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## Grade of Concrete

**Grades of concrete** are defined by the concrete mix proportion and the minimum strength of **concrete** at end of 28 days curing period. The **grade of concrete** is can be known by calculating th**e compressive strength of concrete** in** Mpa**, where **M stands for mix** and the **MPa denotes the overall strength**

There are different **types of concrete mix** which are based on **concrete classification **according to its **compressive strength. **

For making concrete we use **cement**, sand,** aggregate**, and water which are mixed with a certain ratio, and concrete is cast and put in a cube of 150 mm size and put in a water bath for 28 days and afterward, it is tested in a **compression testing machine**. The compressive stress result is known as the “**grade of concrete**“**. It is expressed in N/mm²**

**The concrete grade** is denoted by** M10, M20, M30**, and so on according to their compressive strength.

**Read More:** **Concrete Mix Design Step By Step Full Calculation**

**Concrete Grade **As Per Indian Standards

The “M” refers to **Mix** and Number after M (M10, M20) Indicates the compressive strength of concrete after 28 days of curing and testing.

**M **indicates the proportion of materials like **Cement: Sand: Aggregate (1:2:4) **or Cement: Fine Aggregate: Coarse Aggregate.

If we mention M10 concrete, it means that the concrete has 10 N/mm2 characteristic compressive strength at 28 days.

In the designation of **concrete mix M** to the mix and the number to the specified compressive strength of **150 mm size cube at 28 days**, expressed in** N/mm^2.**

**Read More:** **How To Check Compressive Strength Of Concrete**

**Concrete Grade Per British/European standards:**

As per BS 8500-2 British/European standards the grade of concrete is denoted as C10, C15, C20, C25, etc., **‘C’ **which means ‘**Concrete** **Strength class’ **and the number behind **C** refers to characteristic Compressive strength of Concrete in N/mm2 @ 28 days when tested with the 15 cm dia. & 30 cm height **cylinder **in a direct compression test**.**

The
grade of concrete is also denoted as C16/20, C20/25, C25/30, etc., which
means **Concrete Strength Class
(C) **the number behind** C refers** to Compressive strength of
Concrete in N/mm^{2} when tested with** Cylinder / Cube.**

Different mix proportions of the materials used to make concrete namely

- Cement
- Coarse aggregate
- Fine aggregate
- Water

Result in concretes with different properties.

## Concrete Classification

Following are the Standard Concrete Grade with their Mix Proportions and Strength

Grades of Concrete | Mix Ratio (Cement : Sand : Aggregates) | Compressive StrengthMPa (N/mm2) | psi |

Lower Grade 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 Grade of Concrete | |||

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 |

**The Selection of the Grade of Concrete Depends on the Situation and Uses:**

Concrete Grade (N/mm2) | Ratio Cement, Sand, and Aggregates | Usage |

10 | 1:3:6 | PCC |

15 | 1:2:4 | PCC |

20 | 1:1.5:3 | Normal Construction Concrete |

25 | 1:1:2 | Reinforced concrete/precast |

30 | Concrete Mix Design | Heavy Reinforced concrete/pre-cast |

35 | Concrete Mix Design | Pre-stressed/pre-cast concrete |

40 | Concrete Mix Design | Very heavy reinforced concrete/pre-cast/prestressed |

45 | Concrete Mix Design | Very heavy reinforced concrete/pre-cast/prestressed |

**Watch Video: What is Grade of Concrete and Different Types used in Construction**

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