BANGLADESH POWER DEVELOPMENT BOARD TENDER ... - BPDB

aggregates shall be washed prior to use in order to remove clay, silt, dust andadherent materials.The aggregates shall be stored on drained concrete paved areas in such a mannerthat intermingling of different sizes and types of aggregates is prevented. Thestock piles of the aggregates shall be protected from rubbish or wind blown dust.Coarse and fine aggregates shall be well graded within the standard limitsspecified as follows.17.6.8 STANDARD GRADINGa. Coarse aggregatePERCENTAGE BY WEIGHTSieve size 50.8 38.1 31.7 25.4 19.1 15.9 9.52 4.72 2.38Size ofCoarse 100 95-100 - - 37-70 - 10-30 0-5 -Aggregate(40-5 mm)(20-5 mm) - - 10095-100 - 30-70 - 0-10 0-5b. Fine aggregateSieve size (mm)Percentage passing by weight9.52 1004.76 90 - 1002.38 80 1001.19 50 900.595 25 650.297 10 350.149 2 20Limits of injurious material content Maximum (percent by weight)Silt/ClayVolume lost by Less than specificwashing test gravityCoarse aggregate 0.25 1.5 1.0Fine aggregate 1.0 7.0 1.017.6.9 CONCRETE MIXINGAll concrete except where specifically approved by the Board shall be mixed inweigh batch mixing machines. The machine shall have a Water storage tank withGhorasal 200 MW to 300 MW Gas Turbine Peaking Power Plant Project (Vol-2 of 3)170