Impact of high polymer modification on reflective cracking performance life of asphalt concrete overlays

Reflective cracking is one of the major type of distresses associated with the use of asphalt concrete (AC) overlays for rehabilitating deteriorated asphalt pavements. The differential movements across the underlying cracks due to the combined effects of heavy wheel loads and temperature fluctuations result in physical tearing of the AC overlay. Thus, the long-term performance of AC overlays highly depends on their ability to resist reflective cracking. While conventional polymer-modified (PMA) AC mixtures with 2–3% polymer content have shown improved long-term performance when used as overlays, it is also believed that AC mixtures with higher polymer content may offer additional advantages for flexible rehabilitated pavements subjected to heavy and/or slow-moving traffic loads. This paper describes the research effort completed to evaluate the reflective cracking performance life of high polymer-modified (HP) AC mixtures used as overlays. Sixteen AC mixtures were produced in the laboratory using PMA and HP asphalt binders. These mixtures were evaluated in terms of their dynamic modulus and resistance to reflective cracking. The engineering properties and laboratory performance data were combined into a mechanistic analysis that took into consideration the existing AC pavement condition, mixture-specific material properties, traffic condition, and climate. Overall, the HP AC mixtures resulted in an increase in both time to reach initial cracking and reflective cracking performance life of the AC overlay when compared to their respective PMA AC overlay mixtures.