The major cements: composition and properties
Portland cement is made up of four main compounds: tricalcium silicate (3CaO SiO2), dicalcium silicate(2CaO SiO2), tricalcium aluminate (3CaO Al2O3), and a tetra-calcium aluminoferrite (4CaO Al2O3Fe2O3). In an abbreviated notation differing from the normal atomic symbols, these compounds aredesignated as C3S, C2S, C3A, and C4AF, where C stands for calcium oxide (lime), S for silica, A for alumina, and F for iron oxide. Small amounts of uncombined lime and magnesia also are present, along with alkalies and minor amounts of other elements.
Types of portland cementFive types of portland cement are standardized in the United States by the American Society for Testing and Materials (ASTM): ordinary (Type I), modified (Type II), high-early-strength (Type III), low-heat (Type IV), and
sulfate-resistant (Type V). In other countriesType II is omitted, and Type III is called rapid-hardening. Type V is know