For an M20 grade of concrete, the ratio is (1:1.5:3) ie, (1 part of cement: 1.5 part of sand: 3 part of Aggregate)

Let us assume for 1 Cum. Of M20 concrete,

So, Wet volume of concrete = 1 Cum

Dry volume of concrete = 1.54 times of the wet volume of concrete (Here 1.54 stands

as “Factor of safety” to counter the shrinkage)

= 1.54 Cum

Total of ratio = 1 + 1.5 + 3 =5.5

Therefore, Volume of Cement = (1/5.5) x 1.54 = 0.28 m3

No. of Cement Bags = 0.28 x (1440 Kg/cum / 50 Kg/Cement Bag)

= 0.28 x 28.8 = 8.064 Bags

Say, **8 Bags of Cement**

** ** Volume of Sand = (1.5/5.5) x 1.54 = 0.42 m3

Say, **0.42 Cum of Sand**

** **Volume of Aggregate = (3/5.5) x 1.54 = 0.86 m3

Say, **0.86 Cum of Aggregate**

**NOTE: **Density of Cement = 1440 Kg/Cum for one bag of 50 Kg cement