable adjustment to be made on the combination proportion. (5) COMBINATION OF DIFFERENT SIZES OF AGGREGATE. Coarse aggregate of different sizes and the fine aggregate shall be placed in different Bins. Each aggregate sizes and the fines shall be sieved and plotted on appropriate log chart. Simple arithmetic calculation may be used to determine the combination proportion. Alternatively, careful study of the graphs, coupled with experience will enable user to guess the proportion by trial and error. Once a suitable mix proportion is established, the grading of each size of aggregate shall be checked from time to time, to ensure that there is no deviation or variation. (6) ESTABLISHING MIX CONTROL CRITERIA. 164 When a mix proportion has been established, representative sample of each material shall be combined and quartered to make six number of CBR mould specimens, moisturized to 5% of dry weight of sample and kept in air tight* container for 18 hours. Before the samples are compacted the moisture shall be checked using calibrated SPEEDY TESTER. If the moisture is lower than 5% more water to attain this moisture shall be added. When the material is mixed thoroughly it shall be compacted using Modified AASHO compactive effort or using a vibrating kango hammer. Whichever compactive effort is used, (not B.S.) it shall be in five layers and the thickness of compacted specimen shall not be less than 125mm or more that 130mm, otherwise it shall be discarded. The loose material on the specimen after compaction shall be removed carefully, and with a straight edge placed across the mould, in a minimum of two directions, the depth of the compacted specimen surface from the top shall be determined in three places along each direction of the straight edge. The mean of six readings shall be used to determine the depth of the specimen and thereafter its volume. Unless directed to the contrary the six specimens will be tested for Dry Density only. Alternatively 3 specimens may be soaked for 24 hours (complete immersion in water with 25mm water head above the specimen) tested for CBR after the specimen is allowed to drain for 15 minutes. The remaining specimens shall be tested for CBR (strength) unsoaked. The average of two close results shall be the CBR or Dry Density of the specimen. If CBR of over 100% is obtained the dry density established with corresponding moisture content shall be the design criteria and control for the works. GRADING OF CRUSHED STONE 6252. The grading of crushed stone for use in crushed stone base course shall be as follows:(I) DRY PROCESS (A) 75mm to 12mm or 50mm - 12mm hereinafter referred to as coarse stone. (B) 12mm to dust hereinafter referred to as screening. (II) WET PROCESS Gradation: The composite mixture of coarse aggregate and binder material, processed as hereinafter specified shall conform to one of the applicable gradations shown in Table VI-7 and shall not vary from the low limit on one sieve to the high limit on adjacent sieve or vice versa, but shall be uniformly graded from coarse to fine. Gradation requirement specified herein shall apply to the completed base course after undergoing the mixing, placing, compacting and other operations. The portion of the aggregate passing No 75 m sieve shall not be greater than one-third of the portion passing the No. 425 m sieve. The aggregates shall continuously be well graded within the limits of Gradation A, B. C, D or E as specified below. The methods of test used will be ASTM Standards C117, C127, C128, C136 and D422. Sieves shall conform to ASTM Standard E.11 or B. S. sieve. TABLE VI-7 GRADING ENVELOPE FOR STONE BASE COURSE WET METHOD SIEVE DESIGNA TION PERCENTAGE BY WEIGHT PASSING SQUARE MESH SIEVE 165 GRADING A GRADING B GRADING C GRADING D OPENING GRADING E 75mm 100 100 100 100 50mm 100 50mm 85 -100 85 -100 90 - 100 90 - 100 37.5mm 95 - 100 25mm 60 - 95 65 - 95 75 - 100 80 - 100 20mm 60 - 80 10mm 30 - 65 40 - 75 50 - 85 60 - 100 10mm 40 - 60 5mm 25 - 55 30 - 60 35 - 65 50 - 85 5mm 25 - 40 2mm 15 - 40 20 - 45 25 - 50 40 - 70 2.36mm 15 - 30 425m 8- 20 13 - 30 15 - 30 25 - 45 600m 8 - 22 75m 2-8 5 - 10 5 - 10 5 - 15 75m 6 - 12 Note:The table is based on aggregate of uniform specific gravity, and the percentages passing the various sieves may require appropriate correction by the Engineer when aggregates of varying specific gravities are used. WORKMANSHIP PREPARATION OF SUBGRADE 6253. The subgrade shall be prepared and compacted in accordance with terms as contained in Section VI Clause 6161 of this specification. Note:- No subgrade shall be considered as a working platform for the stone base as this will promote the early collapse of the pavement. This is due to the fact that the elastic property of the subgrade (of which strain is a part) will not be able to sustain the wheel load from the crushed stone base to the subgrade without any intermediate superior layer. Where the subgrade or subbase is formed of material liable to be forced up into the crushed stone during compacting operations, the Engineer's Representative may direct that a 50mm thick blanket layer of approved material shall be superimposed upon the subgrade prior to the laying of crushed stone. See clause 6133. FORMS 6254 Where kerb or concrete haunches are not specified, the Contractor shall ensure that the edges of crushed stone base course, laid by either the wet or dry process, are true to line and level and properly compacted to the same standard as the test of the Base course by the use of forms, hunching stones or other methods approved by the Engineer's Representative. CRUSHED STONE TO 6255. Crushed stone Base course laid by either the wet or dry method shall be laid in layers BE LAID AND of not less than 150mm compacted thickness to the satisfaction of the Engineer’s COMPACTED IN Representative. LAYERS LAYING AND 6256. When crushed stone Base-course is to be laid by the dry process the method of laying COMPACTING and compacting shall be as follows:CRUSHED STONE DRY PROCESS (I) The coarse stone 75mm to 12mm or 50mm to 12mm shall be spread in a manner approved by the Engineer's Representative to an even depth which, after compaction will produce the specified thickness of layer. 166 (II) The coarse stone shall then be regulated and compacted by not less than three passes of an approved roller. (III) Successive uniform layers of screening 12mm to dust shall then be applied over the surface and shall be vibrated into the interstices of the coarse stone by means of an approved vibrating plate compactor or other approved means. Screenings may be spread by hand shovel using a sweeping motion or by approved tailboard spreaders attached to lorries. In no case shall screenings be dumped on the surface in piles and spread therefrom. Great care shall be taken to ensure that screenings are not applied either so quickly or so thickly as to "CAKE" or bridge on the surface in a manner which prevents the filling of the interstices or causes the vibrating or compacting equipment from bearing directly on the coarse stone. The addition of screenings and vibrating into the interstices of the coarse stone shall continue until all the voids are filled in. (IV) The surface of the crushed stone shall then be checked transversely and longitudinally for level and camber and any indicated variations adjusted. The surface shall then be sprinkled with water from a water bowser and rolled with a smooth wheel roller having a weight of roll of not less than 58 kilograms per centimetre. Voids in the Base-course which occur during this process shall be filled by sweeping screenings into them. The sprinkling, sweeping and rolling shall continue until all voids are filled with grout to the satisfaction of the Engineer's Representative. (v) The final surface shall be smooth and even, free from irregularities or loose material and true to line and level having regard to the tolerances for base course finish specified elsewhere herein. CRUSHED STONE BASE COURSE LAID BY THE WET PROCESS 6257. When crushed stone Base course is to be laid by the dry or wet process the method of laying and compaction shall be as follows:(I) The approved crushed stoned, graded as specified shall be mixed with between 3% and 5% of water as directed in a mixer of a type approved by the Engineer's Representative. (II) The mixed material shall be protected from the rays of the sun during transit from the mixer to the site in order to prevent loss of moisture due to evaporation and shall be laid by a self-propelled asphalt finisher or other approved plant in layers of not less than 75mm or more than 150mm thickness after compaction. During this operation care shall be taken to avoid segregation. (III) Water can only be added to any wet laid stone base if it was discovered that evaporation had taken place during rolling. The finished rolled stone base shall not have moisture less than 3% or more than 5% by weight of dry aggregate. Should any patchiness appear during compaction, areas deficient in fines shall be blinded with screenings watered and rolled and areas showing an excess of fines shall be removed and reconstructed with graded material to the satisfaction of the Engineer's Representative. 167 (IV) The final surface shall be smooth and even free from irregularities or loose material, and true to line and level having regard to the tolerances for Base-course finish specified elsewhere herein. PREPARATION OF CRUSHED STONE BASE COURSE TO RECEIVE BITUMINOUS SURFACING 6258 Crushed stone Base course, laid by either the dry or wet process shall be prepared for the addition of bituminous surfacing as specified under the relevant parts of this section of the specification. COMPACTION 6259. Compaction of crushed stone Base course shall be to the satisfaction of the Engineer's Representative. (IV) GENERAL CONCRETE CARRIAGEWAY CONSTRUCTION 6260. In addition to any other clauses of this specification the following shall be deemed to apply in particular to concrete carriageway construction. And shall be read in conjunction with all other relevant clauses of the conditions of contract and this specification. MATERIALS CEMENT 6261. Cement to be used in the construction of concrete carriageways shall comply in all respects with the requirements of all relevant clauses of this specification regarding cement for use in concrete work. AGGREGATE 6262. Fine and course aggregate for use in the manufacture of concrete for construction of concrete carriageways shall comply with the requirements of all relevant clauses of this specification regarding aggregates for use in concrete work. REINFORCING STEEL 6263. Steel reinforcement for use in the construction of concrete carriageways shall, where used, comply with the requirement of all relevant clauses of this specification regarding M.S. reinforced concrete work. DOWEL BARS AND TIE BARS 6264. Dowel bars and tie bars shall consist of mild steel complying with the requirements of British Standard 15, free from oil, paint, dirt and loose rust. Dowel bars for transverse joints shall be straight, free from burred edges or other irregularities and shall have their sliding ends sawn, not sheared, unless otherwise approved by the Engineer. The length and diameter of dowel bars and tie bars shall be as shown on the drawings or directed by the Engineer. SIDE FORMS 6265. Side Forms shall be of steel and of a design to be approved by the Engineer. Curved forms of appropriate radius shall be used for all curves of 30 metres radius or less. The width of the form shall be not less than the pavement thickness, up to a maximum of 250mm and flange branches shall extend outward on the base not less than two-thirds the height of the form. All forms shall be free from warp, twists and kinks, and where the top surface of the forms determines the finished level of the concrete, it shall be accurate in manufacture to within a tolerance of ± 2mm in 3 metres measured in a vertical plane. Repaired forms shall not be used until inspected and approved by the Engineer's Representative. Forms to support rails on which the machine is to run shall be sufficiently robust to support the weight of all plant running on them without deformation. 168 RAILS FOR MACHINE FINISHED CONCRETE CARRIAGEWAYS 6266. Rails shall be of steel and of approved design enabling them to be properly supported on the side forms or on other approved mountings. All rails shall be sufficiently robust to support the weight of all plant running on them without deformation. They shall-be free from warp, twists and kinks and accurate in manufacture to within a tolerance of ± 2mm in 3 metres measured in a vertical plane. PREFORMED FILLER JOINT 6267. Preformed joint filler shall be of the thickness shown on the drawings or directed by the Engineer within a tolerance of ± 2mm. It shall be 25mm less in depth than the thickness of the slab, within a tolerance of ± 3mm and of the full width between road forms. Holes to accommodate dowel bars shall be accurately bored or punched out. The material comprising joint filler shall be of approved quality, such that the filler can be satisfactorily installed in position at the joint. JOINT PRIMER 6268. Joint priming compound shall consist of a suitable bitumen based compound approved by the Engineer. JOINT SEALING COMPOUND 6269. Poured joint sealing material shall consist of an approved rubber-bitumen compound, complying with the requirements of British Standard 2499: test to assess the properties of hot applied joint sealing compounds for concrete pavements, and shall be grade-1. Class B or C. The joint sealing compound shall have the following qualities: (a) Capable of adhering to concrete under all weather conditions. (b) It should be ductile particularly in fairly cold weather as to cover the widening of joint without cracking, and be able to withstand the continuous cycle of expansion and contraction for a long time without a break up or disintegration. (c) It must be durable etc. WORKMANSHIP GENERAL 6270. Concrete carriageways shall be constructed in one or more slab widths as indicated in the drawings. Where a concrete carriageway is constructed more than one slab wide, the first slab or alternate slabs shall be constructed between two forms and the adjacent or intermediate slabs shall be constructed by replacing the flanged wheels on one or both sides of the machine with flangeless wheels, which can travel on the surface of the concrete already completed, or on rails fixed to longitudinal timber laid on the completed concrete to support the flanged wheels. Concrete slabs shall be at least ten days old before they are subjected to the weight of the finishing machine, but, in suitable weather, the Engineer's Representative may permit a shorter period provided that adequate provision is made for protecting the surface of the slab on which the wheels of the finishing machine run and provided that the wheels do not run nearer to the edge of the slab than 150mm and provided further that the Contractor gives an undertaking in writing to be fully responsible for any damage that may occur and to repair same at his own expense to the satisfaction of the Engineer's Representative. THICKNESS OF SLAB 6271. The thickness at any point shall be not more than 6mm thinner nor more than 12mm thicker than that shown on the drawings. 169 CONCRETE DISTRIBUTOR 6272. Unless hand spreading has been sanctioned in writing by the Engineer's Representative, all concrete to be compacted by finishing machines shall be distributed with a hopper type spreader of approved design. Where vibratory screeds instead of finishing machines are used for compaction the arrangements for placing concrete shall be to the approval of the Engineer. Spreaders shall be capable of striking off concrete at the correct level for the placing of reinforcement and for producing a uniform surface. To minimize pre-compaction, hand spreading will be permitted only where the concrete is deposited in loads each not exceeding one cubic metre size, and from height not exceeding 750mm. COMPACTING AND 6273. Compacting and finishing machines shall be approved by the Engineer and shall FINISHING MACHINE compact and finish the concrete either by the action of vibration or by mechanical tamping. The machine shall in addition have a strike-off blade or paddle-roller to control the surcharge and a rear transverse oscillating screed. WATERPROOF UNDERLAY 6274. Where shown on the drawings or directed by the Engineer's Representative, waterproof paper as specified or other approved underlay, shall be used and where more than one sheet is used for the construction of any one slab the overlaps shall be at least 150mm. The waterproof underlay must not be torn or damaged, and water shall not be allowed to collect upon it before the concrete is laid. SETTING, CHECKING AND STRIKING OF SIDE FORMS 6275. ALL SIDE FORMS SHALL:(I) Be so supported that they remain rigid at all times. They shall be set in position at least 20 hours before concrete is placed between them unless the Engineer's Representative agrees to a shorter period. Forms shall be cleaned and oiled each time before they are used. (II) Be bedded on a layer, about 50mm thick and for only the width of the form base, of cement mortar or concrete of the same grade as the slab on a firm foundation so as to ensure the necessary complete rigidity and stability. The base on the line of the forms shall be thoroughly compacted before the forms are set. (III) Be as specified in Clause 6265 set to line and level and secured by using not less than three pins for each 3 metres section, one pin being placed at each side of every joint or as otherwise approved by the Engineer's Representative. Form sections shall be tightly joined together by a locked joint free from play or movement in any direction, so as to prevent the extrusion of concrete. For machine laid concrete the form joints shall be made without any discontinuity in the top surface of the forms and the levels at the joints between the forms shall, where form and rail are not integral, be set within a tolerance of ± 3mm of the levels shown on the drawings. The wheels of finishing machines shall not be run directly on the top surface of the side forms but on rails as indicated in clause 6266 or on the finished concrete as provided in clause 6270. For concrete to be compacted by vibrating screeds the setting of the forms shall be such as to provide the accuracy of finish specified in the relevant clauses of this specification. 170 If corrections are necessary as a result of checking for conformity with the alignments and levels shown on the drawings such correction shall be made before any concrete is placed between them. Where any form has been disturbed it shall be reset and rechecked. Side forms shall be removed not less than 12 hours after completion of the construction of the concrete road slabs. Care shall be taken that the concrete and any projecting rods are not damaged in any way during the removal of the forms. The concrete or mortar bed used at the longitudinal joint in partial-width construction shall be removed at the same time if applicable and the subgrade and subbase made good to the satisfaction of the Engineer's Representative. SETTING CHECKING 6276. The Engineer's Representative may require any or all concreting operations to cease AND STRIKING OF if at any time, the forms or rails are not set in position sufficiently far in advance of the RAILS FOR MACHINE- concreting to enable him to be satisfied as to their compliance with the relevant requirements LAID CONCRETE of this-specification. ALL RAILS SHALL:(A) Be integral with the forms so that they remain rigidly fixed at all times, or where independent, be mounted so that they remain rigidly fixed to the approved mounting during the passage of the spreading and finishing machines. The surface of rails shall be kept clean at all times. (B) Be firmly supported along the length in such a manner that the finishing machine can travel along the line of the carriageway at the correct level. (C) Where the width of slab is continuously varying, it shall be firmly supported throughout its length on cement mortar or concrete as specified each about 50mm thick so as to ensure the necessary rigidity and accuracy of levels. The subgrade or subbase or base course beneath the rail shall be thoroughly compacted before any concrete or mortar is laid. (D) Be so set as to ensure accuracy of level of the surface of the concrete within a tolerance of ± 3mm in 3 metres. (E) Be so set that the screed of the finishing machine operates in relation to the rail, not the form. Where on checking it is found that any rail or the form on which it rests has been disturbed or is incorrectly set, the rail shall be reset, and rechecked before placing of the concrete between the forms is begun. Rails may be removed in advance of removal of the forms on which they rest provided that the latter are not disturbed by so doing. QUANTITY AND DISTRIBUTION OF STEEL REINFORCEMENT 6277. The quantity and distribution of reinforcement shall be as shown on the drawings, with such modification as may be necessary and approved by the Engineer’s Representative to suit manholes and surface boxes, junctions or slabs of different width or length; or as are directed by the Engineer's Representative. No loose rods or small pieces of fabric other than as provided for in the specification shall be permitted in any portion of the work. PLACING OF STEEL 6278. Steel fabric reinforcement for carriageways shall be as pecified in B.S. 1221. All REINFORCEMENT reinforcement shall be so placed that after compaction of the concrete it is in the positions FOR CARRIAGEWAYS shown on the drawings and shall terminate 40mm from the Sedges of all joints in the concrete unless otherwise specified. 171 TREATMENT AT MANHOLES 6279. Manholes shall be housed in separate small slabs, which shall be the size of the exterior of the shaft and shall be formed by casting the main slab against boxes of this size, made from formwork and accurately placed vertically above the exterior of the shaft. This formwork shall be removed at the same time as the remainder of the formwork for the slab. Expansion joint filler 10mm wide shall be placed against the exposed edges of the slab, and reinforcing bars if shown on the drawings or specified shall be placed accurately in position so as to give the required final cover, concrete being placed by hand in the space intervening between the slab and the manhole frame. This concrete shall then be compacted to the same density as that of the adjoining slab. A sealing groove shall be formed and filled at the top of the joints with the surrounding slab, in accordance with Clause 6283 the top arises of both slabs being rounded to a radius of 6mm. JOINTS IN CONCRETE 6280. All joints shall be constructed by methods to be approved by the Engineer, and with CARRIAGEWAYS vertical faces. Grooves in the surface of the concrete over joints shall be sawn except that GENERAL alternative methods of forming the grooves may be submitted and may be considered by the REQUIREMENTS Engineer in lieu of a sawn grooves, provided that the Contractor demonstrates to the Engineer's satisfaction, that the surface finish so obtainable is within the appropriate tolerance permitted. TRANSVERSE JOINTS 6281. Expansion joints shall comprise an approved performed joint filler as specified and dowel bars. The joint filler, together with the sawn groove, shall provide complete separation of adjacent slabs. The dowel bars as specified shall be provided at mid depth of the slab, parallel to the finished surface and to the centre line of the road within a tolerance of ± 2mm in 300mm Provision shall be made for ensuring that the dowel bars and joint filler are held securely in position during spreading and compacting of the concrete. Dowel bars shall be provided at one end with a closely fitting sleeve 100mm long, consisting of cardboard or other approved material. A loose plug equal in thickness to the width of the expansion joint, and consisting of cotton waste or a disc of expansion joint filler, shall be inserted within the sleeve at the end of the dowel bar. The free half of each dowel shall be greased or painted with joint priming compound as specified or directed. The method of assembling and securing joints shall be approved by the Engineer. Where contraction joints are required, these shall be formed by a groove sawn in the surface of the hardened concrete and a timber fillet cast into the base of the slab, all as shown on the drawings. The sawn groove shall be located vertically above the timber fillet to within a tolerance of ± 12mm. Dowel bars shall be provided as for expansion joints. Construction joints shall be installed only under the conditions detailed in Clause 6287. They shall be formed by means of a drilled and split cross-form which shall allow tie bars to be inserted and which shall permit the reinforcement to project through the joint for a distance of at least 400mm. On recommencing work the cross-form shall be removed and the vertical face of the concrete roughened. The next reinforcing mat shall completely overlap the projecting reinforcement. Joints shall be formed in a straight line at right angles to the longitudinal axis of the carriageway except where this cannot be achieved as at road junctions and roundabouts and corresponding joints on either side of a longitudinal joint shall be in line with each other. Where possible all transverse joints shall be staggered. LONGITUDINAL JOINTS 6282. When slabs are constructed to multi-lane widths, tie additional reinforcement as shown on the drawings shall be bars or provided as specified in clause 6264. The 172 longitudinal joints shall be placed symmetrically about the middle of the slab in the form of a dummy joint, as shown on the drawings, or as directed. For slabs of single lane width, tie bars shall be provided as above and as shown on the drawings. Provision shall be made for maintaining the tie bars accurately in position during spreading and compacting of the concrete. When the adjoining slab is constructed, a groove shall be sawn or formed by other approved means to the requirements of clause 6283. SAWING AT JOINTS 6283. Except when an alternative method is approved by the the Engineer, a groove shall be sawn in the concrete immediately over the position of the joint. Sawing shall take place by a method to be approved by the Engineer as soon as possible but not before the concrete has hardened sufficiently to ensure clean faces to the groove. In considering the type of construction joints to be adopted, causes precipitating the joint must be considered and the instruments available. In addition to the above these other methods may be found useful: (a) Stepping method (vertical) (b) Tongue method (c) Grooving method The depth of grooves shall be 40mm. Groove over expansion joints shall be 6mm wider than the width of the preformed joint filler, and shall be accurately located over the joint filler. Grooves forming longitudinal or contraction joints shall be of the width shown on the drawings, or as directed by the Engineer. SEALING OF JOINTS 6284. All dust or grit shall