Performance enhancement of asphalt binders using upcycled waste tires and plastics: A UAE-based study on alternatives to SBS-modified binders

Incorporating upcycled waste composites into asphalt binders presents a promising approach for enhancing pavement performance while addressing environmental concerns in the United Arab Emirates (UAE). This study evaluated the impact of upcycled composites on the mechanical properties of two commonly used neat binders in the UAE. The upcycled composites were produced from devulcanized rubber (DVR) and waste plastics, specifically low-density polyethylene (LDPE) and polypropylene (PP). Two distinct formulations of upcycled composites were analyzed in this study: DVR-LDPE and DVR-PP. The fundamental idea behind developing these waste materials into upcycled composites was to combine the elastic properties of DVR with the stiffness provided by the plastics. This composite approach not only seeks to mitigate the individual weaknesses of each material but also capitalizes on their synergistic effects, yielding a binder with enhanced performance characteristics. Two base binders from different sources, categorized as PG 64-22 and widely employed in UAE asphalt applications, were modified with 20 % DVR-LDPE and DVR-PP composites by weight of the binder. The performance of the composite-modified binders was juxtaposed with that of SBS-modified bitumen (PMB). Mechanical performance indicated that the upcycled composites, significantly improved the elastic response, stiffness, rutting resistance, and fatigue life, often matching or surpassing PMB. According to AASHTO M 332, both upcycled composites improved the high-temperature PG grade from 64S (standard traffic) to 64E (extreme traffic), similar to the PMB, which also falls within the 64E grade. The upcycled composites also resulted in enhanced fatigue response, particularly the DVR-LDPE binder, which demonstrates superior fatigue resistance compared to PMB at both 2.5 % and 5.0 % strain levels. Thermo-chemical analysis revealed the transformative effects of upcycling on waste polymers, demonstrating their superiority over conventional recycled materials, leading to enhanced binder formulations. Overall, the investigation supports the DVR-LDPE binder as a potential alternative to traditional PMB in the UAE.