Grade of Concrete (IS code)

IS 456:2000, "Code of Practice for Plain and Reinforced Concrete," is the Indian Standard (IS) code used to specify the grades of concrete. For the design and building of reinforced concrete structures, this code is utilized.

A number is used to identify the various grades of concrete, followed by the letter "M," which stands for "Mix." The amount in megapascals (MPa) represents the concrete cube's typical compressive strength at 28 days.

Grade of Concrete

Concrete Mix ratio

Compressive Strength (Mpa-N/mm2)

Initial grades/Normal grades of concrete

M5

1:5:10

5

M10

1:3:6

10

M15

1:2:4

15

M20

1:1.5:3

20

Mid grades/Standard grades of concrete

M25

1:1:2

25

M30

Design mix

30

M35

Design mix

35

M40

Design mix

40

M45

Design mix

45

High strength concrete grade

M50

Design mix

50

M55

Design mix

55

M60

Design mix

60

M65

Design mix

65

M70

Design mix

70

 

Important points:

M5 / M7.5 = They are used in foundation beds to avoid direct soil contact with the foundation.

M10 = They are used in the construction of roads, levelling projects, and footing bases.

M15 = They serve as Plain Cement Concrete (PCC). They are employed in the construction of roads, levelling projects, and footing bases.

M20 / M25= They are utilized in Reinforced Cement Concrete (RCC). They are employed in the building of slabs, beams, columns, etc.

M30 / M35 / M40 = They should all be designed according to IS 10262-2009.

M45 / M50 = In general, runways, concrete roads, RCC columns, pressurized concrete girders, and pressurized beams employ M45 or M50.

M55 = M55 is identical to M45, however, it is solely used for piers and girders.

M60 to M80 =

  • It is used for concrete of high-rise buildings, spillways of dams, long-span bridges etc.
  • It can be used, where the environment is quite aggressive.

Based on the anticipated construction's load-bearing capability and structural requirements, the suitable grade of concrete is selected. When choosing the right grade of concrete for your particular project, always consult the advice of a civil engineer or follow to local building laws and standards.