he removed from the grooves which shall first be dried if necessary for this purpose. Unless an alternative method of sealing is approved by the Engineer, the dried joints shall then be coated with priming compound, complying with clause 6268 and an approved sealing compound heated to a temperature not exceeding 180 C, shall be poured in so as to fill the groves completely. When filling grooves in expansion joints, allowance shall be made for normal variations of ground temperature in the locality, so as to avoid the extrusion of the sealing compound with an expected increase in ground temperature. COMPRESSIVE STRENGTH OF CONCRETE 6285. During the whole progress of concreting, test cubes shall be made in the manner described for concrete work. Not more than 1 per cent of cubes tested at 28 days shall show a strength of less than specified. If rapid-hardening cement is used, reference in this clause to 28 days, which is the period for ordinary portland cement, shall be the period between concreting and opening to traffic. Cubes shall be made each day in sets at intervals and locations as decided by the Engineer's Representative. At the start of the work, and until such time as the Engineer's Representative may order a reduction in the number of cubes required, six sets shall be made during each day's work, half of each set for testing at 28 days for determination of the minimum permissible crushing strength and the other half for testing at seven days for the information of the Engineer's Representative as to quality of the mix. When the results of the first thirty sets are available and for so long as the Engineer's Representative is satisfied with the quality of the mix, he may reduce the number of cubes required to two sets per day. If the minimum specified crushing strength is not so attained the Contractor may without expense to the Employer, cut cores from locations selected by the Engineer's 173 Representative. Where this is done the strength of cores when tested in accordance with British Standard 1881 methods of testing concrete will be accepted as taking precedence over the cubes strengths in determining the strength of the concrete and a core strength of not less than 75 per cent. of the specified crushing strength at 28 days (tested vertically) will be accepted for a core having a height/diameter ratio of 2. The method which shall be adopted for correcting the strength of cubes and cores for age shall be as directed by the Engineer. In order to check the depth of concrete laid, the state of compaction and the position of the reinforcement, the Engineer's Representative may order cores to be cut, and the Contractor shall carry out same, and repair all holes so formed at his own expense, and to the satisfaction of the Engineer's Representative. The unit prices to be inserted by the Contractor in the bill of quantities shall include for preparing, cutting, packing, any transporting and testing cubes and cores required by the Engineer or his Representative. In addition, for cores the price shall include for all costs incurred in connection with drilling and making good to the satisfaction of the Engineer's Representative. TRIAL MIXES AND TRIAL SLABS 6286. The Contractor shall make trial mixes using the aggregates proposed for the work to ensure that the concrete mix is sufficiently workable and that segregation of the mix during transportation and placing does not occur. The composition of the trial mixes shall comply with the requirements of the specification in all respects. The Contractor shall construct a trial slab of the same thickness as that to be laid in the work, to the full width of the finishing machine, and at least 30 metre long. The slab shall be constructed with the approved mix to be used in the work, and in a position as shown on the drawings or directed by the Engineer's Representative. Construction of the trial slab shall be commenced sufficiently in advance of the main construction to enable cores to be cut from the trial slab. Six cores shall be cut therefrom and shall be tested at 7 days, to ensure that the mix as designed and the equipment proposed to be used are both suitable to achieve a fully compacted concrete of the specified strength, workability and surface finish. PLACING CONCRETE 6287. When concreting of a slab has commenced no cessation of the work will be allowed until concreting of the slab is completed. In the event of mechanical break down or adverse weather, however, the Engineer's Representative may permit the use of a construction joint and the Contractor shall carry out any additional precautionary measures stipulated at his own expense. Any of the following joints may be considered by the Contractor: (i) (ii) (iii) (iv) Construction joint Expansion joint Warping joint Contraction joint The placing, compacting and finishing of the concrete shall be carried out as rapidly as possible and operations shall be so arranged that in any vertical section the concrete shall be fully compacted throughout the whole depth and finished within 1 hour from the time of the completion of the mixing of the first batch of concrete in that section. SPREADING AND COMPACTION WITH A FINISHING MACHINE OF REINFORCED CONCRETE ROAD SLABS 6288. For concrete slabs of 200mm, thickness or less the concrete may either:(a) be spread and compacted in one layer, or (b) be spread in two layers which shall be compacted as one 174 When the concrete is spread in one layer a travelling jig or a type approved by the Engineer's Representative shall be used to hold the reinforcement in position while the concrete is being placed so after compaction the top cover to the reinforcement is as specified. When the concrete is spread in two layers the first layer shall be spread to such a level that after subsequent compaction it will support the reinforcement at a level which will ensure the specified top cover. The layer of reinforcement shall then be placed in position and covered with concrete. Whichever method of spreading is adopted the concrete shall be struck off at the appropriate surcharge and compacted true to line and level by one or more traverses of the machine to give the slab the final thickness required. The compaction and surface finish shall be to the satisfaction of the Engineer's Representative. For concrete slabs exceeding 200mm. in thickness the concrete may either: (a) be compacted in two layers or, (b) be compacted in one layer, if it can be shown to the satisfaction of the Engineer's Representative that, with the plant and methods to be used, full compaction can be achieved through out the full depth of the slab. If the concrete is to be compacted in two layers a layer of concrete shall be spread, struck off at the appropriate surcharge and compacted to a level that will ensure the specified top cover to the reinforcement. The layer of reinforcement shall then be placed in position and covered with concrete, which shall be struck off at the appropriate surcharge and compacted true to line and level by one or more traverses of the machine to give the slab the final thickness required. The compaction and surface finish shall be to the satisfaction of Engineer's Representative. If the concrete is to be compacted in one layer the concrete shall be spread and the reinforcement placed in position by one of the methods specified for slabs of 200mm thickness or less. SPREADING AND COMPACTION WITH A VIBRATING SCREED OF REINFORCED CONCRETE ROAD SLABS SPREADING AND COMPACTION WITH A FINISHING MACHINE OR VIBRATING SCREED ON CONCRETE SLABS OR HAUNCHES USED AS ROAD BASES CURING CONCRETE 6289. A layer of concrete shall be spread, struck off at the appropriate surcharge and compacted to a level that will ensure the specified top cover to the reinforcement. The layer of reinforcement shall then be placed in position by hand, or by mechanical means approved by the Engineer’s Representative and shall be covered with concrete, which shall be struck off at the appropriate surcharge and compacted true to line and level by means of a vibrating steel or hardwood screed. The compaction and surface finish shall be to the satisfaction of the Engineer's Representative. 6290. In exceptional circumstances where reinforced concrete slabs or haunches are used as road bases, the concrete shall be spread struck off at the appropriate surcharged and compacted in a single layer by machine or by a vibratory steel or hardwood screed and finished true to line, and level to the required thickness. The compaction and surface finish shall be to the satisfaction of the Engineer’s Representative. 6291. Immediately after completion of the finishing process, all exposed surfaces of the concrete shall be protected from the sun and drying winds by frames covered by canvas or other approved material until the concrete is sufficiently hard to bear the weight of other protective material without the surface becoming marked. The sides and ends of the frames shall be covered to exclude drying currents of air. Thereafter all exposed surfaces of the concrete shall be protected and kept damp by covering with suitable matting, sand or other approved material: if sand is to be laid a 175 minimum depth of 50mm, will be required. The curing material shall be kept wet for a period of at least seven days or longer as directed by the Engineer's Representative. Alternatively waterproof paper in accordance with the relevant clause of this specification, or other approved sheeting may be used, and this shall be laid dry and kept in contact with the surface of the concrete for at least seven days. The sheets shall be lapped by at least 230mm and shall be weighted down and well fastened along the edges to prevent the wind blowing beneath. As an alternative method of curing the surfaces may be protected, where approved by the Engineer by treating with an approved resinous curing compound, mechanically sprayed on to the surface of the finished concrete at a rate of 4.5 - 6 litres/sq. m as soon as it is possible to produce a membrane of uniform thickness. Unless otherwise directed by the Engineer, the compound shall be applied as soon as practicable after completion of the laying and finishing of the concrete. Any groove over a point shall be protected from the entry of curing liquid. ACCURACY OF 6292. The concrete surface shall not show a departure from the true surface greater than CONCRETE SURFACE 3mm when tested with a 3 meter straight-edge or template in the manner described for USING FINISHING OR checking Base course finish. VIBRATING SCREED If at any point tested the tolerance is outside these limits, the Contractor may make not more than two additional passes of the vibrating beam of the finishing machine and one further pass of the oscillating screed. The surface shall again be tested in the specified manner whereupon if the irregularity so measured still exceeds 3mm in 3 meter, the Engineer's Representative shall direct that the concrete be removed to the level of the top surface of the reinforcement or for unreinforced concrete to a depth of 50mm. The area to be removed shall be that represented by the length of the straight edge in the position of measurement across the full width of the screed. The concrete so removed, shall not be re-used. Where the point of measurement in default is less than 5 metres from a transverse expansion joint, the whole area up to the joint shall be removed to the required depth. Fresh concrete of specified quality shall be placed to the appropriate surcharge. It shall then be compacted and finished in the normal manner and shall again be subject to test for accuracy of finish. Although the concrete may be removed immediately following measurement of the irregularity and while it is still wet, this shall not absolve the Contractor from complying with the requirements of this clause if for any reason the concrete to be removed has hardened. The removal of concrete under this clause and its replacement shall be carried out as directed by the Engineer's Representative to his approval and without extra charge. The accuracy of surface required by this clause shall apply also to the surface across any joint whether formed initially or as a result of replacement of concrete arising out of the requirements of this clause. In exceptional circumstances, where concrete road slabs are to be surfaced with asphalt, coated macadam or dense tar surfacing, the requirements as to the finished surface of the concrete shall be those in this clause except that the specified tolerance shall be 6mm in 3 metres instead of 3mm in 3 metres. 176 TRAFFIC OVER FINISHED WORK 6293. No vehicular traffic shall be allowed on the finished surface within 20 days of its completion where ordinary portland cement is used or 10 days where rapid-hardening cement is used and until the joints have been sealed unless otherwise authorized by the Engineer. TESTS SELECTION AND CONTROL TESTS 6294. The selection and control tests to be carried out under this section of this Specification shall be those specified to be carried out for concrete and reinforced concrete work and shall be conducted in the manner stipulated in all relevant clauses of this specification. In addition to the making, curing and testing of concrete test cubes as control tests on concrete carriageways, the Engineer's Representative may order cores to be cut from the finished work so as to check the state of compaction, the thickness of the concrete and the position of the reinforcement. These cores shall be drilled and tested in accordance with the provisions of B.S. 1881, or any amendment thereto as directed by the Engineer. TRIAL SECTIONS 6295. The Contractor's attention is particularly drawn to the necessity for carrying out trial sections with the proposed materials and plant prior to the start of the main construction to determine the most efficient construction technique and the suitability of the proposed materials and plant, as described by the relevant clause of this specification. (CLAUSES 6296 - 6299 INCLUSIVE NOT USED) PART (D) - SURFACING (I) GENERAL TWO COAT BITUMINOUS SURFACE DRESSING 6300. In addition to all other relevant clauses of the conditions of contract and this specification, the following shall be deemed to refer more particularly to two coat bituminous surface dressing work, and shall be read in conjunction with same. MATERIALS MATERIALS FOR SURFACE DRESSING 6301. Materials used in surface dressing are to be:(i) CUT-BACK BITUMEN FOR PRIME COAT:- Either a cut-back bitumen known as M.C-O, having a viscosity of 75/150 seconds at 25 C as measured by the furol viscosimeter, or a cut-back bitumen known as M.C-1 having a viscosity of 75/100 seconds at 50 C as measured by the furol viscosimeter. (ii) CUT-BACK BITUMEN FOR WEARING COAT: (For first wearing coat: Either a cut-back bitumen having a viscosity of 100/150 seconds at 40 C as measured by the standard tar viscometer, or a cut-Back bitumen having a viscosity of 300/400 seconds viscosity at 40oC as measured by the standard tar viscometer. (III) STRAIGHT RUN BITUMEN FOR WEARING COAT: Straight run bitumen for first wearing Coat shall have a penetration grade of 80/100 at 25 C and a flash point (open) of 107 C (Minimum). 177 (IV) BLINDING MATERIALS - Sand for blinding prime coat surface shall consist of clean sharp sand of 6mm maximum size with not more than 20% passing 600 m. sieve, and shall be approved by the Engineer's Representative. Alternatively grit arising from the crushing of the rock may be used provided it is approved by the Engineer's Representative, and the grading complies with the specification for sand earlier discussed. (V) MATERIALS FOR SURFACE DRESSING - Materials for blinding the first wearing coat surface dressing on the carriageway, shall consist of clean crushed rock or clean crushed or uncrushed gravel from an approved source, as specified, graded into single sizes as defined in B.S. 63 latest edition or any amendment thereto; "Single Sized Road Stone and chippings", or in B.S. 1984 latest edition -"Single Size Gravel Aggregate for Roads as appropriate. Two single sizes l9mm and 12mm shall be used for blinding on the carriageways, while 10mm single size material may be allowed for non-trafficked surfaces (like verges) but only with the written approval of the Engineer's Representative. The grading of the material shall be carried out by means of an approved mechanically operated screening plant, fitted with screens having square perforations corresponding to the B.S. sieve size of the material it is intended to produce. Screens with circular perforations will be permitted, provided the diameter of the perforations is increased so as to be equivalent to the corresponding B.S. sieve size. The different sizes of materials shall be stored in separate stockpiles and shall not be mixed. If the Engineer's Representative considers it necessary the blinding material shall be washed before use. The aim of the Contractor shall be to obtain the maximum production of 19mm and 12mm single sized material from the plant and either size may be used in blinding a continuous section of surface dressing of not less than 2 kilometres in length. The crushing aggregate value of all material used for surface dressing shall not exceed 30% and its abrasion test result not more than 25%. All samples shall be tested as described in B.S. 882. Samples of all blinding materials to be used in the works shall be submitted to the Engineer's Representative for approval prior to being used. Prior to the commencement of surface treatment works the Contractor will carry out tests under the direction of the Engineer for the purpose of assessing the adhesive qualities of the materials which are to be used in the works. As a result of these tests the Engineer may decide that it is necessary to use an additive to the bitumen for the prevention of strippings of the stone surfacing, and the Contractor shall comply with the directions of the Engineer in this respect. Strip test is recommended. BITUMINOUS EMULSION 6302. Bitumen emulsion shall contain 30% of bitumen and shall comply in all other respects with B.S. 434 (latest edition and amendment thereto) except that the basic bitumen used in the manufacture may have a penetration of 80/100. Bitumen emulsion containing 30% of bitumen may be made by mixing thoroughly together in the correct proportions emulsion complying with B.S. 434 (amendment thereto) with clean soft water. (CLAUSES 6303 - 6309 INCLUSIVE NOT USED) WORKMANSHIP 178 HEATING OF CUT BACK BITUMEN 6310. The cut-back bitumen shall be heated in a bitumen heater complying with B.S. 167, which shall have a capacity commensurate with the output required. The heater shall be so operated that the temperature of the bitumen applied to the road shall be within the specified range. Accurate thermometers shall be incorporated in the heater to give a clear indication of the bitumen temperature. Should the temperature be in excess of that specified, the Engineer's Representative may direct that this overheated bitumen be disposed off at the Contractor's expense. CUT-BACK BITUMEN 6311. The prime coat shall be of a medium curing cut-back bitumen of either M.C.O. PRIME COAT Grade or M.C.1 Grade as specified. The actual grade to be used shall be determined by the Engineer after carrying out site tests to determine the penetration of each grade. The bitumen shall be applied strictly in accordance with the provisions of the relevant clauses of this specification on an approved Base course free from all dust and loose material and slightly damped prior to applying the bitumen. After spraying the surface shall be left for a minimum of three hours before blinding is applied, or longer if considered necessary by the Engineer's Representative to effect the maximum penetration. Blinding consisting of sand or grit complying with the provisions of the relevant clauses of this specification shall be applied so that a uniform covering of sufficient thickness is obtained to ensure that no bare or fat patches of bitumen are showing. The blinding shall then be rolled in with not more than two passes of a roller. SPRAYING OF CUT-BACK BITUMEN PRIME COAT 6312. The prime coat as specified shall be evenly applied to the prepared Base course by means of an approved presuure feed mobile distributor and complying with the requirements of B.S. 1707: "Binder distributors". In addition to the special requirements detailed in section three of B.S. 1707, the pressure feed mobile distributor shall be fitted with a spray bar through which the hot bitumen can be circulated while the distributor is not spraying. The jets shall be so arranged in the spray bar that they are effectively preheated to the same temperature as the circulating bitumen. The Contractor shall provide a set of 50mm wide troughs as described in Appendix "A" of B.S. 1707 and shall carry out depot tray test A in the presence of the Engineer's Representative to demonstrate that the lateral distribution is in accordance with B.S. 1707. This test shall be carried out prior to using the spraying plant for the first time on the contract, and subsequently at the discretion of the Engineer's Representative. In the event of the quantity of bitumen in any trough or troughs being found to lie outside the prescribed tolerance from the average, the faulty jet shall be located and cleaned or replaced. The bitumen shall be applied at a temperature in accordance with the Table given below, and at a rate of spray of between 0.8 and 1.2 litres per square metre depending on the texture of the surface. From the calibration charts and tests made on the distributor, the spraying speed shall be determined to give the required rate of spray. OR Alternatively rate of spray may be checked as follows:Check the initial and final quantity of cut back and record. The difference between initial and final readings divided by the area sprayed can be used to check compliance with approved rate of spraying. Note:- Initial and final reading shall take place at same position. 179 TABLE VI-8 SEALING COATS TEMPERATURE OF APPLICATION BITUMEN GRADE M.C.0 M.C.I TEMPERATURE OF APPLICATION MIN 38 C 54 C MAX 66 C 79 C The Contractor shall carry out trial sections, as directed by the Engineer's Representative to determine the most suitable grade and rate of application of bitumen. Immediately before any spraying run is begun, the spray bar shall be tested by allowing all the jet to discharge simultaneously for about half a minute with a slotted metal tray placed beneath the spray bar whilst a visual inspection is made. Any jet which is seen not delivering a uniform spray cone shall be cleaned or replaced. After testing the spray bar, the distributor shall proceed with the spraying run without delay. No spraying shall be carried out when rain appears imminent, during rain, or after rain, until the surface has dried. The Contractor shall ensure that joints between spraying strips are straight and without excess or deficiency of bitumen which would cause either fattening up or scabbing along the joint. The Contractor will be required to respray at his own expense any section which show deficiency of binder, or to burn off and respray at his own expense any sections which show an excess of binder and which subsequently fat up. FIRST COAT SURFACE DRESSING 6313. The wearing course of the surface dressing shall not be laid until at least 10 days after the application of the prime coat. During this period additional blinding sand shall be added if directed and brushed over the surface to prevent damage. After such period all damaged or weak spots shall be cut out, refilled, recompacted flush with the existing surface, sealed and blinded as specified and rerolled to the satisfaction of the Engineer's Representative. After all repair work has been allowed sufficient time to harden, the surface shall be swept clean of all loose material immediately prior to the application of the wearing coat. Before spraying is begun the surface shall be dry. Bitumen for the wearing coat of the surface dressing shall be an approved cutback bitumen or straight run bitumen as specified in the relevant clauses of this specification. The bitumen as specified shall be evenly sprayed on the surface by means of an approved mechanical spraying machine as specified. The temperature of the bitumen at the time of spraying shall be in accordance with the table given below. The grade of bitumen to de used shall be determined by the Engineer. TABLE VI-9 BITUMEN VISCOSITY AND TEMPERATURE OF APPLICATION BITUMEN VISCOSITY STV AT 40 C 100/150 SECS 300/400 SECS 180 TEMPERATURE OF APPLICATION MIN 132 C 149 C MAX 160 C 177 C The rate of spray of the bitumen shall be determined according to the type of base, type and size of chippings which are to be used as detailed in the table given below, and the Contractor shall carry out trial sections, as directed by the Engineer's Representative to determine the most appropriate rate of application of bitumen. TABLE VI-10 SIZE OF CHIPPING AND RATE OF SPRAY OF BITUMEN NOMINAL SIZE OF CHIPPINGS RATE OF SPRAY OF BITUMEN LITRE./SQ.M. 10mm 12mm 20mm 0.60 - 0.90 0.75 - 1.20 1.20 - 1.50 Immediately after spraying the surface shall be blinded with approved single size chippings as specified. The chippings shall be distributed on the sprayed surface by means of mechanical spreaders or tailboard gritters so that a single layer of closely packed chippings is obtained. Any bare or lean areas shall be made good by a follow-on gang using hand blinding. Rolling shall be carried out immediately after the chippings have been spread with an approved roller weighing not less than 3,629 kilograms or more than 5,443 kilograms. The minimum number of passes of the roller shall be used to press the chippings into the film of bitumen. Two passes of the roller should generally be sufficient. Pneumatic tyre rollers are preferable to smooth wheeled rollers. Prior to the commencement of spraying a section of the road for the first coat, a 2 metres wide paper strip shall be laid over the end of the previous section. The bitumen sprayer shall then commence its run from over this paper strip. FINAL SURFACE OF CARRIAGEWAY 6314. The finished surface of the carriageway shall be left as smooth as possible and the accuracy of finish in the longitudinal direction shall not vary at any point by more than 6mm from a 3 metre straight edge, placed in any position on the finished surface parallel to the centre line. The transverse profile shall conform to the same accuracy, using a correctly shaped template instead of the straight edge. The surface shall be evenly textured and show no lean or fat areas and shall not have any low or flat spots where water will collect. WET WEATHER 6315. No surfacing work shall be done in wet weather or when rain is imminent. Only dry chippings shall be used. REGULATION OF TRAFFIC OVER PRIME COAT AND SURFACE DRESSING 6316. After laying the prime coat surfacing, barriers shall be erected to keep the area surfaced free from traffic. It shall remain free from traffic for such a period as the Engineer’s Representative may direct after which it shall be opened to traffic for not less than 3 