In India, concrete grades are classified based on their compressive strength. Common grades include M15, M20, M25, and so on. The “M” stands for mix, and the number denotes the characteristic compressive strength of the concrete in megapascals after 28 days of curing.

**For example:**

1. M15: 1:2:4 (cement:sand:aggregate)

2. M20: 1:1.5:3 (cement:sand:aggregate)

3. M25: 1:1:2 (cement:sand:aggregate)

These ratios represent the proportion of cement, sand, and coarse aggregates in the mix.

According to Indian standard concrete grade is indicated as M20, which M is stand for concrete mix followed by a numerical figure 20, which is compressive strength of concrete after 28 days of mixing on axial compression test on cubic concrete block.

Characteristic strength of concrete is their compressive strength which can be determined by axial compression test on cubic concrete block or cylinder shape. If Compression test is carried on cubic concrete block that’s known as Cubic test and their strength is called cubic strength. And compression test is carried on cylinder shaped concrete block that is known as cylinder test and their strength is called cylinder strength.

Value of cube strength and cylinder strength are different for same mix. Value of cube strength is higher than cylinder strength. Using Thumb Rule, value of cube strength is is 1.25 times higher than cylinder strength.

**Cube strength = 1.25× cylinder strength**

Indian Standard codes concrete grade generally refers cube test, for finding out compressive strength of different mix of concrete at 28 days after mixing. In this article we read about types of concrete grade and their ratio as per Indian Standard.

**Types of concrete grade and their ratio as per Indian Standard**

According to Indian standard concrete grade is indicated as M20, which M is stand for concrete mix followed by a numerical figure 20, which is compressive strength of concrete after 28 days of mixing on axial compression test on cubic concrete block.

**What are the grades of concrete**

As we know that concrete are made of mixing of cement sand and aggregate in required proportion. What are the grades of concrete, according to Indian standard the grades of concrete represented as M5, M7.5, M10, M15 & M20 is known as normal grade of concrete, M25, M30, M35, M40 & M45 is known as standard grade of concrete and M50, M55, M60, M65, & M70 is known as high strength concrete grade.

**How many types of concrete grade are there**

According to Indian standard, concrete grade is categorised according to their compressive strength based on cube test and cube strength, generally, there are 3 types of concrete grade -1) normal grade of concrete, whitch is represented by nominal mix of concrete grade like M5, M7.5, M10, M15 & M20, (2) standard grade of concrete, which is represented by design mix of concrete grade like M25, M30, M35, M40 & M45 and (3) high strength concrete grade, which is represented by design mix of concrete grade like M50, M55, M60, M65, & M70.

**Types of concrete grade and their ratio**

As per Indian standard, different types of concrete grade are normal grade of concrete like M5, M7.5, M10, M15 & M20 and M25 are prepared according to their nominal mix ratio and standard grade of concrete and higher strength concrete grade are prepared according to their design mix.

**M5 concrete grade mix ratio**

The mix ratio for M5 grade concrete is typically 1:5:10, which means 1 part cement, 5 parts sand, and 10 parts aggregate (stone). This ratio is measured by volume.

Nominal mix ratio of M5 concrete grade is 1 : 5 : 10, in which one part is cement mixed with 5 part of fine aggregate/sand and 10 part of coarse aggregate with required quantity of water to reach compressive strength 5 Newton per square millimetre (N/mm2) at 28 days after mixing.

**M7.5 concrete grade mix ratio**

The mix ratio for M7.5 grade concrete is typically 1:4:8, which means 1 part cement, 4 parts sand, and 8 parts aggregate (stone). This ratio is measured by volume.

Nominal mix ratio of M7.5 concrete grade is 1 : 4 : 8, in which one part is cement mixed with 4 part of fine aggregate/sand and 8 part of coarse aggregate with required quantity of water to reach compressive strength 7.5 Newton per square millimetre (N/mm2) at 28 days after mixing.

**M10 concrete grade mix ratio**

The mix ratio for M10 grade concrete is typically 1:3:6, which means 1 part cement, 3 parts sand, and 6 parts aggregate (stone). This ratio is measured by volume.

Nominal mix ratio of M10 concrete grade is 1 : 3 : 6, in which one part is cement mixed with 3 part of fine aggregate/sand and 6 part of coarse aggregate with required quantity of water to reach compressive strength 10 Newton per square millimetre (N/mm2) at 28 days after mixing.

**M15 concrete grade mix ratio**

The mix ratio for M15 grade concrete is typically 1:2:4, which means 1 part cement, 2 parts sand, and 4 parts aggregate (stone). This ratio is measured by volume.

Nominal mix ratio of M15 concrete grade is 1 : 2 : 4, in which one part is cement mixed with 2 part of fine aggregate/sand and 4 part of coarse aggregate with required quantity of water to reach compressive strength 15 Newton per square millimetre (N/mm2) at 28 days after mixing.

**M20 concrete grade mix ratio**

The mix ratio for M20 grade concrete is typically 1:1.5:3, which means 1 part cement, 1.5 parts sand, and 3 parts aggregate (stone). This ratio is measured by volume.

Nominal mix ratio of M20 concrete grade is 1 : 1.5 : 3, in which one part is cement mixed with 1.5 part of fine aggregate/sand and 3 part of coarse aggregate with required quantity of water to reach compressive strength 20 Newton per square millimetre (N/mm2) at 28 days after mixing.

**M25 concrete grade mix ratio**

The mix ratio for M25 grade concrete is typically 1:1:2, which means 1 part cement, 1 parts sand, and 3 parts aggregate (stone). This ratio is measured by volume.

Nominal mix ratio of M25 concrete grade is 1 : 1 : 2, in which one part is cement mixed with 1 part of fine aggregate/sand and 2 part of coarse aggregate with required quantity of water to reach compressive strength 25 Newton per square millimetre (N/mm2) at 28 days after mixing.

**Different types of concrete grade and their uses**

There is three types of concrete grade, normal grade of concrete, standard grade of concrete and high strength concrete grade. Concrete grade is represented as M5, M7.5, M10, M15 & M20 are normal grade of concrete, M25, M30, M35, M40 & M45 are standard grade of concrete and M50, M55, M60, M65, & M70 higher strength concrete grade.

M5 concrete is very low strength concrete, it is not used for any type of structural construction work, M7.5 concrete also low strength concrete built for supporting Foundation, cover slab of single room for domestic animals and PCC flooring. M10 concrete grade is used for PCC flooring, patio making, slab and Pathways.

M15 grade of concrete is used for pavement making, PCC flooring, PCC for garage. M20, M25 and M30 grade of concrete used in all structural work of building construction in RCC beam, column, Foundation,slab and in other RCC structure.

M35, M40 and M45 standard grade of concrete for basement making septic tank water tank, and it is used in extreme environment condition also. M50 m60 so on concrete are higher strength concrete grade are used in lower floor of high rise building where maximum load is applied.