Performance evaluation of semi-flexible permeable pavements under cyclic loads

Traditional permeable pavements are constructed with rigid aggregates and have low load-bearing capacity. The crack development due to loads and unpredicted ground movements reduces their service life. The widespread cracks on the surface of conventional asphalt accelerate the pavement structure deterioration and reduce the overall service life. In this research, the end-of-life tyre products shredded to tyre-derived aggregates (TDAs) were utilised along with crushed rock (CR) in different fractions of a porous structure to enhance the flexibility of permeable pavement whilst maintaining the minimum load-bearing capacity for use in footpath and low-volume roads. The transitional behaviour from a semi-rigid structure owing to the rigidity of CR aggregates to a more flexible structure for mixtures at higher TDA content was investigated. The impact of rigid-rigid and flexible-rigid inter-particular contacts at low and high stress levels is investigated. The plastic and recoverable deformations of the flexible-rigid blends under monotonic and repeated loadings are compared. Also, the impact of polyurethane binder content on improving the mixtures flexural strength is investigated. The lightly bonded flexible-rigid mixtures are a viable replacements for traditional porous pavements to improve the load-bearing mechanism and increase the flexibility of pavement.