Conversion of calcium aluminate cement hydrates at 60°C with and without water

Abstract

Abstract There have been different hypotheses about the transformation mechanisms of calcium aluminate cement hydrates and this work aims to clarify the long‐running debate about the conversion approaches. In this work, CAH 10 and C 2 AH 8 were produced from the pastes of calcium aluminate cement ( CAC ) cured for 24 hours at 10 and 20°C separately. And the cured pastes were continually cured at 60°C for 3 days with water and without water, respectively. The hydration of the pastes was halted by freeze‐drying, and the phases and microstructure of hydrates were investigated by XRD and SEM , respectively. The results indicate that CAH 10 and C 2 AH 8 converted into C 3 AH 6 and AH 3 in water presence at 60°C, but did not transform into C 3 AH 6 and AH 3 without water. It is confirmed that the conversion of CAH 10 and C 2 AH 8 to C 3 AH 6 and AH 3 happens through preceding solution of CAH 10 and C 2 AH 8 and subsequent precipitation of C 3 AH 6 and AH 3 .