Characterization of hydrates in quaternary Portland cement-blast furnace slag-calcium sulfoaluminate clinker-limestone or gypsum systems: Experimental and thermodynamic modeling approaches

초록

To address the complexity of using multiple binders in a single system, the present study was designed as part of an initiative to blend commercially available Portland cement (PC) and calcium sulfoaluminate (CSA) clinker with supplementary cementitious materials (SCMs). Blast furnace slag and limestone or gypsum were selected as the SCMs in the experimental program to study the compound effect of limestone or gypsum on the properties of the proposed binders. For the widespread adoption of such binder systems, quaternary binders composed of PC–slag–CSA clinker–limestone or gypsum were elucidated in the present study. The PC–slag–CSA clinker–limestone or gypsum quaternary binders were characterized using experimental and thermodynamic modeling approaches. The evolution and quantification of the hydration products were conducted experimentally, and a thermodynamic model was constructed based on the information obtained from the experimental outcomes to observe and predict the phase assemblage and corresponding properties over a widened timeframe. The addition of limestone enhanced the compressive strength in the later stages of curing, whereas the addition of gypsum accelerated the initial strength development. The addition of both limestone and gypsum increased the degree of reaction of the raw materials, leading to the formation of more C-(A)-S-H, especially C-S-H, with higher Si polymerization. The thermodynamic modeling results indicate that the addition of limestone or gypsum can promote the formation of monocarbonate over hemicarbonate and delay the conversion of ettringite into monosulfate. © 2025 Elsevier Ltd

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