BANGLADESH POWER DEVELOPMENT BOARD TENDER ... - BPDB

Sieve designationPercentage by(Square Mesh Sieves)Weight Passing38.1 mm (1 1/2") 95 10019.1 mm (3/4") 60 902.5mm (No.8) 20 500.074 mm(No.200) 2 1017.7.1.3 Construction of Aggregate Sub-base for Concrete PavementThe aggregate sub-base material shall be placed on the prepared and approvedsub-grade. The deposition and spreading of the material shall bc as directed bythe Board. It shall start at the point farthest from the point of loading, and shallprogress continuously without breaks. The materials shall be deposited andspread in a uniform layer and without segregation of size, to such a loose depthof not more than 15 cm each layer, making allowance for any filler to be blendedon the road, that when compacted, the layer shall have the required thickness.Spreading shall be from spreader boxes or from moving vehicles, or by placing ina windrow followed by spreading to required depth and width by means of ablade grader. After the sub-base material has been spread, it shall be bladed toa smooth surface conforming to the cross section.The Contractor shall schedule his operations so as to assure completion ofspreading within 48 hours after processing. Immediately following the finalspreading and smoothing, all materials placed shall be compacted to the full widthby rolling with a power roller weighing not less than 10 tons. The rolling shall startlongitudinally at the sides and shall progress toward the centre, overlapping onsuccessive trips by at lest one-half of the width of the roller unit. In confinedareas the direction of rolling shall be as ordered by the Board. Alternate trips ofthe roller shall be slightly different in length. The rollers, unless directedotherwise, shall operate at a speed between 3 to 5 kilometres per hour. Rollingshall be accompanied by watering if necessary and as directed by the Board.17.7.1.4 Concrete Pavement(1) Materials(i) Cement and reinforcing steel will be furnished by the Contractor. Theconcrete to be used for concrete pavement shall be not less than 240kg/sq.cm inthe strength at 28 days. The concrete pavement shall be 20cm in thickness or asdesigned.(ii) Fine and coarse aggregates, and water shall conform to the applicableSection of the Specification.(iii) Preformed Expansion Joint Filler Board - The preformed expansion jointfiller for the concrete pavement shall be l9mm (3/4") in thickness, non-extrudingtype, shall conform to the requirements of ASTM Dl 752-67, "Specifications forPreformed Expansion Joint Fillers for Concrete Paving and Structural Construction,Non-extruding and Resilient Non-bituminous Types", Type II.(iv)Dowel bars All dowel bars except at the expansion joints, shall beGhorasal 200 MW to 300 MW Gas Turbine Peaking Power Plant Project (Vol-2 of 3)176