Effect of Soybean Oil Derived Additives on Improved Performance of Polymer-Modified Asphalt Binder and Mix Containing 50% Fine-Graded RAP

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.