How to calculate Water- Cement ratio in concrete ?

What is water cement ratio

The ratio between the weight of water to the weight of cement in the concrete mix is called Water Cement (W/C) ratio.

A low water to cement ratio is the number one issue effecting concrete quality. On an average 25% of water by weight of cement is required for the completion of chemical reactions in the process of hydration of cement.

For any nominal mix of concrete, there is a maximum free water cement ratio as per of IS 456:2000. Depending upon the exposure condition the water/cement ratio will vary.

Take Example

Let cement volume = 50 kg

Required amount of water = W/C Ratio X Cement Volume

Therefore, Required amount of water = 0.5 X 50 kg = 25 liters / 50 kg cement bag.

Normally, the water cement ratio being between 0.4 to 0.6 as per IS standard.

Note :-

1. If we keep on adding water to increase the work ability then the concrete has lots of fluid materials where the aggregates will settle down, this known as Bleeding . Once the water evaporated it leaves lots of voids in concrete which affects the concrete strength.And causes cracks in the strucrure
2. If the amount of water is low, the hydration process will not be as good as required, and our concrete will not be able to gain strength accordingly​.