Analysis of mechanism and time-temperature equivalent effects of asphalt binder in short-term aging

Abstract

Abstract The degradation of asphalt pavement performance is severely affected by the aging of asphalt. In order to improve the anti-aging performance of asphalt, it is necessary to study the aging mechanism of asphalt first. The objective of this paper was to systematically study the characteristics and mechanism of short-term aging of neat asphalt based on rheological indexes and chemical indexes, including complex modulus (G*), phase angle (δ), stiffness (S), m-value, fatigue performance parameter (Nf), carbonyl index (IC O) and polydispersity (PDI). The short-term aging of asphalt was performed by the rolling thin film oven test (RTFOT) at different temperatures and durations, the rheological properties were evaluated by the dynamic shear rheometer (DSR) and bending beam rheometer (BBR), the chemical indexes were got by the Fourier transform infrared (FT-IR) and the gel permeation chromatography (GPC). Meanwhile, the time-temperature equivalent effects based on the high/low-temperature performance of asphalt were analyzed. The relationships between asphalt rheological properties and chemical indexes were discussed. The results showed that the fatigue resistance was most sensitive to aging while compared with the high/low-temperature performance of asphalt. The indexes including G*, S, and Nf tended to increase as the aging degree increased, whereas other rheological indexes had opposite trends. According to the changing characteristics of the high/low-temperature performance of asphalt, a time-temperature equivalent effect model of asphalt aging was constructed. Moreover, both the oxidation and volatilization of asphalt components were accelerated as the aging temperature increased, but the volatilization was more sensitive to temperature than the oxidation. Based on the correlation analysis, both IC O and PDI exhibited a strong correlation to rheological properties. Therefore, prediction models based on IC O and PDI were constructed to predict the rheological properties of aged asphalt.