Guayule resin: An innovative bioresource for asphalt cement replacement

Novel resources can contribute to replacing asphalt with sustainable, flexible pavement options. In this study, asphalt was replaced by guayule resin as a bioresource by-product extracted during guayule natural rubber production. Crumb rubber modifier (CRM) was used as an asphalt enhancer. According to the Superpave criteria, the designated binders were exposed to tests covering the construction process (mixing and compaction requirements), rutting, fatigue, and thermal cracking resistances through viscosity, high-, intermediate-, and low-temperature measurements, respectively. The original, short-term aging, and long-term aging conditions were simulated using tank, rolling thin film oven, and pressure aging vessel materials, respectively. Additionally, component analysis using Fourier-transform infrared spectroscopy was performed to link the rheological properties with the chemical changes. Outcomes showed a relatively lower viscosity for guayule resin than asphalt at the same high-temperature grade, thus indicating savings in plant energy consumption and environmental emissions. The CRM enhanced guayule, but not as much as asphalt, as proven by polymeric component migration through the liquid binder. This enhancement was reflected in the rheological performance in addition to other factors. The as-received guayule resin had a high oxygen content confirmed by strong absorption peak intensities of oxidative bonds (e.g., Carbonyl and sulfoxide). Such pre-oxidation was negatively reflected in the intermediate- and low-temperature performances of guayule resin and guayule-based binders. However, the investigated guayule resin compensated for asphalt replacement by 23–42% of the blend's weight. •Introducing an innovative asphalt replacer based on guayule resin.•Presenting a comprehensive assessment of the bio-binder by the Superpave system.•Providing savings in plant energy consumption and reduced environmental emissions.•Enhancing the guayule-based binder's performance by rubber addition.•Guayule resin compensated for overall asphalt performance by up to 42% replacement.