Modeling the Influence of Microcrack Healing on Deformation of Asphalt Concrete Using NDT

saad sarsam; Nazar Sajad Kadium

doi:10.3759/ttea.v6i3.3384

Abstract

Asphalt concrete pavement practices heavy loading and environmental impacts through its service life. Micro cracks usually initiate and accumulate to form various types of distresses. However, asphalt concrete has the ability of self-healing with rest periods and hot environment conditions. The mechanical properties of Asphalt concrete is complex due to its dependency of temperature, loading frequency, and strain level. In this investigation, asphalt concrete specimens of wearing, binder and base courses have been prepared in the laboratory and subjected to repeated indirect tensile stresses to initiate the micro-cracks. The test was terminated after 1200 load repetitions, and the specimens were stored in an oven at 60°C for 120 minutes to allow the micro crack healing process by external heating to start. Specimens were returned to the testing chamber and were subjected to another round of load repetitions. Specimens were tested before and after load repetitions and crack healing with the aid of ultrasonic pulse velocity using pundit instrument, while the permanent deformation was monitored. The healing indicator was the change in pulse velocity before and after the repeated load test and before and after healing process. Test results were modeled. It was concluded that the crack healing impact model can explain 95% of the variations in permanent deformation of asphalt concrete.