Fatigue performance of glass fibre-reinforced admixture-stabilised rock sludge dust as a base layer for low-volume roads

Rock sludge dust (RSD), a by-product of granite and dolerite stone processing, poses significant environmental disposal challenges due to its large-scale accumulation. This study evaluates the fatigue performance of glass fibre-reinforced admixture-stabilized RSD as a sustainable base layer material for low-volume roads. RSD stabilized with 10% clay, 5% lime and 10% Class-F fly ash was reinforced with glass fibres (0.25–1.5%), with 0.5% identified as the optimum content. Laboratory evaluation encompassed indirect tensile strength (ITS), resilient modulus (MR), indirect tensile fatigue testing (ITFT) at stress ratios of 0.6, 0.7 and 0.8, and stress-based fatigue modeling. Fatigue-life reliability was assessed using a two-parameter Weibull reliability analysis, and equivalent pavement layer thickness was estimated using IITPAVE. Compared with the unreinforced mix, fibre reinforcement increased ITS and MR by 24% and 28%, respectively, while improving fatigue life by 62–127% across the tested stress ratios. To achieve 1,00,000 load repetitions, fibre-reinforced-RSD requires a base thickness of only 94 mm, compared with 268 mm for cement-treated-base (CTB). Material cost analysis based on Central Public Works Department (CPWD) rates demonstrated substantial savings relative to conventional CTB. These results establish glass-fibre-reinforced admixture-stabilized RSD, a structurally efficient, sustainable and economical alternative for low-volume road base layers.