How to calculate the water-cement ratio for concrete?

Water Cement Ratio means the ratio of the weight of water to the weight of cement used in the concrete mixture.

Or in easy words it is the amount of water required in the cement concrete mixture.
As we know that water cement ratio directly affects the strength of concrete. So, by being in limits of water-cement ration for concrete mixture to get the good strength of concrete.

Why we Use Water to make concrete mixture?

There are no other cheapest and easily available things which can be used to mix cement with aggregate to make a concrete. If we don’t use the water we can not mix cement with aggregate to make concrete mixture.

And also, water perform great role in Concrete, therefore water is the main key for Cement concrete which can combine all the material with each other.

According to the ration of water-cement we get strength on any Construction work. Besides the quantity of water in concrete, the quality of water used in concrete have important effects on fresh concrete properties, such as setting time as well as work-ability.  Also it have important effects on the strength and durability of concrete.

Water cement ratio table

How to calculate the water-cement ratio for concrete? 1

As per IS Code 10262.

Now, let us take a example to calculate the W/C ratio..

We need to know following thing to calculate water cement ratio:

  1. Grade of concrete. Eg: M25, M20, M10 etc.
  2. Amount of cement per m³.
  3. Water-cement ratio.

Calculation Procedure

Let us assume, Grade of concrete is M15.

Let, Cement required for 1 m³ of M15 grade concrete be 6 bags.

Each bag of cement contains 50 kg of cement.

∴ 6*50 = 300 Kg of cement required.

Let’s assume that the water cement ratio is 0.5.

Formula used to find W/C ratio:

W/c ratio =Water content /Cement content

Water content = Cement content x W/c ratio

Water content = 300 Kg x 0.5 = 150 Kg.

Here, 1 Kg =1 liter

So water content = 150 Kg. = 150 Litres

Add 3-5% wastage of water during mixing, handling,

We used 5%,

∴ Total Water content = 5× 150/100 + 150 = 157.5 liters.

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