ELECTROKINETIC STABILISATION OF ENGINEERED SAND BACKFILL ADMIXED WITH RECYCLED TYRE WASTES

Abstract

Malaysia’s abundant sand resources support construction, manufacturing and geotechnical works such as embankment backfills, but rising demand and intensive extraction have increased environmental pressures, especially in sensitive coastal zones. This study examines a sustainable approach to improving sand-based backfill materials through electrokinetic (EK) stabilisation combined with recycled crumb rubber and steel fibres from waste tyres. EK stabilisation enhances soil behaviour via electro-osmotic flow, ionic migration and mineral precipitation, improving shear strength, consolidation and permeability characteristics of the soil. Crumb rubber contributes ductility and energy absorption, while steel fibres increase tensile strength and load-bearing capacity. Mixtures containing 10–40% crumb rubber, 1–4% steel fibres, and 4% proprietary polymer-modified cementitious soil stabiliser (PMC) for enhanced structurisation were evaluated to identify optimal shear strength and moisture-management performance. Results show that EK treatment promotes mineral-based aggregation and fabric restructuring, producing microstructural densification and cementation that markedly increase undrained shear strength (c_u) even without significant moisture reduction. The EK-stabilised rubber–steel fibre system offers a promising solution for developing stronger and more resilient backfill materials for sustainable geotechnical applications.