days and for not more than 7 days. During this period additional blinding 181 material shall be added and all damage by traffic made good. After the application of the first coat surfacing, the area surfaced shall be kept free from traffic for at least 24 hours. The section shall then be opened to traffic and suitable traffic notices and barriers shall be erected for a period of one week restricting traffic speeds to 25 KPH During this period empty bitumen drums or other obstacles, which shall be well lighted, or alternatively removed during the hours of darkness, shall be placed on the newly surfaced areas for the purpose of limiting the speed of traffic, and shall be moved to different positions from day to day in such a way that the whole width of the surface receives equal wear and compaction from the wheels of vehicles. (CLAUSES 6317 - 6319 INCLUSIVE NOT USED) TESTS TESTS FOR BITUMEN 6320. The Contractor shall produce manufacturer's test certificate if requested, otherwise the Engineer may require the Contractor to carry out the following tests as described in "standard methods for testing petroleum and its products" published by the Institute of Petroleum, 26 Portland Place, London W.1. Penetration of bitumen IP.49/56 Soluble bitumen content: bitumen and asphalt IP.47/55. Flash-point by means of the cleveland apparatus IP.36/55 Specific gravity IP.59/57. Method C. Specific gravity of liquids or solids - pycnometer method. Specific gravity of liquids or solids - method F. The determination of viscosity by the standard tar viscosimeter or the furol viscosimeter may also be required by the Engineer. The cost of carrying out these tests if required by the Engineer shall be deemed to be included in the tendered rates and prices. TESTS FOR AGGREGATES ROADSTONE AND CHIPPINGS 6321. In determining the suitability of aggregates for use as road surfacing material the Engineer may require the Contractor to carry out any of the test specified in B.S. 812Mineral aggregates sand and fillers, B.S. 882, 1201 - Concrete aggregates from natural sources B.S. 1881 - Methods of testing concrete, B.S. 1200 - building sands from natural sources, B.S. 63 - Single-sized roadstones and chippings. The cost of carrying out these tests if required by the Engineer shall be deemed to be included in the tendered rates and prices. TESTS FOR BINDER DISTRIBUTORS 6322. The Contractor shall provide a set of 50mm wide trough as described in Appendix A of B.S. 1707 and shall carry out depot tray test A in the presence of the Engineer's Representative to demonstrate that the lateral distribution is in accordance with B.S. 1707. This test shall be carried out prior to using the spraying plant for the first time on the contract and subsequently at the discretion of the Engineer's Representative. In the event of the quantity of bitumen in any trough or troughs being found to lie outside the prescribed 182 tolerance from the average, the faulty jet shall be located, cleaned or replaced and a further test carried out if required by the Engineer's Representative. TESTS FOR RATE OF APPLICATION 6323. The Contractor shall test the rate of application of bitumen at regular intervals, as directed by the Engineer's Representative by means of the "tray test" as described in Road Note No.11: "Binder distributors for surface dressing", issued by the Road Research Laboratory, England. (CLAUSES 6324 - 6329 INCLUSIVE NOT USED) (II) GENERAL BITUMINOUS MACADAM SURFACINGS 6330. In addition to all other relevant clauses of the conditions of contract and this specification, the following shall be deemed to refer more particularly to bituminous macadam surfacing work and shall be read in conjunction with same. MATERIALS BITUMEN MACADAM GENERAL 6331. The manufacture and grading of the bitumen macadam shall be in accordance with B.S. 1621 "bitumen macadam with crushed rock or slag aggregate except where stated otherwise in these specifications. BITUMEN MACADAM MATERIALS 6332. (A) AGGREGATE. Coarse aggregate shall be hard clean and durable crushed igneous rock from a source to be approved by the Engineer and in accordance with B.S. 812. Fine aggregate shall be quarry fines produced from the crushing of igneous rock in a secondary plant. They are to consist of hard non-absorbent moderately sharp particles and to be free from clay, loam, and other foreign matter. If filler is used it shall consist of finely ground particles of hydrated lime, portland cement or crushed rock and at least 75% of the filler shall pass 75 m sieve. (B) Binder: The binder shall be a straight-run bitumen with a penetration ranging from 40/50, 60/70, 80/100 at 25 C. BITUMEN MACADAM 6333. Representative samples of all materials proposed for use under these specifications APPROVAL shall be submitted to the Engineer by the Contractor at the Contractor's expense for test and OFMATERIALS for preparation of trial mixes to determine job-mix formula. The Engineer shall make tests of the proposed materials and inform the Contractor if the tests indicate compliance with the specifications. BITUMEN MACADAM COMPOSITION OF MIXES 6334. The grading of the combined aggregate to be used in the respective mix for each course shall be within the limits stated below and when plotted graphically with the particle size to a logarithmic scale shall lie on a smooth curve within the envelope of these limits. TABLE VI-11 GRADING ENVELOPE FOR BITUMINOUS BINDER COURSE 50MM BINDER COURSE SIEVE SIZE % PASSING 183 38mm 100 25mm 50 - 100 12.5mm 26 - 50 6mm 18 - 30 2.8mm 12 - 22 1.25mm 8 - 17 600 m 7 - 14 300 m 4 - 11 150 m 2- 8 75 m 0- 5 BITUMEN 4 - 5.5%BY WT. OF AGGREGATE OR AS PER DESIGN TABLE VI-12 GRADING ENVELOPE FOR BITUMINOUS WEARING COURSE 40MM WEARING COURSE SIEVE SIZE 25mm 19mm 12.5mm 9.5 mm 6.4mm 3.2mm 1.25mm 600 m 300 m 150 m 75 m BITUMEN % PASSING 100 95 - 100 70 - 90 55 - 75 40 - 60 25 - 40 15 - 30 12 - 24 8 - 18 5 - 12 3-6 4 - 7% BY WT.OF AGGREGATE OR AS PER DESIGN The exact job-mix formulae will depend on the nature and grading of the aggregate and the type of bitumen. The exact job-mix formulae for the respective courses will be determined by the Engineer. CLAUSES 6335 - 6339 INCLUSIVE NOT USED) WORKMANSHIP BITUMEN MACADAM MIXING PLANT 6340. The materials shall be mixed in an approved mixer of batch or continuous type from which mixed materials can be delivered and laid hot. The mixing plant shall be maintained in good working condition and shall be subject to inspection by the Engineer's Representative. The weighing, measuring and recording apparatus shall be checked at frequent intervals and maintained in perfect adjustment throughout the contract. BITUMEN MACADAM MIXING 6341. The aggregate and binder shall be heated separately, aggregate to a temperature range of 121°C -149°C and the binder to 135°C -163°C. The respective temperatures of the aggregate and the binder are to be within 14°C on each other at the time of mixing. 184 Prolonged and excessive heating of the materials is to be avoided and particular care is to be taken with binders. A dry mixing period of at least 10 seconds - shall precede the addition of bitumen to the mix. Wet mixing shall only continue as long as is necessary to obtain a thorough blend. Aggregates, including fillers, if any shall be thoroughly dry immediately before mixing. When moisture is detected in the mixed materials all aggregates in the hot bins are to be removed and replaced in their respective stock piles. BITUMEN MACADAM 6342. The mixed materials shall be transported from mixing plant to site in clean metal TRANSPORTING lined vehicles. Every precaution is to be taken to avoid segregation of mixed materials and MIXED MATERIAL to ensure that they do not become contaminated with dust or foreign matter. Should any load be wetted excessively by rain, they will be rejected by the Engineer's Representative. BITUMEN MACADAM PREPARATION OF SURFACE PRIOR TO LAYING BITUMEN MACADAM LAYING 6343. Before the macadam is laid on the newly constructed based course, the surface will be inspected by the Engineer’s Representative and testing using an Engineer’s level 3 metre straight edge or any other means to ensure that the surface conforms with the requirements of this specification. Any irregularities in the surface shall be corrected to the satisfaction of the Engineer's Representative before surfacing work will be allowed to proceed. 6344. After mixing the material must not be reheated other than by the means provided in or on the spreading machine. Material must not be laid when the surface on which it is to be placed is wet or when rain appears imminent. Immediately prior to laying the bitumen macadam, the surface of the Base course shall be swept clean of all loose and caked dirt. The macadam as specified shall be laid by approved means to compacted thickness of 50mm binder course and 65mm wearing course, subject to design. It is essential that the material is laid at a temperature not less than 107°C and not more than 149°C. The Contractor is to provide at each spreader and finisher a suitable thermometer for testing the temperature of the material as it is being spread and is to take such temperature reading continually and record them hourly throughout each day's laying. This record shall be available for inspection by the Engineer or his Representative who will himself make such additional temperature checks as he considers desirable. BITUMEN MACADAM SPREADER OR FINISHER 6345. The materials shall be laid by approved mechanical spreaders and finishers. The spreader and finisher shall be in in good mechanical condition and shall be capable of laying to the required width and profile without causing segregation, dragging, burning, irregularities or other surface defects and it shall be capable of being operated at a speed consistent with the character of the mixture and the thickness of the course being laid, so as to produce a surface having a uniform density and surface texture. When not operated-on side forms the spreader will employ equalizing runner evener arms or other automatic compensating devices to adjust the profile and confine the edges of the course to true lines. 185 The mixer capacity and the operating speed of the spreader shall be so adjusted as to ensure continuous laying and to avoid intermittent stopping of the spread as far as is practicable. HAND SPREADING NOT ALLOWED 6346. Hand spreading will not be permitted for general work, but will only be allowed for filling localized depressions, or as directed by the Engineer or his Representative. Where hand spreading and tamping is permitted the mixed material is to be dumped on delivery upon an existing hard clean surface or an approved metal sheets outside the area where it is to be spread and shall be distributed in to place immediately by hot shovels. It shall be spread with hot rakes in a uniformly loose layer to the full depth required. BITUMEN MACADAM ROLLING 6347. As soon after laying as conditions permit and when the material is still at a temperature of not less than 95°C the materials will be uniformly compacted with 3 wheeled smooth rollers by rolling in a longitudinal direction, progressing gradually from side to centre of work and so lapping the rolling as to obliterate all roller marks on completion. A sufficient number of rollers shall be employed to ensure that the entire surfacing as laid is compacted at the correct temperature. At least two rollers are to be provided, one is to be three-wheeled and is to have a weight per centimetre width of rear wheel of between 44 and 63 kilograms. The second roller shall preferably be a pneumatic-typed roller and shall be of multiple-axle, multiple-wheel type with smooth-tread pneumatic tyres of equal size staggered on the axles at such spacings and overlaps as will provide uniform compactive pressure for the full compacting width of the roller when operating. Oscillation of the wheels, if provided, shall be in vertical plane only. The pneumatic tyre roller shall be capable (A) of being ballasted sufficiently to bring its loaded weight to at least 2½ times its own weight. Gross weight to be preferably 18 - 21 Tonne and (B) of-exerting compactive ground pressures of at least 5.6 kilograms per square centimetre (5.6 - 8.4 Kg/sq.cm). For the pneumatic rollers compaction should be done within 65°C - 80°C range. All roller wheels are to be kept slightly moist by the use of water tanks and spray bars attached to the machines to prevent the material being picked up or disturbed. Rollers must not be left standing on the new surface while there is any risk of it being damaged thereby. The sequence of rolling operation shall be: (a) breakdown rolling with the-3-wheeled smooth roller; (b) intermediate rolling with the high pressure tyre pneumatic roller; and (c) the final rolling with a steel wheeled tandem roller. Rolling will continue until the specified density is obtained. This can be checked by using non-destructive method i.e. Nuclear gauge apparatus. FIELD DENSITY OF COMPACTED BITUMEN MACADAM 6348. Density tests of the bitumen macadam surfacing after compaction shall be taken from the trial area and later at intervals throughout the course of the work and compared with the density of control specimens taken from the same material before laying, all in accordance with the following procedure:186 (A) A sample of mixed material will be taken from a lorry before the material is delivered to the spreader, and three control specimens shall be made and their density measured by the Engineer's Representative by the marshall method. The average of two close results from the specimens taken as the control density of that particular batch. (B) The pavement will be marked with the batch numbers to show where the lorry load of material (from which the sample was taken) is laid, so that field density samples can be taken for comparison with the control specimens. (C) After completion of rolling, two samples are to be cut from each area so marked in positions indicated by the Engineer's Representative. (D) The samples shall be taken in accordance with part 1 section 3 of B.S. 598 and the density calculated by weighing in air and weighing in water in accordance with part 6 of B.S. 598. The average of two close results will be taken as the density of the compacted material in that area. (E) The field density will not be less than 100% of the control density determined as above. When an approved rolling procedure has been established, each course will be sampled in accordance with the above at the rate of one sample area for each 1670 sq.m or one sample area every four hours (whichever is the more frequent). Material which does not achieve the required density will either be cut out and replaced or be further compacted until the require density is obtained. TRIAL AREAS 6349. The first 30 metres of the approved bituminous macadam which is laid by the spreader shall be regarded as a trial area in order to establish a rolling procedure which will produce the required field density. At least four samples of the material after rolling will be taken in accordance with part 1 section 3 of B.S. 598 (1958) When the work is at least 12 hours old in order to determine the degree of compaction. If the required specified density determined in accordance with the foregoing clause is not obtained, the field rolling procedure will be changed so as to achieve the desired field density and the trial area will be cut out and replaced to the satisfaction of the Engineer or his Representative. BITUMEN MACADAM 6350. (A) The surfacing will be finished to the required levels shown on the drawings. FINISHED LEVELS The finished surface shall be of such smoothness that when tested with a 3 metre straight edge placed anywhere in a longitudinal direction on the surface, there shall not be a gap greater than 5mm between the bottom of the straight edge and the surface of the pavement anywhere along the pavement. Any deviation exceeding 5mm will be corrected at the Contractor's expense by scarifying, cutting out and removing all loosened materials, adding new materials as required, re-shaping and rolling. No materials loosened by scarifying and cutting out, will be left in position or otherwise reused. The surface shall be similarly tested, and corrected if necessary in a transverse direction using a correctly shaped template instead of a straight edge. 187 (B) It is essential that the surface of the road is free from waves, any depression which retain water on the surface are immediately to be corrected as described above to the satisfaction of The Engineer's Representative. BITUMEN MACADAM 6351. All joints shall be vertical, properly formed to the correct line and level; if necessary, JOINTS they shall be cut back to achieve this. The exposed edges of the bitumen macadam already laid shall be coated thinly with bitumen emulsion containing 30% to 50% bitumen before laying adjoining work. All joints on completion shall present the same texture, density and smoothness as other sections of the surface. Surfaces and projections which the new paving will abut shall be thoroughly cleaned and coated with bitumen emulsion containing 30% - 50% bitumen. The new paving shall then be tamped around and against the projection to such a depth that, on completion of compaction the finished surface of the wearing course is level with the top of the projection. BITUMEN MACADAM DAMAGED WORK 6352. Should the new bitumen macadam be dragged, churned up, become soft, show signs of segregation, show that stripping of the binder from the aggregate has occurred, or suffer other damage during or after being laid, the Contractor will remove the damaged or faulty work at his own expense and replace with fresh material, laid and compacted to the correct level to the approval of the Engineer's Representative. (CLAUSES 6353 - 6359 INCLUSIVE NOT USED) TESTS BITUMEN MACADAM 6360. The Contractor shall provide equipment, labour and such trained staff as may be TESTS required by the Engineer's Representative for carrying out the following tests on materials to be used in the manufacture of bitumen macadam in accordance with the following standards: (A) Grading tests on aggregates in accordance with B.S. 812: "sampling and testing of mineral - aggregates and fillers". (B) Determination of binder content of mixed materials in accordance with hot extraction method BT 1 described in B.S. 598: - "Sampling and Examination of Bituminous Road Mixtures". The Contractor is required to comply to the requirements of B.S. 598. FREQUENCY OF TESTS: BITUMEN MACADAM 6361. Aggregates shall be sampled and tested at source, on delivery to the mixing plant and after each extraction test and the result of each test shall be submitted to the Engineer's Representative within 24 hours of the sample being taken. The number of such tests shall be adequate for proper control of the materials and shall not be limited to those made on specific instructions of the Engineer's Representative. Samples of mixed materials shall be taken and tested during the first day's mixing and throughout the work to confirm that the grading and binder contents are as specified. Such samples shall be taken either at the place and time of mixing or at the place of laying both may be necessary as the results will complement one another as directed by the Engineer's Representative. Samples for testing shall also be cut from the surfacing as laid when directed by the Engineer's Representative. The frequency of sampling mixed materials shall be at least once per day or once for each 90 tonne of material mixed whichever is the more frequent. The result of each test on 188 mixed materials shall be submitted to the Engineer's Representative within 24 hours of the sampling and any adjustments shown to be necessary shall be made immediately. Until such adjustments have been made and until a certificate to the effect has been forwarded to the Engineer's Representative no further batches of mixed material shall be made. INDEPENDENT TESTS: BITUMEN MACADAM 6362. Independent sampling and testing may be carried out by the Engineer's Representative throughout the contract period and for this purpose the Contractor shall grant free access to the mixing plant and storage depots, supply materials and provide every facility for the Engineer's Representative to take samples whenever required. In particular, throughout the contract, the Engineer's Representative will carry out control tests on the plant mix as he requires. The Engineer's Representative shall be supplied with all necessary equipment, labour and materials to perform any additional tests he may wish to carry out. MANUFACTURER'S CERTIFICATE FOR BITUMEN 6363. A certificate is to be obtained from the suppliers with each consignment of bitumen delivered, stating the grade of material being supplied, and these certificates are to be handed to the Engineer's Representative. CONTRACTOR TO TEST MATERIALS: BITUMEN MACADAM 6364. Notwithstanding the production of any manufacturer’s test certificates if the Engineer so requires, the Contractor shall arrange for the testing in an approved manner of all materials used throughout the contract to ensure that they are up to the standard specified, i.e. Aggregates, bitumen and such other materials as specified or decided by the Engineer. The Contractor shall arrange for the testing of materials incorporated in the works to ensure that they have been manufactured or supplied as specified, or as ordered by the Engineer. NOTICE OF TESTS: BITUMEN MACADAM 6365. Whenever the Contractor intends to carry out any of the above tests, he shall give the Engineer's Representative sufficient notice to enable him, should he so wish, to be present during the test. The Engineer's Representative shall be given the results in writing of all tests, as soon as they are available, and in any case not later than 24 hours after samples have been taken. SAMPLES TO BE IN DUPLICATE 6366. Whenever the Contractor takes samples for testing, and where so directed he is to take duplicate samples and hand them to the Engineer's Representative. Such samples are to be properly packed and labelled as directed. COST OF TESTS BITUMEN MACADAM 6367. The cost of these tests including the provision of samples, will be deemed to have been included in unit price for bitumen macadam. (CLAUSES 6368 - 6369 INCLUSIVE NOT USED) (III) GENERAL HOT ASPHALTIC CONCRETE 6370. This item consists of hot mixed, hot laid asphaltic concrete composed of mineral aggregate and asphalt cement thoroughly mixed in an approved plant until all aggregate particles are uniformly coated with asphalt. The asphaltic concrete shall be laid in two courses - surface and binder courses, with or without wedge or levelling course or any combination of these as shown on the drawings. Unless specified in Volume III or on the drawings, the compacted thickness of each course shall not be less than 60mm for the binder and 40mm for the surface course. The compacted 189 thickness of any single constructed course shall not exceed 75mm for binder or levelling course or 60mm for surface course. Priming of untreated base and application of tack coat to existing paved surfaces shall be done as follows: For Priming Base: MC-O or MC-l shall be used at the rate of 1.0 - 2.0 Litres/ sq.m For Applying Tack Coat: Litres/sq.m Bitumen emulsion, quick breaking type applied at the rate of 0.25 - 0.70 Tack coat shall be applied in all areas to take the binder course if warranted by surface conditions and directed by the Engineer's Representative. All materials and method of preparation and construction shall conform with the requirements of these specifications. The finished pavement shall conform in all respects with the lines, grades, dimensions and cross sections shown on the drawings or as may be otherwise specified or directed by the Engineer. MATERIAL 6371. The materials used shall be those prescribed for the several parts which constitute the finished work and shall conform with all the requirements for such materials as set out herein. (A) AGGREGATE (I) Coarse aggregate shall be the portion of the aggregate retained on the No. 5mm opening sieve and shall be hard, clean and durable crushed igneous rock from a source to be approved by the Engineer. The crushed stone shall be free from dirt or other objectionable matter. The coarse aggregate when tested by the methods described in B.S 812 shall have properties not exceeding the following values:- 190 TABLE VI-13 AGGREGATE SPECIFICATION FOR DENSE BITUMEN MACADAM, ASPHALTIC BASE AND WEARING COURSES Pavement Course Aggregate Crushing Value Flakiness Index 30 35 1.5 30 35 0.5 30 35 0.5 30 35 0.5 Dense Bitumen Macadam Base Dense Bitumen Macadam Base-course Asphaltic Concrete Basecourse Asphaltic Concrete Wearing Course Absorption Factor (II) Fine aggregate shall be the portion of the aggregate passing the No. 5mm opening sieve and shall be quarry fines produced from the crushing of igneous rock. They shall be composed of clean, tough, rough surfaced and angular particles, free from lumps, or ball of clay, loam and other deleterious substances. (III) Mineral filler shall consist of finely ground particles of hydrated lime, Portland cement or other non-plastic mineral matter approved by the Engineer. It shall be free from foreign or other objectionable material, and shall meet the following grading requirements: TABLE VI-14 SPECIFICATION FOR MINERAL FILLER SIEVE 300 m 200 m 75 m %BY WEIGHT PASSING 100 95 - 100 85 - 100 (B) BITUMINOUS MATERIAL 191 TABLE VI-15 QUALITY OF ASPHALTIC CEMENT PROPERTY ASPHALT CEMENT 80 - 100 PEN SPECIFIC GRAVITY @ 25C 1.00 - 1.05 1.01 - 1.06 SOFTENING POINT R AND B (C) 45 - 52 48 - 56 PENETRATION @ 25C---0.1 mm 80 - 100 60 - 70 DUCTILITY @ 25C---CM MINIMUM 100 100 LOSS ON HEATING FOR 5 HOURS AT 163C % BY WEIGHT----- MAX 0.5 0.2 SOLUBILITY IN CS2, % BY WT... MIN 99 99 DROP IN PENETRATION AFTER HEATING % ORIGINAL ----- MAX. 20 20 FLASH POINT (OPEN CUP) C MIN. 225 250 ASH. 0.5 0.5 % BY WT. MAX. (II) (III) APPROVAL OF MATERIALS 60 - 70 PEN Bitumen emulsion for tack coat shall be emulsion quick breaking type containing 30% - 50% bitumen. Cutback bitumen for priming shall be MC-O or MC-1. 