Assessing the environmental aging behaviour of antioxidant modified bitumen via chemo-mechanical analysis

Abstract

Antioxidants can mitigate bitumen aging, improving asphalt durability. This study evaluates the aging prevention performance of zinc diethyldithiocarbamate (ZDC). Three laboratory aging methods (extensive thermal (3xPAV), thermo-chemical, and photo-thermal aging) were compared with recovered binder from six-month field aging of loose mixtures. Samples were analysed using DSR, Infrared spectroscopy, and SARA fractionation. The antioxidant potential after aging was quantified through a ZDC-specific absorption band of the aromatic fraction. The results reveal that ZDC mitigated thermal aging most effectively. In contrast, photo-thermal aging revealed strong dependency on the binder source. Field aged materials showed significant signs of aging and effectiveness of ZDC was evident. The intensity loss of the ZDC-specific signal in the aromatic fraction indicated measurable residual antioxidant potential under thermo-chemical aging, but almost none after photo-thermal and field aging. These findings emphasise the need to tailor antioxidant selection to the specific aging environment and application.