Practical Approach to Mix Design with High Binder and Aggregate Replacement in Iowa using Fractionation

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.