Permeability and mechanical property measurements of reinforced asphalt overlay with paving fabrics using novel approaches

In order to study the mechanical behavior of asphalt overlay reinforced with paving fabrics (a system composed of non-woven geotextile and asphalt cement) a new methodology was developed based on three new pieces of laboratory equipment including 3-point bending test (3-PBT) method on cylindrical specimens, crack widening device (CWD) and water-vacuum permeability device (WVPD). The 3-PBT and CWD were designed to simulate generation and propagation of thermally driven cracking from an existing discontinuity in the pavement system into a new asphalt overlay. In addition, the WVPD was assembled to accelerate the movement of water through a low porosity medium. On such basis, representative parameters have been suggested by the authors as: crack resistance index of the system to determine the reinforcement effect and coefficient of permeability (K) to evaluate the waterproofing benefit of the paving fabrics. The experimental results of two different rehabilitation strategies of bituminous pavements were compared during this research: a traditional strategy, as a reference case, in which asphalt overlay is directly attached to the existing surface with an asphalt emulsion and a new strategy with the inclusion of paving fabric as an interlayer system between two asphalt layers, as the reinforced case. The results indicate that the reinforced case has enhanced mechanical properties, in terms of lower crack width manifested at the surface and higher crack resistance index and reduced water permeability. In addition, the proposed methodology appears to be suitable to evaluate the mechanical performance of reinforced asphalt overlays.