Plain Cement Concrete(Grades of concrete)

Grades of Concrete ( With Uses) | IS | British Standard | European Standard | American Standard | Australian Standard

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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.

 

Grades  of Concrete

Different nations have their own grades of concrete. We will discuss some of them.

 

Grades of Concrete Based on IS

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 M20 grade concrete

“M” stands for Mix ratio of cement:sand: aggregate  &  “20 “Stands for Compressive Strength.

grades of concrete

 

Table – Gardes of Concrete Based on IS

Concrete GradeMix Ratio (cement: sand: aggregates)Compressive Strength
MPa (N/mm²)psi
Normal Grades of Concrete
M51: 5: 105 MPa725 psi
M7.51: 4: 87.5 MPa1087 psi
M101 : 3: 610 MPa1450 psi
M151: 2: 415 MPa2175 psi
M201: 1.5 : 320 MPa2900 psi
Standard Grade of Concrete
M251: 1: 225 MPa3625 psi
M30Design Mix30 MPa4350 psi
M35Design Mix35 MPa5075 psi
M40Design Mix40 MPa5800 psi
M45Design Mix45 MPa6525 psi
High Strength Concrete Grades
M50Design Mix50 MPa7250 psi
M55Design Mix55 MPa7975 psi
M60Design Mix60 MPa8700 psi
M65Design Mix65 MPa9425 psi
M70Design Mix70 MPa10150 psi

 

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 5 MPa.

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

 

b. M7.5 Grade

~ Mixing Ratio is 1:4:8 ( 1 cement 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. M35 Grade

~  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.

 

Tricks to remember the different mixture of grades of concrete

M5 has 1:5:10

M7.5 has 1:4:8

M10 has 1:3:6

M15 has 1:2:4

M20 has1:1.5:3

M25 has 1:1:2

From this list we can note;

 The ratio of cement is constantly 1 for M5 to M25.

 The ratio of sand is in descending order from 5 to 1.(except M20 of 1.5)

 The ratio of aggregate is equal to 2 times of ratio of sand of grades.

Examples:

For M5,

5 part sand: ( 5×2) part aggregate

For M7. 5,

4 part sand: ( 4×2) part aggregate

And so on.

 

 

Grades of Concrete Based on British Standard (BS)

As per BS 8500-2; the grades of concrete is represented as C10, C20, C40, etc.

{

Note: 

In C10 grade concrete

‘C’ represents Concrete Strength Class and 10 represents 10 N/mm² Compressive Strength of Concrete @ 28 days when tested with the 15cm dia & 30cm height cylinder in a direct compression test.

}

 

Standard Strength Concrete Grades

 

a. C10 Concrete Grade

~ It is also known as Gen1 concrete.

~ It gains 10 N/mm² compressive strength in 28 days.

~ It can be used in trench fills, general floor binding, agricultural formations and drainage.

~ It is not suitable for structural mass formations.

 

b. C15 Concrete Grade

~ It is also known as Gen2 concrete.

~ It gains 15 N/mm² compressive strength in 28 days.

~ It can be used in construction of short walls, residental flooring, temporary structures, etc.

~ It is not suitable for large scale projects.

 

c. C20 Concrete Grade

~ It is also known as Gen3 concrete.

~ It gains 20 N/mm² compressive strength in 28 days.

~ It is used in the construction of lightweight foundations, internal floor slabs, driveways, garages, and sheds.

 

d. C25 Concrete Grade

~ It is also known as  ST2.

~ It is used in residential and commercial building projects for the construction of foundations, reinforced bases, etc.

 

High Performance Concrete Grades

 

e. C30 Concrete Grade

~ It is also known as ST3 or PAV1.

~ It gains 30 N/mm² compressive strength in 28 days.

~ It is used in reinforced bases, pavement construction, etc.

 

f. C35 Concrete Grade

~ It is also known as PAV2.

~ It gains 35 N/mm² compressive strength in 28 days.

~ It is used in large scale projects and constructions.

 

g. C40 Concrete Grade

~ It gains 40 N/mm² compressive strength in 28 days.

~ It is used in construction of large industrial support beams and foundations.

 

 

Grades of Concrete Based on European Standard

The grades of concrete are also represented as C16/20, C20/25, C25/30, C30/45, etc. ; which means C represents Concrete Strength Class the number behind C refers to Compressive strength of Concrete in N/mm² when tested with Cylinder / Cube.

concrete grades

{ Note:

1MPA = N/mm2 }

Concrete Gradefck (MPa)fck, cube (MPa)Ecm (GPa)
C12/15121527
C16/20162029
C20/25202530
C25/30253031
C30/37303733
C35/45354534
C40/50405035
C45/55455536
C50/60506037
C55/67556738
C60/75607539
C70/85708541
C80/95809542
C90/1059010544

 

Ecm = Elastic modulus of concrete

 

 

Grades of Concrete Based on American standard:

Concrete MixCylinder Strength (psi)Cylinder strength (MPa or N/mm²)
2000200013.8
3000300020.7
4000400027.6
5000500034.5
6000600041.3
8000800055.2
100001000068.9

 

 

Grades of Concrete Based on Canadian Standard:

The concrete grades of strength 20 Mpa to 40 MPa are listed in Canadian standard for the general use. The strength of concrete greater than 70 MPa are classified into high strength concrete. Highest strength of concrete 220 MPa has also been used in building applications.

 

 

Grades of Concrete Based on Australian Standard:

Prefix N is used to symbolize concrete grades and value of strength of concrete ranges from N20 to N100 in Australian standard.

Concrete MixCylinder Strength (MPa)
N2020
N2525
N3232
N4040
N5050
N6565
N8080
N100100

 

Read More: Peg in Surveying

Read More: Types of Concrete 

Read More: Lintel Level

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