Cements are classified primarily on the type of the main constituents such as Portland cement or blast furnace cement. (In addition, there may be minor constituents up to 5% and also additives up to 1% by weight.)

The standard BS EN 197–1: 2011 lists five main types of cement:

CEM I Portland cement
CEM II Portland-composite cement
CEM III Blast furnace cement
CEM IV Pozzolanic cement
CEM V Composite cement

Within these five main types of cement, a wide range of constituents is permitted, including silica fume, natural or industrial pozzolanas, calcareous or siliceous fly ash and burnt shale, may be incorporated. The full range of products is listed in below Table , but not all are commercially available within the UK. In addition to Portland cement, CEM I, current UK factory pro -duction includes Portland-limestone cement, Portlandfly
ash cement and low early strength blast furnace cement, and these composite cements now account for about 25% of the total supply (i.e. bulk plus bagged/ packed) in the UK market. Calcium aluminate cement (also known as high alumina cement (HAC)) has a totally different formulation compared with the range of Portland cements based on calcium silicates.