Strategies for Producing Asphalt Mixtures with High RAP Content

Using reclaimed asphalt pavement (RAP) in asphalt mixtures has become a common practice to reduce construction costs of asphalt pavements, maintain dwindling natural resources, and improve sustainability. However, utilization of high RAP contents poses technical challenges in terms of asphalt mixture production, compaction, and long-term cracking performance. To meet these challenges, mixture component and/or proportioning adjustments are recommended, such as using a softer virgin binder and/or adding a recycling agent (also called rejuvenator) at a specified dose. In this study, the effect of these adjustments on asphalt mixture stiffness, intermediate- and low-temperature cracking resistance, and rutting resistance at high temperatures was evaluated. The effect of these adjustments on the rheological properties of binder blends was also evaluated. Test results showed that only the mixtures/binder blends with an appropriate dose of recycling agent consistently yielded the best performance after short- and long-term aging conditions.