Portland Cement is a binder produced by the intergrinding of clinker, natural gypsum and other mineral components (pozzolana, limestone etc.).

The main component, Clinker, is manufactured by the sintering at high temperature (~1500 °C) of an intimate mixture of milled and dried limestone and clay.

Gas temperatures of excess of 2000°C are required to sinter the raw materials and are generated by the combustion of coal or oil.