Mechanical characterization of grid-reinforced interfaces within rehabilitated bituminous layers

Abstract

The installation of a layer of grid, as an interlayer between bituminous layers, enhances the mechanical performance of the entire system under repetitive action of traffic loads, typically by increasing the tensile and shear strength at the interface level. At the same time, this mechanical improvement is accompanied by changes in mechanical responses of the system in terms of axial stiffness and structural integrity, which needs to be well defined in performance-based design methods. This research was dedicated to know how to characterize the mechanical alterations at the reinforced interface of bituminous layers from different mixtures, concerning axial stiffness and adhesion quality through a comparative analysis with corresponding unreinforced cases. In doing so, a new configuration of extensometers in the tension–compression complex modulus test was suggested to elucidate the changes in structural responses at different heights relative to the interface. Furthermore, a uniaxial tension–compression test was utilized to evaluate the adhesion bond at the interface level. The results demonstrated that the proposed methodology of doing complex modulus test could be employed as a practical tool to compare the rheological behavior of the interfaces with dissimilar conditions. In addition, the 2 Springs, 2 Parabolic creep elements, and 1 Dashpot (2S2P1D) model could be reliably employed to predict the mechanical behavior of any type of interface at high frequencies or low temperatures. Also, the strain amplitude, determined at one million loading cycles, i.e. ε6, provided a proper indication of the adhesion bond in reinforced and unreinforced systems at the interface level under cyclic loading.