Study of stabilized phases in high alumina cement mortars Part I Hydration at elevated temperatures followed by carbonation

The use of temperatures higher than 30°C during the hydration of 1:3 high alumina cement mortar leads to the formation of the cubic hydrate C3AH6, hence avoiding the conversion of CAH10 to C3AH6. The subsequent carbonation of C3AH6 with CO2 and thermal treatment leads to the formation of stable carbonated phases. The optimum hydration ages are the minimum necessary times to get C3AH6: 3 hours at 80°C, 6 hours at 60°C. The product is in a state we call “semiplastic” in which the next structural transformation - carbonation - occurs more easily than when the specimens have a rigid structure. The effect of a super-water-reducing admixture has also been studied.