Feasibility and environmental assessment of reusing aluminum tailing slurry in Asphalt

Abstract

The massive piling of aluminum tailings waste has led to serious resource wastage and environmental pollution problems. Previous research has mainly focused on the exploitation of aluminum tailings residues (red mud), with little attention paid to the aluminum tailings slurry (ATS) discharged from the washing process. For surveying the feasibility of using ATS as a modifier of asphalt binder, a series of tests and analyses on ATS powder and ATS-modified asphalt have been performed in this study. The results demonstrate that ATS is alkaline and has a coarse surface and fine particle sizes, which make it miscible with asphalt. The ATS-based modification of asphalt is dominated by physical mixing and melting, accompanied by a slight chemical reaction. ATS modifies the microstructure of asphalt, leading to a reduction in the size and quantity of its “bee” structures, which may reduce the self-healing ability of the asphalt to some extent. With the increment in the dosage of ATS, the thermal stability of asphalt is enhanced. When the ATS dosage exceeds 9%, the storage stability of asphalt decreases significantly. Further, the complex modulus (G*), rutting factor (G*/sinδ), and recovery rate (R) increase, whereas the phase angle (δ) and nonrecoverable compliance (Jnr) decreases, which indicates that ATS improves the resistance of the asphalt to deformation and elasticity. Furthermore, ATS does not pose any risk of pollution if it is used as the material for road construction on a large scale and provides considerable economic benefits. Therefore, ATS has a wide prospect of being used as a road asphalt modifier from the perspectives of its performance, environmentally-friendly nature, and economical cost.