Quantification of damage recovery of asphalt concrete as a consequence of rest time application using dissipated energy

Spontaneous damage recovery or healing is an intrinsic behavior of asphalt mixtures. This characteristic plays an important role on extending the service life of asphalt concrete. In the present work, the cyclic controlled-stress IDT tests have been conducted on the asphalt concrete specimens to study their recovery potential using a newly developed energy based parameter named normalized dissipated creep strain energy (NDCSE). It is believed that this parameter shows an average energy demand for a material to withstand 1 μm/m. During the research, the effect of environmental and external factors such as aging, temperature, rest time ratio, and stress level on the damage recovery of asphalt concrete has been studied using the NDCSE. The conventional DCSE parameter was also calculated for the test results. The NDCSE showed a good reverse correlation with the conventional cumulative dissipated creep strain energy parameter. The observations on the stress level in the cyclic IDT test, suggested that very high or very low stress levels might reduce the effect of rest time on asphalt concrete specimens recovery potential. A recovery index was also developed based on the NDCSE. This index testified that aging and rest time are the most effective factors on recovery potential of asphalt concrete. According to the index, increasing the temperature can enhance the recovery potential of un-aged mixtures while it was almost ineffective on that of aged mixtures. However, the overall effect of temperature on mixtures’ recovery index was not statistically meaningful based on the analysis of variance.