Repeated load test on bituminous systems reinforced by geosynthetics

This paper focuses on a better understanding of the influence of geosynthetic reinforcement materials on the flexural behaviour of bi-layer bituminous systems, and evaluates the effects of these materials on bituminous system resistance to repeated loading cycles. In this research project, three different bi-layer reinforced systems were investigated and compared with a non-treated bi-layer system and a bi-layer system with tack coat. In particular, three different geosynthetics were used: a Glass fiber Geogrid, a Polyester Geogrid and a Geomembrane. All bi-layer bituminous systems were tested by means of a four-point bending test under repeated loading cycles. The failure criterion was defined as the number of loading cycles corresponding to the flex point of the permanent deformation evolution, i.e., where the permanent deformation evolution inverts its trend (from decreasing to increasing rate). In order to precisely determine the number of loading cycles corresponding to the flex point of a permanent deformation evolution curve, a descriptive model, based on a classic power law, is presented. The proposed model precisely simulates the mechanical behaviour of bituminous mixtures and allows a reliable comparison amongst the different bituminous systems tested.