A novel combined healing system for sustainable asphalt concrete based on loading-microwave dual responsive capsules

The cracked asphalt concrete with calcium alginate/Fe3O4 capsules can get partial strength recovery under cyclic loading or microwave irradiation. This paper introduced a novel combined healing system for sustainable asphalt concrete based on loading-microwave dual responsive capsules in different service condition. In this paper, the capsules were synthesized and their morphological structure, mechanical performance and thermal resistance were characterized respectively. The rejuvenator release ratio of the capsules and the healing level of asphalt concrete were evaluated after cyclic loading and microwave irradiation. Meanwhile, the rheological characteristic of extracted asphalt binder was explored after cyclic loading and microwave irradiation treatment. Besides, the surface temperature of asphalt concrete after microwave irradiation was observed. The results revealed that the mechanical strength and mass loss of prepared capsules were 11.8 N and 3.8% at 200 °C respectively. The capsules experiencing a higher cycles of loading events released more rejuvenator during microwave irradiation period. The combined healing level of asphalt concrete with capsules could reach 91.7% after 64000 cycles of loading and 30s of microwave irradiation. Meanwhile, the released rejuvenator softened asphalt binder and improved its flow ability. The novel combined healing system provides a new way of pavement maintenance strategy under the background of low carbon maintenance.