Long-term hydration of CaSiO4 with combined additions of silica fume, calcium sulpha aluminate and gypsum

Slow hydration of γ-C2S in mixtures of β and γ polymorphs was observed between 17 and 40 months of curing, but did not occur in the presence of silica fume. The detection of cross-linked silicate species by nuclear magnetic resonance (Q3) is attributed to the formation of silica gel because of the low effective CIS molar ratio in mixtures containing silica fume. The formation of ettringite from additons of C4A3S and gypsum prevents the hydration of β-C2S unless free lime is also present in the mixture.