6372. Representative samples of all materials proposed for use under these specifications shall be submitted to the Engineer by the Contractor at the Contractor's expense for test and for the preparation of trial mixes to determine the job mix formula. The Engineer shall make tests of the proposed materials and inform the Contractor if the tests indicate compliance with the specifications. Suitable sizes of aggregate shall be stored in bins at each point where bituminous materials are mixed. The bins shall be in such numbers and of such capacities as to ensure that an uninterrupted supply of all the necessary sizes of aggregates is available at the mixer. If aggregates are stockpiled prior to their transference to the bins, the stockpiles shall be formed on concrete floors laid to falls sufficient to permit drainage at the base of the stockpiles. Aggregates shall be handled to and from the stockpiles in a manner such that they are not contaminated by the ground or by extraneous matter and also in a manner such that segregation is prevented. In as much as possible the bins shall be covered to prevent dampness of aggregate by rain. Coarse and fine aggregates and aggregates from different sources shall be stockpiled separately and if aggregates of different gradings or from different sources are stockpiled in close proximity, the stockpiles shall be separated by partitioning. All aggregates produced or handled by hydraulic methods and all washed aggregates shall be stockpiled under cover for draining for at least 24 hours before use. 192 Material used as filler shall be stored in dry conditions to the satisfaction of the Engineer's Representative. No material shall be used until it has been approved by the Engineer. Permission to use material shall not be construed as an approval of its source nor any acceptance as continued acceptance. SAMPLING 6373. (1) The Contractor shall provide equipment, labour and such trained staff as may be required by the Engineer for carrying out the following tests on materials to be used in the manufacture of hot asphaltic concrete in accordance with the following standards: (A) Grading tests on aggregates in accordance with "Sampling and testing of mineral aggregate and fillers." (B) the latest B.S. 812 - Determination of binder content of mixed materials in accordance with either (I) Hot extraction method BT1 described in B.S. 598 (1974) - "Sampling and examination of bituminous road mixtures." The Contractor is to comply with the requirements of B.S. 598: and to the need of providing results in duplicate. or (II) By reflux extractor method. (2) Aggregates shall be sampled and tested on delivery to the mixing plant and after each extraction test and the result of each test shall be submitted to the Engineer or his Representative within 24 hours of the sample being taken. The number of such tests shall be adequate for proper control of the materials and shall not be limited to those made on specific instructions of the Engineer or his Representative. Samples of mixed materials shall be taken and tested during the first day's mixing and throughout the work to confirm that the gradings and binder contents are as specified. Such samples shall be taken either at the place and time of mixing or at the place of laying as directed by the Engineer or his Representative. Samples for testing shall also be cut from the surfacing as laid when directed by the Engineer or his Representative. The frequency of sampling mixed materials shall be at least once per day or once for each 90 tonne of material mixed whichever is the more frequent. The result of each test on mixed materials shall be submitted to the Engineer or his Representative within 24 hours of the sampling and any adjustments shown to be necessary shall be made immediately. Until such adjustments have been made and until a certificate to the effect has been forwarded to the Engineer or his Representative no further batches or mixed material shall be made. (3) Independent sampling and testing may be carried out by the Engineer throughout the contractor period and for this purpose the Contractor shall grant free access to the mixing plant and storage depots, supply materials and provide every facility for the Engineer or his Representative to take samples whenever required. In particular, throughout the contract, the Engineer will carry out control tests on the plant mix material using the marshall test apparatus. 193 (4) A certificate is to be obtained from the suppliers with each consignment of bitumen delivered, stating the grade of material being supplied, and these certificates are to be handed to the Engineer's Representative. (5) If the Engineer so requires, the Contractor shall arrange for the testing in an approved manner of all materials used throughout the contract to ensure that they are up to the standard specified, i.e. Aggregates, bitumen and such other materials as specified or decided by the Engineer. The Contractor shall arrange for the testing of materials incorporated in the works to ensure that they have been manufactured as specified, or as ordered by the Engineer. (6) Whenever the Contractor intends to carry out any of the above tests, he shall give the Engineer's Representative sufficient notice to enable him, should he so wish, to be present during the test. (7) Whenever the Contractor takes samples for testing, and where so directed he is to take duplicate samples and hand them to the Engineer's Representative. Such samples are to be properly packed and labelled as directed. (8) The Engineer's Representative shall be given the results in writing of all tests, as soon as they are available, and in any case not later than 24 hours after samples have been taken. (9) The Engineer shall be supplied with all necessary equipment, material and labour to perform any additional tests he may wish to carry out himself. (10) The cost of these tests including the provision of samples, will be deemed to have been included in the bill of quantities under the appropriate item. COMPOSITION OF MIXES 6374. Hot asphaltic concrete prepared under these specifications shall be composed of graded aggregates and asphalt cement within the limits set forth below. When plotted graphically the aggregate grading shall lie on a smooth curve within the envelope. 194 TABLE VI-16 GRADING ENVELOPE FOR BINDER AND WEARING COURSES % BY WEIGHT PASSING SIEVE SIZE 40mm - 65mm BINDER-COURSE 31.8mm 25mm 19.0mm 12.5mm 9.5mm 6.4mm 2.8mm 1.25mm 600m 300m 150m 75m 100 90 - 100 70 - 90 55 - 80 47 - 70 40 - 60 27 - 45 20 - 34 14 - 27 8 - 20 5 - 15 2 - 7 Bitumen Content % by weight of aggregate 4.5 - 6.5 40mm - 50mm WEARING-COURSE 85 75 65 50 36 26 18 13 7 100 100 100 - 100 - 92 - 82 - 65 - 51 - 40 - 30 - 24 - 14 5 - 8.0 Asphaltic Concrete mixes designed by the Contractor prior to the selection of JobMixes (see below) shall have combined aggregate gradings approximating as closely as possible to the plotted averages of the respective limits of grading specified above and shall comply with the following requirements: TABLE VI-17 PROPERTIES OF COMPACTED ASPHALTIC CONCRETE Property Base-course Optimum Bitumen Content 4.5% - 6.5% Stability, not less than 3.5KN Flow 2mm - 6mm Voids in total mixture 3% - 8% Voids filled with bitumen 65% - 72% Wearing-course 5.0% - 8.0% 3.5KN 2mm - 4mm 3% - 5% 75% - 82% The exact job-mix formula will depend on the nature and grading of the aggregate and the grade of bitumen and will be determined by the Engineer using the marshall method of mix design. For this purpose the Contractor shall supply to the Engineer without charge adequate samples (in separate containers) of coarse and fine aggregates and bitumen which he intends to use. The Engineer will, after testing, furnish the Contractor with the exact job-mix formula, which will be within the specified limits. 195 Before any asphaltic concrete is laid, the Contractor shall produce sufficient dry mixes in the plant and carry out sieve analysis to ensure that the correct grading is being obtained. In addition he shall produce a number of trial mixes to which the specified quality of bitumen has been added. He will then carry out extraction tests on this material and further sieve analysis on the aggregate in accordance with clause 6373 of the specification. The results of these tests on both the dry and wet mixes shall be approved by the Engineer before any surfacing is laid in the permanent works. JOB MIX FORMULA DEFINED: The job-mix formula is the single definite percentage of aggregate passing each required sieve size, a single definite bitumen content to be added to the aggregate, a single definite temperature at which the mixture is to be emptied from the mixer and a single definite temperature at which the mixture is to be delivered on the road. Unless specifically changed in writing by the Engineer, the maximum permissible variation from the job-mix formula shall be as follows: TABLE VI-18 PERMISSIBLE VARIATION PERCENT BY WEIGHT OF TOTAL MIX PERMISSIBLE VARIATION % BY WEIGHT OF TOTAL MIX Passing sieve 9.5mm and layer ± 5% Passing sieve 9.5m - 600m ± 4% Passing sieve 600m - 150m ± 3% Passing sieve 150m - 75m ± 0.1% Bitumen content ± 0.3% Notes: Temperature of Mixture when Temperature of Mixture on delivery on the road emptied from mixer145 C± 5 C 130°C ± 5°C The job-mix formula is liable to alteration by the Engineer throughout the progress of the work but at all times it will be within the specified limits. PREPARATION 6375. (1) PREPARATION OF AGGREGATES The coarse and fine aggregate shall be separately fed by feeders to the cold elevator or elevators in their proper proportions and at a rate to permit correct and uniform temperature control of the heating and drying operation. The aggregate shall be heated before entering the mixer to a temperature range of 120 C - 149 C. All aggregates in the bins of a temperature that will produce a mix outside the limits stated above or that contain moisture or expanding gases to cause "Foaming" in the mixture, shall be removed and replaced in their respective stock piles. All 196 aggregates that have been overheated shall be cooled before being deposited in the feeder. All unsuitable aggregates that may be in the weigh box or that become combined in the process of "Pulling" the bins shall be discarded. The screening efficiency shall be maintained within the limits set forth in Clause 6383. When these limits are exceeded, the material shall be discarded and the cause for such condition shall be corrected. (2) PREPARATION OF ASPHALT CEMENT The asphalt cement shall be delivered to the asphalt bucket at a temperature between 135 C and 163 C. All asphalt cement heated beyond 177 C at the plant before mixing or heated beyond 163 C during the mixing shall be rejected. No asphalt shall be used while "foaming". (3) PREPARATION OF MIXTURES: The exact proportions within the limits specified for each mix shall be regulated so as to produce a satisfactory mixture with all particles uniformly coated with bitumen. When batch mixing is used, the aggregate at the temperature specified, shall be mixed dry for a minimum of 15 seconds; the asphalt cement shall then be added in an evenly spread sheet over the full length of the mixer. The mixing shall be continued for a minimum of 30 to 45 seconds for all mixtures. The "initial time of mixing" shall be the interval of time between the opening of the weigh box and the opening of the mixer gate. The number of batches produced in one hour from the mixer shall not exceed 60. When continuous mixing is used the dry aggregates shall be thoroughly mixed before the addition of the asphalt cement. The asphalt cement shall then be added in an evenly spread sheet over the full width of the mixer by means of spray bars. The mixing shall be continued for a period of not less than 30 seconds. The "total time for mixing" shall be the ratio of the "dead load" in the mixer to the kilograms per minute delivered. The kilograms per minute delivered shall be determined by timing and weighing a load of mixed material. The "dead load" shall be determined by weighing the "mixer-full" of material. The dry mixing shall be the product of the ratio of dry mixer length to the total mixer length and total mixing time. The Engineer may vary the length of the dry and wet mixing periods, but under no circumstances shall the total mixing time be less than 45 seconds. The mixture shall be loaded into trucks in such a manner that segregation will not occur. The temperature of the mixture on arrival at the project site shall be as determined by the Engineer in keeping with the temperature range set for the mix design and heat losses in transit. TRANSPORTING MIXED MATERIALS 6376. The mixed materials shall be transported from mixing plant to site in clean metal lined vehicles. Every precaution is to be taken to avoid segregation of mixed materials and to ensure that they do not become contaminated with dust or foreign matter. Covers such as water-proof canvas and other insulation shall be provided when directed. 197 PREPARATION OF AREA TO BE PAVED 6377. The area to be paved shall be true to line and grade, having a dry and properly prepared surface prior to the start of paving operations. The area to be paved shall be free from all screenings, and other loose or foreign material. Where a base is rough or uneven, a levelling course shall be placed by use of a motor grader or spreader and shall be properly compacted before the placing of subsequent paving courses. When a levelling course is not required, all depressions and other irregularities shall be patched or corrected in a manner satisfactory to the Engineer. All fatty and unsuitable patches, excess crack or joint filler, and all surplus bituminous material shall be removed from the area to be paved. Blotting of excessive deposits of asphalt with sand or stone shall not be permitted. Where the area to be paved is an untreated soil or aggregate, it shall be primed. The prime coat shall consist of an application of the asphaltic material indicated, and at the rate specified in clause 6370. The prime coat shall be allowed to cure properly before any further operations are permitted on the primed area. A tack coat shall be applied when the surface to be paved is an existing Portland Cement concrete, or dry asphalt pavement. When a tack coat is required, it shall consist of an application of the asphaltic material indicated, and at the rate specified in clause 6370. In all cases the emulsion shall be allowed to break before laying. Prior to application of the tack coat, all loose or objectionable material will be removed from the surface by brooming or other approved method. After cleaning, the surface shall be inspected by the Engineer before the tack coat is applied. The tack coat will be applied evenly and by mechanical sprayer of approved type which is to comply with B.S. 1707. Where the time between the completion of one surface course and the laying of the subsequent surface course exceed 72 hours, a tack coat shall be applied to the preceding course as above but at a rate of spread of 4 - 4.5 square metres per litre. Such tack coat shall be at the Contractor's expense unless compliance with the 72 hours limit was impracticable. Tack coats shall be applied 24 hours in advance of bituminous surfacing work, or such longer period as is necessary to ensure complete breaking of the bitumen emulsion before bituminous surfacing are laid thereon. Traffic shall not be allowed on the tack coat before surfacing work begins. Concrete kerbs, channels, and similar objects shall be adequately masked and protected during the application of tack coats. The surface of curbs, gutters, vertical faces of existing pavements and all structures in actual contact with asphalt mixes shall be painted with a thin uniform coating of asphalt material to provide a closely bonded water-tight joint. TRIAL AREAS 6378. The first 30 metres of the approved bituminous mixture which is laid by each spreader shall be regarded as a trial area in order to establish a rolling procedure which will produce the required field density. 198 At least four samples of the material after rolling will be taken in accordance with part 1 section 3 of B.S. 598: when the work is at least 12 hours old in order to determine the degree of compaction. If the required density determined in accordance with clause 6381 is not obtained, the field rolling procedure will be changed so as to achieve the desired field density and the trial area will be cut out and replaced to the satisfaction of the Engineer. After mixing, the material must not be reheated other than by the means provided in or on the spreading machine. Materials must not be laid when the surface on which it is to be placed is wet or when rain appears imminent. It is essential that the material is laid at a temperature not less than 121 C and not more than 163 C. The Contractor is to provide at each spreader and finisher a suitable thermometer for testing the temperature of the material as it is being spread and is to take such temperature readings continually and record them hourly throughout each day's laying. This record shall be available for inspection by the Engineer who will himself make such additional temperature checks as he considers desirable. The materials shall be laid by approved mechanical paver in accordance with clause 6384. The spreader paver shall be in good mechanical condition and shall be capable of laying to the required width and profile without-causing segregation, dragging, burning, irregularities or other surface defects. When not operated on side forms, the paver will employ equalizing runners, evener arms or other automatic compensating devices to adjust the profile and confine the edges of the course to true lines. As soon as the first load of material has been spread, the texture of the unrolled surface shall be checked to determine its uniformity. The adjustment of the screed, tamping bars, feed screws, hopper feed, etc., shall be checked frequently to ensure uniform spreading of the mix to proper line and grade and adequate initial compaction. Segregation of materials shall not be permitted. If segregation occurs, the spreading operation shall be immediately suspended until the cause is determined and corrected. Any irregularities in alignment left by the paver shall be corrected by trimming directly behind the machine. Immediately after trimming, the edges of the course shall be thoroughly compacted by tamping. Distortion of the pavement during this operation shall be avoided. Edges against which additional pavement is to be placed shall be vertically formed to true line. A rake shall be used immediately behind the finisher, when required, to obtain a true line and vertical edge. Any irregularities in the surface of the pavement course shall be corrected directly behind the paver. Excess material forming high spots shall be removed by a shovel. Indented areas shall be filled with hot mix and smoothed with the back of a shovel being pulled over the surface. Fanning of materials over such areas shall not be permitted. The mixer capacity and the operating speed of the spreader shall be so adjusted as to ensure continuous laying and to avoid intermittent stopping of the spreader as far as is practicable. Hand spreading will not be permitted for general work, but will only be allowed for filling localized depressions, or as directed by the Engineer. 199 Hand laying of any bituminous material will only be permitted in the following circumstances:(i) for laying regulating courses of irregular shape and varying thickness. (ii) in confined spaces where it is impracticable for a paver to operate. (iii) for footways. (iv) at the approaches to expansion joints at bridges or viaducts. When a paver laying base material approaches an expansion joint at a bridge or viaduct it shall be taken out of use as soon as there is a danger of the material being laid fouling the joint. In laying the remainder of the pavement up to the joint and the corresponding area beyond it by hand, the joint or joint cavity shall not be fouled with surface material. Hand-raking of wearing course material which has been laid by a paver and the addition of such material by hand-spreading to the paved area for adjustment of level will only be permitted at the edges of the layers of materials or where otherwise directed by the Engineer. Where hand spreading and tamping is permitted, the mixed material is to be dumped on delivery upon existing hard clean surface or on approved metal sheets outside the area where it is to be spread and shall be distributed in to place immediately by means of hot shovels. It shall be spread with hot rakes in a uniformly loose layer to the full depth required. Materials are to be laid to the depths necessary to give the required thickness after compaction and they are to be finished true to profile. The Contractor shall break out and remove at his own expense any asphaltic concrete laid in trial areas if such asphaltic concrete fails to meet the specified requirements for asphaltic concrete surfacing. If for any reason the quality, grading or supply source of aggregates or the quality or source of bitumen is changed, or at any time the cause of variations outside the permissible limits cannot be corrected for reasons beyond the Contractor's control, the Engineer may require the Contractor to carry out additional laboratory tests and/or the construction of additional trial areas depending on the extent of the change or variation. COMPACTION 6379. After spreading, the mix shall be thoroughly and uniformly compacted by rolling. The initial 'breakdown' rolling shall be done with three wheel smooth roller, followed by intermediate rolling with high- pressure typed pneumatic roller. The final rolling shall be with a tandem roller. During rolling, the roller wheels shall be kept moist with only sufficient water to avoid picking up material. Heavy equipment or rollers shall not be permitted-to stand on finished surface until it has thoroughly cooled. In the initial rolling the three-wheel smooth roller shall proceed on-to the fresh material with-the rear or driven wheels leading. The rolling shall start as soon after laying as conditions permit and when the material-is still at a temperature of not 200 less than 99 C. The weight per unit width of the rear wheel shall be between 45 - 65 Kg per centimetre width. After the longitudinal joints and edges have been compacted rolling shall start longitudinally at the sides and gradually progress towards the centre of the pavement, except on super-elevated curves where rolling shall begin on the low side and progress to the high side. Each pass of the roller shall overlap the preceding one by about one half width of the rear wheel. The roller should move at a slow but uniform speed not exceeding 8 kilometres per hour. The roller shall be in good condition, and capable of being reversed without back lash, and the line of rolling shall not be suddenly changed or the direction of rolling suddenly reversed, thereby displacing the mix. If rolling causes displacement of the material the affected areas shall be loosened at once with shovels or rakes and restored to the original grade of loose material before being re-rolled. The intermediate rolling shall be done with a pneumatic roller exerting compactive ground pressures between 5.6 - 8.4 kilograms per sq. cm. The Contractor shall furnish to the Engineer charts or tabulations showing the contact areas and contact pressures for the full range of tyre inflation pressures and for the full range of tyre loadings for each type and size compactor tyre furnished. The intermediate rolling shall follow the breakdown rolling as closely as possible and while the mix is still at a temperature of 70 C - 85 C. Rolling shall be continuous until the mix is thoroughly compacted and the density specified in Clause 6381 is achieved. Turning of pneumatic rollers on the hot mix which causes undue displacement shall not be permitted. The final rolling shall be accomplished-with two-wheel tandem roller while the material is still warm enough for the removal of roller marks. JOINTS 6380. All joints shall be vertical, properly formed to the correct line and level; if necessary they shall be cut back to achieve this. A template made to the shape of the true line and width may be placed at each end of the construction joint to create vertical straight finish. Joints in the surface course should be staggered with those in the binder course and must be kept straight, when the abutting lane is not placed the same day or if the edge of the first strip has been distorted by traffic the joint shall be cut back to an even line and then be coated with bitumen before laying the adjoining strip. All joints on completion are to present the same texture, density and smoothness as other sections of the course. FIELD DENSITY OF ROLLED ASPHALT 6381. Density tests of the asphalt surfacing after compaction shall be taken from the trial area and later at intervals throughout the course of the work and compared with the density of-control specimens taken from the same material before laying, all in accordance with the following procedure: (a) A sample of mixed material will be taken from a lorry before the material is delivered to the spreader, and three specimens shall be made and their density measured by the Engineer by the immersion method. The average of the two close specimens will be taken as the control density of that particular batch. (b) The pavement will be marked to show where the lorry load of material (from which the sample was taken) is laid, so that field density samples can be taken for comparison with the control specimen. 