Rheological Assessment of Asphalt Binders: Effects of Aging Progression and Rejuvenator Incorporation

The incorporation of recycled materials, such as Reclaimed Asphalt Pavement (RAP) and Reclaimed Asphalt Shingles (RAS), has become an important approach for improving material reuse and promoting sustainability. Because aging can adversely affect binder performance, rejuvenating agents are commonly introduced to recover selected properties of aged binders and facilitate their subsequent use. In this context, the present study examines the rheological response of asphalt binders by considering three primary variables: binder origin, aging severity, and the presence or absence of a rejuvenating additive. Different aging states were produced through laboratory conditioning using the Rolling Thin Film Oven (RTFO), Pressure Aging Vessel (PAV), and Vacuum Degassing Oven (VDO). The resulting changes in binder behavior were characterized using five rheological and mechanical tests: Frequency Sweep Testing (FST), Linear Amplitude Sweep (LAS), Multiple Stress Creep Recovery (MSCR), Bending Beam Rheometer (BBR), and Rotational Viscometer (RV). Quantitatively, viscosity increased by approximately 45% for Source 1 and 6% for Source 2 after RTFOT, reaching 1.396 and 1.196 Pa.s after PAV aging, respectively. At −12 °C, BBR stiffness was 203 and 173 MPa, while m-values were 0.325 and 0.341, demonstrating measurable source-dependent differences in aging response. The corresponding recoverable strains at 3.2 kPa were 1.20% and 0.90%, respectively, whereas the non-recoverable strain fractions reached 98.85% and 99.10%. According to the MSCR test results, the corresponding recoverable strains at 3.2 kPa were 1.20% and 0.90%, respectively, whereas the non-recoverable strain fractions reached 98.85% and 99.10%. This study evaluates the effects of environmental exposure and aging on the performance characteristics of asphalt binders. Two PG64-22 binders sourced from different origins were comparatively characterized in terms of their mechanical and rheological properties. Laboratory aging procedures were employed to simulate binder deterioration, followed by an assessment of the extent to which rejuvenation can restore the performance of aged binders. Overall, binder stiffness increased with aging, whereas the addition of rejuvenators reduced stiffness. These changes were quantitatively characterized using the relevant experimental tests. Although some differences were observed among binder sources, the overall trends in aging and rejuvenation responses were similar, suggesting that binder source had a limited influence on the evaluated properties under the conditions investigated.