The use of geogrid reinforcement for enhancing the performance of concrete overlays: An experimental and numerical assessment

The use of thin concrete overlays as a rehabilitation option of existing distressed pavements is, similar to other overlay options, prone to the phenomenon of reflective cracking. Being a thin layer, consisting of thin Portland cement concrete (PCC), and lacking reinforcement allows the cracks in existing pavements to propagate through the concrete due to the horizontal and vertical movement of the underlying layer. This study investigates the use of geogrids as a reinforcement-crack arresting layer in thin concrete overlays to enhance their performance by: (1) providing additional tensile strength, (2) ductility, and more importantly: (3) controlling crack propagation to mitigate reflective cracking. Two experimental setups are utilized to assess and quantify the effect of inclusion of the geogrids for mode I cracking: the direct tension test to simulate thermal loads, and the flexure test to simulate the traffic loads. The outcomes from these experiments are then used to calibrate finite element models simulating the behavior of geogrid reinforced overlays under the above conditions. The FEM models are used to study the sensitivity of varying the location of the geogrid reinforcement. The obtained results verify that the use of geogrid reinforcement significantly enhances the overlay performance in the post-cracking regime in terms of strength, ductility and mode of failure.