Analyzing the Damage-Healing Performance of Asphalt Mixture from Macroscopic and Mesoscopic Scales

Owing to their self-healing ability, asphalt mixtures have great potential for improving the service life of asphalt pavement, and can play an important role in sustainable infrastructures. In this study, a semicircular bending damage-healing-fracture experiment was conducted to evaluate the healing effect of a 90# asphalt mixture and styrene-butadiene-styrene copolymer modified asphalt mixture. The digital image correlation technique was used to synchronously observe the semicircular specimen to analyze its surface displacement and strain changes during the healing process. The experimental results showed that, on the macroscopic scale, the healing index HIFE based on fracture energy density was recommended to evaluate the healing effect of asphalt mixtures, and the healing effect of the 90# asphalt mixture was better than that of the styrene-butadiene-styrene copolymer modified asphalt mixture. On the mesoscopic scale, the horizontal displacements of the notch of the specimen position gradually recovered under self-healing conditions. The strain concentration at the crack gradually weakened, and the strain degree in the non-cracked area of the specimen also decreased gradually under self-healing conditions. The recovery of the macromechanics of the specimen is related not only to the healing of the crack area but also to the recovery of the non-cracked area.