Healing kinetics of asphalt binder based on a new testing approach

Abstract

Self-healing capability is one of the most important characteristics of asphalt binder, which has a significant influence on field performance of asphalt pavements. Although the internal stress has been proven to be the driving force of healing, limited studies have been conducted for this part. As a result, this study aims at proposing a new approach to measure the internal stress and quantify the relationship between healing capability and damage levels of asphalt binder from its causal relationship based on healing kinetics. Specifically, a new approach called creep and zero-strain-rate recovery (CZSR) test to measure the internal stress is proposed. The accuracy of this new approach is verified in both undamaged and damaged asphalt binder. Then, the application of this new approach is expanded from creep-recovery condition to multiple-cyclic-loading-recovery condition. This action not only expands the application fields of this proposed new approach, but also provides a bridge to evaluate the relationship between healing capability and damage levels from its causal relationship. After that, the healing-kinetics method is used to characterize the healing capability of asphalt binder under different damage levels on the basis of energy-based mechanistic (EBM) approach. Moreover, the healing capability and damage level of asphalt binder are expressed as healing activation energy and crack length, respectively. Final results indicate that the healing activation energy increases with the growth of crack length, and there is a negative relationship between healing capability and damage levels of asphalt binder.