Influence of water removal techniques on the composition and microstructure of hardened calcium sulfoaluminate cement pastes

Influence of different drying techniques, namely, vacuum drying, oven drying (40 degrees C) and D-drying on the composition and microstructure of the calcium sulfoaluminate (CSA) cement was investigated in this study. The vacuum drying and oven drying were performed after the samples were immersed in acetone or ethanol. The results show that D-drying decomposes ettringite (AFt) greatly. Following solvent replacement, oven drying slightly decomposes AFt when compared with the vacuum dried sample, possibly due to the carbonation of AFt in the oven drying process. The decomposition of AFt due to D-drying and oven drying affects both the compositional and microstructural analysis of CSA hydrates. In addition, the soaking time of the samples in the solvents has no effect on the thermogravic (TG) analysis of the hydration products of CSA cement, which indicates that the CSA cement hydrates have no interaction with the solvents.