ABSTRACT
Fourier Transform Infrared (FT-IR) spectroscopy is a convenient and quick way to investigate chemical changes for asphalt aging. The aging process changes the concentration of both Carbonyl and Sulfoxide in an asphalt binder. In this study, the limitation of considering the sulfoxide as an aging indicator for asphalt binders is investigated. Laboratory binder and mix aging showed that, increase in Sulfoxide index is dependent on laboratory aging method. Inconsistent increase of sulfoxide index made it unreliable to be considered as a metric for quantification of aging. Furthermore, Sulfoxide index for aged mixtures showed unusually higher values contributed by the presence of fines in the mixtures. This is also another disadvantage to establish this index as an indicator to quantify mixture aging. Although Sulfoxide index changes with the extent of aging, this study affirms that it should not be considered as a reliable indicator to detect the aging of an asphalt binder or a mixture.
