This study investigates the potential of two bitumen modifiers, high-density polyethylene (HDPE) and nano clay (NC), to enhance the rutting resistance of asphalt mixture. Four HDPE asphalt binders were prepared by mixing the HDPE at percentages of 2%, 4%, 6%, and 8% with the virgin binder, while four NC asphalt binders were produced by mixing the NC at percentages of 1%, 2%, 3%, and 4%. The consistency and flow of virgin binder, HDPE binders, and NC binders were evaluated by penetration, softening point, and viscosity tests. The results show a gradual increment in the binder stiffness by increasing the percentage of both modifiers. The static creep test was conducted at a temperature of 40 °C to evaluate the rutting resistance. The results confirm that both modifiers can greatly improve the rutting resistance of the asphalt mixture, where 8% HDPE and 3% NC modifications reduce the strains provoked in the asphalt mixture under loading by about 50%. According to the correlation analysis, the mixture rutting performance is highly attributed to the binder stiffness, where the lower the penetration value of the asphalt binder, the lower the strains in the asphalt mixture and the higher the stiffness modulus of the asphalt mixture.

Reclaimed asphalt modified by crumb rubber-modified binder aroused great interest due to its advantage of using two waste materials without compromising the mechanical performance. Apart from the economic and environmental benefits, many studies revealed that excellent mechanical characteristics could be obtained at some particular rubber and reclaimed asphalt percents. In this study, a binder bond test was performed to evaluate the binder bond strength of reclaimed asphalt modified by rubber modified binder in dry condition. Twenty-four binders with various rubber and reclaimed asphalt contents were prepared and tested. The 24 binders can be divided into four binder categories: virgin binder, reclaimed asphalt modified by a virgin binder, rubber modified binder, and reclaimed asphalt modified by rubber modified binder. Three aggregate types, limestone, basalt, and granite, were fostered. The results showed a fair correlation between binder viscosity and bond strength, indicating that higher bond strength can be achieved by increasing the reclaimed asphalt content in the reclaimed asphalt modified by rubberized binder. Even more, for binder # 70, reclaimed asphalt modified by rubberized binder with 40% reclaimed asphalt content has bond strength similar to the virgin binder, irrespective of the aggregate type.