Calcination effects on titanium-lithium-aluminium layered double oxides in sulfoaluminate cement

Calcined layered double hydroxides are promising nano-additives for regulating cement hydration, but their performance depends strongly on calcination-induced structural evolution. In this study, titanium-lithium-aluminium layered double hydroxides (TiLiAl-LDHs) were calcined at 200°C, 300°C, 400°C and 500°C to obtain titanium-lithium-aluminium layered double oxides (TiLiAl-LDOs), and their effects on the hydration and strength development of sulfoaluminate cement-based materials were investigated. The results showed that increasing calcination temperature progressively destroyed the layered structure and promoted the formation of mixed oxide phases. Among the samples, LDO300 exhibited the most favourable pore structure and the strongest hydration-accelerating effect. Isothermal calorimetry and separation hydration experiments confirmed that LDO300 enhanced early hydration by providing effective heterogeneous nucleation sites for ettringite and monosulfate. Ion dissolution tests further showed that LDO300 released relatively high concentrations of Li+ and Ti4+ under alkaline conditions, contributing to hydration regulation. Consequently, LDO300 refined the pore structure by increasing gel pores and reducing capillary pores, leading to increases of 45.6% and 26.0% in 4-h and 28-day compressive strengths, respectively. This study provides guidance for designing efficient TiLiAl-LDO nano-additives for sulfoaluminate cement-based materials.