The application of bio-oils in asphalt and polymer-modified asphalt (PMA), has recently received considerable attention as a pivotal method for enhancing the high-temperature performance of asphalt mixtures while maintaining good binder’s workability. In this study, Jatropha curcas oil (JCO) was selected and evaluated as an PMA modifier. JCO-rHDPE-modified bio-asphalt was prepared with different JCO contents: 1, 3, and 5 wt.%. Physical tests (penetration, softening point, and ductility), rheological tests (dynamic viscosity and rolling thin-film oven test–RTFOT), and thermogravimetric analysis (TGA) were employed to evaluate the effect of JCO on the rheological, aging, and thermal properties of unmodified and HDPE-modified asphalt. The addition of JCO was effective in reducing the age hardening of asphalt binders due to an increase in penetration and ductility and a decrease in the softening point, and penetration index values. Aged asphalt binder with a combination of JCO and rHDPE has improved resistance to thermo-oxidative aging, exhibiting lower oxidation and volatilization after RTFOT. TGA indicated that the addition of JCO and rHDPE increases the thermal stability of modified binders by delaying the initial decomposition temperature of neat asphalt by 10ºC. The incorporation of JCO leads to a decrease in the viscosity of both virgin and rHDPE-modified asphalt. Thus, JCO-rHDPE-modified asphalt has better workability as well as potentially reduced fuel consumption and harmful emissions at pavement service temperatures.
