Evaluating Crumb Rubber Modified (CRM) Asphalt as a Sustainable Binder Alternative for High-Friction Surface Treatments

High-friction surface treatments (HFSTs) are widely applied to improve pavement safety by enhancing long-term skid resistance. Although epoxy resins are commonly used due to their strength and durability, their high cost, susceptibility to delamination, incompatibility with substrates of flexible pavements, and adverse environmental concerns limit their long-term performance. This study presents crumb rubber modified (CRM) asphalt as a sustainable alternative binder for HFST applications. CRM binders offer high performance and compatibility with existing pavement surfaces, cost effectiveness and reduced environmental impacts as compared to epoxy binders. In addition, the binder development utilizes enhanced recycling technologies for interacting with used tire rubber with asphalt. The evaluated CRM binders were prepared under varying interaction temperatures, crumb rubber contents, and types. The developed binders were evaluated for friction performance with two aggregate sources, calcined bauxite (CB) and rhyolite (Rhy). Binder characterization included rheological testing conducted through both frequency sweep and temperature sweep procedures. HFST mixes were evaluated using the British Pendulum Test (BPT), the Dynamic Friction Tester (DFT), and the Circular Track Meter (CTM) in collaboration with the Three-Wheel Polishing Device (TWPD) to simulate the traffic-induced polishing effect. The results showed that CRM content influenced binder performance under polishing. CRM asphalt-based HFST with a relatively high CRM content (15%) maintained a greater coefficient of friction (COF) and exhibited polishing resistance, showing low reduction in the COF after the total number of polishing cycles. In contrast, mean profile depth (MPD) analysis revealed that the most macrotexture efficiency was found in binders with a lower CRM content (10%) after completing the total number of polishing cycles. Analysis of Variance (ANOVA) showed a significant effect of the interaction conditions and rheological properties of CRM binders on the British pendulum number (BPN) loss due to the polishing process. As expected, aggregate source further influenced the resistance to polishing; CB outperformed Rhy with significantly lower aggregate loss under polishing. Overall, the results confirmed that CRM asphalt binders can effectively serve as a sustainable, flexible, and cost-effective alternative binder in HFST.