Understanding the low-temperature fracture behavior of rejuvenated high viscosity modified asphalt utilizing a combined microstructure-component analysis

This study aims to establish the correlation between the low-temperature fracture behavior of rejuvenated high viscosity modified asphalts (HVMAs) and their microstructures and components. Various rejuvenated HVMAs were prepared using two types of oil-based rejuvenators and two types of polymer-based rejuvenators, and the low-temperature fracture performance was investigated using the force-ductility test. Then, the Fourier transform infrared spectroscopy, gel permeation chromatography, fluorescence microscopy, and atomic force microscopy were employed to study the chemical composition, molecular composition, and microstructure of rejuvenated HVMAs. Finally, the relationship between the low-temperature fracture performance and microstructure/component characterizations of rejuvenated HVMAs was established. The results indicate that the effect of oil-based rejuvenators on the low-temperature toughness of rejuvenated HVMAs are limited, whereas polymer-based rejuvenators significantly enhance the low-temperature toughness of rejuvenated HVMAs. Oil-based rejuvenators can regulate asphalt components and promote colloidal structure stability, but they cannot rebuild the polymer phase structure. In contrast, polymer-based rejuvenators not only supplement polymer molecules but also facilitate polymer phase structure reconstruction. Larger-sized polymers contribute more to the reconstruction of polymer network structures, thereby dominating the improvement of low-temperature performance in rejuvenated HVMAs. Higher proportion of light components and more effective polymer reconstruction in polymer-based waste rubber oil (SWRO) lead to better rejuvenation effects compared to polymer-based waste cooking oil (SWCO). This study provides theoretical guidance for improving the low-temperature performance and promoting the efficient application of reclaimed asphalt mixtures.