Concrete is sometimes called ‘poured in place concrete’, as it is poured into formwork molds on a construction site. The dimensions and texture of poured-in-place concrete are dictated by the formwork into which the wet concrete is poured.
Modern concrete is generally a mixture of a binder (cement), fine aggregate (sand) and coarse aggregate (gravel), combined with water. The binder can be made up of different cementitious materials, but modern concrete is usually made with Portland cement. In addition to the binder and aggregates, concrete may contain pigment or admixtures. Admixtures may improve the concrete’s strength or hardness, the speed at which it hardens, or the temperature at which it hardens, amongst other things. For tinted concrete, finely-ground pigment is added to the concrete mixture, while the color of untinted concrete can vary depending on the color of the concrete’s aggregate. Concrete contains steel reinforcing bar (rebar) to improve the concrete’s tensile strength.