*Concrete is the homogeneous mixture of cement or lime, sand, aggregate and water with their proportion. The cement used in concrete is called cementing material. The sand used in the concreting is fine aggregate. The aggregate used in concreting is obtained either from stone or from over bond bricks. When the concrete mixture is allowed to cure, hard mass is formed. Grade of concrete is given by:*

**Grade of concrete**

**Grade of concrete**

Concrete Grade | Mix Ratio (cement : sand : aggregates) | Compressive Strength | |

MPa (N/mm2) | psi | ||

Normal Grades of Concrete | |||

M5 | 1 : 5 : 10 | 5 MPa | 725 psi |

M7.5 | 1 : 4 : 8 | 7.5 MPa | 1087 psi |

M10 | 1 : 3 : 6 | 10 MPa | 1450 psi |

M15 | 1 : 2 : 4 | 15 MPa | 2175 psi |

M20 | 1 : 1.5 : 3 | 20 MPa | 2900 psi |

Standard Grade of Concrete | |||

M25 | 1 : 1 : 2 | 25 MPa | 3625 psi |

M30 | Design Mix | 30 MPa | 4350 psi |

M35 | Design Mix | 35 MPa | 5075 psi |

M40 | Design Mix | 40 MPa | 5800 psi |

M45 | Design Mix | 45 MPa | 6525 psi |

High Strength Concrete Grades | |||

M50 | Design Mix | 50 MPa | 7250 psi |

M55 | Design Mix | 55 MPa | 7975 psi |

M60 | Design Mix | 60 MPa | 8700 psi |

M65 | Design Mix | 65 MPa | 9425 psi |

M70 | Design Mix | 70 MPa | 10150 psi |

In the grade of concretes like M10, M20, M30, etc. “**M**” stands for **Mix of the ratio of cement:sand: aggregate**** **and **10/20/30** Stands for **Compressive Strength**.

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

**Different grade of concrete with applications:**

**Different grade of concrete with applications:**

**Normal Grade of Concrete**

**Normal Grade of Concrete**

**a. M5 Grade **

**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**

**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**

**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**

**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**

**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 Grade of Concrete**

**Standard Grade of Concrete**

**a. M25 Grade **

**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**

**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**

**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**

**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**

**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**

**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**

**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 Grade of Concrete**

**High Strength Grade of Concrete**

**M60 & M80 Grade of Concrete**

-They are used in the following:

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.

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