Abstract
The development of more sustainable asphalt materials requires modified bitumen binders that combine thermal resistance, adhesion, and deformation capacity. In this study, soft paving-grade bitumen was modified with styrene-butadiene-styrene polymer, oil refinery sludge, titanium slag, and lead-furnace cyclone dust. Binders with bitumen-to-modifying-system ratios from 90:10 to 60:40 were characterized by FTIR, TGA/DSC, XRD, and portable XRF analyses and evaluated using penetration-type consistency, softening-point, qualitative adhesion, and tensile deformation tests. The modifying-system content produced non-monotonic changes in binder properties. Among the investigated formulations, the 75:25 composition provided the most balanced response, with a penetration depth of 8.6 mm, a softening point of 65.0 °C, a maximum elongation of 355.66 mm, and high qualitative film retention on mineral aggregate. In contrast, the 60:40 binder showed increased penetration and the lowest elongation, indicating that excessive modifier loading was unfavorable. The 75:25 binder was subsequently used in small-scale asphalt concrete sections and showed acceptable preliminary behavior during mixture preparation, placement, and compaction. The results demonstrate composition-dependent relationships in the investigated multicomponent system and support further evaluation of selected industrial by-products in modified bitumen binders.