Enhancing interfacial and rheological properties of asphalt binder modified with plasma-treated Fischer–Tropsch wax

Fischer–Tropsch (FT) wax is widely used as an organic additive for asphalt binders; however, its limited compatibility with asphalt remains a key challenge. In this study, oxygen-plasma treatment was employed to modify FT wax, and the effects of treatment duration on surface activation, its time-dependent persistence, and the rheological and microstructural responses of the resulting FT-wax-modified asphalt binders were systematically investigated. Among the examined conditions, oxygen-plasma treatment at 100 W–5 min produced the most favorable overall response, enhancing high-temperature rheological properties and creep-recovery behavior while modifying the low-temperature viscoelastic response of the binder. The atomic force microscopy and dielectric results provided further evidence of plasma-induced changes in binder microstructure and interfacial interactions. These results demonstrate that controlled oxygen-plasma treatment is an effective strategy for tailoring the interfacial characteristics and rheological performance of wax-modified asphalt binders.