Multiscale mechanistic characterization of reclaimed asphalt pavement

The Superpave test methods are based on unmodified asphalt binders and mixes; researchers have reported limitations of these methods in evaluating modified binders. An Atomic Force Microscope (AFM) has the potential to determine morphology and nanomechanistic properties of modified and unmodified asphalt binders. In this study, different amounts of binders recovered from four selected reclaimed asphalt pavements (RAP) are blended with a virgin Performance Grade (PG) binder and tested by following Superpave tests and AFM techniques. Binders with high RAP are found to have more rutting resistance than the virgin binder but less cracking resistance due to their brittleness. Toward improving their cracking resistance, the role of a rejuvenator is investigated and found to be effective. The nanomechanical properties are found to be related to the binder morphology and in agreement with Superpave test results. Finally, the AFM is found to be as a viable tool for characterizing asphalt binders.