Preparation of performance-enhanced alkali-activated slag using a plant-derived chelator

This study aims to investigate the effects of tannic acid (TA) as a plant-derived chelator on the performance of alkali-activated slag (AAS). The influence of different dosages of TA (0.1 %, 0.2 %, 0.3 %, and 0.5 %) on rheological behavior, setting time, hydration evolution, hydration products, ion concentration, pore structure, elastic modulus, compressive strength and shrinkage character of AAS mortar was analyzed. The results indicate that, due to the particle adsorption and Ca²⁺ complexation abilities of TA, it can significantly and multi-dimensionally enhance the performance of AAS. As the content of TA increases, the setting time of AAS is prolonged by 125–820 min, while the flowability grows by 8–43.9 %. Most importantly, TA reduced the 28d autogenous shrinkage of AAS mortar by 21.3–54.5 % while significantly increasing the compressive strength by 25.4–46.1 %, highlighting the effectiveness of TA as an additive for AAS. Compared to commercial additives, TA is economical, efficient, and offers significant ecological benefits. The results contribute to the decarbonization of AAS admixture and the development of specialized admixture for AAS.