Utilization of molybdenum tailings as an alternative mineral filler in asphalt mastic: Rheological performance and environmental aspects

The generation and accumulation of molybdenum tailings (MT) have led to various environmental problems. This paper explores the feasibility of MT as a filler instead of limestone filler (LF) from the perspective of asphalt mastic. The physical and chemical properties of LF and MT are analyzed using Laser particle size, X-ray diffraction, X-ray fluorescence, and scanning electron microscopy tests. Four filler/asphalt weight (F/A) ratios (0.3, 0.6, 0.9, 1.2) are selected to prepare asphalt mastic. The rotational viscosity test, dynamic shear rheometer test as well as bending beam rheometer test, were conducted to study the rheological properties of mastics. Results show that physical interactions dominate the interaction between MT and asphalt. MT particles have large particle size, rough surface and tight internal structure. MT is conducive to bonding with asphalt. MT increased the viscosity, complex modulus, rutting factor and creep stiffness of asphalt. MT reduced the viscosity temperature sensitivity index, phase angle and creep rate. From the perspective of rheological properties, MT has great potential as filler to replace LF in asphalt mixture and reduce environmental pollution. • MT particles have many edges and corners, rough surfaces, and tight internal structures. • The surface of MT particles adsorbs more asphalt, which enhances adhesion capacity. • The |G*| and |G*|/sin δ of MT mastic are more significant than those of LF mastic. • Under the same F/A ratio, the S of MT mastic is greater than that of LF mastic. • Physical interactions dominate the interaction between MT and asphalt.