Effects of Microcapsules on Self-Healing Performance of Asphalt Materials under Different Loading Modes

Abstract

This study used two types of self-healing microcapsules to evaluate the healing performances of asphalt materials that contained different dosages of microcapsules under three different loading modes: shear, tension, and bending loads. The optimum dosage of the microcapsules was determined in asphalt materials. The healing performance of the asphalt materials that contained softening and bonding microcapsules under shear load was evaluated by a dynamic shear rheometer (DSR) test. The optimum dosage was determined based on the healing indexes (PDSR1 and PDSR2) of the ratio of the initial shear modulus and loading times. The healing performance of the asphalt material that contained softening microcapsules under tension load was evaluated by a low-temperature tensile (LTT) test. The optimum dosage was determined based on the healing index (PLTT) of the ratio of maximum tension. The healing performance of the asphalt materials that contained bonding microcapsules was evaluated under bending load by a semicircular bending (SCB) test. The optimum dosage was determined based on the healing index (PSCB) of the ratio of the maximum load. The results revealed that the optimum dosages of the softening microcapsules of virgin asphalt binder, aged asphalt binder, and asphalt mortar were 0.5%, 1.0%, and 2.0%, respectively. The optimum dosage of the bonding microcapsules for emulsified asphalt was 1.0% as determined by the DSR test, whereas it was less than 3.0% as determined by the SCB test.