Fracture and fatigue characteristics of high performing novel hot mix asphalt composites

Long-term performance and sustainability of asphalt pavements could be achieved by developing hot mix asphalt (HMA) composite that possesses enhanced resilience, toughness, ductility, and durability under repeated traffic loading and extreme weather conditions. The main goal of this study was to investigate the fracture and fatigue characteristics of a novel HMA composite fabricated with combination of crumb rubber (CRM) and polyvinyl alcohol (PVA) fiber. The fracture properties of the control, CRM modified, PVA reinforced, and novel rubber-fiber HMA composites, was conducted through semicircular bending beam test. Moreover, resistance to reflective and fatigue cracking was assessed to validate the long-term performance of the novel HMA composite. Experimental results revealed that a suitable proportion of CRM and PVA significantly affected the performance of novel rubber-fiber HMA in resistance to fracture, reflective, and fatigue cracking. Fracture energy and flexibility index of the rubber-fiber HMA containing 2% CRM and 0.2% PVA quadrupled relative to PG76-22 HMA after long-term aging. The developed novel HMA composite presented around 8- and 29-times higher resistance to reflective and fatigue cracking, respectively. Additionally, digital image correlation analysis showed that the rubber-fiber HMA composite had a larger strain distribution and a more twisted and intricate fracture pattern. The multi-functional properties of CRM and PVA were visible in scanning electron micrographs, where the rubber act as hyper elastic inclusion and properly coated fibers with asphalt, effectively bridged across cracks thus hindering the crack propagation and increased tolerance to post-peak load deformation. Cost comparison and benefits of conventional and selected modified HMA mixtures indicated that the developed mixture could be a valuable long-term economical alternative pavement material.