Behavior of Asphalt Overlays with Geogrids and Geocomposite Interlayer Systems

Abstract

Geosynthetics in the form of geotextiles, geogrids, and geocomposites have been incorporated into pavement systems to enhance the service life of asphalt overlays by retarding reflective cracking. In this study, the performance of asphalt overlays reinforced with geogrids and geocomposite interlayer systems placed on pre-existing asphalt layer was evaluated. Specifically, both unreinforced and geosynthetic-reinforced, two-layered asphalt beam specimens prepared with a pre-existing 25 mm-deep notch (crack) in the bottom layer were tested under repeated four-point bending load conditions. The two-layered asphalt specimen consisted of a 45 mm-thick, old pavement layer collected from an existing highway as a bottom layer, a binder tack coat, the tested interlayer, and a 45 mm-thick hot mix asphalt (HMA) overlay. A glass-geogrid composite (GGC) involving a geotextile backing interlayer and two different types of geogrid interlayers, namely, a polyester geogrid (PET) and a polypropylene geogrid (PP) were used in this study. Repeated loading was applied to all specimens using a four-point bending configuration in a load-controlled mode at a frequency of 1 Hz. The performance of the different geosynthetic-reinforced specimens was compared against that of the control specimen (CS) and the improvement in fatigue life was estimated. Considering the specific products in this study, results indicate that all the geosynthetic-reinforced specimens resulted in extended fatigue life of overlays in relation to the CS, and among them, the best performance was obtained using the GGC.