Application of low-activity lithium slag in ternary alkali-activated materials: enhancement of mechanical strength and environmental sustainability

In the contemporary construction industry, the efficient utilization of solid wastes and the pursuit of low-carbon development have emerged as critical challenges. To address the challenge of utilizing low-reactivity lithium slag (LS), this study used LS as a precursor, combined with ground granulated blast furnace slag (GGBS) and fly ash (FA), to develop a novel ternary alkali-activated material (AAM) system. Multiple mixes of GGBS, FA, and LS were prepared and tested for fresh, mechanical, and microstructural properties, along with cost and environmental assessments. The experimental results showed that the mix with a GGBS:FA:LS mass ratio of 5:3:2 achieved the highest compressive strength. Specifically, compared with the reference sample without LS, the strength enhancement rates at 3 d and 28 d were 102.0 % and 22.8 %, respectively. This is because the incorporation of LS promotes the hydration of AAM and enhances the structural density. After achieving excellent mechanical performance, from a cost perspective, ternary AAM systems fabricated using LS also exhibit significant cost advantages. Under the condition of optimal compressive strength, an impressive energy savings of 190 MJ and a substantial carbon footprint reduction of 24.90 % were achieved. This work reveals that in the AAM system, LS synergistically interacts with GGBS and FA. The GGBS:FA:LS = 5:3:2 mix is an optimized and validated option, offering valuable insights for solid-waste utilization and low-carbon construction development. • Low - reactivity LS can be effectively utilized by formulating ternary AAM systems. • LS achieves 102 % and 22.8 % strength enhancement rates for AAM at 3 d and 28 d, respectively. • LS expedites the reaction kinetics of the ternary AAM, thereby augmenting the mechanical strength of the AAM matrix. • Ternary AAM systems incorporating LS demonstrate outstanding environmental advantages.