201 (c) After completion of rolling, three samples are to be cut from each area so marked in positions indicated by the Engineer. (d) The samples shall be taken in accordance with part 1 section 3 of B.S. 598 (1974) and the density calculated by weighing in air and weighing in water in accordance with part 6 of B.S. 598 (1974). The average of two close results of the samples will be taken as the density of the compacted material in that area. (e) This density will not be less than 100% of the control density determined as above. When an approved rolling procedure has been established, each course will be sampled in accordance with the above at the rate of one sample area for each 84 square metres placed or one sample area every 2 hours (whichever is more frequent). Material which does not achieve the required density will either be cut out and replaced or be further compacted until the required density is obtained. FINISHED LEVELS 6382. The surfacing will be finished to the required levels shown on the drawings. Any deviation exceeding 5mm from these levels will be corrected at the Contractor's expense by scarifying, cutting out and removing all loosened materials, adding new materials, as required, re-shaping and rolling. No materials loosened by scarifying or cutting out, will be left in position or otherwise re-used. Except across the crown of a camber, the finished surface shall be of such smoothness that when tested with a 3 metre straight edge placed anywhere and in any direction on the surface, there shall not be a gap greater than 3mm between the bottom of the straight edge and the surface of the pavement anywhere along the straight edge. Should the new asphalt surface be dragged, churned up, become soft, show signs of segregation, show that stripping of the binder from the aggregate has occurred, or suffer other damage during or after being laid, the Contractor will remove the damaged or faulty work at his own expense and replace with fresh material, laid and compacted to the correct level and density to the approval of the Engineer. ASPHALTIC CONCRETE 6383. (1) GENERAL EQUIPMENT REQUIREMENT MIXING PLANT All equipment furnished by the Contractor shall be of approved design and shall be maintained in its best mechanical condition. Equipment shall be serviced and lubricated away from the paving site; units that drip fuel, oil and grease shall be removed from the project until such leakage is corrected to the satisfaction of the Engineer. This is necessary because fuel leakage can be injurious to newly laid asphaltic concrete. (2) ASPHALTIC PLANT SITE The plant site shall have sufficient storage space for separate stock piles; bins or stalls for each size of aggregate, and the different aggregate sizes shall be kept separated until they have been delivered by the feeder or feeders to the boot of the cold elevator or elevators in neat and orderly condition and the separate stock piles shall be readily accessible for sampling. Samples from each bins shall be graded from time to time for conformity to design size otherwise adjustment may be necessary. (3) THE ASPHALTIC CONCRETE PLANT 202 The plant shall be either the batch mixing type or the continuous mixing type meeting the following requirements. (A) REQUIREMENTS FOR ALL PLANTS (I) UNIFORMITY: The plants shall be so designed, co-ordinated and operated to produce a mix uniformly within the job-mix tolerances as specified in Clause 6374 Table VI-18 Paragraph 5. (II) EQUIPMENT FOR PREPARATION OF ASPHALT. Tanks for storage of asphalt shall be provided with a device for controlled heating of the material to temperature requirements set forth in the specifications. Heating shall be accomplished by steam or oil coils, electricity or other means such that no flame shall come in contact with the heating tank. All lines shall be checked periodically under full pressure for leakage. All line valves shall have clear and permanent markings to indicate all openable and closable positions. A circulating system for the asphalt of adequate size to ensure proper and continuous circulation between storage tank and mixer during the entire operating period shall be provided. All pipe lines and fittings shall be properly insulated and heated. The discharge end of the circulating pipe-line shall be maintained below the surface of the asphalt in the tank while the pump is in operation. Storage tank capacity shall be sufficient for at least one day's run. (III) COLD AGGREGATE FEEDER The plant shall be provided with an accurate mechanical means for uniformly feeding the mineral aggregate into the drier to secure a uniform production and a uniform temperature. The feeder or feeders shall be capable of delivering the maximum weight of aggregate sizes required in their proper proportion. The feeder shall provide for adjustment of total and proportional feed and be capable of being locked in any position. When more than one cold elevator is used each shall be fed as a separate unit and the individual controls shall be integrated with a total master control. (IV) DRIER The plant shall include a rotary drum drier that will continuously agitate the mineral aggregates during the heating and drying process. It shall be capable of heating and drying all aggregates specified in the necessary quantities to supply the mixing unit continuously at its operating capacity and at the temperature and maximum bitumen content specified. (V) SCREENS The plant shall have screens of the shaker or vibrating type and be capable of screening all aggregates to the sizes required for proportioning. The screens shall have normal capacity slightly in excess of the full capacity of the mixer or the drier. The plant screens shall have an efficiency such that when measured by weight there will be not more than 5% of oversize material in bin No. 1 (fine aggregate), not more than 15% undersize and/or 10% oversize in bin No. 2 and not more than 20% undersize and/or 5% oversize in bin No. 3, and not more than 20% undersize and/or 0% oversize in bin No. 4. The Contractor shall expose the screens for inspection at the request of the Engineer. These 203 screen tolerances are for general guidance and shall not invalidate the specified job-mix tolerances. (VI) BINS Bins shall be divided into at least three compartments for any mix composition other than a base (binder) composition, and at least four compartments for a wearing course. They shall be arranged to ensure separate storage of the appropriate fractions of aggregate. The bin sizes shall be adequate for continuous operation of the plant at rated capacity. Adequate additional dry storage shall be provided for mineral filler when required and provision made for proportioning it into the mix Each compartment shall be provided with an overflow pipe that shall be of such size and location as to prevent any backing up of material into other compartments or bins or against the screens. The overflow material shall be wasted. (VII) ASPHALT CONTROL UNIT Satisfactory means, either by weighing, metering or volumetric measurements, shall be provided to obtain the required amount of asphalt in the mix within the tolerances specified. Where the quantity of asphalt is controlled by metering, provision shall be made whereby the amount of asphalt delivered through the meter may be readily checked by weight. Suitable steam jacketing or other insulation for maintaining the specified temperature of asphalt in pipe lines, metres, weigh buckets, spray bars, flow lines, or other containers shall be provided. (VIII) THERMOMETRIC EQUIPMENT An armoured thermometer reading from 90 C to 205 C shall be fixed in the asphalt feed line at a suitable location near the discharge valve at the mixer unit. The plant shall be further equipped with an approved dial-scale, mercury-actuated thermometer, a recording electric pyrometer or other approved thermometric instrument having an accuracy of ± 2 C and a sensitivity which will provide an indication of temperature change at the rate of not less than 5 C per minute. It shall be so placed at the discharge chute of the drier to register automatically or indicate the temperature of the heated aggregate. The Engineer shall have the right to test the efficiency of thermometric instruments for better control of asphalt, aggregate and mix temperatures. The Engineer shall direct the immediate repair or replacement of any instrument yielding inaccurate or inconsistent readings. (IX) DUST COLLECTOR The plant shall be provided with a dust collector, designed to waste, or return uniformly to the hot elevator, all or part of the material collected, as directed by the Engineer. Prior to permitting the return of such collected dust, the Engineer shall examine its characteristics in relation to the mix requirements, and shall designate the quantity to be returned. When dust is permitted to be returned to the hot elevator, it shall be accomplished by mechanical means in a constant and uniform flow. All plants shall have mixer covers and such additional housing as may be necessary to ensure the proper collection of dust (X) SAFETY REQUIREMENTS 204 Adequate and safe stairways to the mixer platform and guarded ladders to other plant units shall be provided. All gears, pulleys, chains, sprockets and other dangerous moving parts shall be well guarded and protected. Ample and unobstructed space shall be provided on the mixing platform. A clear and unobstructed passage shall be maintained at all times in and around the truck loading space. This space shall be free from drippings from the mixing platform. A ladder, or platform, shall be so located at the truck loading space to permit easy and safe inspection or sampling of the mix as it is delivered into the truck. Adequate overhead protection should be provided where necessary. It is the Contractor's responsibility to ensure the plant or the plant site shall be free from fire hazard. (XI) MIXING TIME All plants shall be equipped with a positive means to govern the time of mixing. (B) SPECIAL REQUIREMENTS FOR BATCH TYPE PLANTS (1) PLANT SCALES Scales for any weigh-box or hopper may be of either the beam or springless dial type and shall be of a standard make and design, accurate to 0.005 of the indicated load. When scales are of the beam type, there shall be tare beam for balancing the hopper and a separate beam shall be provided which shall be capable of functioning when the load being applied is within 45 kilograms of the weight desired. Each beam shall have a locking device designed and so located that the beam can easily be suspended or thrown into action. Dial scales shall be springless and of a standard make. They shall be designed, constructed and installed in such a manner as to be free from vibration. They shall also be of such size that the numerical figures on the dial can be read at a distance of 3 metres. All dials shall be so located as to be plainly visible to the operator at all times. The end of the pointer shall be set close to the face of the dial and shall be free from excessive parallax. The scale shall be provided with adjustable pointers for marking the weight of each material to be weighed into the batch which shall automatically cut off feeder system when the required weight is attained. Scales for the weighing of asphalt shall conform to the requirements for aggregate scales, except that beam scales shall consist of a full capacity beam and a tare beam. The minimum graduation shall not be greater than 1 kilogram and there shall be attached a tell-tale device which will start to function when the load being applied is within 10 kilograms of the weight desired. Dial scales for weighing the asphalt shall read to the nearest 450g. All scales for weighing the asphalt shall have a capacity of not more than 15% of the normal capacity of the mixer. Scales shall be satisfactory to the Engineer and shall be tested and sealed as often as the Engineer may deem it necessary to ensure their accuracy. All weighing equipment shall be substantially constructed and of a design which will permit easy realignment and adjustment. Weighing equipment that easily gets out of adjustment shall be replaced when so ordered. The Contractor shall provide and have at hand at least ten 25 kilogram standard weights for frequent testing of all scales. For each scale, a suitable cradle, 205 or platform, shall be provided for applying the test load so that the load is uniformly distributed. The test weights shall be kept clean and stored near the scales. Volumetric proportioning of heated and screened aggregates shall be permissible provided the volumetric system is a standard equipment furnished with the plant when first sold by the manufacturer. Convenient and accurate scales and facilities shall be provided for checking the measuring devices by weight. (II) BINS In addition to the requirements stated in clause 6383 (3A), each compartment shall be provided with its individual outlet gate, designed and constructed so that when closed there shall be no leakage into the weigh box. The gates shall be cut off quickly, completely and easily and prevent excessive overdrawn. (III) WEIGH BOX OR HOPPER Equipment shall include a means for accurately weighing each bin size of aggregate in a weigh box or hopper suspended on scales ample in size to hold a full batch without hand raking or running over. The weigh box or hopper shall be supported on a fulcrum: with knife edges and shall be so constructed that they will not easily be thrown out of alignment. Gates on hopper shall be so constructed as to prevent leakage when they are closed. Proportioning of aggregates and charging of mixer shall be performed so as to blend the aggregates thoroughly and prevent segregation in the mixer. (IV) ASPHALT MEASURING EQUIPMENT Asphalt measuring equipment provided on the plant shall be capable of accurately measuring into each batch the required amount of asphalt within a tolerance of ±0.3%. When an asphalt bucket is used, it shall be a non tilting type provided with a loose sheet-metal cover. The capacity of the asphalt bucket shall be at least 10% in excess of the weight of asphalt required for a one-batch mix. The plant shall have a steam-jacketed quick-closing, non-dripping, charging valve. The length of the discharge opening or spray bar shall not be less than three-fourths of the length of the mixer and it shall discharge directly into the mixer. The discharge system shall be designed and arranged to deliver the asphalt the full length of the mixer in a thin, uniform sheet or in multiple streams or sprays except in the case of a rotary mixer where the asphalt is sprayed. When a volumetric meter is used, the meter shall be designed and constructed so that it will automatically meter the asphalt into each batch. The dial to indicate the amount of asphalt shall have a capacity of at least 10% in excess of the weight of asphalt required in one batch. The meter shall be constructed so that it may be locked at any dial setting and will automatically reset to this reading after the addition of asphalt to each batch. The dial shall be in full view of the mixer operator. The flow of asphalt shall be automatically controlled so that it shall begin when the dry mixing period is over and all of the asphalt required for one batch shall be discharged in not more than 15 seconds after the flow has started. The size and spacing of the spray bar openings shall provide a uniform application of asphalt the full length of the mixer. The section of the asphalt flow line between the charging valve and the spray bar shall be provided with a valve and outlet for checking and testing the accuracy of the meter. 206 (V) MIXER The plant shall have a mixer of approved type such as standard twin pug-mill batch type, steam-jacketed and a batch capacity of not less than 1000 kilograms. It shall be capable of producing a uniform mix within the job-mix tolerances established by the Engineer. Deviation in size of batches will be permitted to provide for mixing batches 20% below or 15% above the rated capacity of the mixer, provided the quality of the mix is not impaired. The paddles shall be set in such a manner to ensure a completely uniform mix. If not enclosed, the mixer box shall be equipped with a dust hood to prevent loss of dust. The mixer shall be so constructed as to prevent leakage of contents until the batch is to be discharged. (VI) TIME LOCK AND BATCH COUNTER The mixer shall have an accurate time lock to control the operation of a complete mixing cycle by locking the weigh box gate after the charging of the mixer, until the closing of the mixer gate at the completion of the cycle. The time lock shall also lock the asphalt bucket throughout the dry mixing period and shall lock the mixer gate throughout the dry and wet mixing periods. The dry mixing period is the interval of the time between the opening of the weigh box gate and the application of asphalt. The wet mixing period is normally the interval of time between the application of all asphalt and the opening of the mixer gate for discharge. When asphalt is applied by a spray system, the wet mixing time shall begin with the start of asphalt spray. The Engineer shall, after tests of a few trial mixes, designate the length of both dry and wet mixing periods to ensure a uniform and completely coated mix. Excessive wet mixing shall be avoided. Control of the timing shall be flexible, permitting timed intervals of not less than five seconds throughout cycles up to three minutes. A mechanical batch counter, designed to register only completely mixed batches shall be installed. (C) SPECIAL REQUIREMENTS FOR CONTINUOUS MIXING PLANTS (I) BINS In addition to the requirements stated in clause 6383 (3A), each compartment shall have sufficient capacity to ensure the minimum depth of aggregate necessary for the proper cut-off action of the bin outlet, and to compensate for normal variation in depth due to aggregate grading. The bin partitions shall extend close enough to the apron or vibrating plate to prevent cross-flow of the unstrucked material. (II) GRADATION CONTROL UNIT The plant shall include a means for accurately proportioning each bin size of aggregate either by weight or by volumetric measurement. When gradation control is by volume, the unit shall include a feeder mounted under the compartment bins. Each bin shall have an accurately controlled individual gate to form an orifice for volumetrically measuring the material drawn from each respective bin compartment. The orifice shall be rectangular, with one dimension, adjustable by positive mechanical adjuster and provided with a lock. Indicators shall be provided on each gate to show the gate opening in millilitres. Mineral filler, if specified, shall be proportioned separately from a suitable hopper equipped with an adjustable feed 207 which may be accurately and conveniently calibrated and which shall be interlocked with the aggregate and asphalt feeds. The feeder equipment for the mineral filler shall meet the approval of the Engineer. (III) CALIBRATION AND SAMPLING The Contractor shall provide qualified personnel to calibrate the plant so that it will produce the specified composition of mixture within the accuracy and uniformity tolerances specified. The plant shall be calibrated at the beginning of each project and whenever there is any change in source, size or unit weight of aggregate. The plant shall be re-calibrated whenever the actual weight of bituminous concrete varies from its theoretical weight by more than the specified limit or when the tolerance set forth in "formula for job-mix" for the specified item are exceeded. The plant shall be equipped so that bin samples weighing approximated 4.5 kg can be conveniently obtained without intermingling or segregation of the aggregate. (IV) SYNCHRONIZATION OF AGGREGATE AND ASPHALT FEED Satisfactory means shall be provided to afford positive interlocking control between the flow of aggregate from the bins and the flow of asphalt from the meter or other proportioning device. This control shall be accomplished by interlocking mechanical means or by any positive method approved by the Engineer capable of being controlled by the operator. The aggregate bins shall be provided with automatic controls and signal devices which will warn of low levels and which will automatically stop the flow of all aggregate and asphalt to the mixer when the aggregate in any one bin is so low that the feeder will not operate at set capacity. The asphalt storage system shall be provided with automatic controls and signal devices which will warn of low levels of asphalt and which will automatically stop the entire plant operation when the asphalt storage level is to the point of exposing the feed end of the asphalt suction line. (V) MIXER The plant shall have a steam-jacketed, twin-pugmill, continuous type mixer of not less than 700 kilograms per minute rated capacity. The mixer shall be in first class condition equipped with a sufficient number of blades or paddles and operated at such a speed as to produce a properly and uniformly mixed composition within the job-mix tolerance specified. The paddles shall be of a type adjustable for angular position on the shafts and reversible by remote control to retard the flow of the mix. The mixer shall carry a manufacturer's plate giving the net volumetric contents of the mixer at the several heights inscribed on the permanent gauge. The mixer shall have a cut off gate at its discharge and adequately sealed against leakage between truck loads. The determination of mixing time shall be by a weight method under the following method unless otherwise required:Mixing Time in Seconds = pugmill dead capacity in kilograms Pugmill output in Kilograms per second. 208 The weights shall be determined for the job from the tests made by the Engineer. (VI) TRUCK SCALES The Contractor shall provide conveniently accessible platform trucks scales at the plant site for use in obtaining the net weight of each load of finished mix. ASPHALTIC CONCRETE PAVERS 6384. Bituminous concrete pavers shall be self-powered machines capable of spreading and finishing the mixtures true to the line, grade and crown with or without the use of forms or side supports. For two lane construction, pavers shall be capable of laying to half widths plus or minus 150mm. The screed assembly shall be such that it will be capable of laying courses from a minimum of 2.5 metres in width in steps of 150mm to a maximum of 3.85 metres in width. Pavers shall employ mechanical devices such as equalizing runners, straight-edge runners, evener arms or other compensating devices that will adjust the grade and confine the edge of the courses to true lines. Pavers shall be equipped with hoppers and distributing screws of the reversing type to evenly place the mixtures in front of the screeds. The screed shall be a strike-off device operated by cutting, crowding or other practical action which is effective on the mixtures without tearing, shoving or gouging, and which produces a finished surface without segregation. The screed shall be adjustable as to level and shall have an indicating level attached thereto in full view of the operator. The pavers shall be further equipped with blending or joint levelling devices for smoothing and adjusting all longitudinal joints between adjacent stripes of surface course. The paver shall be capable of being operated at variable forward speeds consistent with the satisfactory laying of the mixtures. The paver shall be equipped with an efficient steering device, and shall be capable of travelling both forward and in reverse. ROLLERS Rolling equipment shall consist of steel-wheel and pneumatic tyre rollers, or a combination of both described as follows:(A) STEEL-WHEEL ROLLERS May be of three types: Three-Wheel Rollers of 10 to 12 tonne in weight, Two-Axle Tandem Rollers of 7 to 12 tonne in weight and Three-Axle Tandem Rollers of 12 to 16 tonne in weight. These rollers shall be equipped with power units of not less than four cylinders and under working conditions shall develop a compression in the rear wheels of 45-65 Kg per centimetre of roller width. Rollers shall be in good working condition and be free from backlash, faulty steering mechanism, or worn parts. Rollers shall be equipped with adjustable scrapers to keep the rolls clean and with efficient means of keeping the wheels wet to prevent mixes from sticking to the rolls. Rollers shall also be free of flat areas, openings or projections which will mar the surface of the pavement. 209 The Three-Axle Tandem Rollers shall be so constructed that, when locked in position for all treads to be in one plane, the roller wheels are held with such rigidity that, if either front or centre wheel is unsupported, the other two wheels will not vary from the plane by more than 6mm. (B) The pneumatic-tyre rollers shall be self propelled, multiple-axle multiple-wheel type with smooth-tread pneumatic tyres of equal size and diameter. The tyres shall be staggered on the axles at such spacings and overlaps as will provide uniform compactive pressure for the full compacting width of the roller, when operating. Oscillation of the wheels, if provided, shall be in vertical plane only. The pneumatic tyred roller shall be capable of: (I) Being ballasted sufficiently to bring its loaded weight to at least 2½ times its own weight and (II) Of exerting compactive ground pressures at least 5.6 kilograms per square centimetre, 5.6 - 8.4Kg/cm² preferred. Vehicles used for the transportation of hot-mix asphalt from the plant to the site of work shall have tight metal bottoms and shall be free from dust, screenings, petroleum oils, volatiles or other mineral spirits which may affect the mix being hauled. The truck beds shall be painted, or sprayed with a lime-water or soap solution, at least once a day or as often as required. After this operation the truck bed shall be elevated and thoroughly drained, no excess solution shall be permitted. When ordered by the Engineer, trucks shall be suitably insulated and provided with covers of canvas or other material of sufficient size and weight to protect the load from adverse weather conditions. When variations in size, speed and condition of trucks are such as to interfere with orderly and continuous operation, the Engineer may order suitable substitutions to be made. INSPECTION AND 6385. (1) CONTROL OF ASPHALT MIXING PLANT (2) GENERAL PROVISIONS For verification of weights and measures, character and quality of materials and determination of temperatures used in the preparation of the paving mixes, the Engineer or his Representative shall at all times have access to all portions of the paving plant, aggregate plant, storage yards and other facilities for producing and processing the materials of construction. All sampling and testing of processed and unprocessed material shall be under the control and direction of the Engineer. JOB-MIX FORMULA The Engineer shall make frequent gradation analyses of the hot aggregate and of the completed mix to be certain that the materials being used and produced are within the tolerances of the job-mix formula and the specifications of the mix number being used. If the mix is found to be outside of the job-mix formula tolerances, or outside of the specification limits, corrections shall be made in quantities measured from the hot bins and suitable changes made at the cold bin feeders. 