Concrete is a versatile and durable construction material that can be used for various purposes. Concrete is made of cement, water, and aggregates (such as sand, gravel, or crushed stone) that are mixed in different proportions and undergo a chemical reaction called hydration. Depending on the type and amount of ingredients, admixtures (chemicals that modify the properties of concrete), and the method of construction, concrete can have different characteristics and uses. Some of the common types of concrete are: