When cement is gauged with water, the C3A, C3S and C4AF phases react very rapidly
and gauging water becomes saturated with Ca (OH)2 formed in the hydration reaction.
C2S phase hydrates rather slowly. The gypsum in the cement also dissolves rapidly, and
reacts with aluminate to give calcium sulpho aluminate, 3CaO.Al2O3. 3CaSO432H2O,
which also occurs in nature as ettringite. The important engineering properties of