Effect of micro-sized alumina powder on the hydration products of calcium aluminate cement at 40 °C

In this work, the effect of different micro-sized alumina powders on the hydration products of calcium aluminate cement (CAC) during hydration at 40 degrees C is studied. The cement hydration at the designated times is terminated by the freeze-vacuum method. The phase development and microstructure evolution during the cement hydration are investigated by XRD and DSC, and SEM, respectively. It is found that 3CaO center dot Al2O3 center dot 6H(2)O (C(3)AH(6)) is the dominant product of the pure CAC after hydration at 40 degrees C for 3.5 h. But 2CaO center dot Al2O3 center dot 8H(2)O (C(2)AH(8)) is the dominant hydrate and C(3)AH(6) is not found in the mixtures of CAC and micro-sized alumina powder under the same condition. The results indicate that the addition of alumina powders promotes the formation of C(2)AH(8) and retards the conversion of C(2)AH(8) to the C(3)AH(6) phase. Moreover, such phase development with alumina addition is discussed. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.