Performance and Aging Characteristics of Asphalt Binders and Asphalt Mixtures Incorporating High Recycled Asphalt Pavement and a Recycling Agent

The increased use of recycled asphalt pavements (RAP) is motivated by the need to enhance resource efficiency and reduce environmental effects. Asphalt recycling agents may also be added to high RAP mixtures to mitigate the impact of stiff, brittle RAP binder, leading to enhanced performance. This study evaluated the properties of binders and mixtures that contain high RAP (i.e., 40%) and a recycling agent. The results were compared against a mixture with 25% RAP and no recycling agent. Concerning the binder properties, the recycling agent enhanced the low-temperature properties and decreased stiffness more than it affected the high-temperature properties. However, the recycling agent increased the aging susceptibility of the asphalt binder. Mixture performance tests showed that the high RAP mixture with recycling agent had comparable or even better performance at intermediate and high temperatures than the mixture with 25% RAP. These findings demonstrate the benefits of adding the recycling agent utilized in this study to increase the RAP content in the mixture while restoring binder properties and improving cracking resistance. However, one must consider the potential impact of recycling agents on accelerating mixture aging.