Complete Guide on Grades of Concrete

Today, we will discuss grades of concrete, concrete mix ratios, uses, and many other things related to grades of concrete. First, let me tell you what you mean by the word concrete.

Concrete Meaning

Concrete is the paste made by mixing Portland cement, sand, fine or coarse aggregates, and water proportionally. Its main purpose is to bind all the building materials together and enhance the strength of the structure. We can determine the strength of the concrete mix by the number of materials such as cement, sand, aggregates, and water used to prepare the mixture. Now, let’s dive into the grades of concrete.

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What are the Grades of Concrete?

To make concrete, we mix all the ingredients such as cement, sand, fine and coarse aggregates, and water in a fixed proportion. Then, the mixture or paste is subjected to cast and placed in a cube of size 150 mm. After that, it is placed in a water bath for at least 28 days. Thereafter, it is subjected to the compression test. The result determined is the compressive stress of the concrete. This compressive stress is termed as Grades of Concrete. Its unit is N/mm².

You can find several grades of concrete in the market based on the proportions of materials used. These are M10, M20, M30, M35, and so on. Grades of Concrete are characterized by M10, M20, M30, etc as per their compressive strength. You might be thinking what does this M10 or M20 characterize.

Also Read : What Is Concrete With Definition & History

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What do you mean by M10 or M20? What does it represent?

The letter “M” exemplifies mix or mixture.  Mix or mixture depicts concrete with its specified proportions of the building materials such as cement, sand, and fine or coarse aggregate. And the number such as 10 or 20 placed after the letter “M” depicts the compressive strength of that concrete mix. It is denoted by N/mm² after the water bath of 28 days.

Let’s take an example to understand in a better way. For instance, if we consider M20 grade of concrete mix, it exemplifies the compressive strength of the concrete after the water bath of 28 days is 20 N/mm².

Now, have a look at the Concrete Mix Design Table.

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Concrete Mix Design Table

Here is the current chart table exhibiting several grades of concrete mix design along with their mixed ratios of cement, sand, and aggregates employed.

S.N	Grades of Concrete	Ratios of Concrete Mix Design	Compressive Strength (N/mm²)	Psi
1.	M5	1:5:10	5 N/mm²	725
2.	M7.5	1:4:8	7.5 N/mm²	1087
3.	M10	1:3:6	10 N/mm²	1450
4.	M15	1:2:4	15 N/mm²	2175
5.	M20	1:1.5:3	20 N/mm²	2900
6.	M25	1:1:2	25 N/mm²	3625
7.	M30	1:0.75:1.5	30 N/mm²	4350
8.	M35	1:0.5:1	35 N/mm²	5075
9.	M40	1:0.25:0.5	40 N/mm²	5800
10.	M45	Design Mix	45 N/mm²	6525

High Strength Concrete Grades or Grades of high-performance concrete

S.N.	Grades of Concrete	Ratios of Concrete Mix Design	Compressive Strength (N/mm²)	Psi
1.	M50	Design Mix	50 N/mm²	7250
2.	M55	Design Mix	55 N/mm²	7975
3.	M60	Design Mix	60 N/mm²	8700
4.	M65	Design Mix	65 N/mm²	9425
5.	M70	Design Mix	70 N/mm²	10150

According to the rules of IS 456:2000, the grade of concrete below M20 should not be utilized in any RCC works. M25 is considered as the standard grade of concrete.

You can recognize in the table, the quantity of aggregate is kept double of that old sand in these concrete mix designs. You can estimate these ratios by utilizing buckets or standard cubes during the construction project. It helps to maintain consistency.

You might be thinking of what should be the water content ratio in the concrete mix design.

Also Read : Different Types Of Concrete

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Water content ratio in concrete mix

The water content ratio in the concrete mix design defines the workability and strength of the concrete. If you use an adequate amount of water, it increases the workability of concrete. But it decreases the strength of concrete. If you use less amount of water, workability reduces and it’s difficult to use such type of concrete in construction works. The quantity of water varies for the different grades of the concrete.

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What are the several types of concrete grades and their uses?

Selecting the proper concrete grade for the construction job is a difficult task. We are here to help you choose the best concrete grade for your construction projects. You might be curious to know where these grades of concrete can be used. Here we will discuss some of the grades of concrete and their uses in the construction job.

C5

C5 is utilized to provide the smooth surface to the foundation concrete and to stave off the direct touch of foundation concrete from the soil.

C7.5

C7.5 is utilized to provide the smooth surface to the foundation concrete and to stave off the direct touch of foundation concrete from the soil.

C10

C10 grade of concrete is basically utilized for Patio slabs, paths ys, and non-structural work.

C15

C15 is utilized for pavement curbs and floor binding works.

C20

C20 is utilized for both domestic floors and foundations. It is also used for workshop bases, garages, internal floor slabs.

C25

C25 is utilized for construction in all areas as it is considered as Standard Concrete. It is also known as the multi-purpose concrete mix, usually in foundations.

C30

C30 is mainly utilized for pathways and roadways. 

C35

C35 is mainly employed for commercial buildings. This heavy concrete mix design is basically used for building external walls and slabs along with structural piling.

C40

C40 is utilized for building foundations and beams for structural backing and roads.  

C45

C45 is utilized as RCC (Reinforced Cement Concrete) for runways, concrete roads, RCC columns, RCC beams, etc.

C50

C50 is utilized as RCC (Reinforced Cement Concrete) for runways, concrete roads, RCC columns, RCC beams, etc.

C55

C55 is utilized for Pressurised Concrete Girders and Pier.

C60

C60 is utilized for RCC work where high compressive strength is employed such as high-rise buildings, long-span bridges, etc.

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Frequently Asked Questions