BANGLADESH POWER DEVELOPMENT BOARD TENDER ... - BPDB

than 15 cm in size containing suitable quantities of fines to a grading and qualityapproved by the Board.17.4.6 REPLACEMENT OF UNSUITABLE MATERIALIn a case where the in-situ soils are found unsuitable for proper construction ofthe foundations, such materials shall be excavated and replaced with sand orother suitable granular material to be approved by the Board. The Contractor shallsubmit materials samples, laboratory test results and the proposed method ofcompaction and construction to the Board for approval prior to commence theconstruction.17.5 Deleted17.6 CONCRETE WORKS17.6.1 GENERALStandards of design, materials, and workmanship shall be in conformity with thisSpecification, ACI Standard or other internationally accepted Standards approvedby the Board.For the purpose of the Contract, this Specification shall be applicable to allconcrete works to be included in the civil engineering and building works.17.6.2 COMPOSITIONThe Contractor shall make trial mixes using samples of aggregates and cementstypical of those to be used at least four weeks before commencing any concretingin the Works. The strength requirements for each grade of concrete proposed inthe design shall be determined by the Contractor by means of trial mixes tosatisfy the conditions specified in Table 17.1.Table 17.1Class A B CMaximum size ofaggregate (mm) 20 – 40 20 20Water-cement Less than Less than Less thanratio 0.55 0.55 0.55Maximum slump 7 - 10 7 7(In cm)Compressive strengthat 28th day 240 210 160(kgf/sq. cm)ApproximatePercentage of aircontent 2 ± 1 2 ± 1 2 ± 1Ghorasal 200 MW to 300 MW Gas Turbine Peaking Power Plant Project (Vol-2 of 3)168