The rapidly rising demand for fiber-reinforced plastics (FRPs) has led to large volumes of manufacturing and end-of-life waste. Recycling fiber-reinforced thermosets is very difficult owing to their complex structure and heterogeneity. Landfill and incineration have become the most commonly used methods for eliminating non-degradable FRP waste, which adversely affects the environment and ecology. The purpose of this review is to evaluate end-of-life FRP recycling technologies in terms of optimizing the reuse/recycling of resources and eliminating waste, thereby improving FRP waste management. The technical progress made in the recycling of thermosetting composites is reviewed, including mechanical, thermal (pyrolysis and fluidized-bed), and chemical (critical fluid and low-temperature solvent) methods. The technical feasibility of each method was compared, and the economic and environmental impacts were considered. The challenges and opportunities facing the establishment of a composite recycling market in the future are examined. Finally, we provide a comprehensive summary of the scope of each recycling method.

Concrete coating technology is a key measure that enhances the durability of concrete structures. This paper systematically studies the performance, applicability, and impact of different types of anti-corrosion coatings on concrete durability, focusing on their resistance to chloride ion penetration, freeze–thaw cycles, carbonation, and sulfate corrosion. The applicability of existing testing methods and standard systems is also evaluated. This study shows that surface-film-forming coatings can create a dense barrier, reducing chloride ion diffusion coefficients by more than 50%, making them suitable for humid and high-chloride environments. Pore-sealing coatings fill capillary pores, improving the concrete’s impermeability and making them ideal for highly corrosive environments. Penetrating hydrophobic coatings form a water-repellent layer, reducing water absorption by over 75%, which is particularly beneficial for coastal and underwater concrete structures. Additionally, composite coating technology is becoming a key approach to addressing multi-environment adaptability challenges. Experimental results have indicated that combining penetrating hydrophobic coatings with surface-film-forming coatings can enhance concrete’s resistance to chloride ion penetration while ensuring weather resistance and wear resistance. However, this study also reveals that there are several challenges in the standardization, engineering application, and long-term performance assessment of coating technology. The lack of globally unified testing standards leads to difficulties in comparing the results obtained from different test methods, affecting the practical application of these coatings in engineering. Moreover, construction quality control and long-term service performance monitoring remain weak points in their use in engineering applications. Some engineering case studies indicate that coating failures are often related to an insufficient coating thickness, improper interface treatment, or lack of maintenance. To further improve the effectiveness and long-term durability of coatings, future research should focus on the following aspects: (1) developing intelligent coating materials with self-healing, high-temperature resistance, and chemical corrosion resistance capabilities; (2) optimizing multilayer composite coating system designs to enhance the synergistic protective capabilities of different coatings; and (3) promoting the creation of global concrete coating testing standards and establishing adaptability testing methods for various environments. This study provides theoretical support for the optimization and standardization of concrete coating technology, contributing to the durability and long-term service safety of infrastructure.

In order to solve the serious environmental problems caused by the rapid increase in the number of waste tires and unproper storage of waste tires, modifying the asphalt mix for roadway pavement by adding rubber crumb from recycled waste tires is one of the highly effective approach to solve the problem and can achieve the sustainable use of rubber resources. The application of warm-mix crumb rubber-modified asphalt (CRMA) overcomes some issues of the hot-mix CRMA, such as high temperature and high energy consumption. However, there is a lack of estimation methodology for the energy conservation and emission reduction during the production process of warm-mix CRMA. This study develops the estimation models for the evaluation of energy conservation and emissions reduction during different production stages of waste rubber powder, asphalt, CRMA, hot-mix CRMA, and warm-mix CRMA. A list for gas emissions during the mixing and paving process of CRMA mixtures was established through the simulated mixing measurement and paving site measurement. The results show that for each metric ton of CRMA mixture produced, warm mixing can reduce energy consumption by 18~36% and decrease gas emissions during different stages by 15~87% compared to hot mixing. The Evotherm warm-mix CRMA mixture with DAT as warm mix agent (Ev-DAT warm-mix CRMA mixture) is more energy-efficient by saving approximately 108.56 MJ of energy and reducing gas emissions during mixing and paving by at least 32% and 73%, respectively. This model can improves the technical standard of warm-mix CRMA and the energy conservation assessment.

