what is the meaning of M15,M20,M25 concrete?

Grade of concrete is defined as the minimum strength the concrete must posses after 28 days of construction with proper quality control. Grade of concrete is denoted by prefixing M to the desired strength in MPa.

- M15 concrete mix has a mix proportion of 1:2:4 of cement, fine aggregate, and coarse aggregate respectively.
**M15 – M represents Mix and 15 N/mm2 is the characteristic compressive strength of concrete cube at 28 days**. Contents: Required Data M15 Grade Concrete. - for a grade of concrete with 20 MPa strength, it will be denoted by M20, where M stands for Mix. These grade of concrete is converted into various mix proportions. For example, for M20 concrete, mix proportion will be 1:1.5:3 for cement:sand:coarse aggregates.
- M25 grade concrete is type of grade of concrete that would achieve a compressive strength of 25 N / mm2 after 28 days of curing period of initial construction.