Optimising G-CLSM properties through alkali activator conditions and sensitivity analysis of mix parameters

This study addresses two key research gaps in the development of geopolymer-based controlled low-strength materials (G-CLSM): (1) the lack of a systematic evaluation of the sensitivity of G-CLSM performance to key mix design parameters, and (2) the limited understanding of how the physical state of the alkali activator – liquid (LAAM) or solid (SAAM) – affects material behaviour. G-CLSM was prepared using waste soil (WS) and ground granulated blast furnace slag (GBFS), and evaluated in terms of unconfined compressive strength (UCS), flowability and flow loss. Sensitivity analysis using grey system theory revealed that GBFS dosage (<i>C_G</i>) had the strongest influence (<i>λ</i> = 0.790), followed by activator dosage (<i>C_A</i>, <i>λ</i> = 0.785) and modulus (<i>n</i>, <i>λ</i> = 0.585). These findings offer practical insights for prioritising mix design parameters and improving design efficiency in engineering applications. Furthermore, comparative experiments showed that LAAM significantly outperformed SAAM, with approximately 5% higher initial flowability, reduced flow loss and more stable UCS across varying <i>n</i> values. This superior performance is attributed to the complete dissolution and enhanced activation efficiency of liquid activators. Overall, the results provide a quantitative framework for G-CLSM mix design optimisation and offer guidance for selecting appropriate activator types in practical construction scenarios.