The proportionsand methods of use shall ge specified

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Unformatted text preview: s permitted as admixtures shall have established merit for improving any specific quality of the concrete without causing deleterious effects. 3.3 Water-Water for mixing concrete, g-rout, or mortar, and also for washing the aggregates and Curing concrete, shall be clean and free from injuriWs quantities of acid, alkali, silt, oil, organic matter,.or other impurities. 3.4 Aggregates 3.4.1 Agbqegates for concrete shall conform to @IS: 383-1952 or tIS: 515. 3.4.2 The maximum size of coarse aggregate, as determined by the biggest square hole through which not less than 95 percent of the aggregate shall pass shall be as large as can be ‘used practicably and economically under given conditions, but shall be not -larger than any one of the following : a) one-fourth the narrowest dimension between the faces of forms, b) one-third the depth of any slab, c) three-fourths of the clear space between reinforcement bars, and d) three-fourths of the narrowest space through which the concrete shall have to be passed. 3.5 Reinforcement - Reinforcement shall be any of the following: Mild steel and high tensile steel bars and hard-drawn steel wire conforming to: IS: 432-1953, Structural steel sections conforming to 5 IS : 226-1955, Cold twisted steel bars complying with the requirements of Appendix A of ?i IS: 456-1957, and Such other reinforcement as may bc proved suitable, having regard to the yield point stress, ductility, ultimate resista!lce to tension and other essential properties of the completed rebforcement as produced in readiness for use in reinforced concrete. 3.5.1 Mill scale and rust scale, if any, shall be removed inforcemen t before 3.6 Storaee from the re- use. of Materials 3.6.1 Cement shall be stored in a damp proof place. Handling and storage facilities shall be such that no cement is stored before use for more than 120 days counted from the date of despatch by the manufacturer. l ecmd S revision tSince withdmwn. @econd revision $ Fifth revision B Second r&irion in 1970. in 1966. in 1975. h 196+. 8 IS : 457 - 1957 Cement stored beyond 120 days but not exceeding 180 days shall be tested and rejected if found defective in any way. Cement stored beyond 180 Cement shall be ch:ckLd days shall not be used for major construction. on the job for contamination or partial setting due to exposure to moisture during transit. 3.6.2 Aggregates shall. be stored and handled in such a manper as to prevent the intermingling of various sizes of aggregates required.separately for grading purposes. No foreign matter shall be allowed to be mixed up with the aggregates. Stockpiles shall be built in layers of uniform thickness. 3.6.3 Reinforcement rusting of steel. shall be stored in such a manner as to minimize 4. CONCRETE 4.1 General - The concrete used in dams and other structures may vary in character from mass concrete having a maximum size of aggregate from 10 cm ( preferahly 15 cm ) to 23 cm [ or 4 in ( ljreferably 6 in ) to 9 in I and a cement content ran...
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