Question

Calculate the approximate number of cement bags required for preparing wet concrete of 10 m³ by volume in 1 ∶ 3 ∶ 6 mix proportion. Consider dry volume of concrete to be 1.54 m³ per cubic metre of wet concrete.
1. 50 bags
2. 45 bags
3. 35 bags
4. 40 bags

Answer 1

Correct Answer - Option 2 : 45 bags

Concept:

i) Wet volume of concrete = 1 m3

ii) Dry volume of concrete should be taken to be 54 % more than its wet volume

iii) Concrete ratio = 1:3:6, which implies for 1 cubic meter of concrete contains 1 part cement, 3 part sand or fine aggregates and 6 parts coarse aggregates.

iv) 1 bag of cement = 50 kg of cement

v) Density of cement = 1440 kg/m3

Calculation:

Dry volume of concrete = 1.54 x 10 m3 = 15.4 m3

Volume of cement required:

\(V = \frac{1}{10} × 15.4 = 1.54\;{m^3}\)

Weight of cement required:

W = Volume of cement × Density of cement = 1.54 × 1440

Weight of cement required = 2217.6 kg

Number of cement required:

\(N = \frac{{Total\;weight\;of\;cement\;required}}{{Weight\;of\;1\;bag\;of\;cement}}\)

∴ \(N = \frac{{2217.6}}{{50}} = 44.35\;bags\approx45\;bags\)