The heating and compaction of asphalt mixtures as a self-healing mechanism

Abstract

Asphalt mixtures can recover their strength completely autonomously, or only with a small external stimulus, like heat. Therefore, this paper aims to investigate the recovery of asphalt mixtures by heating and recompacting them. Asphalt mixtures AC25 (maximum aggregate size 25 mm) were produced with conventional bitumen, varying asphalt content, ie 3.7, 4.0, 4.3, and 4.6%. In order to evaluate the self-healing mechanism, prismatic beams were heated to 120 °C and recompacted with 300kPa dynamic pressure. The complex modulus and fatigue strength were evaluated at 20 °C. Fatigue tests were conducted at 10 Hz frequency. The recoverability of each asphaltic mixture was assessed by the Healing Potential Index (HPI). The proposed index was calculated in two different ways, both using fatigue laws, one obtained with dissipated energy at failure and other obtained using the tensile strain. It has been found that the heating and compaction process allows the mixtures to recover part of their initial strength.