Connections between chemical composition and rheology of aged base asphalt binders during repeated freeze-thaw cycles

The chemical composition and rheological properties of asphalt binder play a key role in the performance of the asphalt pavement. However, pavement diseases (cracks, pitted surface, potholes and slurry) caused by the degradation of pavement performance have shortened the service life of the asphalt pavement and increased maintenance and repair costs, seriously affected the smooth flow of traffic and traffic safety. In this study, the sum of the different absorption peak areas of the asphalt binder spectroscopy was selected as a reference. Fourier Transform Infrared Spectroscopy (FT-IR) quantitative analysis was carried out on the Rolling Thin Film Oven (RTFO) test with different aging cycles and Pressure Aging Vessel (PAV) test of the asphalt binder after aging. Based on the above analysis, the author tries to establish a reliable FT-IR quantitative analysis method. An FT-IR specimen which could be subjected to multiple freeze-thaw cycles could be prepared by the self-designed test sample preparation device. By carrying out the freeze-thaw cycle aging test of asphalt binder for 0, 3, 6, 9, 12, 15 and 18 times, combining FT-IR and Dynamic Shear Rheological (DSR) testing techniques, the author explored the relationship between chemical composition and rheological performance parameters of asphalt binder in cold region, which were based on the Levenberg-Macquarie method and test data of universal global optimization algorithm regression analysis. The results show that FT-IR can not only qualitatively analyze and study the structure and chemical composition of asphalt binder before and after aging on a micro level, but also quantitatively represent the changes of characteristic functional groups before and after aging of asphalt binder. It is feasible to calculate the absorption peak area for FT-IR quantitative analysis using the tangent at the lowest point on both sides of the spectral absorption peak as the calibration baseline. It is recommended to use the range of 2000-650 cm−1 absorption peak area sum as a benchmark for FT-IR quantitative analysis. The complex shear modulus of the asphalt binder shows a linear growth with the increase of freeze-thaw cycles, and phase angle of asphalt binder also shows a linear growth with the increase of Ln T. There is a multivariate linear relationship between the rheological index and chemical functional groups after the aging freeze-thaw cycle.