2021 Volume 75 Issue 1 Pages 18-25
The purpose of this study was to understand the effects of the coexistence of C-A-S-H, and differences in curing water, sulfate ion source, and curing temperature on the formation of ettringite and thaumasite in the presence of carbonate ions, especially in the presence of monocarbonate. The necessary materials were reacted as a reaction suspension, and the ettringite and thaumasite formation behaviors were investigated. Results show that the secondary formation of ettringite was promoted by the coexistence of C-A-S-H, and the effect of Al supply from Q2ｂ （bridging site） in C-A-S-H was considered to be significant in terms of Al substitution site. In addition, the formation of thaumasite was suppressed by the effect of Na in seawater. Furthermore, it was confirmed that ettringite was decomposed into AFm phase under both temperature and pH conditions.
