Evaluation of Marble Dust as a Filler Material in Bituminous Concrete Mixes in Abuja Federal Capital Territory

This study evaluates marble dust, a quarrying by-product from marble processing operations in the Abuja environs, North Central Nigeria, as a filler material in bituminous concrete mixes. Marble quarrying generates large quantities of dust waste that are typically deposited without value recovery, while mineral filler for road construction is conventionally sourced from limestone grinding, adding to material costs. Marble dust is collected from a quarrying facility in Kubwa, Abuja, and characterised for fineness, specific gravity, Plasticity Index, and chemical composition following Superpave filler specifications. Marshall mix design is applied at filler replacement levels of 0, 25, 50, 75, and 100 percent marble dust substitution for conventional limestone filler. Marshall stability, flow, air void content, and voids filled with bitumen are measured. Wheel tracking tests are performed to evaluate rutting resistance. Stiffness at 25 degrees Celsius is determined by indirect tensile stiffness modulus testing. Results indicate that marble dust at 50 and 75 percent substitution levels produces Marshall stability values exceeding the minimum 8 kN requirement for medium traffic roads, and wheel tracking tests show satisfactory rutting resistance. Full substitution reduces stability marginally below specification. The study recommends 50 to 75 percent marble dust as technically and economically justified for bituminous concrete production in Federal Capital Territory road construction programmes. Keywords: marble dust, bituminous concrete, Marshall mix design, filler, Abuja.