How to work out the quantity of cement, sand and aggregate in 1m3 of Concrete
You should possess adequate knowledge on various grades of concrete to work out the necessary amount of cement, sand and aggregate in 1m3 of concrete. The grades of concrete is categorized into M5, M7.5, M10, M15 etc. on the basis of strength. Here M denotes Mix and the number denotes characteristic Compressive strength(fck) of the concrete in 28 days while appear in direct compression test.
The ratio for M20 grade of concrete is 1:1.5:3, it signifies1 part of cement, 1.5 part of sand (fine aggregate) and 3 parts of aggregate (crushed stone) in volume and then batched for mixing. The concrete mix design is demonstrated as follow :-
Mix Design (M) = Cement: Sand :Aggregate
With adherence to IS456:2000, various grades of concrete contain diverse proportions of cement, sand and aggregate which are mentioned under (Concrete Mix Design) :
Grade : Proportion
M5 : 1:5:10
M7.5 : 1:4:8
M10 : 1:3:6
M15 : 1:2:4
M20 : 1:1.5:3
M25 : 1:1:2
M30 : 1:1:3
How to work out quantities of cement, sand and aggregate in 1m3 of concrete :-
Concrete Mix Design for M20 Grade Concrete :-
According to IS456:2000 concrete proportion for M20 grade is = 1 : 1.5 : 3
By summing up, we get the total volume as = 1 + 1.5 + 3 = 5.5
The wet concrete becomes solidified after specific standard time as soon as it is arranged throughout concreting. As a solution, the Civil design Engineers suggest to choose a factor of safety that varies from 1.54 to 1.57 to resist that shrinkage.
Volume of dry Concrete = 1.54 to 1.57 times Volume of wet concrete
Here, 1.57 is considered as factor of safety
Therefore, total volume of necessary concrete is 1.57 Cum
How to work out the volume of cement in 1m3 of concrete :
Volume of cement = Cement/Cement + Sand + Aggregate x 1.57
= 1/1+1.5+3 x 1.57 = 0.28m3
1m3 of cement = 1440 Kg
0.28 m3 of cement = 0.28 x 1440 = 403.2 kgs
So, 403 kgs of cement is required for 1m3 of M20 grade concrete.
The weight of every bad of cement = 50 kgs
No. of cement bags = 403.2/50 = 8.06 = 8 bags (approx)
So, for 1 cum of concrete, 8 bags of cement is required.
To learn how to determine the quantity of sand (fine aggregate), aggregate and water, go through the following link civilread.com