At the frontline for mitigating the undesired effects of recycled asphalt: An alternative bio oil-based modification approach

Abstract

Soybean oil-derived modifiers were used for the improvement of properties of asphalt materials prepared for a pavement demonstration project. The rheological properties of base, biomodified and extracted binders were measured/compared using rheometers. The binder modification resulted in a decrease of 1.2 °C and 2.3 °C in, respectively, the high-and low-temperature grades of base binder, and when the effect of RAP binder was considered, the continuous performance grade (PG) became almost identical with that of base/control binder. Due to the biomodification and the presence of RAP, the binder’s elastic recovery (R) increased by 8.0% and its non-recoverable creep compliance (Jnr) decreased by 0.13 kPa−1. The tests conducted to evaluate the mechanical performance of the mixtures proved the efficacy of the bio-modifiers used in reversing the undesired effects of reclaimed asphalt pavement (RAP) and improving the performance of asphalt pavements at different temperatures. For instance, the Hamburg wheel tracking (HWT) test results revealed that the presence of bio-modifiers resulted in the increase of stripping inflection point (SIP) by 3619 passes. The disk-shaped compact tension (DCT) test proved the effectiveness of the bio-modifiers used, as these modifiers increased the fracture energy by 113 J/m2. The master curves constructed for the asphalt binders and mixtures indicated an increased stiffness/elasticity at intermediate and high temperatures.