Development of High RAP–High Performance Thin-Lift Overlay Mix Design Using a Soybean Oil-Derived Rejuvenator

Abstract

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 asphalt pavement (RAP) that would meet the criteria for the State of Iowa using a bioderived rejuvenator called sub-epoxidized soybean oil (SESO). Two groups of binder and mix specimens were created for this investigation: (1) a control with no SESO, and (2) a rejuvenated group with 0.28% SESO by total mix weight (4.88% by total binder content-RAP binder + PG58-34E+), where the binder groups were evaluated using the multiple stress creep recovery (MSCR) test and bending beam rheometer (BBR), while the mix groups were evaluated using rutting, low-temperature, and fatigue performance tests. Binder results showed that the optimal dosage of SESO must be higher than 8% to achieve a PG46-46E+ to account for RAP inclusion in the mix design. Binder performance had a significant effect on low-temperature mix and fatigue performance, while rutting performance was found to be acceptable for the rejuvenated group.