Mechanical and Microstructural Properties of Asphalt Binders Containing Various Proportions of Reclaimed Asphalt Pavement (RAP)

This study aims to characterize the mechanical and microstructural properties of asphalt binders prepared with 25 and 35% of RAP contents. A base binder of pen 60/70 (PG 64-22) was used in this study. The binders were characterized by conducting performance grading, multiple stress creep recovery, and frequency sweep tests. The performance of RAP blended binders were compared with the control binder. In addition, microstructural investigation was carried out using an atomic force microscope (AFM) to evaluate the mixing and adhesion between the conventional and recycled binder. From the rheological studies, the dynamic modulus of binder increased with an increase in RAP proportion. The binder testing results showed higher rut resistance characteristics for 35% RAP binder compared to 25% RAP and control binders. In microscopic studies, as the proportion of RAP increased from 0 to 35%, the surface roughness increased and the phase contrast decreased. The results of this study would be of value to the highway authorities and contractors as they move towards adopting more RAP material in the construction of asphalt pavements.