Portland cement is the product obtained by pulverizing clinker, consisting of hydraulic calcium silicates to which some calcium sulfate has usually been provided as an interground addition. When first made and used in the early 19th century in England, it was termed portland cement because its hydration product resembled a building stone from the Isle of Portland off the British coast. The first patent for portland cement was obtained in 1824 by Joseph Aspdin, an English mason. The specific gravity of portland cement particles is about 3.15

There are four primary phases in portland cement: tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and tetracalcium aluminoferrite (C4AF). The strength and other properties of concrete are mainly derived from the hydration of tricalcium and dicalcium silicates. The composition of any of these phases in a particular clinker will not be precisely in the composition indicated.