ZDC vs. Bitumen Aging: A Comparative Study of Aging Methods

ABSTRACTBitumen, widely used as a binder in asphalt pavements and as a sealing material in roofing membranes, exhibits pronounced viscoelastic behavior that changes over time due to oxidative aging. This process is strongly driven by environmental factors such as elevated temperatures, solar radiation, moisture, and reactive oxygen species (ROS). A promising strategy to slow down oxidation is the addition of antioxidants to unaged bitumen. Among these, zinc diethyldithiocarbamate (ZDC) has been reported to reduce binder stiffening under standardized laboratory aging, such as the Pressure Aging Vessel (PAV).This study investigates the performance of ZDC under thermal, photothermal, and thermochemical conditions in the laboratory, and compares its effectiveness with field-aged materials. The samples were characterized using Dynamic Shear Rheometry (DSR), Fourier Transform Infrared (FTIR) spectroscopy, and SARA fractionation. The results show that ZDC effectively limits thermal oxidation, as seen in reduced asphaltene and resin formation and reduced stiffness under PAV aging. However, its protective effect diminishes under photothermal and thermochemical conditions, with photothermal aging in particular showing behavior close to the reference. This indicates that ZDC is less effective in scenarios where sunlight is a dominant aging factor, raising questions about its suitability in exposed surface layers. Findings from SARA fractionation, FTIR spectroscopy, and DSR were consistent, confirming the observed trends across methods. Overall, the study highlights both the potential and the limitations of ZDC, underscoring the importance of developing antioxidant strategies tailored to the prevailing environmental conditions.