Recycling of graphite tailings: Effect of graphite tailings on property asphalt mortar and environmental impact evaluation

Abstract

The accumulation of graphite tailings (GT) in the tailings dam has caused severe damage to the ecological environment. This study investigates the feasibility of using GT as an alternative aggregate to fine aggregates (FA) in asphalt mortar. Various analytical tools, including a laser particle size analyzer, scanning electron microscope, X-ray diffractometer, and X-ray fluorescence, were utilized to characterize the properties of GT and FA. Asphalt mortar was prepared with four aggregate/asphalt weight ratios (0.3, 0.6, 0.9, 1.2). Scanning electron microscopy and FTIR spectroscopy were used to analyze the asphalt mortar's surface morphology and blending mechanism. The rheological properties of the asphalt mortar were evaluated using rotational viscosity test, dynamic shear rheological test, and bending beam rheological test. The environmental and economic aspects of GT were assessed through leaching toxicity and cost-benefit analysis. The results showed that GT has larger particle size and rougher surface, promoting better bonding with asphalt. With increasing GT content, the viscosity, complex modulus, rutting factor, and creep stiffness of the asphalt mortar also increased, indicating improved rheological, stiffness, and elastic properties. GT was found to pose no risk for large-scale use as a building material and can offer substantial economic benefits. The study concludes that utilizing GT in asphalt pavement engineering benefits environmental protection.