The previous chapter dealt with the properties of Portland cement in general, and we have seen that cements differing in chemical composition and physical characteristics may exhibit different properties when hydrated. It should thus be possible to select mixtures of raw materials for the production of cements with various desired properties. In fact, several types of Portland cement are available commercially and additional special cements can be produced for specific uses. Several non-Portland cements are also available.
Before describing the various types of Portland cement, a more general discussion of the cementitious materials used in concrete may be useful.