C3S hydration in diluted and stirred suspension: (II) Properties of C-S-H precipitated during the two kinetic steps

The properties of C-S-H formed during the two kinetic steps have been investigated by hydrating mixtures of C3S and C-S-H, in water or saturated lime solutions. C-S-H precipitated during the two kinetic steps (C-S-H(SI) and C-S-H(SII)) have different properties concerning the nucleation rate and the formation of a protective layer around C3S grains. C-S-H(SI) is able to transform into C-S-H(SII) by increasing its C/S ratio when the lime concentration becomes higher than 20 mmol/l. Thus, C-S-H(SI) and C-S-H(SII) may correspond to two different types of C-S-H.