by To ask why concrete is classified into strength grades, one should first understand what concrete strength grades are.
The strength grade of concrete is artificially classified based on the compressive strength value of concrete cubes, which is the characteristic strength of concrete.
According to current relevant standards and specifications, the compressive strength of concrete cubes is determined by using standard methods to produce cube specimens with a side length of 150mm and a standard size.
The specimens are cured in a standard curing room with a temperature of 20 ± 2 ℃ and a humidity of 95% or higher, consistent with ISO testing methods, until 28 days of age.
The compressive strength of the concrete cube is measured according to the standard testing method.
.
