**Example **

Let suppose we have a two way slab having a length of 20 feet and same as width of 20 feet and use M-15 grade of concrete, Calculate the quantity of cement ,sand and aggregate that are used in a slab and thickness of the slab is 6 inches?

**Given Data**

Length = 20 feet

Width = 20 feet

Thickness = 7 inches

**Solution**

First, we calculate the volume of the slab and then this volume are converted into a wet condition to dry condition and then find out the how much material is required for the slab.

Total volume of slab = L x W x H

= 20 x 20 x 0.583 = 233.2 cft

Convert wet volume to dry volume

Dry volume = wet volume x 1.54 (Wastage of sand Bulking all included)

= 233.2 x 1.54 = 359.13 cft

Ratio of concrete ( 1:2:4 = 7)

**1- Volume of cement**

Vol. of cement = ratio of cement / total ratio x dry volume

= 1 / 7 x 359.13

= 51.30 cft

convert this volume into cement bags. you know that 1.25 cuf in one cement bag.

= 51.30 / 1.25

=** 41.04 bags.**

**2- volume of sand**

Vol. of sand = ratio of sand / total ratio x volume

= 2 / 7 x 51.30

= **14.65 cft.**

**3- Volume of aggregate**

Vol. of aggregate = ratio of aggregate / total ratio x volume

= 4 / 7 x 51.30

= **29.31 cft.**

## 3 comments

How we calculate the materials for plaster … how much black sand and how much cement for 1 meter area

Simple and useful mathed of construction work

Volume of cement is correct but then the volume of sand and aggregate is calculated wrongly. When we have got the value of 1/7 then we just have to multiply it by 2 and 4 to achieve the volume of sand and aggregate respectively.

Therefore calculating the value 51.30 × 2 and 51.30× 4.