Water cement ratio formula -Table-Calculation for Mortar Example

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In this post, you will get water-cement ratio formula, water-cement ratio table, and calculation for Mortar. The water cement ratio is the ratio between the weight of water to the weight of cement used in the concrete mix. or the amount of water that we used in the cement concrete.

It is one of the major factors but not the only one influencing the strength of concrete. It is responsible mainly for the porosity of the hardest cement paste.

It was first developed by Duff A. Abrams in 1918. Abram’s equation for water cement ratio:

Where,

S = Compressive Strength

W/C = Water Cement Ratio

Why we should maintain water-cement ratio?

We know that the water-cement ratio directly affects the strength of concrete. If we use the limited amount of water for concrete then it will decrease the workability of concrete and so it will cause honeycomb in concrete.

If we add more water than required then it may cause bleeding in concrete which reduces the strength of concrete in a bad manner.

Water cement ratio Table

Water cement ratio calculation for different grade of concrete M15, M20

Calculation for Water Cement Ratio

          For proper workability, the water-cement ratio varies from 0.4–0.6. However, maximum strength is derived at w/c = 0.4 at which minimum capillary are expected to form.

In arriving at the water-cement ratio values it is assumed that aggregates are saturated with the surfaces in dry condition. Suitable adjustment should be made for dry aggregates, Sometimes cement-water ratio versus strength.

Normally, water cement ratio is calculated as :

Water cement ratio formula

Water-Cement Ratio = Weight of water/ Weight of cement.

Let us calculate water quantity for 1 bag of cement.

1 bag of cement = 50 kg

Assuming W/C ratio = 0.50

Water-Cement Ratio = Quantity of water/ Quantity of cement

Quantity of water = W/C ratio * Quantity of cement

Quantity of water= 0.50 * 50

                             = 25 kg (ltr).

Water Cement Ratio in Mortar:

          Mortar may be defined as a paste (capable of setting and hardening) obtained by adding water to a mixture of fine aggregates such as sand and binding materials, e.g., clay, gypsum, lime, or cement or their combinations. For the calculation of the quantity of sand, cement, and water in a mortar,

Quantity of Mortar

Assuming, volume of mortar = 1 meter cube

Mix ratio = 1:4

Dry volume of mortar = wet volume * 1.33

                                      = 1*1.33

                                      = 1.33 meter cube.

Quantity of cement

Quantity of cement = ( dry volume of mortar * cement ratio) / (sum of ratio)

Water cement ratio calculation for different grade of concrete

Density of cement = 1440 kg/meter cube

Water cement ratio calculation for different grade of concrete

1 bag of cement contains 50 kg of cement.

Number of bag = 383.04/ 50

                             =7.661.

Quantity of sand

Here, cement:sand :: 1:4

Water cement ratio calculation for different grade of concrete

Therefore,

Weight of sand = 1.064 * 1920     

Since, (1 Meter Cube=35.3147cubic feet)                                                        

=2042.88kg

If divided by 1000 => 2.0428 tonnes

Quantity of water

Here, water cement ratio = 0.50

Water Cement ratio = weight of water / weight of cement

Weight of water = 383.04*0.5

                             = 191.52 kg (ltr)

From above method, we can calculate the quantity of sand, cement and water in mortar.

Water Cement ratio of different grade of Concrete – Table

Normally, we used the water-cement ratio falls under 0.4 to 0.6 per IS Code 10262(2009) for nominal mix i.e. M7.5, M10,M15,M20,M25.

Here, M denotes Mix and Number denotes characteristics compressive strength of concrete of 150 mm cube after 28 days.

Concrete GradeMix RatioWater/Cement Ratio
M7.51:4:80.40
M101:3:60.45
M151:2:40.50
M201:1.5:30.55
M251:1:20.60
Water Cement ratio in different grades of concrete

I hope this post remains helpful for you.

Happy Learning – Civil Concept

Contributed by,

Civil Engineer – Suraj Khatri

Read Also,

Soundness test of cement- Procedure (By Le-Chatelier Method)

Fineness test of cement | Formula with Table of Calculation

Different grades of cement- IS Codes, Compressive Strength, Uses

17 Types of cement used for construction of the structure

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