How to find out the materials quantities in a concrete slab

In this construction video tutorial, you will learn the step-by-step process for determining the materials quantities for a concrete slab. The materials include cement, sand, coarse and fine aggregate.

In the video, the length of the slab is taken as 30 feet, breadth 18 feet and thickness 6 inch or 0.5 feet.

The concrete mix ratio is taken as 1:2:4 (1 part cement, 2 parts sand and 3 parts aggregates). By summing up, we get 7.

To find out the volume of slab, the following formula is used :-

Length x Breadth x Thickness = 30 x 18 x 0.5 = 270 cubic feet
The result obtained is wet volume.
To convert it to dry volume, just multiply it with 1.5 i.e. 270 x 1.54 = 415.8 cubic feet.
So, dry volume of concrete slab is 415.8 cubic feet.

The quantities of cement can be obtained in the following way :-

Cement = ratio of cement/sum of ratio x dry volume = 1/7 x 415.8 = 59.4
To convert it to bags, divide the quantity of cement with volume of one cement bag.
59.4/1.25 = 47.52 = 48 bags
So, number of cement bags required is 48.

The quantities of sand can be obtained as follow :-
Sand = 2/7 x 415.8 = 118.8 ft3 (same process followed for finding out the cement quantities)

The quantities of aggregates can be obtained as follow :-
Aggregates = 4/7 x 415.8 = 237.6 ft3

To get online demonstration, watch the following video tutorial.

Video Source: Online Engineers