Water Cement Ratio | Water Cement Ratio Calculation | W/C Ratio Formula

What Is Water Cement Ratio?

It Is the ratio of the mass of water to the mass of cement added to concrete. The water cement ratio directly affects the strength of the concrete mix. The typical w/c ratio for different grades of concrete varies between 0.40 to 0.60.

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Importance of Water Cement Ratio

 In concrete, the most important ingredient that influences that property of concrete is cement and water.

In concrete, the ratio of the weight of water to the weight of cement is called the water to cement ratio (w/c). The cement and water are the two main ingredients responsible for binding everything together.

The water-cement ratio is the ultimate factor for the strength and durability of the concrete when it is cured properly.

For example, if the W/C ratio is 0.40 that’s meant for every 100 lbs of cement used in the concrete, 40 lbs of water is added.

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What Happens? If You Add Too Much Water

Adding too much water to concrete can result in shrinkage, cracking, and reduced overall strength. Excessive water makes loose concrete difficult to handle, leads to segregation and bleeding problems in concrete.

Read More: Grade Of Concrete – Their Ratio, Uses & Suitability

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What Happens? If You Add Less Water

However, without enough water, it will make concrete to stiff, difficult to fill and compact and it can also result in honeycombing in concrete. it increases the labor effort to move the concrete.

How to calculate the proper amount of water required for concrete?

With the proper water-cement ratio concrete becomes more durability, porosity, and color will be balanced.

Recommended Water cement ratio for concrete,

• For ordinary concrete work (sidewalks and driveways): 0.6 to 0.7
• If required higher quality concrete is desired: 0.4

The practical best water-cement ratio is from about 0.40 to over 0.60.

• A ratio of 0.3 is made concrete too stiff (unless superplasticizers are used).
• A ratio of 0.8 makes concrete wet and fairly weak concrete.

Normal compressive strengths when concrete is properly cured are:

• 0.4 w/c ratio –> 5600 psi
• 0.8 w/c ratio –> 2000 psi.

Water-Cement Ratio Table

The following table indicate the water cement ratio for different grades of concrete as per exposure condition,

Water Cement Ratio Formula

The formula of water cement ratio calculation is water/cement. In simple words, water quantity is divided by cement quantity and result of calculation gives the w/c ratio.

It can be also calculated from Water Cement Ratio IS 10262 (2009) Code Chart

Water Cement Ratio Calculation

For example, if the water-cement ratio is 0.50 for concrete and cement is added is about 50 kg (weight of 1 bag of cement)

Water required for concrete will be,

Water/ cement = 0.50

Water / 50 kg = 0.50

Water = 0.50 x 50

Water = 25 liters = 6.60 gallon

Similarly for W/C = 0.40

Water = 0.40 x 50

Water = 20 liters = 5.28 gallon

As you see that there is water reduced as we decrease the water-cement ratio. It is a fact that water reduced in concrete increases its strength. But there is some limit to the water-cement ratio. The minimum water-cement ratio is 0.30 to 0.35, beyond this concrete becomes too stiff and impractical to handle.

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FAQs: Water Cement Ratio

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