Many northern hemisphere countries have experienced exceptionally heavy snow, blizzards, and cold snaps in recent years, causing considerable public concern about the high crash rate and safety issues in road traffic. This study used the CarSim dynamics simulation to recreate several vehicle driving scenarios in snow and ice conditions. To explore the influence of speed, curve radius, and road adhesion coefficient on vehicle sideslip and rollover, four lateral stability evaluation indicators, namely lateral offset, lateral acceleration, yaw rate, and roll angle, are chosen. Unfavorable combinations of these factors result in vehicle deviation from their intended trajectory and dramatically increase the likelihood of sideslip and rollover incidents. In particular, road adhesion coefficients ranging from 0.10 to 0.20 lead first to sideslip, while coefficients of 0.21 to 0.35 lead straight to rollover. Additionally, in the initial segment of the curve, cars are more susceptible to lateral instability. Curve radius has the greatest influence on sideslip when the three influencing factors are combined, while speed is the key component affecting rollover incidents. Smaller curve radii and higher speeds are major factors in such incidents. The results are helpful for proper road alignment parameter selection and dynamic speed-limit measures. This can provide a theoretical basis for traffic management departments to take targeted measures, which is of great significance to improving road traffic safety in snowy and icy weather.

The blind zone that accompanies the right-turn process of semitrailer trucks is a major cause of crashes and the high fatality of vulnerable road users (VRUs). Understanding the relationship between the blind zone and right-turn collisions will play a positive role in preventing such accidents. The purpose of this study was to investigate the formation of right-turn blind zones for semitrailer trucks and to determine the factors (turning speed, turning radius, and collision position) influencing the severity of accidents through real-world vehicle tests and PC-CRASH simulation. The results show that the calculation model of the inner wheel difference blind zone established for semitrailer trucks can provide more accurate estimation than the model for rigid trucks, due to the consideration of a virtual third axle between the tractor and the trailer. On the other hand, the PC-CRASH simulation test indicates the turning speed and turning radius directly affect the scale of the inner wheel difference blind zone, and larger blind zone and encroachment on adjacent lanes increase the potential for collision. Moreover, the difference in collision position is closely related to whether the rider suffers a secondary crush. Front position is more likely to cause the cyclist to be crushed. For further analysis, the long-term interaction between the blind zones resulting from the right rearview mirror and the inner wheel difference also increases the risk during a right turn. Therefore, reducing the blind zone in the right-turn process is the key to improving right-turn safety for semitrailer trucks and VRUs.

Bio-oil as a substitute or modifier for petroleum asphalt has significant environmental, economic, and sustainable development implications. However, the insufficient high-temperature and anti-aging characteristics of bio-asphalt lead to the limited application of bio-oil in road engineering. In this study, the characteristics of bio-asphalt were reinforced by nano-Al₂O₃ and nano-SiO₂. The nanomaterial-modified bio-asphalt was evaluated using basic characteristics, viscosity, and high- and low-temperature rheological characteristic tests. Meanwhile, the road behavior of nanomaterial-modified bio-asphalt mixtures was assessed. The test results demonstrated that incorporating bio-oil improved the low-temperature performance of PA. Compared with PA, BA’s ductility was increased by 83.87%. Nano-Al₂O₃ and nano-SiO₂ positively affected the bio-asphalt’s temperature sensitivity and high-temperature and anti-aging characteristics but inhibited the low-temperature characteristics. Combining the results of the high- and low-temperature characteristics of nanomaterial-modified bio-asphalt, a nano-Al₂O₃ dosage between 4 and 6% or a nano-SiO₂ dosage between 6 and 8% can realize the enhancement of high-temperature and anti-aging characteristics of bio-asphalt, and the low-temperature characteristics are better than those of petroleum asphalt. Meanwhile, the dynamic stability, crack resistance, and water loss resistance of the nanomaterial-modified bio-asphalt mixtures meet the specification requirements. The adjustable and designable high- and low-temperature characteristics of bio-asphalt can be realized by adjusting the dosage of nanomaterials. The application of bio-oil and nanomaterials promotes the resourceful utilization of waste and provides new possibilities for road engineering materials.