A group of hydraulic cements composed of milled clinker usually mixed with calcium sulfate (commonly gypsum) as a set retarder. The most common Portland cement is called Ordinary Portland Cement (OPC). The name Portland cement was derived from the Isle of Portland, U.K., where Portland stone, which looked similar to cement, was quarried. Portland cement sets as a result of hydration reactions, and thus is required to be wet while curing for best stability (strength).
Cf., cement, binder, clinker