is made up of four main compounds: tricalcium silicate (3CaOSiO2), dicalcium silicate (2CaOSiO2), tricalcium aluminate (3CaOAl2O3), and a tetra-calcium aluminoferrite (4CaO Al2O3Fe2O3). In an abbreviated notation differing from the normal atomic symbols, these compounds are designated 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 Hydration. The most i ....