Analysis of viscous flow properties of asphalt in aging process

• The visco-flow properties of asphalt in the aging process are analyzed.
• The visco-flow activation energy (Eη) is used to evaluate the visco-flow property of asphalt.
• Eη increases continuously with the deepening of aging.
• Eη shows a good negative correlation with the rate of creep stiffness (m).
• Eη shows a good linear correlation with colloidal instability index (Ic).

The inevitable change in asphalt properties owing to aging exists in the cycle of pavement decay under the loading from both weather and traffic. To analyze the viscous flow properties of asphalt in the aging process, a series of aging simulation tests were conducted on five regular asphalt samples for different time by rolling thin film oven (RTFO) in the laboratory, and then Brookfield rotational viscosity (RV), dynamic shear rheological test (DSR), bending beam rheometer (BBR) and component analysis (CA) tests were carried out on these samples. The parameter visco-flow activation energy (Eη) was obtained by means of Arrhenius equation according to the viscosity values of asphalt at different temperatures. The changing regularity of Eη during the aging process was analyzed. On the base of DSR, BBR and CA test result analysis, the relationship of Eη with G∗sin δ, tan δ, m-value and Ic was discussed respectively. The results and analysis indicate there is significant effect of aging on viscous flow behavior of asphalt. With the deepening of aging, Eη increases continuously. The average growth rate of Eη for the same asphalt in several aging stages varies considerably due to the difference in anti-aging performance. There is no remarkable relationship between Eη and DSR rheological parameters, while Eη shows a good negative correlation with the rate of creep stiffness (m) and also a good linear correlation with colloidal instability index (Ic). Therefore, the viscous flow property of asphalt is closely related to the low temperature creep behavior and colloidal structure.