Interfacial Shear Properties of Geosynthetic Interlayered Asphalt Overlays

Hot mix asphalt (HMA) overlays are the most common and cost effective rehabilitation technique available to restore the serviceability of existing distressed pavement surfaces. It is often observed that within a short span of placing HMA overlays, the distress in the existing pavement surface reflect to the new overlay surface and this process is termed as reflective cracking. To reduce the effect of reflection cracks and to improve the performance of HMA overlays, the geosynthetic interlayers are placed at the interface of old and new pavement layers. The current study aims to understand the interfacial shear properties of geosynthetic interlayered HMA overlays placed on a distressed pavement surface. The interfacial shear properties are determined in the laboratory using a large scale interface shear test apparatus. The geosynthetic interlayers used in the current study are biaxial geogrids with varying material properties and aperture sizes and a geo-jute mat. The results indicate a reduction in the interfacial bond strength (shear) between the old and new pavement layers with the inclusion of geosynthetic interlayers at the interface zone. Among different types of geosynthetic interlayers used, the polymer modified polyester grid has shown least reduction (17%) in the interface bond strength. The maximum reduction of 46% in the interface bond strength was observed in the geo-jute mat interlayers.