Investigation of graphite tailings as a substitute for filler in asphalt mastics

As a solid waste, graphite tailings (GTs) have caused serious harm to the environment and nearby residents, and using GTs as pavement materials can not only solve the environmental problems but also promote sustainable pavements. To this end, this study experimentally explored the feasibility of using three kinds of GTs (named GT-A, GT-H, and GT-W) as fillers to prepare asphalt mastics and analysed their micro properties, mechanical properties, asphalt-filler interaction, and dielectric properties. The results show that graphite tailings asphalt mastics (GTAMs) have less bee-like structures, which causes greater average adhesion compared with limestone asphalt mastic (LAM). Besides, because GTs have a rougher micromorphology, a larger particle size, a greater density, a higher specific surface area, and a stronger interaction with asphalt than those of limestone, they exhibit better mechanical properties than LAM. Further, GTAMs possess superior dielectric properties than LAM due to the chemical composition of GTs, which contains more polar components than limestone. Among the three GTAMs, GTAM-A has the best overall performance, followed by GTAM-H, and then GTAM-W. This study proposes a feasible solution for the comprehensive recycling and reuse of GTs as raw materials for sustainable asphalt pavements while lowering economic and environmental costs.