What is grade of concrete, mix ratio and water cement ratio?

The mix design, water cement ratio and mix ratio values are main important properties it will affects the strength of the concrete. In this article you can able to learn about complete concepts of grade of concrete, mix ratio and water cement ratios

Grade of the concrete

The grade of the concrete is the mixture of materials which are used in the concrete making process. The materials like cement, fine aggregates, coarse aggregates and suitable amount of water are used in order to achieve the specified characteristic strength of concrete. In the concrete when the water is added to the cement material there will be reaction occurs in the mix of the concrete that reaction is called as the hydration reaction. Grade of the concrete depends upon the 28 days characteristic strength of concrete.

The grade of the concrete is denoted by Mx

Where M is the mix and x is called as 28 days characteristic strength.

For example let us consider M20 grade and M30 grade concrete. Where M is defined as mix and 20, 30 indicates the 28 days characteristic strength for M20 and M30 grade concrete.

The grade of the concrete is classified in to 3 types

1. Ordinary concrete grade
2. Standard concrete grade
3. High strength concrete grade

Ordinary concrete grades

The grades of the concrete related to the M7.5, M10, M15 and M20 grade are comes under the ordinary concrete grades.

Standard concrete grades

The grades of the concrete related to the M25, M30, M35, M40, M45 and M50 grade concrete grades are comes under the standard concrete grades.

High strength concrete grades

The grades of the concrete greater than M50 grade concrete called as the high strength concrete. Example M55, M60 etc.

Mix ratio

Mix ratio is the proportions of the ingredients used in the making of the concrete. Generally in the concrete mixture we will use ingredients like cement, fine aggregates, coarse aggregates and suitable amount of the water.

The mix ratio of the concrete is expressed as A:B:C at W/c

Where A is the proportion of cement, B is the proportion of the fine aggregates and C is the proportion of the coarse aggregates.

Mix ratios are divided in to two types which are shown below

1. Nominal mix
2. Design mix

Nominal mix

The nominal mix ratios are the proportions of concrete ingredients which are directly considered from the IS code standard provisions. Example mixes are M5, M7.5, M10, M15, M20 and M25 grade concrete.

For making M5 grade mix we will consider 1:5:10

For making M7.5 grade mix we will consider 1:4:8

For making M10 grade mix we will consider 1:3:6

For making M15 grade mix we will consider 1:2:4

For making M20 grade mix we will consider 1:1.5:3 and

For making M25 grade mix we will consider 1:1:2

For example consider M15 grade concrete which is having mix ratio of 1:2: 4, Where 1 indicates the cement proportion, 2 indicates the fine aggregates proportion and 4 indicates the coarse aggregates proportion.

Design mix

The design mix ratios are the proportions of concrete ingredients which are calculated by using IS 10262 and IS 456 code standard provisions. The mix proportion values are depends upon the basic material properties.

In order to determine the mix proportions as per the design mix initially we will conduct the basic material properties of cement, fine aggregates, coarse aggregates and suitable amount of the water. After calculating the material properties we will consider design steps according to IS 10262 and IS 456 code standards.

Water cement ratio

The water cement ratio plays an important role in the strength of the concrete. It is the ratio of the weight of the water to the weight of the cement used in the concrete. As per Abrams law it was suggested that if we use water content more than the requirement the strength is decreases. In the same process if we use less amount of the water in the concrete the strength value decreases. To overcome this problem we will use suitable amount of the water according to the standards.

Now we will see how much amount of water required in different grades of concrete for 50kgs of cement.

1. For M5 Grade concrete we will use 60 liters of water
2. For M7.5 Grade concrete we will use 45 liters of water
3. For M10 Grade concrete we will use 34 liters of water
4. For M15 Grade concrete we will use 32 liters of water
5. For M20 Grade concrete we will use 30 liters of water
6. For M25 Grade concrete we will use 25 liters of water

See the complete details of the grade of the concrete, mix ratio and water cement ratio in my YouTube channel Civil engineering by shravan see the details below.

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Conclusions of grade of concrete, mix ratio and water cement ratio

Well now the above concepts are related to the detailed concepts of grade of concrete, mix ratio and water cement ratio. The grade of the concrete is the mixture of materials used in the concrete making process according to the standards. The mix ratio is the proportions of the materials which are used in the concrete making process according to the specified grade. The proportions of materials are comes under two sections which are related to the nominal mix and design mix. Finally the water cement ratio plays important role in the strength of the concrete. If the water in concrete increases the strength values are decreases in the same process if the water in concrete decreases the strength values are increases.

For more information related to the civil engineering concepts and updated follow my YouTube channel Civil engineering by shravan.

Note: The above explained concepts are only for the education purpose for gaining the knowledge not suitable for the real time applications.

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