Composition of concrete

cement

water

Aggregate

Concrete is composite construction material mainly of cement, water and aggregate. The aggregate is mostly a course aggregate (gravel) or crushed rock like limestone or granite with fine aggregate (sand). The reason of water and cement mixing together is to form the plastic mass which can be molded into requested shape. There are many different type of cement available and each ingredient has different chemical composition which can give different properties to concrete.

Water also one of the important factors to determine the quality and durability of concrete. The purpose of using water is for hydration in making concrete. Pure drinking water is considerable for making concrete as it is free from minerals and salt. If there is some impurities in the water may affect the quality of the concrete. Salt water (contain chloride and sulphates) cannot use for mixing concrete because it will cause corrosion of steel.

Other ingredient of concrete such as stone and sand must be clean and free from any contaminating substances in making a durable and fine quality concrete.  Substance like wood, humus and coal should not contain in the aggregate because this will affect the durability of concrete due to its weak nature. Moreover, aggregate must be hard and strong because it play an important roles in the formation of desired and durable concrete according to the shape and size of it.

The following video shows how to mix concrete