Laboratory performance of warm mix asphalt containing recycled asphalt mixtures

This study aims to evaluate the laboratory performance of warm mix asphalt containing reclaimed asphalt pavement (WMA–RAP) materials. The WMA mixtures containing 0% and 40% RAP were produced using Evotherm-DAT and S-I WMA additives. The laboratory performance tests included rutting, bending, freeze–thaw splitting, Marshall immersion, aging, freeze–thaw cycles splitting, and fatigue tests. The moisture and low temperature cracking resistance were evaluated for aged mixtures. The results showed the WMA mixtures without RAP performed better moisture and low temperature cracking resistance, and lower rutting resistance than the WMA–RAP mixtures. The WMA mixtures suffered from the short-term aging exhibited a slight increase as compared to the unaged mixtures, whereas the long-term aging resulted in a distinct reduction in terms of the moisture resistance. After the short- and long-term aging, the WMA mixtures exhibited a greater decrease than the unaged mixtures in terms of the low temperature cracking resistance. The tensile strength ratio (TSR) results of the WMA–RAP mixtures generally decreased with the increase of freeze–thaw cycles, while the TSR results showed an obvious increase after three freeze–thaw cycles. The addition of RAP significantly reduced the fatigue resistance of the WMA–RAP mixtures in comparison with the WMA mixtures without RAP. Based upon the study findings, the moisture resistance under freeze–thaw cycles conditioning remains an issue to be considered in the WMA–RAP mixtures.