Aging Sensitivity of Recycled Asphalt Binder Blends - Multiscale Evaluation of Aging in RAP Binders with Recycling Agents

The increasing use of reclaimed asphalt pavement (RAP) in asphalt mixtures offers significant economic and sustainability benefits; however, the aged nature of RAP binders introduces concerns related to brittleness and accelerated aging. Recycling agents are commonly used to restore binder properties, yet their long-term influence on aging susceptibility remains insufficiently understood. This webinar presents a comprehensive investigation into the aging sensitivity of recycled asphalt binder blends incorporating varying RAP contents and a bio-based recycling agent.

The study employs a multi-scale characterization approach combining rheological testing (DSR, BBR, ABCD), chemical analysis (FTIR and SAR-AD), and nano-mechanical evaluation using Atomic Force Microscopy (AFM). Aging was simulated using RTFO and PAV procedures, and an Aging Rate (AR) parameter was used to quantify changes in binder properties due to laboratory aging. Results show that increasing RAP content elevates oxidative aging indicators such as carbonyl and sulfoxide indices, stiffness, and nano-scale modulus.

While the recycling agent improved initial rheological performance and reduced stiffness by disrupting polar associations within the binder matrix, it also increased aging susceptibility after long-term aging. The findings highlight a critical trade-off between short-term performance enhancement and long-term durability, emphasizing the importance of optimizing RAP content and recycling agent dosage. This work provides practical insights for agencies and practitioners aiming to design more durable and sustainable asphalt binder systems.

Attendees will learn how to:

1. Evaluate the aging sensitivity of RAP binder blends using rheological, chemical, and nano-mechanical tests.
2. Interpret FTIR and SAR-AD results to quantify oxidative aging and chemical fraction changes in recycled binders.
3. Understand AFM-based nano-mechanical behavior, including DMT modulus evolution with aging.
4. Apply the Aging Rate (AR) concept to compare aging susceptibility across different binder properties.
5. Assess the benefits and limitations of recycling agents, balancing initial rejuvenation with long-term aging performance.