Characterization of Rutting Resistance and Deformation Uniformity of Dry-Process SBS Asphalt Mixtures: A Comprehensive Field and Laboratory Database Analysis in Vietnam

Rutting and moisture-induced damage are critical challenges for asphalt pavements in tropical regions such as Vietnam, where high temperatures and heavy traffic accelerate permanent deformation. This study aims to evaluate the rutting performance, deformation uniformity, and stripping resistance of conventional and dry-process SBS-modified asphalt mixtures using a comprehensive Hamburg Wheel Tracking (HWT) database of 212 specimens (74 conventional and 138 SBS-modified) collected from 2021 to 2025. The analysis incorporates both laboratory-prepared and field-extracted specimens with different aggregate types and gradations, tested under submerged conditions at 50 °C and 60 °C with loading up to 40,000 passes. The results show that dry-process SBS modification significantly improves rutting resistance, reducing rut depth by 42% at 20,000 passes. SBS mixtures maintained high stability even at 40,000 passes, with a mean rut depth of 5.60 ± 0.95 mm. The Stripping Inflection Point (SIP) is substantially delayed in SBS mixtures (approximately 17,800–20,300 passes) compared to conventional mixtures (~9000 passes), with 63% of SBS samples exhibiting no stripping within the 40,000-pass protocol, indicating enhanced resistance to moisture damage. In addition, SBS-modified mixtures exhibit improved deformation uniformity and benefit from coarser aggregate gradations. Overall, the findings demonstrate that dry-process SBS modification provides a reliable and practical solution for enhancing asphalt pavement performance under high-temperature and heavy-traffic conditions in Vietnam.