elevated temperatures and it is merely the γ form that is thermodynamically
stable at room temperature [13,16]. Each polymorph shows
different reactivity with water. The α and α′ phases stabilised by
Al2O3, Na2O, MgO and K2O show considerable reactivity with water
[13]. The β-C2S, which is stabilised usually in the presence of some
impurity ions, is one of the principal components of Portland cement
clinker [17,18]. It is known as belite in cement chemistry, and compared
to the other polymorphs it reacts rapidly with water [19].