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Recent work has shown that epoxidized plant oil materials work well as rejuvenators in recycled asphalt pavement (RAP) and as enhancers of polymer modification of neat binders. Earlier work using a small-angle x-ray scattering (SAXS) device (Xenoncs Xuess 2.0 UHR) with asphaltenes modified and unmodified with a rejuvenator called epoxidized methyl soyate (EMS) showed a decrease in asphaltene particle size by up to 20% when the rejuvenator was used at a dosage of 2.75% by total weight of the binder for modification. In addition, past work also showed epoxidized plant oil materials when used with sulfur eliminated phase separation of SBS polymers from the asphalt matrix and promoted improved elastic recovery. For this work a series of experiments were undertaken in rheology, and mix performance with a interlayer mix design containing 50% RAP to better understand why epoxidized plant oil materials have these effects. Two epoxidized plant oil materials and a commercial rejuvenator derived from corn oil were used for comparison purposes. In this work it was shown that the two epoxidized plant oil materials made significant improvements to beam fatigue and low temperature mix performance as well as low temperature binder performance. However, only one of them sub epoxidized soybean oil (SESO) did not degrade the elastic recovery of the base polymer modified binder as shown through multiple stress creep recovery (MSCR) testing of the rejuvenated binders.

A laboratory study was conducted to examine the effect of fractionated reclaimed asphalt pavement (FRAP) materials on the performance of a standard surface hot mix asphalt (HMA), as well as a HMA crack relief interlayer. The surface mix contained a PG58-28S binder, 3.3% of a bio-rejuvenator (0.12% by total mix weight), and 50% FRAP containing 30% fine fraction and 70% coarse fraction. The interlayer mix contained a polymer modified PG76-28 binder, 3.5% of the bio-rejuvenator (0.16% by total mix weight), and 50% FRAP containing 100% fine fraction. The surface mix was evaluated for HMA rutting resistance, moisture susceptibility, and low temperature fracture resistance, while the interlayer mix was evaluated for interlayer fatigue resistance. The rejuvenated FRAP surface mix performed better than the control FRAP surface mix in rutting and moisture susceptibility (stripping inflection point of 19,582 versus 17,805 for the control), and had a 100% improvement in low temperature fracture (768 J/m2 versus 354 J/m2 for the control) all due to the addition of 0.12% of a bio-rejuvenator by total mix weight. From the interlayer test there was a 57.7% and 33.6% improvement in number of cycles to failure and cumulative dissipated energy due to the addition of 0.16% of a bio-rejuvenator by total mix weight. Neither the FRAP control nor rejuvenated FRAP interlayer mixtures passed the interlayer test criteria. There is room for further improvement in the future, however, and the bio-rejuvenator is shown to improve performance substantially for mixtures with high asphalt binder and high aggregate replacement.

A laboratory study was conducted to develop a thin-lift overlay (Thinlay) mix design containing a polymer-modified PG58-34E+ binder with a 3.5% add to the mix, and 40% fine reclaimed asphal...