Sustainable enhancement of fly ash/steel slag composite cement: The role of TriDiethanolamine Citrate in promoting hydration and microstructure

The development of sustainable cementitious materials is critical for reducing the environmental impact of the cement industry. This study examined the feasibility of using the new amide-alcohol organic hydration promoter, TriDiethanolamine Citrate (TriDECA), in fly ash or steel slag (FA/SS) composite cement. The effects of TriDECA on the hydration process, hydration products, microstructure and compressive strength of FA/SS composite cement, as well as its impact on the dissolution of FA and SS, were systematically investigated. Results demonstrated that TriDECA significantly accelerated the dissolution of FA and SS, promoted the formation of hydration products (C-S-H, AFm), and refined the pore structure. Additionally, TriDECA increased the concentration of critical ions in the pore solution, promoted hydration and enhanced overall performance. At 28 days, FA-TriDECA and SS-TriDECA showed 8.1 % and 14.2 % higher strength than FA-TEA and FA-Ref, respectively. For SS-TriDECA, the increase was 13.2 % and 11.2 % compared to SS-TEA and SS-Ref, respectively. These findings suggest that TriDECA is a promising additive for enhancing the sustainability and performance of FA/SS composite cements, offering advantages in hydration promotion and microstructure improvement over traditional alkanolamines.