Effect of HMA ageing and potential healing on top-down cracking using HVS

It is well known that age-hardening is a major deteriorating factor for cracking in the asphalt pavement, while healing may play a beneficial role in enhancing pavement fatigue life, though healing potential of hot mix asphalt (HMA) mixture may decrease with ageing. However, there is limited direct evidence and understanding of the combined effects of these two factors on cracking performance, particularly in full-scale pavements. In this article, the effects of ageing and healing on top-down cracking performance were evaluated on the basis of three full-scale tests conducted in the Florida Department of Transportation's accelerated pavement testing (APT) facility using the heavy vehicle simulator (HVS). The test results showed that ageing and potential healing appeared to have played key roles in the cracking performance of the asphalt pavement in the APT facility. When the pavement was subjected to slight-to-moderate ageing, it may be able to maintain a relatively high level of healing which helped to effectively recover damage due to HVS loading. The extensively aged pavement might have completely lost the ability to heal, which made it more susceptible to cracking. In addition, the analysis of cracking using the enhanced HMA fracture model (HMA-FM-E) showed that the predictions of the model agreed well with the observations from the tests, which further demonstrated that the loss of healing potential with ageing must be considered to better understand cracking performance of asphalt pavements.