C3S - tricalcium silicate (3CaO SiO2)
C2S - dicalcium silicate (2CaO SiO2)
C3A - tricalcium aluminate (3CaO A1203)
C4AF - tetracalcium alumina ferrite (4Ca0 A1203 Fe203)
A small amount of magnesium oxide (MgO) and calcium oxide (CaO – free lime) is also formed. Sulfate in the form of gypsum (CaS04 2H20) or anhydrite (CaS04) is then added to the clinker during the grinding principally for the purpose of controlling the chemical reactions during the early hardening period.