Editing Cement (section)

=== Portland cement ===
{{Main|Portland cement}}
Portland cement, a form of hydraulic cement, is by far the most common type of cement in general use around the world. This cement is made by heating [[limestone]] (calcium carbonate) with other materials (such as [[clay]]) to {{convert|1450|C}} in a [[kiln]], in a process known as [[calcination]] that liberates a molecule of [[carbon dioxide]] from the calcium carbonate to form [[calcium oxide]], or quicklime, which then chemically combines with the other materials in the mix to form calcium silicates and other cementitious compounds. The resulting hard substance, called 'clinker', is then ground with a small amount of [[gypsum]] ({{chem2|CaSO4*2H2O}}) into a powder to make ''ordinary Portland cement'', the most commonly used type of cement (often referred to as OPC).
Portland cement is a basic ingredient of [[concrete]], [[mortar (masonry)|mortar]], and most non-specialty [[grout]]. The most common use for Portland cement is to make concrete. Portland cement may be grey or [[White Portland cement|white]].