Summary

Basically, the problem of designing a concrete mix consists of selecting the correct proportions of cement, fine and coarse aggregate and water to produce concrete having the specified properties. Sometimes additional ingredients such as ground granulated blastfurnace slag (ggbfs), pulverized-fuel ash (pfa), or admixtures are used. There are many properties of concrete that can be specified, e.g. workability, strength, density, thermal characteristics, elastic modulus, and durability requirements. The properties most usually specified are: the workability of the fresh concrete; the compressive strength at a specified age; and the durability, by means of specifying the minimum cement content and/or the maximum free-water/cement ratio, and in some cases requiring the use of selected types of materials.