Performance and Mesostructural Characterization of Asphalt Mixtures with Molybdenum Tailings as Mineral Filler

This study evaluates molybdenum tailings (MT) as a substitute for limestone filler (LF) in asphalt mixtures. MT replaced LF on an equal volume basis. The replacement ratio ranged from 0% to 100%. The study conducted wheel tracking tests, three-point bending tests, immersion tests, and indirect tensile splitting tests. A representative MT100 mixture was selected for industrial CT scanning with VGStudio Max. The maximum entropy method was used for image segmentation. The method quantified aggregate, mastic, and air void phases. The results show that MT improved rutting resistance. Dynamic stability increased from 1071 passes/mm at 0% replacement to 1548 passes/mm at 100% replacement. The flexural stiffness modulus increased by 73.60% relative to the control at 100% MT replacement. Residual stability reached 86.92% at 100% replacement. CT observations of the 100% MT specimens showed an asphalt mastic phase surrounding the aggregate skeleton and dispersed air voids. The observed vertical nonuniformity was interpreted as a compaction-related structural feature associated with Marshall mold boundary effects. In conclusion, MT shows potential as an alternative mineral filler for improving asphalt mixture performance.