## Every time when a civil engineer goes to site the first few questions he ask is What is Water Cement Ratio?

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Things we are going to see in this article is **water to** **cement ratio, **Roles of **cement water ratio , **What will be the **Effects of too much water in concrete **and **How to calculate Water Cement Ratio?**

**Water Cement Ratio**

The ratio of weight of water to the weight of cement used in a concrete mix is known as

**water to cement ratio.**

If a mix have low

To overcome the issues we use

**w/c**(**water cement**) ratio, the mix tends to show high concrete strength and durability but the*disadvantage*of this is due to low water to cement ratio, the concrete shows*low workability (ability of concrete to handle, transport and placing without any segregation)*.To overcome the issues we use

*admixtures such as plasticizers and super- plasticizers*to overcome the workability problem and make the concrete flow workable.- Usually we take w/c ratio 0.4 to 0.6 as per IS Code 10262 (2009) for nominal mix (M10, M15, M20,M25)

For concrete greater tha M25, we design-mix the concrete with proper admixtures as per requirements of strength, Durability and flow.

## Role of water in concrete mix

When the water is mixed in a concrete mix, It results in chemical reaction between cement and water. This reaction is termed as

**"Heat of hydration".**
The water added in mix uses 23-25% of the cement volume in the chemical reaction of hydration process and 15-18% turns up in a form of

*gel or slurry or water cement paste*which fill the voids of the mix, making the concrete gain strength and durable.## Effects of adding too much water in concrete mix

Adding too much of water in concrete mix may lead to

- Segregation of sand and aggregate from cement mix
- As low as 10 percent more water gives you 17 percent less strength.
- The excess water not consumed in chemical reaction of hydration will result in
.*bleeding of concrete*

## How to calculate water cement ratio?

Normally the water to cement ratio is provided by structural engineers with grading of concrete mix.

But in site conditions we can

**calculate water to cement ratio**as
Consider we have to calculate for

**0.50 w/c ratio.**
Lets consider we need to take out water required for 1 bag of cement, ie. 50kg

So, we can calculate as,

W/C = 0.5

W/50= 0.5

W= 0.5x50

W=25 liters.

So for 1 bag of cement at 0.5 w/c ratio, we require 25 liters of water for the mix.

If you want to learn about Grade of concrete (concrete mix design) click here

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