Age hardening of asphalt mixtures is an irreversible process, which reduces durability of flexible pavements and increase maintenance cost. In pavement structure, aging of asphalt mixture is mainly associated with changing in asphalt cement properties due to oxidation and ultraviolet (UV) radiation. Intensive studies can be found on oxidation of asphalt cement compared to effect of UV, although UV is one of the predominant factor in age hardening. Therefore, understanding the propensity of UV aging on asphalt cement hardening could lead to enhanced mix design, novel material selection procedures and enhanced long-term performance. In this study, a set of asphalt cement specimens were aged using natural UV exposure for 3, 7, 28 and 45 days. Rheological study was conducted using Dynamic Shear Rheometer (DSR) on these controlled aged samples to investigate the effect of UV aging and compared with unaged controlled specimen. The analyses of rheological properties including complex modulus and phase angle showed incremental hardening trend of asphalt cement with increasing duration of UV aging. The findings can be used in multi-scale modeling to link the pavement long-term performance with the trend observed in this UV aging controlled study.
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