What Is the Formula for Cement?

Tricalcium silicate, also called alite, is one of the most abundant compounds found in cement and has the chemical formula Ca3SiO4. Its shorthand formula is C3S. Another abundant compound in cement is dicalcium silicate, which has the formula Ca2SiO5, or C2S in shorthand.

Although there are different types of cement, Portland cement is most commonly used for general purposes. This type of cement is created by crushing and milling calcium oxide, alumina, gypsum, silica and iron. All of these components, except the gypsum, are heated to 2,600 degrees Fahrenheit to form an intermediate substance called clinker, and then the gypsum is added after cooling.

In addition to tricalcium silicate and dicalcium silicate, some other compounds that make up the clinker include tetracalcium aluminoferrite, tricalcium aluminate and potassium oxide. Each compound provides the cement with important properties.

Tricalcium aluminate, which has the chemical formula Ca3Al2O6 and the shorthand formula C3A, does not provide the cement with much strength but is necessary for releasing heat during the manufacturing stage. Meanwhile, tricalcium silicate hardens quickly and helps the cement set early on. Much of the early strength of the cement is attributed to its tricalcium silicate content. After about one week, dicalcium silicate provides additional strength gain.