2023 Volume 77 Issue 1 Pages 257-264
In this study, we synthesized three types of ettringite with different crystal morphologies and investigated the changes in crystal structure upon thermal dehydration and rehydration. The XRD peaks of ettringite before and after thermal history were analyzed, the crystal morphology was observed by SEM, and the molecular bonding state was analyzed by FT-IR, TG-DTA, and 27Al-MAS NMR. As a result, it was confirmed that the crystal morphology of the hydrate changed to granular by heating, dehydration and rehydration, regardless of the synthesis method. In addition, the molecular bonding states after heating, dehydration and rehydration changed depending on the crystal morphology, and the degree of change also changed depending on the crystal morphology. Therefore, we conclude that the crystal morphology of ettringite is closely related to the ease of crystal structure change.
