Performance Evaluation of Hybrid Hot-Mix Asphalt toward Balanced Mix Design

Abstract

Hot-mix asphalt (HMA) pavements experience premature cacking and rutting due to increases in traffic volume and environmental conditions. It is imperative to develop advanced materials that can withstand a wide spectrum of pavement distresses. This study investigated the permanent deformation and fracture characteristics of a hybrid HMA fabricated with a combination of crumb rubber (CRM) and polyvinyl alcohol (PVA) microfiber. A frequency sweep test was performed on asphalt mastic to evaluate rutting potential of control, CRM-modified, PVA-reinforced, and hybrid HMA. Based on the asphalt mastic results, six mixtures were selected for HMA design and laboratory performance evaluation. Resistances to rutting, fracture, and reflective cracking were assessed to validate high and moderate temperature permanent deformation and cracking performance of the selected mixtures. The experimental results revealed that a suitable proportion of CRM and PVA significantly affected the high temperature rutting and moderate temperature cracking performance of hybrid mixtures. Interestingly, there was only a slight difference in the moduli of control and hybrid HMA; however, an enhanced resistance to plastic deformation was observed. The flow number and flow time of the hybrid HMA were improved by 8- and 20-times relative to the control HMA, respectively. Further, the hybrid HMA presented approximately 1.3- and 4.5-times higher resistance to fracture and reflective cracking, respectively. The performance map of hybrid mixtures indicated an optimum balance to address multiple distresses in pavement, including rutting, fracture, and reflective cracking. The superior ductility and resilience under repeated traffic loading of these mixtures could enhance the service life and long-term performance of pavement infrastructure.