Different types of concrete grades and Mix ratio

Grade of concrete denotes its strength required for construction. For example, M30 grade signifies that the compressive strength required for construction is 30MPa. The first letter in grade M is the mix and 30 is the required strength in MPa.                                                                                                                                                                Based on various lab tests, the grade of concrete is presented in Mix Proportions. For example, for M30 grade, the mix proportion can be 1:1:2, where 1 is the ratio of cement, 1 is the ratio of sand, and 2 is the ratio of coarse aggregate based on volume or weight of materials.                                                                                                                               The strength is measured with concrete cube or cylinders by civil engineers at the construction site. Cube or cylinders are made during casting of the structural member and after hardening, it is cured for 28 days. Then the compressive strength test is conducted to find the strength.

Grades of concrete are M15, M20, M25, etc. For plain cement concrete works, generally, M15 is used. For reinforced concrete construction minimum M20 grade of concrete is used.