Investigation on the Effect of Long-Term Aging on Low-Temperature Viscoelastic Behavior of Bitumen through Physicochemical Characterization

The long-term aging of bitumens and its effect on low-temperature performance is a detrimental phenomenon. In order to investigate the effects of the aging phenomenon on the low-temperature performance of bitumens, it is very important to accurately simulate the behavior of bitumens in repeated aging cycles and to investigate related viscoelastic, chemical, and microstructural changes. In this research, three types of bitumen with penetration grades of 40/50, 60/70, and 85/100 were subjected to one to three cycles of pressure aging vessel (PAV) aging. Comprehensive data on the bitumen's behavior were obtained by conducting bending beam rheometer, Fourier transform infrared spectroscopy, and atomic force microscopy tests. Using the results of the conducted tests, an attempt was made to find precise relationships between different indicators of bitumen aging in terms of chemistry and viscoelasticity. The results revealed a linear correlation between the aging index and the Delta Tc and dissipated energy ratio (DER) values, as well as the aging index and the vertical shift factor of the stiffness-time curve. The fitting coefficients of these linear relationships were R2=0.8 and above, indicating a strong linear relationship between these parameters. Furthermore, the viscoelastic indices DER and the derivation of creep compliance (J ') exhibited a fairly good linear relationship.