Mechanical behaviour and load bearing mechanism of high porosity permeable pavements utilizing recycled tire aggregates

The benefits of Permeable Paving Systems (PPS) in minimizing surface water run-off which in turn reduces the imposed pressure on stormwater collection systems at the time of flash flooding have been recently remarked profoundly. In addition, the PPS have additional advantages such as filtering the pollutants for downstream water collection systems and accommodating transformation of nutrients and water to the surrounding vegetation. Inclusion of end-of-life tire products in the mixture of PPS can adjust the flexibility of the final product. Tire aggregates will potentially enhance the final product performance in areas where the ground movement or intrusion of roots can cause damage to conventional rigid pavement systems. The effect of addition of waste tire and rubber aggregates to solid granular material have been investigated in the past; however, their focus have been mainly on creating highly compacted mixtures. In contrast; in this study; mixtures of soft (end-of-life tire aggregates) and rigid aggregates (crushed rock) with a relatively high porosity was tested to evaluate their suitability for construction of permeable pavements which require high porosity. The flexibility of mixtures and their stress dependant behaviour was investigated based on the volumetric fraction of soft aggregates in the blend. The transitional soft-rigid behaviour of the mixture can be utilized to mitigate the unexpected deformation induced on the pavement. The compressive behaviour of highly permeable mixtures under ko loading and deviatoric shear provides an insight on the formation of force chains in the mixtures between the rigid particles. In addition, monitoring the compressive behaviour of rigid-soft aggregates under ko loading explains soft aggregates cushioning impact on improving the compressibility and shear behaviour of the mixture.