Microstructural development of limestone-calcined clay cement (LC3) with ethanol-diisopropanolamine addition

This study investigated the effect of EDIPA on LC 3 hydration and phase assemblage development, with particular emphasis on its role in enhancing calcined clay reactivity. The effect of EDIPA on calcined clay reactivity was negligible at early ages but became significant at later ages, mainly due to an aluminum reservoir shift from ferrite to calcined clay triggered by earlier ferrite depletion. However, the additional aluminate released with EDIPA did not lead to further AFm formation because limited pore space constrained its precipitation and instead favored the incorporation of Al into C-A-S-H. Correspondingly, limestone reactivity was also limited at later ages even with EDIPA. Nevertheless, strength still improved, primarily because more C-A-S-H formed at later stages. Additionally, gypsum dissolution was delayed with EDIPA, but ettringite formation remained unaffected and even accelerated after sulfate depletion. The delayed silicate reaction appears to play a major role in controlling this behavior. These findings underscore the multifaceted role of EDIPA in LC 3 hydration and provide insights into the optimization of ternary blended systems using alkanolamines.