Nanomechanical mapping of rejuvenated asphalt binders

To recycle reclaimed asphalt pavement (RAP) derived from porous asphalt (PA) surfacing into a new PA mix, a fundamental understanding of RAP binder properties is needed. In this paper, properties of two PA RAP binders, with and without rejuvenation, were evaluated using quantitative nanomechanical atomic force microscopy (QNM AFM) and performance grading (PG) testing. A model that describes the effect of a bio-rejuvenator on RAP microstructure was developed. A strong correlation was found between the properties measured at nanoscale and macroscale, indicating that the macro properties of RAP binders are driven by the level of polar associations and intermolecular interactions in the bitumen microstructure. This indicates that the microstructures observed in AFM are representative of the bulk properties. Addition of bio-rejuvenator in RAP resulted in the dispersion of polar associations. Finally, it was found that one percent of the rejuvenator can reduce PG critical temperatures by approximately 2 degrees.