A Comprehensive Investigation into whether RAP from Polymer-Modified Asphalt should be Treated Similarly to Conventional RAP Based on Asphalt Mixture Performance

Polymer-modified bitumen (PMB) is a high-performance bitumen typically used for asphalt applications where conventional bitumen cannot cope with traffic and weather effects. In Australia, PMB-RAP, reclaimed asphalt pavement (RAP) milled from PMB asphalt pavements, is often treated like conventional RAP during stockpile management and reuse. Polymers are known to enhance pavement performance, but can they increase pavement durability to the next level when used in PMB-RAP? To answer this question, a comprehensive study was conducted to evaluate the performance of laboratory-aged asphalt mixes containing 15% and 30% PMB-RAP to simulate durations of approximately 10 and 20 years in the field. The compaction aspect (through the compactability test) and mechanical behavior of the asphalt mixtures, including moisture resistance, nondestructive viscoelastic behavior through the four-point bending stiffness test, fatigue cracking through the four-point bending fatigue test, and rutting through the Hamburg Wheel tracking test, were investigated. The study revealed that PMB-RAP enhanced the performance of the asphalt mixtures more than did conventional RAP. The findings of this study suggest that separating the stockpiles of PMB-RAP from conventional RAP at the plant and a more robust tracking system for projects using PMB can enhance future asphalt mixes.