Although often used interchangeably in casual conversation, cement and concrete are distinct construction materials. Cement is a finely ground powdery binding substance manufactured by heating limestone and clay in a kiln. Concrete, on the other hand, is a complete composite construction material created by mixing cement, water, fine aggregates (such as sand), and coarse aggregates (such as gravel or crushed stone). In this mixture, cement acts strictly as the active binder that holds the solid aggregates together.