Preparation and characterization of lithium slag-based alkali-activated gelling materials

The utilization of lithium slag (LS) to prepare clinker-free alkali-activated cementitious materials provides an alternative product to traditional cement, which addresses the environmental and land issues caused by lithium slag stockpiling and landfilling. Employing a composite alkali activator comprising sodium silicate and NaOH, this investigation synergistically activated two ultrafine industrial byproducts-lithium slag and blast furnace slag (BFS)-ultimately yielding a novel lithium slag-dominated alkali-activated cementitious material (LAAM). The effects of the internal parameters and equivalents of the alkali activator and the material ratio on the flow properties of the mortar and the mechanical properties of the samples were systematically studied. The hydration products were characterized via microscopic testing techniques to elucidate the activity mechanism. The results show that the alkali equivalent and alkali modulus have complex effects on the sample strength and mortar fluidity. The optimal experimental ratio is determined by testing the mechanical properties and mortar fluidity in the orthogonal test. The 28-day bending strength, compressive strength and mortar fluidity are 12.36 MPa, 51.25 MPa and 17.9 cm, respectively. Under alkaline conditions, LS dissolution was significantly enhanced, with liberated Si⁴⁺ and Al³⁺ ions functioning as reactive precursors that catalyzed the polymerization process. This ionic activation mechanism facilitated the concurrent crystallization of the C-S-H and C(N)-A-S-H gel phases, ultimately inducing structural densification and thermodynamic stabilization within the cementitious matrix. The use of LS effectively solidified harmful heavy metals such as Cr and Mn. It can not only meet its environmental requirements but also contribute to the realization of waste resource utilization.