Field performance monitoring of waste tire-based permeable pavements

Traditional pavements in urban areas are often impervious, resulting in augmented surface run-off during rainfalls, thereby leading to flash floods and pollution of waterways. In contrast, permeable pavements allow percolation of water through their surface layers, thus alleviating the harmful impacts associated with traditional pavements. This study reports on the mechanical performance of a large-scale permeable pavement trial site constructed by tire- and rock-derived aggregates (TDA and RDA) bonded together using a polyurethane (PUR)based binder - located at a car park in South Australia. An area of approximately 400 m(2) was paved using different TDA-based mix designs, i.e., different RDA contents and sizes/shapes, and different PUR contents. A series of unconfined compression tests were carried out alongside a six-month field performance monitoring program - including in-situ light-weight deflectometer tests, and strain measurements by optic fiber sensing to assess the pavement's true potential under live traffic. The greater the TDA and PUR contents, the lower and higher the pavement's strength and stiffness, respectively. Meanwhile, the development of strain (and hence deformability) was in favor of both the TDA and PUR contents. An increase in RDA size, which promotes an induced inter-particle frictional resistance in the soft-rigid matrix, was also found to enhance the pavement's strength/stiffness while offering a further reduction in its developed strain. Moreover, the greater the RDA angularity, the more effective the mechanical interlocking (and hence interfacial friction) generated between the soft and rigid particles, and thus the higher the developed strength/stiffness. Although effective under low-medium traffic loads imposed by passenger vehicles inside the parking bays, the TDA-based technology (with the implemented mixture designs) was not as effective in sustaining high traffic flows within the parking aisles, e.g., U-turns imposed by light-medium trucks.