Assessment of aging behaviour of reclaimed asphalt binders: multi-scale mechanical and microstructural characterisation

This study provides a comprehensive multi-scale characterization of the aging resistance of reclaimed asphalt pavement (RAP) binder blends. The analysed samples included different dosages of a RAP binder and a recycling agent (REC). At low strain levels (2.5% and 5%), the use of up to 40% RAP did not adversely affect the Nf value; however, the effect of RAP was clear at 10% strain in the macro scale. At the microscopic scale, the AFM analysis showed that among all samples, the 100% RAP binder was affected the least by laboratory aging. However, the aging susceptibility increased as the RAP content increased from 0 to 40%. A plausible explanation is that the effects of laboratory aging (temperature and/or pressure) became more concentrated on the base binder when its quantity decreased in the blends. The use of REC reduced the stiffness of the unaged blends, but its effect diminished upon further aging of the blends.