BANGLADESH POWER DEVELOPMENT BOARD TENDER ... - BPDB

17.7.1 CONCRETE PAVEMENTThe roads and yards shall be paved with reinforced cement concrete and shall bedesigned in accordance with the procedures as outlined in the AASHTO Standardor any other acceptable international standard or Design of Pavement Structuresor other internationally accepted methods approved by the Board. Basic designconditions are as followsDesign loadMinimum thickness ofconcrete pavement:Minimum 15 ton axle weight: 20cm17.7.1.1 Sub-grade Preparation and TestThe aggregate sub-base for the concrete pavement shall be prepared by bringingthe sub-grade to a firm and unyielding surface by rolling the entire area with anapproved roller weighing not less than ten (10) tons. The sub-grade shall besprinkled with water, if necessary, to attain satisfactory compaction. All soft,yielding material which will not compact readily when rolled shall be removed asdirected. All holes or depressions shall be filled with suitable material and thewhole surface compacted uniformly. In cut, sections, the ground below thesurface of the sub-grade, shall not be plowed or disturbed, except as otherwisedirected by the Board. When necessary, additional approved material shall beadded to bring the sub-grade to the desired elevations and cross section, and thewhole shall be rolled until compacted thoroughly.The Contractor shall perform a bearing test by a method to be instructed by theBoard on the surface of the sub-grade and he shall examine the thickness of subbase.The Board may instruct a modification to the design of pavement, if requiredbased on test results without any claim on the Board.17.7.1.2 Aggregate Sub-base Materials for Concrete PavementAggregate sub-base material for concrete pavement (roadways, parking areas,etc.) and roadway shoulder shall consist of hard, durable fragments of crushedgravel and stone or other similar materials, including additional selected filler forblending under the direction of the Board. The maximum dimension of anyparticle shall not be greater than two-thirds of the required thickness in which it isto be placed. Oversized material, if present, shall be removed at the quarry byscreens, grizzlies, or by hand. When necessary to obtain proper uniformity,additional filler shall be blended by mixing on the roadway. The faction of theaggregate sub-base material, including any additional filler passing the No.200sieve shall not be more than of that passing the No.40 sieve. The fraction of thematerial passing No.40 sieve shall have a liquid limit not greater than 25 and aplasticity index of not more than 6.The following gradation requirements shall apply to the sub-base for concretepavement and the thickness of sub-base shall be not less than 20 cm after it iscompacted or as otherwise agreed with the Board.Ghorasal 200 MW to 300 MW Gas Turbine Peaking Power Plant Project (Vol-2 of 3)175