UV aging assessment of asphalt binder: influence of duration, zinc oxide, and aging condition

Abstract

ABSTRACT Ultraviolet radiation penetrates the atmosphere resulting in photo-oxidative aging of asphalt. The conventional long-term aging method, such as pressure-aging vessel, ages the asphalt considering thermo-oxidative principle. However, asphalt undergoes predominantly photo-oxidative aging (POA) in field. Giving due importance to UV aging method will result in resilient asphalt, which can negate the impact of climate change on asphalt pavements to a certain extent. In this study, asphalt was aged using UV rays, considering different aging durations; 7, 14, and 21 days, aging temperature (room temperature and 60°C), and modification with zinc oxide nanoparticles (ZnO) as experimental factors. Further, thin asphalt layers were also subjected to natural aging by exposing them to atmosphere to develop equivalencies between laboratory and natural aging. The rheological studies indicated significant aging occurred in the laboratory in the first 7 days, followed by a decreased rate. The naturally-aged specimens depicted significant cracks after 1-, 3-, and 6-months of aging, which was relatively less in specimens with ZnO indicating its anti-POA properties. The carbonyl index was reduced by 30–75% with ZnO compared to binders without ZnO. Zero shear viscosity (ZSV) indicated that one-month naturally-aged asphalt with ZnO resulted in similar ZSV as PAV-aged binder with ZnO.