Influence of Micro-Crack Healing on Viscoelastic Properties of Moisture Damaged Asphalt Concrete

Abstract

One of major asphalt pavement distresses is the moisture damage which influences the degradation of the viscoelastic properties of the mixture. The present work assesses the impact of practicing micro-crack healing on the viscoelastic properties of moisture damaged asphalt concrete. Roller compacted slab samples of asphalt concrete were prepared at optimum binder content. Beam specimens were obtained from the slab samples and subjected to moisture damage. Part of the asphalt concrete beam specimens were then tested under dynamic flexural stresses, while another part of the asphalt concrete beams was subjected to micro-cracks healing process using external heating at 60° C for 120 minutes, then tested under the dynamic flexural stresses. The viscoelastic properties of asphalt concrete in terms of permanent deformation, flexural stiffness, phase angle, and cumulative dissipated energy were monitored and compared among both testing conditions. It was observed that a significant increase in the flexural stiffness could be observed after healing. The increase in the phase angle after healing is significant at the early stages of loading. Higher cumulative dissipated energy could be observed for mixture which had practiced micro-crack healing. It was concluded that healing process does not exhibit positive influence on permanent deformation of moisture damaged asphalt concrete. A significant increase of 41.6 % in the flexural stiffness could be observed after healing after the first load repetition as compared with the mixture before healing. The permanent deformation after healing is higher by 22 % at failure as compared with that of mixture before healing.