Q. In India, for 1.0 cum of M-20 grade concrete, the number of cement bags required is____________(up to two decimal places).
Ans: 5 to 9
Sol:
Composition of M20 grade of concrete is 1:1.5:3 (Cement: Sand : Aggregate) (Total 5.5) i.e. 5.5-unit volume of M20 grade of concrete contains 1-unit volume of cement.
Thus, 1 cu.m. Volume of M20 grade of concrete contains 0.19 cu.m, volume of cement. Wet concrete hardens after some time. Generally, volume of d-y Concrete = 1.54 to 1.57 times Volume of wet concrete
Thus, for 1 cu.m. Volume of wet M20 grade of concrete contains, 0.19 × 1.5 = 0.285 cu.m, volume of cement. 1 cu.m. of cement = 1440 kg.
Thus, 0.285 cu.m, of cement = 410 kg. The standard weight of each cement bag = 50 kg.
Thus, for 410 kg of cement, the number of 50 kg cement bags required = 410 50 = 8.208= 8 bags