Impact of triisopropanolamine on surface composition, crystallographic variation, and thermal behavior of C3A polymorphs

In this study, the impact of triisopropanolamine (TIPA) on both the crystallographic and surface properties of cubic and orthorhombic tricalcium aluminate (C₃A) were investigated together with their hydration behavior and strength development. When TIPA was added during the grinding process, the pre-hydration and carbonation of C₃A were effectively prevented, and crystal structural changes of C₃A were confirmed. It leads to altering the hydration mechanism of C₃A phases: in the case of cubic C₃A, it promotes the formation of Al-hydrogarnet phases instead of OH-AFm phases even on the first day of curing. Similar hydration behavior was observed with orthorhombic C₃A, but the phase transition of OH-AFm phases to Al-hydrogarnet occurs during a specific time period in 1–3 days. The latter was revealed as a very interesting endothermic reaction which can be the only heat absorptive behavior in complex cement hydration as reported so far.