concrete, in construction, structural material consisting of a hard, chemically inert particulate substance, known as aggregate (usually sand and gravel), that is bonded together by cement and water. Among the ancient Assyrians and Babylonians, the bonding substance most often used was clay.
Concrete structures boast some great qualities: In its most common form, concrete consists of aggregate (sand and stone), Portland cement, and water. The cement and water create a paste that acts as a binding agent for the aggregates.