Infrastructure Sustainability: The Use of Recycled Asphalt Shingles in Flexible Pavements

The use of recycled asphalt shingle (RAS) as a partial replacement to petroleum-based virgin asphalt cement binder has received considerable attention in recent years due to economic and environmental reasons. The objective of this study was to conduct a comprehensive laboratory evaluation of dense-graded asphalt mixtures containing RAS, including stone-mastic asphalt (SMA). Dense-graded asphalt mixtures were designed to meet Super pave design criteria. A suite of laboratory tests was conducted to evaluate the low, intermediate, and high temperature performance and moisture resistance of laboratory-produced asphalt mixtures using the Thermal Stress Restrained Specimen Test (TSRST), the Semi-Circular Bending (SCB) test, and the Hamburg Loaded-Wheel Tester (LWT). Results indicate that the draft revision of AASHTO PP53 over-estimates the actual shingle asphalt binder availability factor. In addition, asphalt mixtures containing 5% RAS performed equally to the control asphalt mixture containing no RAS at low, intermediate, and high temperatures. In addition, the utilization of RAS showed an improvement in the permanent deformation (rutting) performance by resulting in a lower rut depth as compared to the control mixture without RAS.