Resin-Based Bio-Binder as a Sustainable Alternative for High RAP Asphalt Mixtures

The shift toward a circular economy in road construction has encouraged the reuse of Reclaimed Asphalt Pavement (RAP) to reduce resource consumption and environmental impact. Nevertheless, the high stiffness of aged binders still limits the RAP content in wearing courses. This study investigates two strategies for producing asphalt mixture with 50% RAP: a conventional approach using a 70/100 pen bitumen with a commercial rejuvenator, and a bio-derived binder formulated with vegetable resin, waste olive oil, waxes, SBS polymer, and crumb rubber. The experimental program included rheological characterization (frequency sweep tests) and mechanical evaluation (Indirect Tensile Strength, stiffness modulus, and fatigue testing). Results showed that the bio-binder effectively restored the rheological balance of the aged binder, while its corresponding asphalt mixture exhibited lower stiffness and comparable fatigue performance at low strain levels. Overall, resin-based bio-binders proved to be a sustainable and technically viable alternative to traditional binders for high-RAP asphalt mixtures. The study provides further insight into the growing body of research on bio-based solutions.