Alkali–silicate–aluminate synergistic hydration mechanisms for enhanced strength development in high-volume lithium slag cement

Lithium slag (LS) demonstrates synergistic reactivity and element complementarity in cement systems. However, LS exhibits low pozzolanic reactivity when blended with ordinary Portland cement (PC). This study designed a new kind of cleaner cementitious material via solid-waste and low-alkalinity activation. Four possible low-alkali activators were investigated: calcium aluminate (CA), sodium aluminosilicate (SS), sodium carbonate (SC), and sodium aluminate (SA), as well as their combinations for activating high-volume lithium slag cement (HVLSC) via microstructural evolution. Results indicate that the SS–SA considerably enhances C–(A)–S–H and N–A–S–H co-gel formation and promotes ettringite (AFt) nucleation, increasing compressive strength by 306 %, 123 %, and 108 % after 7, 14, and 21 days, respectively. The SC activator reduces fluidity in SC systems because CO32− induces CaCO3 precipitation. The SS–SA exhibits the best strength enhancing effect by leveraging the synergy of the Na+–SiO32−–AlO2− ternary system. This synergy optimizes the density of the gel network and considerably enhances the strength of HVLSC and reduces CO2 emissions per unit strength by 52.2 % of the carbon dioxide emission per unit strength.