Laboratory evaluation of rejuvenated asphalt binders

The use of Reclaimed Asphalt Pavement (RAP) material is widespread although the overall amount in the mix and the plant technology to handle it vary for each country. Reusing RAP allows for potential benefits due to less material consumption and possible energy savings although the benefit greatly varies depending upon the technology adopted (hot, warm, or cold mixes) and material performance during the service life. The paper investigates the use of rejuvenator to recover 100% cold RAP mix and evaluates its possible recycle. In particular, the rejuvenated asphalt binder was analysed through several laboratory experimentations including: standard physical tests, rheology tests in the in-service temperature domain, and binder fatigue resistance. The Pressure Aging Vessel (PAV) was also adopted to simulate the in-service aging of the rejuvenated binder. Results highlighted how the rejuvenator provided a differential effect depending on the amount of the rejuvenator which greatly affected the final performance; in particular, a greater content of rejuvenator helps improving performance in the low-temperature domain. Fatigue damage of the binder was increased (compared to oxidized RAP binder without rejuvenator) regardless of the rejuvenator content and the behaviour was similar to virgin bitumen. Finally, the adoption of rejuvenators can be considered as an optimal way to improve the recycling of RAP although the content and type should be carefully calibrated depending upon the RAP and in-service climate conditions of the recycled pavement.