Influences of induced heating-healing on fracture properties and life extension of asphalt mixtures: Experimental investigations

Abstract

In recent years, researchers have concentrated on identifying the effectiveness of induced healing techniques and increasing the healing capacity of asphalt materials. However, the impact of the induced healing method on extending pavement life or the behavior of the pavement in terms of cracking progression has not been evaluated. The main objective of this study is to develop a methodology to evaluate the impact of induced healing on fracture characteristics and life extension of asphalt mixtures. Semi-circular bending (SCB) tests were conducted at both 25 °C and −20 °C. From the SCB test results, fracture-related parameters such as peak load, critical stress intensity factor, strain energy, J-integral, fracture energy, and stiffness were determined. The SCB tests were carried out under cyclic cracking-healing scenarios to assess the effectiveness of the healing process. To quantify the healing efficiency, fracture-related parameters and corresponding healing indices (HI) were measured at each damage cycle. Additionally, service life extensions were calculated based on the analysis of fatigue and thermal cracking resistance. Finally, the HI obtained through other fracture-related parameters were used as a response factor to evaluate the statistical significance of each fracture parameter. The results show that for unaged asphalt mixtures, service life extensions for fatigue and thermal cracking resistance were 3.61 and 3.46 times the initial pavement life, respectively. In contrast, for specimens that experienced 20 years of aging after construction, the corresponding values were 1.50 and 2.23. This suggests that while increasing levels of aging reduce the effectiveness of the induced healing process, the pavement life can still be extended by using the induced healing method. Furthermore, a significant variation was observed in the HI obtained from different fracture-related parameters for asphalt mixtures at different aging levels. This suggests that using the ultimate strength of specimens to determine HI may present conservative results for aged asphalt mixtures since it does not explain the cracking features of the asphalt mixture at intermediate temperatures. The proposed fracture-based method can represent the interactions of cracking and time-dependent behaviors of materials, allowing for the combined effects of the healing process on fatigue and thermal fatigue life extensions to be addressed.