Grades of Concrete

~ Concrete is the homogeneous mixture of cement or lime, sand, aggregate and water in a fixed proportion. Its quality plays a vital role in the strength and durability of the structure. Hence, the quality of concrete is expressed as grades of concrete. Higher the grade of concrete; higher will be the quality and vice versa.

~ The grade of concrete is the minimum strength that the quality controlled concrete posses after 28 days of the construction. There are different grades of concrete like M15, M20, M25, M60, etc. 

~ For small structure constructions; normal grade concretes like M15, M20 & M25 are used.

~ For large structure constructions; standard-grade & high-grade concrete like M40, M45, M50, etc are used. There is a requirement of design mix in high-grade concretes.

Note: 

~ In M25 grade concrete

“M” stands for Mix of the ratio of cement:sand: aggregate  &  “25 “Stands for Compressive Strength.

Grades of concrete

Note:

~ Concrete less than M20 grade should not be used in the RCC work as per code IS 456:2000.

~ PQC stands for Pavement Quality Concrete.

Normal grades of concrete

a. M5 Grade 

~ Mixing Ratio is 1:5:10 ( 1 part of cement, 5 parts of sand and 10 parts of aggregate).

~ Compressive strength is 5MPa.

~ Used in foundation bed to prevent direct contact between soil and foundation concrete.

b. M7.5 Grade

~ Mixing Ratio is 1:4:8 ( 1cement part: 4 sand part: 8 aggregate part).

~ Its compressive strength is 7.5 MPa.

~ Used in foundation bed to prevent direct contact between soil and foundation concrete. (same as M5)

c. M10 Grade

~ Mixing Ratio is 1:3:6 ( 1cement part: 3sand part: 6 aggregate part).

~ Its compressive strength is 10MPa.

~ Used in the base of footing, construction of levelling works, road construction, etc.

d. M15 Grade

~ Mixing Ratio is 1:2:4 ( 1cement part: 2 sand part: 4aggregate part).

~ Its compressive strength is 15 MPa.

~ Used as Plain cement concrete ( PCC).

~ Used in the base of footing, construction of levelling works, road construction, etc.

e. M20 Grade

~ Mixing Ratio is 1:1.5:3 ( 1cement part: 1.5 sand part: 3aggregate part).

~ Its compressive strength is 20 MPa.

~ Used as Reinforced Cement Concrete(RCC).

~ Used for construction of slabs,beams,columns,etc.

Standard grades of concrete

a. M25 Grade 

~ Mixing Ratio is 1:1:2 ( 1cement part: 1 sand part:2aggregate part).

~ Its compressive strength is 25 MPa.

~ Used as Reinforced Cement Concrete(RCC).

~ Used for construction of slabs,beams,columns,etc.

b. M30 Grade

~ M-30 Mix Designs as per IS-10262-2009

~ Used as Reinforced Cement Concrete(RCC).

~ Used for construction of slabs,beams,columns,etc. 

c. M35Grade

~  M-35 Mix Designs as per IS-10262-2009

~ Used as Reinforced Cement Concrete(RCC).

~ Used for construction of slabs,beams,columns,etc.

d. M40 Grade

~  M-40 Mix Designs as per IS-10262-2009

~  Used as Prestressed Concrete.

~ Used for construction of slabs,beams,columns,etc.

e. M45 Grade

~  M-45 Mix Designs as per IS-10262-2009

~ Used as Reinforced Cement Concrete (RCC)

~  Used in the followings:

i. Runways

ii. Concrete Roads (PQC)

iii. Pressurized Concrete Girders

iv. Pressurized beams

v. RCC Columns

f. M50 Grade

~  M-50 Mix Designs as per IS-10262-2009

~  Used as Reinforced Cement Concrete (RCC)

~  Used in the followings:

i. Runways

ii. Concrete Roads (PQC)

iii. Pressurized Concrete Girders

iv. Pressurized beams

v. RCC Columns

g. M55 Grade

~  M-55 Mix Designs as per IS-10262-2009

~  Used in the Pressurized Concrete Girders.

~  Used in the Pressurized Concrete Piers.

High strength concrete grades

For M60  to M80 Grade of Concrete

These grades of concrete are used in the  following sectors:

a. Construction of high rise buildings, spillways of dams, long-span bridges, etc.

b. It can be used in the work where the environment is quite aggressive.