Structural viability and long-term mechanical performance of lime-stabilised laterite as a sustainable alternative to river sand in concrete

The intensive reliance on concrete for natural aggregates poses urgent sustainability challenges, particularly in tropical regions, where resource depletion and environmental degradation of river sand are critical issues. This study addresses these issues by exploring lime-stabilised laterite, a locally abundant but underutilised soil, as a sustainable alternative to conventional sand for producing concrete. This study aimed to optimise the hydrated lime dosage (0–6%) and evaluate partial (50%) versus full (100%) replacement strategies to determine the structural viability and long-term mechanical performance of structural-grade benchmarks (≥ 25 MPa). Adhering to BS and ASTM standards, 96 concrete cubes were produced using mechanical mixing, a technique proven to achieve 15–20% higher strength than in-situ methods, and were evaluated for geotechnical modification, workability (slump), and compressive strength development over a 90-day curing period. The results demonstrated that a 6% lime dosage served as a critical threshold, reducing the silt content and plasticity index by 46% and 55%, respectively, which facilitated a peak compressive strength of 29.63 MPa at 90 days for partial replacement. This performance benchmark is favourable compared to recent innovations using waste glass, volcanic ash, and sawdust-based aggregates. In conclusion, this study supports a circular economy by validating that lime-stabilised laterite can reduce sand dependency by 50% in structural applications, although future investigations into hybrid binders are necessary to mitigate the observed water absorption rate of 1.8%.