Stabilized Rock Sludge Dust for Elevated Pavement Subgrade Applications

Abstract The growing scarcity of suitable high-quality natural soils and the need for performance-based alternatives in pavement and highway embankment construction have encouraged the evaluation of industrial by-products for load-bearing applications. Rock sludge dust (RSD), a fine-grained by-product generated from granite processing units, presents both a disposal challenge and an opportunity for large-scale geotechnical reuse. However, its low reactivity and poor engineering characteristics in its untreated state limit its direct application in pavement subgrades. This study presents a field-scale performance evaluation of RSD stabilized with clay, lime, and fly ash for application in elevated pavement subgrades and pavement layers of low-volume roads. Three stabilized mixes (R-10S-3L, R-10S-5L, and R-10S-5L-10F) selected based on prior laboratory investigations, were assessed through cyclic plate load tests conducted on constructed subgrade sections and simulated pavement systems. The cyclic loading test results indicated that the R-10S-5L mix exhibited superior subgrade performance, with total and permanent deformations limited to 3.37 and 2.79 mm, respectively, under an applied conservative tire pressure of 800 kPa, satisfying the subgrade performance requirements. The simulated pavement system incorporating R-10S-5L as subgrade, R-10S-5L as subbase, and R-10S-5L-10F as base course achieved an elastic modulus of 663.16 MPa and a total deformation of 0.32 mm, under service-level loading (560 kPa), demonstrating enhanced stiffness and load distribution capacity. These findings establish that the stabilized RSD meets both the structural and performance criteria required for pavement subgrades and base layers in low-volume roads, supporting its suitability for practical pavement design and construction applications.