210 (3) SAMPLING AND TESTING Stockpiles and bins shall be sampled for gradation analysis, dust coating and for other purposes, at the option of the Engineer. Gradation analysis of material from each hot bin shall be performed and a combined analyses computed at least twice a day - once in the forenoon, and once in the afternoon. A combined gradation and analyses shall be performed at least twice a day. If materials do not run uniform, more frequent tests shall be made. When requested by the Engineer, the Contractor shall provide representative samples from each of the hot bins from convenient doors in the side of each bin, or by drawing aggregate from each bin through the mixing chamber (without asphalt) into a trunk or other receptacle. At least one sample shall be taken from each 250 tonne of the mix being produced. Samples shall be used to determine compliance with general and special requirements. PLANT TESTING LABORATORY At each plant site, there shall be provided a testing laboratory for joint use of the producer's quality control and acceptance testing functions, and the Engineer's Representative, during periods of mix production, sampling, and testing, and whenever materials subject to the provisions of these specifications are being supplied or tested. The bituminous plant testing laboratory shall have a floor area of not less than 14 square metres, with a ceiling height of not less than 2.3 metres. The laboratory shall be weather-tight, sufficiently heated in cold weather, air-conditioned in hot weather, to maintain temperatures, for testing purposes, of 24 C plus or minus 2.5 C degrees centigrade. It shall be so located on the asphalt plant site as to provide an unobstructed view from one of its windows of the trucks as they are located with the plant mixed materials. The bituminous plant testing laboratory shall have: (1) adequate artificial lighting (2) electrical outlets sufficient in number and capacity for operating the required testing equipment and for drying samples (3) fire extinguishers approved by the Engineer's Representative. (4) work benches for testing with dimensions not less than 0.75 metres by 3 (5) a desk or table and at least two chairs (6) sanitary facilities convenient to the testing laboratory metres. (7) exhaust fan to outside air, with minimum blade diameter of 300mm to adequately handle laboratory dust and fumes (8) telephone (9) 4-drawer legal size file cabinet 211 (10) a sink with running water and attached drain-board and drain capable of handling elutriable material (11) a metal stand to hold sieves used in washing elutriable material. (12) a 2-element hot plate or other comparable heating device, with suitable dial type thermostatically controlled to adjust the heat, for drying aggregates (13) mechanical shaker and appropriate sieves conforming to requirements of current B.S. 812 or ASTM designation E-ll for determining the gradation of coarse and fine aggregates in accordance with ASTM C 136 or AASHTO T-27 (14) testing equipment meeting the requirements of current B.S. 598(1974 or ASTM D 2172 Method A, for the extraction of bitumen from bituminous paving mixtures. (15) apparatus to perform the Marshall procedures as specified in B.S. 812 and ASTM C 127 and C 128 (16) an oven of suitable size to contain enough bituminous paving mixture to prepare 3 Marshall specimens (17) materials other necessary small hand tools required for proper sampling and testing of (18) library containing all British Standards referenced herein, ASTM Parts 10 and 11; and AASHTO Tests, Part II. Approval of the bituminous plant and testing laboratory by the Engineer, will require all the above facilities and equipment in good working order, during all periods of mix production, sampling, and testing; and whenever materials subject to the provisions of these specifications are being supplied or tested. Failure to provide any of the above shall be sufficient cause for disapproving the bituminous plant operations. (CLAUSES 6386 - 6399 INCLUSIVE NOT USED) 212 SECTION VI - ROADWORK PART (E) MISCELLANEOUS KILOMETRE POSTS 6400. Where directed by the Engineer, new precast reinforced concrete kilometre posts shall be provided to indicate distance in kilometres along the road. The kilometre posts shall conform with the accepted standards of the Federal Ministry of Works for kilometre posts on Trunk "A" Roads, as shown on Federal Ministry of Works Drawing No. 28016, or such modification thereof as the Engineer may direct. Normally, the new kilometre posts, shall be constructed of Grade 15 N/mm² concrete, be approximately 2.0 metres in length, and shall have a roughly triangular cross-section the back face being 300mm wide with two 50mm perpendicular offsets and the two side surfaces being 400mm wide with the apex truncated to give a 50mm flat surface. The kilometre posts shall be reinforced longitudinally with three 16.0mm diameter mild steel rods having 6mm mild steel stirrups at 250mm centres. The kilometre posts shall be erected with the apex facing the road and shall be located on the right hand side of the road(when looking towards the higher distance in kilometres). They shall be set in a 600mm x 750mm x 380mm (deep). block of grade 15 N/mm² concrete, and shall project 900mm above the ground level. The distance between the nearest edge of the kilometre post and the edge of the ultimate carriageway shall not be less than 3 metres. All kilometre posts shall be twice painted with a white (non-reflective) paint and have the letters and numbers stencilled on in green reflective paint. The lettering and distance in kilometre. Origin shall be approved by the Engineer. Where existing kilometre posts are in good condition, the Engineer may direct that these be taken down, painted and treated as for new kilometre posts, and re-erected at the correct chainages. CULVERT BEACONS 6401. Where directed by the Engineer, culverts shall be provided with two precast concrete beacons located diagonally near the ends of the culvert as directed by the Engineer. The beacons shall be cast of grade 15N/mm² concrete and shall be 230mm, 150mm thick and 900mm long, and shall project 45mm above the ground level. They shall be set at the left hand side of the road with the broad face facing the traffic and on this face shall be stencilled, in two coats of black oil paint figuring 20mm high on a two coat white painted background, the appropriate mileage and culvert number as directed by the Engineer. The beacons shall be located in a readily visible position from the carriageway and as near as possible to the ends of the culverts, but in no case shall they be nearer than 3.0 metres from the edge of the ultimate carriageway. All markings of culvert beacons shall be completed before the issue of the completion certificate for the section of road in question. Where directed by the Engineer, the appropriate reference marks may be painted on any flat easily visible and accessible surface of the culvert, such as on the head-walls of box culverts, in lieu of culvert beacons. In such cases the figuring shall be stencilled as described above on a white painted rectangular background as directed by the Engineer. ROAD WARNING SIGNS 6402. Where directed by the Engineer, road warning signs shall be provided by the Contractor at approaches to all dangerous curves, narrow bridges, railway level crossings etc. Warning signs shall be of approved standard design complying with the accepted 213 standards of the Federal Ministry of Works for use on Trunk "A" Roads. They shall be constructed of plain single-sided pressed aluminum, shall be suitably braced at the back, and shall be painted in the regulation manner. They shall be mounted on 76mm diameter tabular steel posts when supported from the ground or, where such a support may not cause an obstruction. They may be suspended as shown on the drawings or as may directed by the Engineer. The signs shall be erected in such locations and in such numbers as shown on the drawings or directed by the Engineer. They shall be erected, painted and completed in every way prior to the issue of the completion certificate for the section of the works in question. Payment for road warning signs shall be made under the appropriate item in the bill of quantities, or where no such item is included from the appropriate provisional sum. ADVANCE DIRECTION SIGNS 6403. The Contractor shall provide and erect advance direction signs in such numbers and in such locations as directed by the Engineer. The signs shall be of approved design complying in all respects with the accepted standards of the Federal Ministry of Works for use on trunk A roads. Generally they shall consist of plain single-sided pressed aluminum suitably braced at the back and painted in the regulation manner. The Engineer shall supply to the Contractor a more detailed specification and drawings for all advance direction signs required, showing their locations, sizes, structural details, types of support etc. The signs shall be erected, painted and completed in every way prior to the issue of the completion certificate for the section of the works in question. Payment for advance direction signs shall be from the appropriate item in the bill of quantities or where no such item is included, from the appropriate provisional sum. CARRIAGEWAY MARKINGS 6404. On completion of the surfacing of the carriage ways e.t.c., the Contractor shall construct such carriageway markings as are shown on the drawings or that may be directed by the Engineer. For smooth dense-textured road surfacing the markings shall consist of an approved ready coated self-adhering thermoplastic material. It shall be suitably reflectorised, be durable and long-wearing containing adequate anti-skid properties and the adhesive shall provide sufficient bond between the markings and the road surface as to prevent any undue movement either due to traffic action or due to temperature variations. For coarse-textured road surfacing such as surface dressing, the markings shall consist of an approved quick- setting thermoplastic composition applied hot by an approved 'line laying' machine. The composition shall be suitably reflectorised, have a setting time of not exceeding 60 seconds, be durable, long-wearing and have adequate anti-skid properties. When set the markings shall be sufficiently rigid and provide sufficient bond with the road surface as to prevent any undue distortion or movement due to traffic action or temperature variation. The type and colour of markings to be used shall be decided by the Engineer for the various kinds of usage and road surface, and all markings shall be completed prior to the issue of the completion certificate for the section of works in question. 214 Payment for carriageway markings shall be made per linear metres of marking from the appropriate item in the bill of quantities or, where no such item is included, from the appropriate provisional sum. PRECAST CONCRETE KERBS 6405. All precast concrete kerbs shall be in accordance with B.S. 340 and shall be of the sizes and dimension shown on the drawings or directed by the Engineer. The kerbs shall be manufactured using grade 20 N/mm² quality concrete and shall be cast in steel moulds, and adequately vibrated or pressed. The kerbs shall pass the tests for transverse strength and the absorption of water tests as described in the appropriate B.S 340. After casting they shall be lightly rubbed over with a carborundum stone and later to a smooth finish but shall not be slurried over with cement. The kerbs shall be cured for a period of 14 days by protection from the direct rays of the sun or from drying winds, and for the first 7 days after manufacture they shall be thoroughly saturated with water. Kerbs shall not be incorporated into the works until they are at least 28 days old. The vertical joints shall be filled in with grade M1 mortar and flush pointed. Where expansion joints occur in the carriageway such jointing shall be extended in the same plane through the kerbing, and kerb base and ducking when provided. Kerbs for radius work shall be purposely made to the required internal and external radii. For radii less than 6 metres they shall be 500mm long. All kerbs for radii work in excess of 15 metres radius may be straight kerbs and shall be 500mm long for radii up to 30 metres. Otherwise than above all kerbs shall be 1000mm long. Where shown on the drawings, or directed by the Engineer's Representative, precast concrete kerbs shall be laid on a grade 15 N/mm² concrete bed and haunched at the back as directed. All kerbs shall be bedded on a layer of grade M3 quality mortar and shall be laid true to line and level as shown on the drawings to the satisfaction of the Engineer's Representative. Payment shall be per linear metre of kerb from the appropriate item in the bill of quantities. PRECAST CONCRETE EDGING BLOCKS 6406. Where precast concrete edging blocks are specified, such as edging to footpaths, they shall be of the sizes and dimensions shown on the drawings or directed by the Engineer, shall be in accordance with B.S. 340 and generally shall comply with the provisions of the preceding clause for precast concrete kerbs. They shall be manufactured using 20 N/mm² grade quality concrete and shall be laid as directed true to line and level to the satisfaction of the Engineer's Representative. Payment shall be made per linear metre of edging under the appropriate item in the bill of quantities. PRECAST CONCRETE PAVING SLAB 6407. Precast concrete paving slab shall comply with BS. 368 "Precast Concrete Flags." Except where otherwise stated to the contrary or directed by the Engineer, the slabs shall be 50mm thick, and except where cutting is necessary, be of a uniform width of 450mm and a uniform length of 600mm. The paving slabs shall be adequately vibrated or pressed and shall have a smooth hard-wearing non-skid finish. The paving slabs shall be laid and bedded on approved compacted sand filling to the correct level, grade and cross-fall, so that when tested with a 3 metre straight edge placed in any position on the paving, the maximum deviation shall not exceed 6mm. Joints between the paving slabs shall be filled in with a slurry of cement mortar grade "Ml" brushed over the 215 paving in a circular motion until all the joint cavities are completely filled in to the satisfaction of the Engineer's Representative. Any excess slurry shall be removed and as soon as the joints have sufficiently hardened the whole of the paving shall be washed so as to leave the completed paving in a neat and workmanlike manner. The price for paving shall include all cutting, whether straight or curved, laying, bedding, jointing etc., And payment shall be made per square metre of completed paving from the appropriate item in the bill of quantities. GULLEY KERBS 6408. As shown on the drawings, or as directed by the Engineer precast concrete gulley kerbs shall be inserted at intervals in the kerbing to ensure a quick and complete run-off of surface rainwater from the carriageway. Gulley kerbs shall be constructed to the dimensions shown on the drawings or as directed by the Engineer and shall comply in all respects with the provisions of the relevant clause for precast concrete kerbs. The Contractor's attention is drawn to the necessity for accurate gradients of the kerbs and the edge of the carriageway, especially for flat gradients, to ensure that no surface water ponds on the carriageway, payment shall be per number of gulley kerbs placed from the appropriate item in the bill of quantities. GULLEY PIPES 6409. Gulley pipes shall be inserted into all gulley outlet kerbs to convey the surface water to the side drain or otherwise. The gulley pipes shall consist of approved PVC pipes or Class B asbestos cement pipe (150mm) in diameter, but the Engineer may direct that cast iron pipes be used where the pipe is under an access road etc. Where the depth of cover is less than 300mm on footpaths or less than 900mm on carriageways, the gulley pipe shall be bedded on a 300mm by 150mm concrete bed and given a 76mm thick concrete surround in grade 15 N/mm² concrete. Where a concrete bed or surround is not used the gulley pipe shall be adequately supported and anchored in position at the kerb and at its outlet by a bed and surround of grade 15 N/mm² concrete at least 300mm long. When completed all gulley pipes shall be flushed with water so as to leave the full internal of the pipe free from any mortar, concrete or other debris. Payment for gulley pipes shall be per linear metre of pipe and shall include all anchoring, fixing and necessary joining, but shall not include the provisions of a concrete bed and surround. PRECAST CONCRETE 6410. Where the outlet of gulley pipes is over an embankment, or where the existing CHANNELS ground is liable to erosion or otherwise as directed by the Engineer's Representative, precast concrete half-round channels of 225mm diameter or as directed, shall be laid to form a water course leading from the outlets of the 150mm diameter gulley pipes. The channels shall be cast in 600mm lengths of grade 15 N/mm² concrete and shall be accurately laid on a prepared bed, true to line and level and jointed with Grade M.3 mortar to the satisfaction of the Engineer's Representative. Both extremities of the channel shall be securely anchored and set in a bed of Grade 15 N/mm² concrete approximately at least 75mm wider than the external width of the channel and 150mm thick. Prior to the laying of the channels, the soil bed shall be properly shaped and compacted to provide an even bed for the channels throughout the whole of their length. Payment shall be per linear metre of channel laid, including all necessary bedding, jointing and anchoring, from the appropriate item in the bill of quantities. CAT'S EYES 6411. If shown on the drawings or directed by the Engineer, the Contractor shall provide and fix in position approved standard-type reflecting road studs known as "cats eyes". Payment shall be per number of cats eyes provided and fixed. And shall include for all 216 cutting out of the road surface and making good as necessary to the satisfaction of the Engineer's Representative. STREET LIGHTING 6412. Where provision for street lighting is included in the bill of quantities forming part of the main contract, the Engineer shall issue to the Contractor a separate street lighting specification and drawings for each individual project. The street lighting system shall be of the electrical type and generally shall comply with the relevant provision of the British standard code of practice, "C.P. 1004 parts 1 and 2 - Street lighting", or such other provisions specified by the Engineer. The types of cables, controls, lanterns and mountings to be employed shall be specified by the Engineer and the source and manufacturer's of same shall be approved by the Engineer. The actual electrical installation shall be carried out by a competent electrical sub-Contractor to be approved by the Engineer. Payment for street lighting shall be made from the appropriate items in the bill of quantities, or, where no such items are included, from the appropriate provisional sum. The street lighting shall be completed and tested to the satisfaction of the Engineer's Representative prior to the issue of the completion certificate for the section of work in question. TRAFFIC LIGHTS 6413. Where provision for traffic control lights are included in the bill of quantities forming part of the main contract, the Engineer shall issue to the Contractor a separate traffic light specification and drawings for each individual set employed. The traffic control lights shall be electrically operated and the types of cables, controls, lanterns and mountings shall be specified by the Engineer, and their source and manufacturers shall be approved by the Engineer. The actual electrical installation shall be carried out by a competent electrical sub-Contractor to be approved by the Engineer. Payment for traffic lights shall be made from the appropriate items in the bill of quantities or, where no such items are included, from the appropriate provisional sum. The traffic control lights shall be completed and tested to the satisfaction of the Engineers' Representative prior to the issue of the completion certificate for the section of work in question. ILLUMINATED GUARD POSTS 6414. Where illuminated guard posts, such as “keep right” signs at roundabouts etc., are to be provided, they shall be of the electrically operated, internally illuminated type having a pressed steel fluted type body with a vitreous enamel finish and rust proofed steel lantern with a stove enamel finish. For roundabouts etc., the guard post shall be fitted with a single aspect lantern having one 600mm x 300mm "keep right" glass panel. The Engineer shall issue to the Contractor a comprehensive specification and drawings for each individual type of guard post, indicating the types of cables, controls, lanterns and mountings to be employed and the source and manufacturers of same shall be subject to his approval. The actual electrical installation shall be carried out by an approved competent electrical sub-Contractor. Payment for guardposts shall be made from the appropriate items in the bill of quantities or, where no such items are included, from the appropriate provisional sum. The guardposts shall be completed and tested to the satisfaction of the Engineer's Representative prior to the issue of the completion certificate for the section of work in question. GUARD RAILS 6415. A. Scope 217 The work covered by this Clause consists of the construction of beam guard rails mounted on concrete or steel posts as shown on the DRAWINGS or as ordered by the Engineer's Representative. B. Material 1. Steel rail elements shall conform to the DRAWING and shall be of Armco Flex-Beam Guardrail of 12 gage, non-galvanized or equivalent. The minimum tensile strength when tested in conjunction with splices and end connections shall be 40,000 kg/cm², and the bolts attaching the rail element to posts shall be 15mm in diameter. Splices and end connections shall be as shown on the DRAWINGS and the minimum tensile strength of the splice and end connection assembly shall be 40,000 kg/cm². 2. Concrete posts shall conform to the design shown on the DRAWINGS. The concrete shall be of 20 N/mm² and shall conform to the applicable requirements of SECTION Il - CONCRETE: MASS AND REINFORCED of the GENERAL SPECIFICATION; "PART 8 - WORKMANSHIP". Reinforcing steel shall be as shown on the DRAWINGS and shall conform to the applicable requirements of SECTION ll CONCRETE: MASS AND REINFORCED of the GENERAL SPECIFICATION; PART "B" - WORKMANSHIP 3. Steel posts shall conform to the design shown on the DRAWINGS and shall conform to the applicable requirements of SECTION ll CONCRETE: MASS AND REINFORCED of the GENERAL SPECIFICATION. 4. White paint shall conform to the requirements of the applicable British Standards and the painting clauses set forth in Section V Clause 5049. C. Method of Construction The concrete posts shall be set in excavated holes and the backfill shall be firmly tamped in layers not more than 150mm thick in a manner satisfactory to the Engineer's Representative. All posts shall be plumb, properly spaced and to the prescribed line and grade. Post holes shall be excavated to such depth that backfill below the posts will be kept to the minimum and any such backfill shall be thoroughly compacted before setting the posts. The rail elements shall be erected to the required grade and line with the top edge in a straight line or smooth curve, parallel to or concentric with the roadway. Where a vertical transition is required the top edge of rail elements shall form the chords of a smooth vertical curve. At each end post, a single terminal section of rail element shall be erected and lapped in the direction of traffic. The Contractor's attention is directed to the details of guard rail transition at the approach end of the guard railing as shown on the DRAWINGS. No punching, drilling, reaming. cutting or welding of the rail elements or terminal sections will be permitted in the field unless provided for on the DRAWINGS or specifically approved by the Engineer. 218 All bolts and nuts attaching the rail element to the posts shall be hot-dip galvanized in accordance with the current ASTM Designation 153. All metal parts that are not galvanized shall be thoroughly cleaned and shop-painted with one coat of rust-inhibitive primer. Any metal surfaces from which the shop coat of rust-inhibitive primer has worn off, or on which the primer has become defective otherwise, shall be given a brush coat of the above specified rust-inhibitive primer before the first coat of white paint is applied. All exposed parts of the guard rail shall be given two field coats of white paint. Paint shall not be applied over a previous coat which is not thoroughly dry. D. Measurement The quantity of beam guard rail for which payment will be made will be the sum of the overall lengths of all sections of new beam guard rail constructed in accordance with the DRAWINGS and Specifications or as directed by the Engineer's Representative, measured along the face of the guard rail, including the terminal sections of the rail element. E. Payment Payment for beam guard rail shall be made at the unit rate shown in the Bill of Quantities which price shall include furnishing and erecting the guard rail complete, including excavation, backfilling, furnishing and setting posts, priming, painting, preservation treatment, the furnishing of all materials, labour and equipment, and all else necessary therefor and incidental hereto. DELINEATORS 6416. The Contractor shall furnish and erect delineators of hermetically sealed acrylic plastic prismatic reflector housed in embossed aluminum and provided with a single grommeted mounting hole, mounted on galvanized "U" section channel post as shown on the DRAWINGS or as directed by the Engineer's Representative. 