Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. 

Concrete is a composite material, comprising a matrix of aggregate (typically a rocky material) and a binder (typically Portland cement or asphalt), which holds the matrix together.

A cement, most commonly Portland cement, is the most prevalent kind of concrete binder. For cementitious binders, water is mixed with the dry powder and aggregate, which produces a semi-liquid slurry that can be shaped, typically by pouring it into a form.