Concrete is the most widely used building material and is versatile, used for structural and aesthetic purposes. It is a composite material made of cement, water and aggregates that sets and hardens through a chemical reaction. Concrete can be cast into complex shapes and textures and colored for architectural applications. Admixtures and additions are used to improve properties of fresh and hardened concrete. Aggregates make up the bulk of a concrete mixture. Concrete is used extensively for interior and exterior architectural applications due to its versatility.