The importance of wetting in healing of bitumen

Abstract

Asphalt concrete has the advantageous ability to heal autonomously, however the mechanisms behind this are not fully understood. To increase insight in the healing mecha-nism, the healing model used in polymer science is adopted. It interprets healing as the sum of wetting and intrinsic healing. The presented work introduces a new test set-up, which is de-signed to investigate the relative contribution of wetting and intrinsic healing by measuring the strength gain when two pieces of binder are brought into contact. Results obtained show that for a soft, pure binder, wetting is the dominant process. This can be concluded from the fact that at least 50% of the observed healing can be attributed to wetting. Wetting is highly de-pendent on both the load level and the duration of load application. Consequently, it is shown that the level of healing observed in asphalt concrete is very dependent on the boundary condi-tions