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.