To promote the resource utilization of steel slag and improve the production process of steel slag in steelmaking plants, this research studied the characteristics of three different processed steel slags from four steelmaking plants. The physical and mechanical characteristics and volume stability of steel slags were analyzed through density, water absorption, and expansion tests. The main mineral phases, morphological characteristics, and thermal stability of the original steel slag and the steel slag after the expansion test are analyzed with X-ray diffractometer (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TG) tests. The results show that the composition of steel slag produced by different processes is similar. The main active substances of other processed steel slags are dicalcium silicate (C₂S), tricalcium silicate (C₃S), CaO, and MgO. After the expansion test, the main chemical products of steel slag are CaCO₃, MgCO₃, and calcium silicate hydrate (C-S-H). Noticeable mineral crystals appeared on the surface of the steel slag after the expansion test, presenting tetrahedral or cigar-like protrusions. The drum slag had the highest density and water stability. The drum slag had the lowest porosity and the densest microstructure surface, compared with steel slags that other methods produce. The thermal stability of steel slag treated by the hot splashing method was relatively higher than that of steel slag treated by the other two methods.

This article provides a comprehensive review of the research progress on porous asphalt mixtures, focusing on their durability, permeability, low-temperature performance, and functionality. The study examines factors influencing the anti-raveling performance of porous asphalt, including modified asphalt binders, fibers, aggregates, traffic loads, and environmental conditions. It also discusses the impact of porosity, pore structure, and temperature variations on the low-temperature cracking resistance of porous asphalt. Furthermore, the article explores the permeability of porous asphalt mixtures, emphasizing the influence of pore characteristics, water flow directions, clogging processes, and pavement designs. The sound absorption and skid resistance properties of porous asphalt are also analyzed, highlighting the importance of porosity, texture depth, material properties, and water film thickness. The study concludes by proposing improvement measures and optimization suggestions for porous asphalt mixtures, providing valuable references for future research and applications. Finally, several future research topics for porous asphalt mixture are proposed. Further studies on porous asphalt pavement involves seeking performance balance, ensuring improvement without detriment. Researching factor interactions, building a model, exploring industrial waste use to cut costs, reduce pollution and promote its environmental application for diverse traffic and environment needs.

Semi-flexible pavement (SFP) is made up of a porous skeleton of asphalt mixture and cement grout. This special structure granted SFP superior strength and durability and made it a promising solution for the paving of heavy trafficked area. This paper performed in-depth study on the mechanistic behavior of SFP. Firstly, the volumetric mix design of SFP was introduced, and followed with strength, moisture susceptibility, viscoelastic behavior, fatigue life as well as rutting resistance through a series of laboratory tests. Marshall stability tests and dynamic stability tests suggested that SFP gained fair strength and rutting resistance from the curing of cement grout. Meanwhile, SFP was found not sensitive to freeze–thaw cycles through indirect tensile tests. In dynamic modulus tests, SFP exhibited significant viscoelastic behaviors. In four-point beam fatigue tests, the average fatigue lives of SFP reached 85.4 k loading repetition under 400 µε level. In Hamburg wheel tracking tests, the ultimate rutting depth of SFP was smaller than 2.5 mm. The viscoelastic behavior and rutting propagation of SFP was characterized with master curve and power function by fitting the test results. SFP was also compared with traditional asphalt mixtures in MMLS3 accelerated tests and its performance turned out to be prevailing.

The overall rigidity of the cement concrete pavement is high, but there are defects such as easy cracking and insufficient anti-slip performance. The epoxy resin ultra-thin wearing course overlay can effectively solve these issues. However, there is still a lack of knowledge about the long-term performance of epoxy resin ultra-thin wearing course overlay on cement concrete pavement. Therefore, this article analyzed the interlayer adhesion and durability of epoxy resin ultra-thin wearing course overlay through the Hamburg rutting test and a series of shear tests under damp heat, thermal oxygen aging, and ultraviolet (UV) aging conditions. Shear test results indicated that the shear performance of epoxy resin overlay grew with the increase in epoxy resin content and was severely affected by high temperature, and the optimal content was set as 3.4 kg/m². The Hamburg rutting test results showed that the epoxy resin overlay exhibited satisfactory high-temperature performance and water resistance. For the damp heat effect, it was revealed that damp heat led to more significant shear strength loss compared with the overlay specimens without damp heat. The water immersion caused the shear strength decline due to the water damage to the overlay interface. As for the thermal oxygen aging effect, it was reflected that the short-term thermal oxygen aging had a minor impact on the shear performance of the epoxy resin overlay. However, with the increase in thermal oxygen aging duration, the shear strength of the epoxy resin overlay significantly decreased due to the aging of epoxy resin binders. Regarding the UV aging impact, it was also found that the shear performance of the epoxy resin overlay rapidly decreased as the UV aging duration grew whether at 20 °C or 60 °C. Moreover, UV aging led to a more significant impact on the shear performance of the epoxy resin overlay than thermal oxygen aging.

Pavement performance forecast is the foundation for good pavement maintenance management, and the accurate prediction of the premise is to create a simple and reasonable equation. At present, many countries and regions present a variety of pavement performance models. However, each model of pavement performance has certain limitations. This paper gives a decay model of the deterioration equation for pavement performance, which has a simple form and clear physical significance. The model has been used in pavement preventive maintenance management system development and obtained the certificate of computer software copyright registration (Registration Number: 2011SR066875 issued by the national copyright administration of the People's Republic of China), and the reliability of the model is proved by engineering applications. The model can be used for asphalt pavement performance evaluation, maintenance priority arrangement, and maintenance funds decision analysis.