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.

Share this
3 comments
  1. 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.

Leave a Reply

Your email address will not be published. Required fields are marked *