The strength of concrete is divided into twelve grades, such as C7.5, C10, C15, C20, C25, C30, C35, C40, C45, C50, C55, C60 and so on. The concrete mix ratio refers to the proportion of the components in concrete (cement, water, sand, and stone). There are two methods: one is to use a variety of materials amount per 1 cubic meters, such as ...