High-viscosity modified asphalt binder (HVMA) is used widely as a polymer-modified binder in porous asphalt pavement because it can improve the cohesiveness of the asphalt mixture. However, because of the high voidage in the mixture, HVMA is vulnerable to aging induced by temperature, oxygen, water, sunlight, and other climatic conditions, which degrades the performance of pavement. The properties of asphalt binder are affected adversely by the effects of hygrothermal environments in megathermal and rainy areas. Therefore, it is essential to study the aging characteristics of HVMA under the influence of hygrothermal environments to promote its application as a high-viscosity modifier. A hygrothermal cycle aging test (HCAT) was designed to simulate the aging of HVMA when rainwater was kept inside of the pavement after rainfall in megathermal areas. One kind of base bitumen and three kinds of HVMA (referred to as SBS, A, and B, respectively) were selected in this study. Short-term aging tests, hygrothermal cycling aging tests, and long-term aging tests were performed on the base bitumen and three kinds of modified asphalt binder. Fourier-transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), and dynamic shear rheological (DSR) tests were used to evaluate the properties of the binders on the micro and macro scales. By comparing the index variations of the four binders before and after aging, the effects of the hygrothermal environment on the properties of HVMA were studied. It was found that the effects of the hygrothermal environment expedited the decomposition of the polymer and the formation of carbonyl groups compared with the TFOT and PAV test, which TGA confirmed further. Moreover, the thermal stability of the samples was improved after HCAT. In addition, the master curves of the complex modulus showed that hygrothermal cycles made the high-temperature rutting resistance of asphalt binder increase significantly. All of the results above verified that the effect of hygrothermal cycling could accelerate the aging of HVMA and shorten its service life.

The application of microwave de-icing technology in road engineering is constrained by its low energy utilization rate, which can be attributed to low heat production rates and ineffective heat dissipation to the underlying pavement. In this work, asphalt mixtures are designed as an upper layer (heating layer) and a lower layer (thermal-resistance layer). Magnetite slag was selected as a microwave-sensitive source for generating heat, and expanded perlite powder was incorporated into the lower layer as a thermal resistance material. Structural layer optimization and thermal-resistance layer design of the asphalt mixture were carried out by changing the thickness of the upper and lower layers to further improve the heat production rates. The design effectiveness is comprehensively evaluated by factors such as the changing law of the average surface temperature of mixtures, ice-melting time, and cost-effectiveness analyses. The results show that EP possesses better thermal stability, lower microwave energy conversion ability and more excellent heat-resistance potential compared with mineral powder. The heat-resistance layer with EP can prevent heat from being conducted to the lower layer and promote it to concentrate on the specimen surface, which can endow the microwave heating efficiency of specimens to be further improved by up to 26.97% and the de-icing time reduced by 10%, ascribed to the heat-resistance design. Furthermore, the collaborative design of the structural layer optimization and heat-resistance layer can increase energy utilization efficiency and save microwave-absorbing materials while ensuring excellent microwave de-icing efficiency.