Investigation of the Microwave Heating Effect on Self-healing of Asphalt Mixtures Containing Conductive Fibers

Asphalt concrete is a self-healing material which can repair damages automatically when it is exposed to rest periods. Healing of an asphalt concrete is the recovery of its stiffness and strength due to closure of the internal cracks. Nevertheless¡ healing rate in ambient temperature¡ especially at low temperature¡ is slow and traffic circulation can''t be closed during reaching sufficient healing. Furthermore¡ self-healing of asphalt concrete is much dependent on temperature and pavement healing will increase at high temperatures. In this research¡ microwave heating was used in order to increase asphalt concrete self-healing capacity through temperature increase. Varying amounts of carbon fiber and steel wool were added to the asphalt mixture to increase thermal efficiency by microwave heating. According to the results of type and optimum wool percent test¡ it was observed that samples with carbon fibers have better efficiency compared to other mixtures with steel wool. Also¡ optimum carbon fiber percent was obtained as 0.2% of mixture''s total mass. Moreover¡ in order to investigate self-healing process in asphalt mixture¡ fatigue life test¡ Cantabro durability test and indirect tensile test were conducted on the samples. Test results showed that heating causes an increase in healing rate of fatigue life and tensile strength and failure samples can recover part of their lost properties. Also¡ healing rate increases with temperature rise¡ as well. Also¡ it was revealed that heating should not be applied very late. Cantabro durability test results showed if heating is applied between the rotations¡ aggregate separation will be reduced because of increasing cohesion between bitumen and aggregates.