Characterization of a recycling agent for restoring aged bitumen

High reclaimed asphalt pavement (RAP) content mixes are likely to be susceptible to pavement distress such as fatigue cracking and raveling because of aged bitumen. In this study, the potential of recycling agents to restore hardened binders to desired properties was evaluated. Aged bitumen extracted from field cores was blended with different concentrations of a rejuvenating agent. The rheological properties of the asphalt samples were tested using a Brookfield viscometer and a dynamic shear rheometer (DSR). Furthermore, in order to better understand the recycling effect, the chemical properties of the binders were measured using Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). A correlation was found between percentages of large molecules obtained from GPC and the viscoelastic properties of bitumen blends. The aging characteristics were determined by measuring functional group changes in carbonyl and sulfoxide peak areas by FTIR. Both rheological and chemical analyses are needed to characterize the effects of a recycling agent on bitumen blends. (C) 2018 American Society of Civil Engineers.