Steel slag, a by-product of steelmaking, imposes lots of negative impacts on the environment. For alleviating negative impacts, more and more experiments have been carried out to explore the application possibility of steel slag. The purpose of this study is to explore the feasibility of steel slag being applied in induction healing asphalt concretes to replace coarse and fine aggregate. Surface texture and pore sizes of steel slag were firstly tested, and then steel slag and basalt asphalt mixtures modified with steel fibers were prepared. Moisture susceptibility, dynamic stability, mechanical property, thermal property, induction heating speed, natural cooling speed and healing property of the asphalt mixtures were evaluated. Results showed that steel slags had more obvious holes in the surface while the surface area is much larger than that of basalt. Furthermore, steel fibers and steel slag both have dynamic stability, and steel fibers contribute to increased moisture resistance while steel slag is not. Steel slag asphalt concrete showed better mechanical property and better capacity to store heating. Steel slag asphalt mixtures had a similar heating speed to basalt asphalt mixtures but a significantly slower cooling rate. Finally, the induction healing test and CT scanning test demonstrated that steel slag asphalt mixtures had a similar healing ability to basalt asphalt mixtures. It can be concluded that steel slags have the potential to replace the natural aggregates to be applied in induction heating self-healing asphalt concretes.

The commonly used materials in fog seal are emulsified asphalt and modified emulsified asphalt. Nevertheless, there are some intractable problems including aging under ultraviolet, poor permeability, and moisture susceptibility. Therefore, silicone resin polymer was used as a kind of innovative fog seal material in this study. Physicochemical properties of solidified silicone resin were characterized. X-ray computed tomography and 3D reconstruction technology were used to evaluate permeability and distribution of silicone resin polymer in an asphalt mixture. Moisture sensitivity and high-temperature performance of the asphalt mixture maintained by silicone resin polymer were also detected. The results show that surface characteristic of silicone resin can effectively isolate moisture, thereby improving moisture resistance of the asphalt mixture. Silicone resin was found to be evenly distributed throughout the pores of a sample when the dosage was 400 or 600 mL/m². The pore filling rate increased by 16.3% when the dosage was changed from 200 to 400 mL/m², whereas it only increased by 3.7% when dosage increased from 400 to 600 mL/m². Moisture damage resistance of asphalt mixtures generally increased as the dosage of silicone was increased. However, as the dosage increased from 400 to 600 mL/m², the growth rate in residual Marshall stability (RMS) and tensile strength ratio (TSR) slowed significantly since the pore filling effect of silicone has reached the upper limit. Dosage of silicone resin has little effect on the results of the rutting test while it has significant influence on Hamburg wheel tracking test (HWT). Furthermore, it was found that 400 mL/m² is the optimum silicone dosage for open-graded friction course (OGFC)-13 mixture in consideration of permeability, distribution, performance of mixture, and economic cost.

During the service period, asphalt materials are affected by various natural factors, including heat, ultraviolet light, oxygen and moisture, etc., resulting in the reduction of pavement performance, the increase of pavement distress and shortening of service life. This study aims to investigate the aging performance of asphalt under multiple aging conditions of heat, UV and aqueous solution. Thermal-oxygen aging, UV aging and hydrostatic erosion tests were carried out sequentially on asphalt. The rheological properties, chemical structure and element composition of asphalt were characterized before and after aging, and the effect mechanism of multiple conditions was discussed. The results show that the multiple conditions of heat and UV can increase the rutting resistance and weaken the cracking resistance of asphalt. However, the effect degree of UV decreases gradually with the deepening of aging degree. Additionally, the effect of water on the physicochemical properties is less than that of UV; however, water can increase the sensitivity of physicochemical properties to UV. In summary, this study explored the short-term cycling effect of heat, light and water on asphalt and provided an idea for simulation test of asphalt under multiple aging condition.

Foamed concrete (FC) is a lightweight building material widely used in thermal insulation walls, backfill, and other fields. Generally, foamed concrete is prepared using cement, which consumes a lot energy and resources. In this study, three kinds of special soil (SS) and slag powder (SP) were used to prepare foamed concrete. The content of SS was 25%, and the content of SP was 35%, 45%, and 55%. The mechanical properties, durability properties, and microstructure of special soil-slag foamed concrete (SSFC) were studied. With the increase in SP content, the water absorption and drying shrinkage of SSFC increased and the compressive strength of SSFC decreased. The water stability coefficients of SSFC were all higher than 0.7, which met the requirements of engineering applications. The porosity and the average diameter of pores of SSFC increased with the increase in SP content. The porosity of SSFC was less than 46% when the replacement percentage of SP was less than 35%. The successful application of SS and SP in foamed concrete provides an effective approach to waste utilization.

Asphalt releases a large number of irritating fumes during construction and use, which is a serious emission pollution that not only damages the atmospheric environment but also produces highly toxic and carcinogenic volatile organic compounds (VOCs), posing a health risk to human beings. In this study, a compound-doped modified bitumen for reducing VOC emission was prepared by using zeolite as the main adsorbent material, modified by hydrochloric acid, and LDHs as a synergistic adsorbent material. By determining its basic and rheological properties, the results show that the compounding of LDHs and HCL-modified zeolite added to asphalt can improve the high-temperature performance of asphalt binder, but at the same time, the anti-fatigue property will be decreased. By GC-MS experimental analysis, a total of 72.2% fewer volatile organic compounds (VOCs) were released by the compound modified asphalt compound than by virgin asphalt, which resulted in a significant reduction in asphalt fume emissions. It shows that the asphalt VOC molecules are well adsorbed by the porous adsorption of LDHs and zeolite materials, and it is also found experimentally that they inhibit the emission of VOCs through the blocking and adsorption effects. This study provides a scientific basis for inhibiting the emission of VOCs during asphalt pavement construction.

Fuel oil leaked onto asphalt pavement will damage the asphalt layer by dissolving the binder, softening the mixture and finally resulting in distress such as raveling and pitting. In the meantime, the skid resistance, high temperature stability and water stability deteriorate dramatically. Silicone resin is a fog sealing material for asphalt pavement. It forms a three-dimensional network structure with -Si-O- chains and therefore shows strong hydrophobicity and chemical stability. This paper looks into the effect of silicone resin on the fuel oil corrosion resistance of asphalt mixture. The contact angle, Cantabro test, water stability test, wheel tracking test and three-point bending test were used to investigate the road performance and the corrosion resistance under diesel and gasoline. It was found that, compared with diesel, the contact angle between gasoline and asphalt is smaller, indicating better compatibility. The gasoline corrosion decreases the properties of asphalt mixture more than that of diesel, which indicates that the compatibility is related to the corrosion effect. The results also show that silicone resin can effectively improve the adhesion, strength, water stability and high- and low-temperature performance of asphalt mixture before and after fuel oil erosion, and the improving effect on asphalt mixture after oil erosion is better.