Let's take example of M-25
Which mix proportion is 1:1:2
First part is forr cement is 1
Second part is for sand is 1
Third part of aggregate is 2
This is Volumetric batch.
Now we get concrete grade now we require quantity of all materials.
We want material for 1cubic meter
So we increase the volume 52% (it's nothing but the comes from dry volume to wet volume ratio:-1.54)
Because dry mix volume decrease when we add the water so we take more volume so increse the volume
1 C.M. to 1.52 C.M.(1+0.52)
Now for quantity make total of proportion
1+1+2 = 4 total volume if material.
For Cement
1 *
(1.52 / 4 ) = 0.38 meter cube
For number of cement bag divide 0.38 with one cement bag volume which is 0.035 cum.
So ANSWER is 10.85
So approximately 11 bags are used.
For sand
- quantity is same as cement because proportion is same 1:1:2
1 *
(1.52 / 4 ) = 0.38 meter cube
For Aggregate
2 *
(1.52 / 4 ) = 0.76 meter cube
So you get the quantity of all materials for 1 meter cube.