Effects of polymer lubricants with different chemical polarity on the performance of SBS-modified asphalt

The application of warm-mix technologies in Styrene-Butadiene-Styrene (SBS) modified asphalt is currently hindered by high viscosity and the resulting high energy consumption during production. To address these limitations, this study evaluates the efficacy of five polymer lubricants with varying chemical polarities—polyolefin, polyethylene, polyamide, ethylene vinyl acetate wax (EVA), and ethylene-acrylic acid wax (EAA)—as warm-mix additives. Comprehensive rheological and spectroscopic analyses reveal that these lubricants interact primarily through physical means, significantly enhancing high-temperature stability of storage stability, polyethylene and EVA maintained the system’s equilibrium, whereas other additives induced phase separation. Crucially, polyolefin, polyethylene, and polyamide effectively reduced binder viscosity and mixture processing temperatures, validating their potential as warm-mix agents, while EAA and EVA caused a slight increase in viscosity. Among the candidates, polyolefin demonstrated the most substantial benefits in viscosity reduction and high-temperature performance. Polyamide exhibited the least detrimental effect on low-temperature cracking resistance (maintaining a PG-22 rating with minimal stiffness increase). These findings provide a theoretical framework for selecting polar warm-mix additives to optimize SBS-modified asphalt applications.