Comprehensive Laboratory and Field Evaluation of a High-RAP Asphalt Mixture Containing a Soybean-Based Rejuvenator at the NCAT Test Track

This study evaluates the laboratory and field performance of a high reclaimed asphalt pavement (RAP) mixture incorporating a soybean-oil-based rejuvenator. A dense-graded asphalt mixture containing 50% RAP was designed using a balanced mix design (BMD) approach, with the optimal rejuvenator dosage selected to satisfy both cracking and rutting thresholds. Two mixtures were produced at the plant: one with rejuvenator (R) and the other with no rejuvenator (NR). Only the R mixture was paved at the National Center for Asphalt Technology test track for field evaluation, while both were tested in the laboratory. BMD test results indicated that adding the rejuvenator significantly improved cracking resistance while maintaining rutting performance within acceptable limits. Results from the stress sweep rutting test also showed lower rutting resistance for the R mixture. Nonetheless, cyclic fatigue test results indicated only slight improvement in fatigue resistance, and FlexPAVE ™ pavement modeling predicted no notable difference in damage between the R and NR mixtures. Testing of extracted binders showed that the use of rejuvenator enhanced rheological behavior by reducing stiffness, increasing phase angle, and lowering the binder Glover-Rowe parameter after extended aging, which suggests improved long-term durability. After 1 year of accelerated loading, the test section paved with the R mixture exhibited excellent field performance, with no cracking, minimal rutting, and stable ride quality. These findings support the potential of the bio-based rejuvenator to facilitate higher RAP usage while achieving both performance and sustainability objectives.