Stabilisation of expansive clay using Fe-rich tailings activated with carbonate–peroxide: electro-mechanical correlation and potential for non-destructive strength estimation

The stabilisation of problematic soils using sustainable binders has attracted increasing attention due to environmental concerns associated with conventional cement-based methods. This study investigates the mechanical performance, microstructural characteristics, and durability of a novel Fe–Si geopolymer system developed using iron-rich tailings and recycled glass powder for soil stabilisation. A series of mixtures with varying tailings content, glass powder dosage, and hydrogen peroxide (H2O2) levels were prepared and evaluated. Unconfined compressive strength (UCS) tests were conducted at curing periods of 28 and 90 days to assess strength development. The results indicate that the optimised mixture (FT40–G10–H3) exhibited the highest strength and structural integrity,demonstrating the governing role of Fe–Si interactions in strength development. Microstructural analyses confirmed the development of a dense Fe–Si–Al geopolymeric network with a refined mesoporous structure, leading to enhanced load-bearing capacity. Wet–dry cycling demonstrated superior durability, with higher strength retention and markedly lower mass loss than ordinary Portland cement (OPC) stabilisation. Taguchi and ANOVA analyses identified tailings content and glass powder dosage as the primary parameters governing strength performance. The strong correlation between electrical resistivity and compressive strength provides a reliable basis for non-destructive strength estimation.