1. Materials a. Prismatic Reflectors The housing shall be 0.50mm aluminum formed to approximately 85mm in diameter and 6mm in depth to retain the acrylic reflector. Housing shall be provided with embossed reinforcement ribs. A corrosion resistant metal grommet with 5mm inside diameter shall be expanded within the reflector mounting hole. The reflector shall be acrylic plastic and the Contractor shall specify the manufacturer of the raw material and the identification number of the particular moulding compound to be furnished. Acceptable formulations: TABLE VI-19 ACCEPTABLE FORMULATIONS FOR TYPE OF MOULDING COMPOUND MANUFACTURER 219 TRADE NAME TYPE OF MOULDING COMPOUND E.I. DUPONT DENEMOURS AND CO INC. LUCITE MH-140 ROHM AND HAAS CO. OR EQUIVALENT FLEXIGLASS V The reflector shall consist of a clear and transparent plastic face with 45.0 sq. cm. of reflecting area, herein referred to as the lens with a heat resistant plastic coated back fused to the lens under heat and pressure around the entire perimeters of the lens and control mounting hole to form a unit permanently sealed against dust, water and water vapour. The reflector shall be colourless. The lens shall consist of a smooth front surface free from projection or indentation other than a central mounting hole and identification with a rear surface bearing, a prismatic configuration, such that it will reflect total internal reflection of light. The manufacturer's trade mark shall be moulded legibly into the face of the lens. b. Galvanized Steel Posts Galvanized Steel posts for delineators shall be "U" section channel posts as shown, on DRAWINGS and weigh not less than, 1.0 kg/m nor more than 2.75 kg/metre as approved by the Engineer's Representative. The channel posts shall be drilled or punched as shown on the DRAWINGS. All holes shall be provided before galvanizing. Oversize holes shall be backed up with rectangular washers as stated hereinafter. All steel posts shall be mild steel No. 1 quality entirely in accordance with the requirements of B.S. 15. All sections shall conform to British Standard dimensions. All steel posts shall be entirely galvanized after fabrication, including cutting and punching or drilling, in accordance with Clause 5063 of the GENERAL SPECIFICATION. c. Hardware Bolts for connecting centre mounted reflectors to the posts shall be Phillips round-headed bolts of aluminum alloy 2024-T4 or equivalent with 8-32 or 10-24 thread, and with square or hexagon aluminum nuts. If post mounting holes are larger than 6mm diameter, provide rectangular aluminum backing washers, 1.0mm thick, minimum, with holes 5.0mm to 6.0mm diameter, and large enough to provide satisfactory area of bearing against the post. Reflectors may also be fastened to their respective posts by blind rivets or bolts, provided aluminum washers are used at oversize holes; rivets and riveting or tightening device and technique may be used if only they are approved by the Engineer's Representative. Bolts shall be of such length that in no case shall the exposed threaded length of a bolt extend beyond the tightened bolt more than 10mm 2. Methods of Construction All delineators shall be located and erected in conformance with the DRAWINGS or as directed by the Engineer's Representative and all delineator posts and reflector mountings 220 shall be plumb. The top of posts shall have substantially the same cross sectional dimensions as the body of the posts; no battered heads will be permitted. A suitable driving cap shall be used whenever posts are driven. If posts are set in earth, post holes shall be backfilled with suitable material placed in layers not more than 150mm in depth and each layer shall be thoroughly compacted. All posts shall be in the final position before attaching reflectors. Topmost centre mounted reflectors shall be mounted on posts through holes having an edge distance from the top of post of not less than 10mm or more than 25mm. Centre to centre spacing of delineators shall be 100mm. All fasteners shall securely grip their respective reflectors. Reflectors shall show no sign of damage after being mounted. Rectangular washers described herein above shall be used under nuts whenever mounting holes exceed 6.0mm diameter. The Contractor, at his own expense, shall replace or repair to the satisfaction of the Engineer's Representative any delineators, removed or damaged in any way prior to the acceptance of this work. 3. Quantity and Payment The quantity of delineators for which payment will be made shall be the number of delineators actually furnished in accordance with the DRAWINGS, the Specification, and as directed by the Engineer's Representative. Payment for the delineators shall be made for the quantities as above determined, at the unit price shown in the Bill of Quantities, which price shall include the cost of posts, mounting plates, plastic reflectors, hardware, galvanizing, driving or setting of posts, all excavation and backfilling, drilling in rock and grouting, all material, equipment, labour, and all else necessary thereof and incidental thereto. TELEPHONE POLES 6417. The Contractor shall furnish and install telephone poles where and as shown on the DRAWINGS or as directed by the Engineer's Representative. All work under this Clause affecting the property, right of-way and facilities of the Posts and Telegraphs Department, Ministry of Communication (hereinafter called as Owners) shall be carried out under joint supervision of the Engineer's Representative and the said Owners in a manner satisfactory to both. The Contractor shall submit to the Engineer's Representative detailed working drawings and written description of the intended construction methods and shall obtain approval from the Engineer's Representative. After approval of the working drawings and/or working plans, the Contractor shall furnish the said owners, through the Engineer's Representative, with as many numbers of prints of such drawings as required by the said owners. No work affecting the safety, operation or maintenance of the utilities shall be commenced or prosecuted until written approval of the owners has been obtained. This provision must be complied with before the Contractor begins actual construction work. Payment shall be made at the unit price for this Item tendered in the Bill of Quantities. Payment shall include all costs for furnishing materials, equipment and labour, and for all costs for coordination of all construction activities with the owners. The 221 installation shall be completed and tested to the satisfaction of the Engineer's Representative and of the owners prior to the issue of the completion certificate for the work in question. (CLAUSES 6418-6499 INCLUSIVE NOT USED). ANNEXURE TO THE GENERAL SPECIFICATION (ROAD AND BRIDGES) PENETRATION (GROUTED) MACADAM GENERAL 6500. Penetration macadam shall consist of a compacted wearing course of coarse crushed rock aggregate laid upon a prepared base and grouted with straight run bitumen. For keying the penetration layer 19mm and 10mm crushed rock chippings shall be used. Surface sealing shall be carried out using either a straight run or cut back bitumen as specified and 12mm crushed rock chippings. MATERIALS 6501. The materials to be used in penetration macadam shall comply with the following:(a) The coarse aggregate for the wearing course shall consist of clean crushed rock dry and free from dust. The aggregate crushing value shall not exceed 23%. The aggregate shall be graded as shown in the table below. TABLE VI-20 COARSE AGGREGATE GRADING ENVELOPES FOR PENETRATION MACADAM Sieve Percent Passing 80mm thick base 50mm thick base 63.5mm 100 - 50.8mm 90 - 100 100 38.1mm 30 - 80 80 - 100 25.4mm 0 - 15 30 - 80 19.0mm - 0 - 15 (b) The 19mm aggregate for keying the penetration layer of coarse aggregate shall comply with B.S. 63 - "Single sized Road Stone and Chippings". (c) The 10mm aggregate for keying the penetration layer of coarse aggregate shall comply with the grading shown in the table below: TABLE VI-21 GRADING ENVELOPE FOR KEYING THE PENETRATION LAYER OF PENETRATION MACADAM Sieve 222 Percent Passing 12mm 100 9.5mm 90 - 100 6.4mm 5 - 20 600 m 0 - 10 (d) The 12mm aggregate for the seal coat shall comply with B.S. 63 - "Single sized Road Stone and Chippings". (e) The bitumen for grouting the penetration macadam shall be a straight run bitumen as specified in Clause 6301 (iii). (f) The bitumen for the seal coat shall be either a straight run or cut back bitumen as specified in Clause 6301 (ii) or Clause 6301 (iii). (g) An approved anti-stripping additive shall be incorporated in the bitumen when this is directed by the Engineer. The additive shall be mixed with the bitumen by the supplier during manufacture so as to ensure a uniform dispersion of the additive. (h) The specification for the various grades of aggregate required is devised so that the full range of crushed stone produced will be used except for the fines passing a 5mm screen. Aggregate in the 63.5mm to 19.0mm range will be used in the base layer. Aggregate in the 19.0mm to 12mm and 10mm to 5mm range shall be used as key-stone. Aggregate in the 12mm to 10mm range shall be used as chippings in the seal coat. The above will apply provided always that the efficiency of the screening arrangements is such that the gradings of each range of aggregate comply with the specifications. WORKMANSHIP 6502. (1) The coarse aggregate shall be spread by mechanical means on the prepared base in a uniform loose layer so that after it is fully compacted it shall be of the specified thickness. The layer of coarse aggregate shall be rolled to the correct shape longitudinally and transversely by a three-wheel steel-- tyred roller weighing not less than 9 tonne or by a vibratory roller of same capacity and having a minimum weight of 54 kilograms per centimetre width of rear wheel. Any irregularities shall be corrected by loosening the surface and removing or adding aggregate as required and re-compact. Rolling shall be continued until thorough interlocking is obtained and there is no movement under the action of the roller. Rolling shall be stopped if the aggregate begins to crack or crush. The finished surface shall show uniform voids and when tested with a 3 metre straight edge placed parallel to the centre line of the road shall not show any variation greater than 12mm. The transverse profiles shall conform to the same accuracy using a correctly shaped rigid fabricated metal template instead of a straight edge. The length of this template shall not be less than the width of the base. (2) Straight run bitumen shall then be sprayed as specified in Clause 6313 on the shaped and compacted layer of coarse aggregate at the rate of 0.71 to 0.89 litres per sq.m. per centimetre of compacted thickness. The actual rate of application shall be determined by the Engineer's Representative after tests have been carried out on site, as described in Clause 6503. (3) Immediately following the applications of the bitumen and while it is still warm, the key-stone shall be spread evenly over the surface so as to key the surface voids. The key-stone shall be applied in successive layers. The first layer shall be 19.0mm. Key-stone applied in just sufficient quantity to prevent the roller wheels sticking. As rolling 223 continues further 19.0mm and 10mm key-stone shall be spread and lightly broomed over the surface and rolled until all the voids in the coarse aggregate have been filled but without having an excess of loose key stone on the surface. Rolling shall continue until the key-stone is thoroughly embedded and the stone layer shows no movement under the roller. The proportions of 19.0mm and 10mm key-stone to be used and the order in which they shall be used shall be determined after trial sections have been constructed as described in Clause 6503. (4) When the spreading and rolling of the key-stone have been completed to the satisfaction of the Engineer's Representative, the road shall be opened to traffic as specified in Clause 6316. (5) The seal coat shall not be applied until at least 10 days after the completion of the wearing course. During this period additional key-stone shall be applied if directed and brushed into any voids which may appear under the action of the traffic. After such period any irregularities or areas of failure due to workmanship shall be cut out and made good to the satisfaction of the Engineer's Representative. After all remedial work has been allowed sufficient time to harden and settle under the action of traffic, the surface shall be swept clean of all loose material and the seal coat shall be applied as described for the wearing coat in Clause 6313 except that the bitumen will be sprayed at the rate of 1.30 to 1.50 litres per sq.m. (6) On completion of the seal coat the road shall be opened to traffic and speeds shall be restricted to a maximum speed of 25 km/h for one day following the opening. TRIAL SECTIONS 6503. The Contractor shall construct trial sections at least 90 metres long to determine the most efficient construction technique and the suitability of the materials and plant to be used. If the trial sections are satisfactory they shall be incorporated in the finished work. TESTS 6504. (1) The rate of application of the bitumen shall be checked as specified in Clause 6223. When tests are carried out on the rate of application of the bitumen used in grouting, the test trays shall be provided with lips of sufficient depth to prevent loss of bitumen through over-flowing. (2) Holes 300mm square shall be cut in the stone layer to the full depth where directed by the Engineer's Representative who shall determine by visual inspection the degree of penetration of the bitumen. The Engineer's Representative may order such variation in the rate of spread or application temperature of the bitumen as he may consider necessary to obtain the most uniform penetration of the bitumen through-out the full depth of the stone layer. 224 Notwithstanding the results of tests carried out by the Contractor, approval of workmanship and materials shall be based on the results of these control tests. It is the responsibility of the Contractor to notify the Engineer's Representative when any items of the works scheduled below are completed and ready for approval and the Contractor shall give sufficient notice to allow control tests to be performed. Generally the time required to perform control tests by the Engineer's Representative after the receipt of the Contractor's notification shall be as follows: All filling and subgrade Unstabilized sub-base and 3 days base course 3 days Crushed stone base 3 days Surfacing materials 7 days Structural concrete 30 days Asphalt concrete 10 days Note: Where construction is carried out in arid region where moisture of finished fill, subbase base or stone base can dry out from the surface rapidly, the time of notification may be reduced at the request of the Contractor making representation to the Engineer's Representative on same. 1 PACKING AND MARKING OF BAGS FOR CEMENT After each consignment of cement has been tested and approved as complying with B.S. No. 12 and unless approval is given by the Engineer's Representative for the handling of cement in bulk, all cement shall be packed into bags of an approved type. The bags of each consignment shall be given a distinctive mark, to be agreed between the Contractor and the Engineer's Representative, also a consignment number, so that each consignment can be easily identified on being delivered to the site and when being used subsequently in the works. (10) STORAGE OF CEMENT ON SITE On delivery at the site, the cement shall be stored in suitable, thoroughly dry and well-ventilated lock-up sheds to be erected by the Contractor and approved by the Engineer's Representative. Great care must be taken to provide a perfectly dry floor of timber or concrete for each shed so as to prevent damp rising to the cement. Small quantities left at the site shall be stored on suitable platforms and protected with waterproof covering to the satisfaction of the Engineer. Each consignment, brand and type of cement shall be kept separate in the sheds and suitable labels are to be provided for each consignment, brand and type, on which shall be entered the consignment number, date of despatch, date of delivery at the site, the number of bags, the date when using commenced and the date when using finished. All these labels shall be handed to the Engineer's Representative when the cement has been used and will be retained by him. (13) REJECTION OF CEMENT Notwithstanding the production of test certificates whether from manufacturer tester or independent tester, the Engineer's Representative shall reject any cement found not to comply with this specification, at any time. He shall also reject any cement which has been damaged or which has deteriorated owing to inadequate protection during storage or transport or any other cause. Cement containing lumps of hardened cement or which has been stored for more than 6 months shall not be used. The Contractor shall remove all rejected cement from the site without delay and at his own expense. (5) STORAGE OF AGGREGATES The Contractor shall provide proper means of storing the aggregates at each point where concrete is made and in such a manner that there is no possibility of the various aggregates mixing one with the other. Effective precautions shall be taken to prevent the aggregates segregating in the storage heaps and from being contaminated by the ground and other foreign matter. 24 Storage heaps shall be capable of draining freely. Wet aggregates shall not be used until, in the Engineer's Representative's opinion, they have completely drained. Where aggregates are damp, the Contractor must measure the moisture contents of the aggregates continuously and adjust the amounts of aggregates and added water in each batch of concrete mixed to allow for the water contained in the aggregates. If necessary, to meet the requirements of this Clause, the Contractor shall protect the heaps of aggregates from inclement weather. FINE AGGREGATES 2004. (1) GENERAL Fine Aggregate shall either comprise natural quartz sand or be obtained by crushing clean granite or shall consist of naturally occurring sand obtained from fresh water river deposits or a combination thereof and shall comply with Grading Zone 1 or Grading Zone 2 of B.S.882 or such other grading as may be approved by the Engineer. (see Table II-2) (2) FINE DUST The total quantity of fine dust passing through a 75 m mesh sieve in fine aggregate derived by crushing rock shall be determined by the method described in B.S.812. and shall not exceed 8% by weight. (3) QUANTITY OF CLAY AND SILT The total quantity of clay and silt in natural sand shall not exceed 4% by weight when determined by the field settling test decantation method described in B.S.812. The quantity of organic impurities present in natural sand shall not be such as to produce a reaction as dark as the standard solution when the organic impurities are determined by the method described in B.S.812 (1975). TABLE II - 2 FINE AGGREGATE GRADING ENVELOPES. BS 410 Test sieve Percentage by weight passing B.S. sieves. Grading ZONE 1 10.00mm 100 5.00mm 90 - 100 2.36mm 60 - 95 1.18mm 30 - 70 Grading ZONE 2 100 Grading ZONE 4 100 100 90 - 100 95 - 100 75 - 100 85 - 100 95 - 100 55 - 90 75 - 100 90 -100 90 - 100 25 Grading ZONE 3 600m 15 - 34 35 - 59 60 - 79 80 - 100 300m 5 - 20 8 - 30 12 - 40 15 - 50 150m 0 - 10* 0 - 10* 0 - 10* 0 - 15* * For crushed stone sands, the permissible limit is increased to 20% because of its non clay nature of the fine materials. The 5% tolerance permitted may be applied to the percentages. In the last three sets of sieves, it can be applied as follows: 1% on the first of the three sieves and 2% on the others or 4% on one sieve and 1% on others. The application of tolerance will depend upon the shape of the grading graph. COARSE AGGREGATE 2005. (1) GENERAL Coarse Aggregate shall comprise natural gravel or crushed granite obtained by crushing sound hard granite taken from a source approved by the Engineer's Representative and shall contain no harmful material in sufficient quantity to adversely affect the strength or durability of the concrete or in the case of reinforced concrete to attack the reinforcement. All coarse aggregate shall be washed after crushing if necessary to comply with the specification. The flakiness index when determined by the method described in B.S.812 (1975) shall not exceed 30 per cent. The individual pieces shall be roughly cubical or spherical in shape and have neither glassy nor powdery surfaces. (2) CRUSHING VALUE The aggregate crushing value of coarse aggregate shall not exceed 45 per cent when determined by the method described in B.S.812. (3) THE GRADING The grading of coarse aggregate particles is required to satisfy strictly the percentages,stated for 20mm nominal sizes stated in the B.S.82 with a content not exceeding 1% passing the B.S. 2.4mm sieve size. The percentage passing through 75 m sieve shall be determined by the method described in B.S.812. Sieves shall comply to the requirements of B.S.410. . (5) STORAGE Reinforcement shall be stored on site in racks off the ground and shall be protected from rusting, damage, oil or other deleterious matter and shall be clean and free from all such matter before concrete is placed. 26 2011. Following the Engineer's Representative's approval of the mix designs, the Contractor shall prepare, in the presence of the Engineer's Representative, a trial mix of each design grade of concrete. The mixes shall be prepared as follows: Before mixing, a sieve analysis of the aggregate shall be made by the method described in B.S.812 (1975) and the weight and volume of the cement, fine aggregate, coarse aggregate and water comprising the mix carefully determined. Each trial mix shall be not less than half a cubic meter in bulk before mixing and shall be mixed as specified in Clause 2012 of this specification in a mechanical mixer of the type approved for use in the works. The compacting factor and slump of each trial mix shall be determined immediately after mixing as directed in NIS 12 B.S.1881 (1970)and shall not exceed the maximum value obtained in the mix design. Each trial mix shall be handled and compacted by the methods which the Contractor proposes to use for that mix in the works, and the mixes shall show no tendency of inadequate compaction by the methods proposed. Six cubes of 150mm compression test cubes shall be made from each trial mix. The cubes shall be made, cured, stored and tested in accordance with the requirements of B.S.1881 (1971). 27 28 Three cubes shall be tested 7 days after manufacture and three 28 days after manufacture. The strength requirements of the cubes at each age shall be considered to be satisfied if none of the strengths of the three cubes tested at each age falls below the appropriate design strength or if the average strength of the three cubes is not less than the strength and the difference between the greatest and least strengths is not more than 20 per cent of that average. Failing this, the Contractor shall re-design the mix and make such further trial mixes and test such further cubes as the Engineer's Representative may direct until the requirements of this specification are satisfied. MIXING OF CONCRETE 2012. (1) GENERAL Concrete shall be mixed in mechanical mixers of the weigh-batch type as stated in the Contractor's mix design proposal, complying with the requirements of B.S. 1305 (1967) and fitted with an approved weight measuring device. No hand-mixing will be permitted. Mixing shall continue until there is a thorough distribution of the materials, and the mass is of uniform colour and consistency. The period of mixing, judged from the time that all materials including the water are in mixer, shall be not less than that or should not be more than 2 minutes per m3 or as recommended by the manufacturer. The concrete mixer shall revolve at the speed recommended by the manufacturer, or as ordered by the Engineer's Representative. The entire contents of the drum shall be discharged before materials for the next batch are fed in. Should there, for any reason, be a stoppage of greater than 30 minutes duration, the drum of the mixer shall be thoroughly washed out with clean fresh water before mixing is resumed. Stationary mixers shall be equipped with an acceptable timing device that will not permit the batch to be discharged until the specified mixing time has elapsed. (2) RE-MIXING OF CONCRETE No partly set concrete shall be placed in the works. Concrete which has commenced to set shall not be remixed either with or without additional water and in no case shall such concrete be used in the works. QUALITY OF CONCRETE (5) PROTECTION OF CEMENT During windy weather, effective precautions shall be taken to prevent the cement from being blown away during the process of apportioning and mixing. One method of checking this, is by use of wide planks as wind breakers in the direction of the wind, During wet weather both cement and concrete shall he adequately protected either by covering with polythene or tarpaulin. (3) Notwithstanding the foregoing provisions of the Clause, the quality control exercised at each mixing plant and for each mix shall be such that the overall average 200C compressive strength achieved (measured in N/mm2) minus 1.64 multiplied by the standard deviation achieved (measured in N/mm2) shall be more than or equal to the specified minimum 28 days 200C compressive strength. 1 Overall average compressive strength and standard deviation shall be calculated from the results obtained from the latest forty consecutive sets of 3 test cubes of any one mix and from any one mixing plant. ( x ) 2 N N 1 ( x)  S (x) 2 ( x )  N N 1 2 S where N = Number of cubes tested x = 28 day compressive strength of 150mm cube in N/mm2 S= Standard deviation in N/mm2 Notwithstanding the foregoing, the standard deviation shall not be calculated for a mix until there are at least 40 sets of 3 test cube results available. (12) Overall average 200C compressive strength and standard deviation achieved using the results obtained from the latest forty consecutive sets of 3 test cubes made from the same mix and the same mixing plant. (13) Overall average compressive strength from (12) minus 1.64 multiplied by deviation from (12). If results of the cube tests do not comply with-the Specification, such remedial works as the Engineer may accept or direct shall be carried out. If results of cube tests do not comply with the Specification and/or if the figure from item (13) of the test report is less than the specified minimum 28 day compressive strength, then either the quality control at the relevant mixing plant shall be improved to the satisfaction of the Engineer's Representative or the mix shall be redesigned to the satisfaction of the Engineer's Representative. If directed by the Engineer, redesign of the mix shall include carrying out further preliminary laboratory tests in accordance with the Specification with the redesigned mix. (IV) INDEPENDENT TEST CUBES The Contractor shall arrange for the Engineer's Representative to be present during the sampling of the concrete and the manufacture, storing and curing of the cubes to ensure that there is complete agreement between himself and the Engineer's Representative that the said cubes are entirely acceptable as test cubes. Should the Contractor fail to arrange for the Engineer's Representative to be present when required, or decline to do so, the cubes 2 so manufactured will not be accepted as test cubes. Should the Contractor wish to make independent test cubes he may do so at his own expense, but the results will not be valid unless the cubes are manufactured in the presence of the Engineer's Representative and tested by an approved Agency, all in accordance with B.S. 1881. (V) FAILURE OF TEST CUBES FOR STRENGTH REQUIREMENT Should either the test cubes crushed at 7 days or those crushed at 28 days or both, fail to satisfy the specified requirements, the Contractor shall, on the Engineer's Representative instructions, take one or more of the following steps:(A) He shall alter the design of the mix to increase its average compressive strength (B) He shall alter the method of making the concrete and controlling its quality to reduce the variability of the concrete. (C) He shall cut out and replace concrete placed in the works on any day in which a cube (was made and failed if, in the opinion of the Engineer's Representative, such concrete is likely to be incapable of fulfilling its purpose. The Engineer may require the Contractor to cut out defective concrete from the works even though test cubes made from that concrete have not failed. This may arise if the concrete failed to meet other salient features and quality standard like the following: (i) (ii) TRANSPORTATION OF CONCRETE PLACING AND COMPACTION SURFACE FINISHES Honey combing Cold joint 2014. Concrete shall be taken from the place of mixing to the place of deposition by methods which will prevent the drying-out and consolidation of the concrete, the segregation and loss of the ingredients, and which are sufficiently rapid to ensure that the concrete does not commence to set before it is finally compacted in position. During transportation, the concrete shall be protected from all adverse effects of sun, wind and rain. The concrete shall be deposited as near as possible to its final position in the works, and no concrete shall be dropped freely or deposited by means of chutes through a depth exceeding 3 metres. All mixers, barrows, spades and other mixing and distributing equipment will be thoroughly clean before commencing each period of use and shall be kept free of partly set concrete which shall not be used in the works. No concrete shall be transported over or near to new work that has insufficiently hardened, in order to prevent harmful vibration of the new work and no planks or ways for skips, etc., shall be supported on either formwork or reinforcement for the same reason. 2021. All concrete surfaces not requiring shuttering shall be smooth finished with approved floats to give a dense surface with a minimum of cement and fine materials being brought to the surface. The top surface of deck slabs shall be tamped to a smooth finish, aided by floats if necessary, to the levels, falls and cambers shown on the drawings or as instructed. The tamping shall not be done to the extent of bringing an excess of fine materials to the surface. 