High-viscosity modified asphalt (HVMA) is the most commonly applied method in drainage asphalt pavements. However, some disadvantages of hot-mix HVMA, including high energy consumption and unavoidable environmental pollution, should be improved. Therefore, warm-mix additive (WMA) was introduced. In this paper, the effects of WMA on the rheological and microstructural properties of HVMA were studied to select optimum WMA conditions. WMAs mainly include foam warm mix (1%, 3%, and 5%), Sasobit (1%, 3%, and 5%), Evotherm (0.4%, 0.8%, and 1.2%), and the newly introduced warm additive glow brand (GLWBR) (0.4%, 0.8%, and 1.2%). Dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests were performed on HVMA after rheological processes. Also, microstructural properties were examined by Fourier transform infrared spectroscopy and scanning electron microscopy methods. Based on the obtained results, all WMAs reduced the viscosity (135°C) of HVMA and achieved warm mixing effects. However, absolute viscosity (60°C) was enhanced by Sasobit and GLWBR. In addition, GLWBR improved high-temperature rheological performance and had no significant effect on the low-temperature and aging performance of HVMA. These findings were further verified by morphological observations.

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Today, high-viscosity modified asphalt (HVMA) is widely used in drainage asphalt pavements. However, due to its high construction temperature, HVMA is prone to thermal oxidative aging, which reduces its life cycle and increases the maintenance costs of asphalt pavements. In this study, the effects of warm-mix additives on the physical, rheological and chemical properties of HVMA were studied to determine optimum warm-mix conditions. First, the effects of warm-mix technologies (foam warm mix, Sasobit, Evotherm, and GLWBR at 3%, 3%, 0.8%, and 0.8%, respectively) on the physical and rheological properties of HVMAwere studied. Then, two aging methods [thin film oven test (TFOT) and pressure aging vessel (PAV)] were applied to simulate the short-term and long-term thermal oxidation processes of HVMA and evaluate the influences of different warm-mix technologies on HVMA aging. The results showed that the four warm-mix technologies, especially foam warm mix and Sasobit, reduced the construction temperature of HVMA. In addition, warm-mix technologies also improved the high-temperature rheological properties of HVMA; however, they had adverse effects on the low-temperature cracking resistance of asphalt. Based on asphalt aging index fluctuations, it was evident that warm-mix technology was not conducive to the antiaging performance of HVMA, and foam warm mix had the weakest influence on the antiaging performance of high-viscosity asphalts. Furthermore, according to the results of an analysis of the carbonyl changes in aging asphalts, asphalt aging index can be applied to predicting the degree of aging of warm-mix HVMA.@en