Numerical Analysis of Leutner Shear Tests on Interface Between Geosynthetic and Asphalt Layers

Reflective cracks are the major distress in Hot-Mix Asphalt (HMA) Overlays. Among the several mitigation methods adopted to reduce the reflective cracking, the application of geosynthetic layer between the old pavement and the new overlay is widely adopted due to the ease of application. The application of geosynthetics as interlayers reduces the tensile stress in the old pavement, thereby restricting the crack development. Though the interlayers are effective in delaying the progress of reflective cracking, they lead to a reduction in bond strength. The interlayer may also cause delamination, which affects the overall stability of the pavement. Hence the present study focuses on the analysis of the failure mechanism of the interface. The interface behavior with three different types of overlay fabrics made of glass (synthetic), jute and coir fibers was studied using finite element program ABAQUS at three different temperatures of 10, 20 and 30 degrees C. The interface zone between geosynthetic and asphalt layers was numerically simulated using the Cohesive Zone Model (CZM). The failure mechanism was expressed in terms of Scalar Stiffness Degradation Factor along with the principal strains developed in the geosynthetic layer. Further, the stresses developed at the surface of old pavement were examined to study the initiation and development of reflective cracks. It is concluded that among the natural geosynthetics, the coir geotextile interlaid sample is better compared to jute geotextile as it showed delayed degradation and developed lower stresses at the surface of old pavement.