3 CURING OF CONCRETE (2) WATER CURING Very great importance is attached to the proper curing of the freshly placed concrete and the Contractor must ensure that is effectively done. All newly placed concrete shall be protected from the effects of rain, drying winds and the sun by suitable screens of damp hessian, or damp sand after the concrete has hardened sufficiently to support them directly without marking. The ends and sides of the screens shall be held down at the edges to prevent draughts from getting underneath. As soon as the concrete has hardened sufficiently to support the coverings without marking. It shall be covered with clean sacks, hessians, or a 50mm thick layer of clean sand or other approved material which shall be kept continuously in a wet condition by frequent spraying with fresh clean water. Where the concrete to be cured is enclosed by shuttering, the shuttering shall be covered with clean sacks or hessian which must be kept continuously in a wet condition When the shuttering is removed, the damp hessian or sacks shall be hung directly around the concrete member and kept continuously wet by spraying with clean fresh water. Providing that the shuttering has been covered with approved mould oil which will prevent the timber from absorbing water from the concrete, the time that the concrete remains in formwork under the conditions herein specified shall count as part of the curing period. Curing of all concrete shall continue for at least 7 days, or as directed by the Engineer's Representative, or as otherwise specified. On no account must the surrounding sacks, hessian, etc., be allowed to dry out during the curing period. TABLE II-4 FORMWORK MINIMUM STRIPPING TIME TYPE OF WORK PART OF WORK ORDINARY PORTLAND CEMENT CONCRETE SLABS SOFFIT BOARDS PROPS 5 DAYS 14 DAYS BEAMS SIDE BOARDS BOTTOM BOARDS PROPS 3 DAYS 14 DAYS 28 DAYS COLUMNS WALLS, PIERS AND ABUTMENTS 7 DAYS MASS CONCRETE REINFORCED CONCRETE 3 DAYS 7 DAYS Where props are to be left in position under slabs and beams the formwork shall have been made in such a fashion that it can be removed without disturbing the props in any way, otherwise it must be left in position for the full period that the props are left in position. The formwork shall be removed by gradual easing without jarring and only under competent supervision. Before removal of the shuttering, the concrete shall be examined and removal shall only be proceeded with if the concrete has attained sufficient strength to sustain all the loads to which it will be subjected. 4 REINFORCEMENT SCHEDULES All reinforcement shall be perfectly clean and free from loose scale, rust, oil, grease and any other matter which might reduce the bond between the steel and the concrete. Loose pieces of binding wire and other foreign matter shall be removed. (11) RECONSTRUCTION OF FAULTY WORK Should any portion of the work give evidence, in the opinion of the Engineer or his Representative that the concrete is of inferior quality, insufficiently compacted, segregated or improperly deposited and rammed in the forms or that any of the reinforcement or fittings has been omitted, incorrectly placed or subsequently displaced or that it suffers from any defect, omission or injury from any cause whatsoever which may adversely affect the strength or durability of the construction, the Contractor shall, on the written instructions of the Engineer, remove and reconstruct that portion of the work in such manner as the Engineer shall direct or approve to ensure that the requirements of this specification are fulfilled. BATCHING AND MIXING 3009. All materials used for concrete manufacture shall be batched by weight. 5 SECTION V - BRIDGE WORKS GENERAL EXCAVATION AND BACK FILLING 5005 (A) GENERAL . Should excavations be taken to a depth greater than that required by the Engineer's Representative such extra depth shall be made up at the Contractor,s expense with concrete grade 10 N/mm² or as directed by the Engineer's Representative. TEST ON COMPLETED STRUCTURES 5018 (A) CONCRETE STRUCTURES The Engineer may instruct that a loading test be made on the works or any part thereof if, in his opinion, such a test is deemed necessary for one or more of the following reasons:(a) The site made concrete tests cubes failing to reach the specified strength, (b) The shuttering being prematurely removed, (c) Overloading during construction of the works or part thereof, (d) Concrete improperly cured. (e) Any other circumstances attributable to alleged negligence on the part of the Contractor which, in the opinion of the Engineer may result in the works or part thereof being of less than the expected strength. (f) Any reason other than the foregoing. If the loading test be instructed to be made solely or in part for the reason (a) the test shall be made at the Contractor's own cost. If the test be instructed to be made for one or more of the reasons (b) to (e) inclusive, the Contractor shall be reimbursed for the cost of the test if the result thereof is satisfactory. If the test be instructed to be made for the reason (f) the Contractor shall make the test and shall be reimbursed for all costs relating thereto unless the result of the test is unsatisfactory in the opinion of the Engineer. The test load shall not be applied within eighty-four days of the completion of placing of the concrete in the part of the structure to be tested, and the latter shall not be supported during the test by the shuttering or other non-permanent support. Means shall however be taken to ensure that in the event of failure under the test, temporary support of the loaded members shall be immediately available. The test shall proceed strictly as directed by the Engineer. If the result of the loading test is not satisfactory in the opinion of the Engineer, the Engineer shall instruct that part of the works be taken down or cut out and reconstructed to comply with this specification, or that other remedial measures be taken to make the work secure. All remedial measures shall be carried out expeditiously by the Contractor at his own expense. 1 2 No material shall be used until it has been approved by the Engineer or his Representative. Permission to use any material shall not be construed as an approval of its source nor any acceptance as continued acceptance. UNSUITABLE MATERIAL 6101. In no case will material which contains organic matter or other deleterious substance be used. A maximum quantity of material excavated from cuttings shall be placed to fill and the utmost advantage shall be taken of the natural moisture content of the soil in placing such fill provided the materials meet the qualities for use as such see clause 6102. Fill shall be placed and compacted in layers of a compacted thickness 150mm or such thickness that may be found necessary to achieve the required density over the full width of the formation. The Contractor shall route his earth-moving equipment in such a manner over the full width of the filling as to achieve a uniform compaction over the entire width by this method. All fill including subgrade and vergers shall then be compacted to 100 per cent of the maximum dry density obtained in the British Standard Compaction Test. In the case of extension to existing embankments benching will be required as indicated on the drawings or as directed by the Engineers's Representative and such benching shall be deemed to be included in the tendered rates for earthworks. PAYMENT FOR EARTHWORKS 6123. Payment for earthworks shall be made once on the basis of the total quantity of measured fill by the Contractors together with the quantity of unsuitable material and/or of excess cut placed to spoil, all as determined from the cross sections referred to in clause 6122. The depth of unsuitable material, if any, to the placed to spoil shall be agreed between the Contractor's Agent and Payment for this material will be on the net volume as measured in situ. The quantity of suitable excess cut placed to spoil shall be determined as follows:(i) The net volume of suitable material excavated from cuttings or side drains shall be determined by deducting the quantity of unsuitable material placed to spoil from the total quantity of cut as determined from the cross-sections. (ii) The total volume of filling placed in embankment shall be found from the cross-sections. (iii) The volume of suitable excess cut placed to spoil shall be taken as the volume found in (i) above less the volume found in (ii) above with an adjustment made to the latter to allow for compaction. The adjustment which shall be made for compaction shall be based on the ratio of the maximum dry density of the filling at 100% B.S. Compaction to the in situ dry density of the material in the cutting or side drain. Haulage rates will he assessed on the basis of the use of the nearest acceptable road making materials to the section of work under construction. Stripping of topsoil will not be measured as roadway excavation. The quantity of stripping topsoil for which payment will be made will be the area stripped in accordance with the Drawings or as directed by the Engineer, measured in units as specified in the bill of quantities. SELECTION OF SOIL FOR FILL 6124. Soils shall be obtained from areas of cut including ditching or from approved borrow pits. All grass and vegetation shall be removed from the surface of the areas of cut or borrow pits before excavation of the fill material is commenced and no such grass or 110 vegetation shall be included in the fill. In borrow pits the top soil, shall be carefully removed and stockpiled. Topsoil shall not be removed from any area until excavations or filling operations are about to start in that area. Topsoil on the sites of cuttings and embankments shall be excavated to the average depth directed by the Engineer's Representative or as specified hereinafter. The Contractor shall, at his own expense and to suit his own convenience, make arrangements for and provide such temporary storage sites as may be required for heaps of topsoil. If any materials suitable for subbase, base or aggregates as specified herein are encountered in material removed as roadway excavation, and the Contractor elects to use such material for constructing items, payment for the various items shall be as follows: BORROW PITS 6126. The Contractor shall at his own expense clear bush, topsoil and other inferior materials from the site of borrow pits. The Contractor shall also bear the cost of compensation for borrow pits outside the area of the site. Borrow pits for road materials shall be excavated only where the natural slope of the ground is away from the road, except that where he considers it essential for the proper execution of the works the Engineer's Representative may approve the excavation of borrow pits in ground above road level. UNSUITABLE MATERIAL BELOW FORMATION LEVEL 6130. Where unsuitable ground or other unsuitable material is found below formation level or below the slope of cuttings under areas of fill, this shall be excavated and disposed off as directed by the Engineer's Representative, and the space left void shall be backfilled with selected fill and compacted to at least 100% of the M.D.D. achieved in the British Standard compaction test. MATERIALS Normally the minimum strength of such base course material shall not be less than 80% C.B.R. value being determined at maximum dry density and optimum moisture content unsoaked with either West African or Modified A.A.S.H.T.O. compaction. However, where the Engineer's Representative considers it necessary on account of perched water-table or any other reasons, he may specify that a C.B.R. value of 80% be obtained after at least 24 hours soaking. For construction on perched water area see clauses 6142 and 6142A. Subbase Type 1 When the test section is compacted to 100 percent maximum density at optimum moisture content, the subbase material shall be of such quality that it shall have the minimum CBR of 30% after at least 24 hours soaking. Once established that the subbase meets the CBR quality requirement at 100 percent maximum density it shall be placed and compacted in the field to that density. Subbase course, Type 2 111 The minimum strength of material for Subbase Course type 2, shall not be less than 20% CBR after at least 24 hours of soaking, for light traffic. The C.B.R. values shall be assessed in the same manner as for base course, at the optimum moisture content and maximum dry density of the West African Compaction Test. At the Engineer's Representative discretion material with a liquid limit greater than 35%, and a plasticity index greater than 12 may be disallowed for use as subbase course or base course. WORKMANSHIP SEQUENCE OF OPERATIONS 6205. The pavement construction for the roadway shall consist of the following as specified herein and shown on the drawings:(A) The scarifying of the subgrade where no filling is applied. (B) The compacting of the subgrade. (C) The laying and compacting of the sub-base course and base course. (D) The providing of prime and first coat bituminous surface dressing to the base course of the carriageway if applicable. BORROW PITS FOR SUB-BASE, BASE COURSE AND HARD SHOULDER MATERIALS COMPLETION OF SUB-BASE COURSE Before compaction, the subbase course and base course material shall be brought to the optimum moisture content for the compaction effort of the plant to achieve the density specified. Where the existing moisture content of the material is higher than this, the soil shall be allowed to dry out by aeration; where it is lower sufficient water shall be added to the soil such that uniform wetting of the material to optimum moisture content is achieved. 6207. Immediately before the construction of the base-course, the Sub-base course shall be tested for thickness, surface finish, and accuracy, and if any areas are found to lack the required thickness surface finish, or accuracy or specified density, such areas shall be scarified, recompacted to the specified density or otherwise treated as the Engineer's Representative may require until the required thickness smoothness accuracy or density is obtained. The finished surface of the Sub-base course shall be left as smooth as possible and the accuracy of finish in the longitudinal direction shall not vary at any point by more than 12mm for a 5 metre straight edge, placed in any position on the finished surface parallel to the centre line. The transverse profile shall conform to the same accuracy using a correctly shaped template instead of straight edge. The level of any point on the aforesaid surface shall not vary by more than 12mm from the finished level of the pavement less the specified thickness of the base construction. 112 The thickness of the Sub-base course at any point shall not be less than the specified thickness by more than 12 mm The Contractor shall include in his rates the digging of trial holes, and making good same, to the satisfaction of the Engineer's Representative. COMPLETION OF BASE COURSE 6208. Immediately before the application of the surfacing the base course shall be tested for thickness, smoothness and accuracy as specified below and if any areas are found to lack the required thickness, smoothness and accuracy or the specified density, such areas shall be scarified, reshaped and recompacted with additional approved material added where necessary or otherwise treated as the Engineer's Representative may require until the required thickness smoothness, accuracy or density is obtained. The finished surface of the base shall be left as smooth as possible and the accuracy of finish in the longitudinal direction shall not vary at any point by more than 5mm from a 3.0 metre straight edge, placed in any position on the finished surface parallel to the centre line. The transverse profile shall conform to the same accuracy using a correctly shaped template instead of the straight edge. The level of any point on the aforesaid surface shall not vary by more than 5mm from the finished level of the pavement. The thickness of the base course at any point shall not be less than the specified thickness by more than 12mm and the average thickness over a length of 0.4 kilometres shall be equal to, or in excess of the specified thickness. The Contractor shall include in his rates for digging necessary trial holes, and making good same, to the satisfaction of the Engineer's Representative. In the process of completing the base course it may be necessary to place material to a greater thickness than that specified and to grade it to the specified finish. In so doing excess material will be wasted. Payment for this and for all other operations required to obtain the specified finish shall be deemed to be included in the tendered rates and prices. ROCK LATERITE FOR BASE COURSE 6209. SURFACING OF BASE COURSE 6210. The base course of the carriageway shall, where applicable, be provided with a prime coat and other surfacing as specified in the relevant clauses of this specification. The surfacing shall be laid as soon as possible after the construction of the base course. PREPARATION OF BASE COURSE TO RECEIVE BITUMEN PRIME COAT 6211. Immediately before spraying of the prime coat, the surface of the base course shall be swept clean, and all loose dust, dirt and the like removed. The Engineer’s Representative may also direct that any very smooth surface to which the surfacing is unlikely to adhere, be roughened with wire brushes or other approved means. If any weak areas are found they shall be cut out and refilled with base course material and rolled to correct cross-section and gradient. 6215 The following tests shall be carried out on all material proposed for use as subbase course and base course:- 1. Plasticity Test. 2. Grading Test. 3. Density/Moisture Content Compaction Test. 4. Laboratory C.B.R. Test. 113 These tests shall be carried out as described in Section I of this specification. TEST FOR CLASSIFICATION AND CONTROL OF COMPACTED LATERITIC SUBBASE COURSE AND BASE COURSE 6216. The tests listed below will normally require to be carried out for each 2 kilometres of subbase course and base course. The numbers and types of tests listed are, however, given only as a guide to the Contractor for tender purposes and the actual number and type of tests which will be carried out during the construction of the works will be entirely at the discretion of the Engineer's Representative: CLASSIFICATION TESTS 2 No. Liquid limit tests 2 No. Plastic limit tests 2 No. Sieve Analysis Test 4 No. West African Standard compaction tests, or 4 No. MOD A.A.S.H.T.O compaction. CONTROL TESTS 4 No. Laboratory C.B.R Tests at specified conditions 20 No. Insitu dry density tests per 2 km in an alternate manner, i.e. Right, Centre, Left, Centre, Right, etc. Except where otherwise stated to the contrary these tests shall be carried out as described in Section I of this specification or where no such description is given, in accordance with the appropriate B.S. The sieve analysis shall be carried out in accordance with the standards laid down in the report of the "Material Testing Conference, February 1963" A copy of which shall be made available to the Contractor on request. Gradation requirement specified herein shall apply to the completed base course after undergoing the mixing, placing, compacting and other operations. The portion of the aggregate passing No 75 m sieve shall not be greater than one-third of the portion passing the No. 425 m sieve. The aggregates shall continuously be well graded within the limits of Gradation A, B. C, D or E as specified below. The methods of test used will be ASTM Standards C117, C127, C128, C136 and D422. Sieves shall conform to ASTM Standard E.11 or B. S. sieve. TABLE VI-7 GRADING ENVELOPE FOR STONE BASE COURSE WET METHOD SIEVE DESIGNA PERCENTAGE BY WEIGHT PASSING SQUARE MESH SIEVE 114 TION GRADING A GRADING B GRADING C GRADING D 75mm 100 100 100 100 50mm 100 50mm 85 -100 85 -100 90 - 100 90 - 100 37.5mm 95 - 100 25mm 60 - 95 65 - 95 75 - 100 80 - 100 20mm 60 - 80 10mm 30 - 65 40 - 75 50 - 85 60 - 100 10mm 40 - 60 5mm 25 - 55 30 - 60 35 - 65 50 - 85 5mm 25 - 40 2mm 15 - 40 20 - 45 25 - 50 40 - 70 2.36mm 15 - 30 425m 8- 20 13 - 30 15 - 30 25 - 45 600m 8 - 22 75m 2-8 5 - 10 5 - 10 5 - 15 75m 6 - 12 CRUSHED STONE BASE COURSE LAID BY THE WET PROCESS OPENING GRADING E 6257. When crushed stone Base course is to be laid by the dry or wet process the method of laying and compaction shall be as follows:(I) The approved crushed stoned, graded as specified shall be mixed with between 3% and 5% of water as directed in a mixer of a type approved by the Engineer's Representative. PART (D) - SURFACING (I) GENERAL TWO COAT BITUMINOUS SURFACE DRESSING 6300. In addition to all other relevant clauses of the conditions of contract and this specification, the following shall be deemed to refer more particularly to two coat bituminous surface dressing work, and shall be read in conjunction with same. MATERIALS MATERIALS FOR SURFACE DRESSING TABLE VI-8 SEALING COATS TEMPERATURE OF APPLICATION BITUMEN GRADE M.C.0 M.C.I FIRST COAT SURFACE DRESSING TEMPERATURE OF APPLICATION MIN 38 C 54 C MAX 66 C 79 C 6313. The wearing course of the surface dressing shall not be laid until at least 10 days after the application of the prime coat. During this period additional blinding sand shall be added if directed and brushed over the surface to prevent damage. After such period all 115 damaged or weak spots shall be cut out, refilled, recompacted flush with the existing surface, sealed and blinded as specified and rerolled to the satisfaction of the Engineer's Representative. After all repair work has been allowed sufficient time to harden, the surface shall be swept clean of all loose material immediately prior to the application of the wearing coat. Before spraying is begun the surface shall be dry. Bitumen for the wearing coat of the surface dressing shall be an approved cutback bitumen or straight run bitumen as specified in the relevant clauses of this specification. The bitumen as specified shall be evenly sprayed on the surface by means of an approved mechanical spraying machine as specified. The temperature of the bitumen at the time of spraying shall be in accordance with the table given below. The grade of bitumen to de used shall be determined by the Engineer. TABLE VI-9 BITUMEN VISCOSITY AND TEMPERATURE OF APPLICATION BITUMEN VISCOSITY STV AT 40 C 100/150 SECS 300/400 SECS TEMPERATURE OF APPLICATION MIN 132 C 149 C MAX 160 C 177 C The rate of spray of the bitumen shall be determined according to the type of base, type and size of chippings which are to be used as detailed in the table given below, and the Contractor shall carry out trial sections, as directed by the Engineer's Representative to determine the most appropriate rate of application of bitumen. TABLE VI-10 SIZE OF CHIPPING AND RATE OF SPRAY OF BITUMEN NOMINAL SIZE OF CHIPPINGS RATE OF SPRAY OF BITUMEN LITRE./SQ.M. 10mm 12mm 20mm 0.60 - 0.90 0.75 - 1.20 1.20 - 1.50 Immediately after spraying the surface shall be blinded with approved single size chippings as specified. The chippings shall be distributed on the sprayed surface by means of mechanical spreaders or tailboard gritters so that a single layer of closely packed chippings is obtained. Any bare or lean areas shall be made good by a follow-on gang using hand blinding. Rolling shall be carried out immediately after the chippings have been spread with an approved roller weighing not less than 3,629 kilograms or more than 5,443 kilograms. The minimum number of passes of the roller shall be used to press the chippings into the film of bitumen. Two passes of the roller should generally be sufficient. Pneumatic tyre rollers are preferable to smooth wheeled rollers. 116 Prior to the commencement of spraying a section of the road for the first coat, a 2 metres wide paper strip shall be laid over the end of the previous section. The bitumen sprayer shall then commence its run from over this paper strip. TESTS TESTS FOR BITUMEN 6320. The Contractor shall produce manufacturer's test certificate if requested, otherwise the Engineer may require the Contractor to carry out the following tests as described in "standard methods for testing petroleum and its products" published by the Institute of Petroleum, 26 Portland Place, London W.1. Penetration of bitumen IP.49/56 Soluble bitumen content: bitumen and asphalt IP.47/55. Flash-point by means of the cleveland apparatus IP.36/55 Specific gravity IP.59/57. Method C. Specific gravity of liquids or solids - pycnometer method. Specific gravity of liquids or solids - method F. TABLE VI-15 QUALITY OF ASPHALTIC CEMENT PROPERTY ASPHALT CEMENT 80 - 100 PEN SPECIFIC GRAVITY @ 25C 60 - 70 PEN 1.00 - 1.05 1.01 - 1.06 SOFTENING POINT R AND B (C) 45 - 52 48 - 56 PENETRATION @ 25C---0.1 mm 80 - 100 60 - 70 DUCTILITY @ 25C---CM MINIMUM 100 100 LOSS ON HEATING FOR 5 HOURS AT 163C % BY WEIGHT----- MAX 0.5 0.2 SOLUBILITY IN CS2, % BY WT... MIN 99 99 DROP IN PENETRATION AFTER HEATING % ORIGINAL ----- MAX. 20 20 FLASH POINT (OPEN CUP) C MIN. 225 250 ASH. 0.5 0.5 % BY WT. MAX. 117 TABLE VI-16 GRADING ENVELOPE FOR BINDER AND WEARING COURSES % BY WEIGHT PASSING SIEVE SIZE 40mm - 65mm BINDER-COURSE 31.8mm 25mm 19.0mm 12.5mm 9.5mm 6.4mm 2.8mm 1.25mm 600m 300m 150m 75m 100 90 - 100 70 - 90 55 - 80 47 - 70 40 - 60 27 - 45 20 - 34 14 - 27 8 - 20 5 - 15 2 - 7 Bitumen Content % by weight of aggregate 4.5 - 6.5 40mm - 50mm WEARING-COURSE 85 75 65 50 36 26 18 13 7 100 100 100 - 100 - 92 - 82 - 65 - 51 - 40 - 30 - 24 - 14 5 - 8.0 Asphaltic Concrete mixes designed by the Contractor prior to the selection of JobMixes (see below) shall have combined aggregate gradings approximating as closely as possible to the plotted averages of the respective limits of grading specified above and shall comply with the following requirements: Hand laying of any bituminous material will only be permitted in the following circumstances:(i) for laying regulating courses of irregular shape and varying thickness. (ii) in confined spaces where it is impracticable for a paver to operate. (iii) for footways. (iv) at the approaches to expansion joints at bridges or viaducts. When a paver laying base material approaches an expansion joint at a bridge or viaduct it shall be taken out of use as soon as there is a danger of the material being laid fouling the joint. In laying the remainder of the pavement up to the joint and the corresponding area beyond it by hand, the joint or joint cavity shall not be fouled with surface material. COMPACTION 6379. After spreading, the mix shall be thoroughly and uniformly compacted by rolling. 118 The initial 'breakdown' rolling shall be done with three wheel smooth roller, followed by intermediate rolling with high- pressure typed pneumatic roller. The final rolling shall be with a tandem roller. During rolling, the roller wheels shall be kept moist with only sufficient water to avoid picking up material. Heavy equipment or rollers shall not be permitted-to stand on finished surface until it has thoroughly cooled. the stone layer. 119

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