Hydration of mixtures of C12A7 and granulated blastfurnace slag

Mixtures of C₁₂A₇ and ground granulated blastfurnace slag develop high early strength and produce a fast setting cement. At 50°C the strength of the 1:1 mixture does not show any reduction at least up to 60 days although the ‘conversion’ of the initial calcium aluminate hydrates to the ‘cubic’ C₃AH₆ takes place. The hydration chemistry of these cementive mixtures has been studied by conduction calorimetry and X-ray diffraction. It appears that the formation of the compound C₂ASH₈ may be related to the good strength properties of these cements at higher than ambient temperatures.