A method of deicing using microwave heating is proposed to make scientific and economical road deicing in a cold area, and to make up for deficiencies in the existing methods for melting snow and ice. This paper proposes to define microwave deicing efficiency as the heating rate of a concrete surface when heated to 0 °C (the efficiency of deicing is equal to the difference divided by heating time, which is between 0 °C and the initial temperature at the junction of ice and concrete). Based on the mechanism of microwave heating and deicing, a method combining the finite element simulation model with indoor experiments was proposed to study the deicing efficiency of microwaves, and the effects of different microwave frequencies and different road structure materials on microwave deicing efficiency were analyzed. The results show that the microwave frequency and road structure materials have a great influence on microwave deicing. For asphalt concrete, the ice melting efficiency of 5.8 GHz is 4.31 times that of 2.45 GHz, but the heating depth is less than that of 2.45 GHz. At 2.45 GHz, the melting efficiency of cement concrete is 3.89 times that of asphalt concrete. At 5.8 GHz, the melting efficiency of cement concrete is 5.23 times that of asphalt concrete. Through the consistency of the simulation and experimental results, the validity of the simulation model based on the finite element theory is verified. The results provide theoretical guidance and a practical basis for future applications of microwave deicing.

In order to improve the problem of the bad thermal storage stability of Styrene-Butadiene-Styrene Block Copolymer Modified Bitumen (SBS-modified bitumen), the vulcanization reaction was selected as the basic mechanism for the research and development of the stabilizer. Sulfur, tetramethylthiuram disulfide (TMTD), zinc oxide, butylated hydroxytoluene (BHT), kaolin (Al 2 O 3 •2SiO 2 •2H 2 O) and carbon-white (SiO 2) were used as raw materials, and 32 kinds of components with different contents of raw materials were designed. The 48-h segregation softening point and other modified bitumen technical indicators, such as ductility, penetration, penetration index, viscosity, and so on, were tested and analyzed. The fluorescence microscope test was also conducted to explore the crosslinking situation based on the vulcanization reaction. The results show that the component with good performance of the SBS-modified bitumen stabilizer powder was S:TMTD:ZnO:BHT: Al 2 O 3 •2SiO 2

Carbon nanotubes (CNTs) can improve the storage properties of modified asphalt by enhancing the interfacial adhesion of recycled polyethylene (RPE) and base asphalt. In this study, the interaction of CNT/RPE asphalt was investigated using molecular dynamics simulation. The base asphalt was examined using a 12-component molecular model and verified by assessing the following properties: its four-component content, elemental contents, radial distribution function (RDF) and glass transition temperature. Then, the adhesion properties at the interface of the CNT/RPE-modified asphalt molecules were studied by measuring binding energy. The molecular structural stability of CNTs at the interface between RPE and asphalt molecules was analyzed through the relative concentration distribution. The motion of molecules in the modified asphalt was studied in terms of the mean square displacement (MSD) and diffusion coefficient. The results showed that CNTs improved the binding energy between RPE and base asphalt. CNTs not only weakened the repulsion of RPE with asphaltenes and resins, but also promoted the interaction of RPE with light components, which facilitated the compatibility of RPE with the base asphalt. The change in the interaction affected the molecular motion, and the molecular diffusion coefficient in the CNT/RPE-modified asphalt system was significantly smaller than that of RPE-modified asphalt. Moreover, the distribution of the asphaltene component was promoted by CNTs, resulting in the enhancement of the storage stability of RPE-modified asphalt. The property indexes indicated that the storage stability was significantly improved by CNTs, and better viscoelastic properties were also observed. Our research provides a foundation for the application of RPE in pavement engineering.

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In this paper, an atomic force microscope (AFM) was used to study the nano-morphology characteristics of styrene-butadiene-styrene block copolymer (SBS) modified bitumen. The effects of SBS content and short-term aging on the nano-morphology parameters of bitumen were studied. The correlation between nano-morphology parameters and main pavement performances of SBS modified bitumen was analyzed. The results show that with the increase of SBS content, the average area of bee-like structure and the proportions of bee-like structure area of SBS modified bitumen increases gradually, the roughness of the whole image and the roughness of the lightweight component region decreases gradually, but the increasing or decreasing trend is no longer obvious when the content of SBS is more than 4%. The maximum height difference of SBS modified bitumen is linear with the content of SBS. The larger the content of SBS, the smaller the influence of short-term aging on the nano-morphology of SBS modified bitumen. The penetration degree will decrease and the softening point will increase with the increase of the proportion of bee-like structure area of SBS modified bitumen. The ductility will decrease with the increase of the roughness of the lightweight component region. The ductility and the Brookfield viscosity will increase with the increase of the maximum height difference. The research results provided a reference for defining quantifiable nano-parameters of SBS modified bitumen and establishing the relationship between nano-parameters and pavement performances.

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In this paper, harmless municipal solid waste incineration fly ash (H-MSWIFA) was used to replace part of the mineral powder in asphalt mastic prepared with different ratios of filler to asphalt (F/A). Cone penetration (CPT), rotational viscosity, low-temperature bending, and full section fracture energy(FSFET) tests on the prepared H-MSWIFA asphalt mastic were carried out to evaluate the viscosity at room temperature, viscosity at high temperature, tensile property at low temperature, and crack resistance at room temperature of the asphalt mastic with different F/A and different H-MSWIFA content. An asphalt concrete mixture with a nominal maximum particle size of 13 mm (AC-13) with different F/A and H-MSWIFA replacement ratios was prepared. The effects of F/A and H-MSWIFA content on the high-temperature stability, water stability, and low-temperature cracking resistance of the asphalt mixture were studied. The results showed that the shear strength and viscosity of the asphalt mastic increased after H-MSWIFA replaced part of the mineral powder; and the greater the F/A, the greater the shear strength and viscosity of the asphalt mastic. H-MSWIFA can greatly improve the viscosity of asphalt mastic at high temperatures, and with the increase in H-MSWIFA content, the improvement effect becomes more obvious. The high-temperature stability of the asphalt mixture is not related to H-MSWIFA content but mainly depends on the F/A. Both the F/A and the H-MSWIFA replacement ratio can significantly affect the water stability of the asphalt mixture, specifically, the water stability reaches the best value when the F/A is around 1.0, and the addition of H-MSWIFA harms water stability. Both the F/A and the H-MSWIFA replacement ratio can significantly affect the low-temperature cracking resistance of the asphalt mixture. The higher the F/A, the worse the low-temperature crack resistance. At the same time, the addition of H-MSWIFA harms low-temperature cracking resistance. From the point of view of water stability and low-temperature crack resistance of the asphalt mixture, the H-MSWIFA replacement ratio should not be too high.