Investigation on the effect of high amount of Re-recycled RAP with Warm mix asphalt (WMA) technology

In this paper, the effect of the combined use of re-recycled Reclaimed Asphalt Pavement (RAP) on the performance properties of Warm Mix Asphalt (WMA) was experimentally investigated at both binder and mixture scales. First, a virgin 50/70 Pen Grade binder and fresh Gabbro aggregates were used to prepare a conventional Hot Mix Asphalt (HMA) for surface layers as a reference mixture. Then, the same reference mix type was used to produce a mixture designed with 40% of RAP, 160/220 Pen Grade binder, and Sasobit to prepare the first generation of Warm Mix Asphalt (WMA-1) mixture. Next, WMA-1 was artificially aged to simulate the re-recycled RAP, and the same mix design was adopted to prepare the second generation of WMA with re-recycled RAP identified as WMA-2. Finally, fatigue and low temperature performance of the mixture was evaluated for the three recycling level (reference, first and second recycling). In addition, rheological tests were conducted on the entire set of six asphalt binders used for the mix design, including virgin 50/70, 160/220 Pen Grade binders, extracted binders from RAP, WMA-1, artificial aged WMA-1, and WMA-2. Results of asphalt mixtures indicate that WMA-2 shows better low temperaure properties compared to the other two mixtures associated with limited reduction in the fatigue response. Concerning asphalt binders, similar rheological properties were observed within virgin 50/70, and two WMA extracted binders in a wide range of temperatures. The present study supports the idea of using re-recycled RAP up to 40% together with WMA technology in the mix design.