Study on the Bonding Mechanism and Bonding Performance of Double Layer Fine-Surfacing Technology

Double layer fine-surfacing technology is a thin layer maintenance technology of pavement positive texture, which plays an important role in preventing road safety accidents. Bonding performance is the key quality control index of the double layer fine-surfacing, which directly affects its service performance and durability. In this paper, the bonding mechanism of the double layer fine-surfacing is analyzed, and the bonding strength between the double layer fine-surfacing and the old asphalt pavement surface is studied by using the pullout test method under the factors of different cement dosage and different temperature environment, and the bonding index of the double layer fine-surfacing is put forward. Experiments show that the double layer fine-surfacing technology has the characteristics of super bonding and wear resistance. It is an economical and practical maintenance technology and has broad development prospects.

Performance of Citric Acid-Bonded Oriented Board from Modified Fibrovascular Bundle of Salacca (Salacca zalacca (Gaertn.) Voss) Frond

The fibrovascular bundle (FVB) in palm plants consists of fiber and vascular tissue. Geometrically, it is a long fiber that can be used as an oriented board raw material. This research aimed to examine the performance of citric acid-bonded orientation boards from modified FVB salacca frond under NaOH + Na2SO3 treatment and the bonding mechanism between the modified FVB frond and citric acid. The results showed that changes in the chemical composition of FVB have a positive effect on the contact angle and increase the cellulose crystallinity index. Furthermore, the mechanical properties of the oriented board showed that 1% NaOH + 0.2% Na2SO3 with 60 min immersion has a higher value compared to other treatments. The best dimension stability was on a board with the modified FVB of 1% NaOH + 0.2% Na2SO3 with 30 and 60 min immersion. The bonding mechanism evaluated by FTIR spectra also showed that there is a reaction between the hydroxyl group in the modified FVB and the carboxyl group in citric acid. This showed that the modified combination treatment of NaOH+Na2SO3 succeeded in increasing the mechanical properties and dimensional stability of the orientation board from the FVB salacca frond.

Study on the Bonding Mechanism of Copper-Low Carbon Steel for Casting Compounding Process

The casting compounding process for copper-steel composite material has broad prospects of application, but due to the lack of supporting theories (especially the bonding mechanism of copper-steel at high temperatures), it is developing slowly. In this research, copper-steel composite materials for different casting temperatures have been prepared by the casting compound process. The results show that, for the casting compound process, the stable copper-steel transition layer can be formed in a short time, and the bonding of copper and low carbon steel is the result of both the diffusion of Cu in low carbon steel and the dissolution of Fe in molten copper. The diffusion coefficient of Cu in the low carbon steel is mainly concentrated in the range of 4.0 × 10−15–8.0 × 10−14 m2/s. However, for casting compound process of copper-steel, as the temperature rises the thickness of the copper-steel transition layer gradually decreases, while the Fe content in the copper layer gradually increases. At the same time, the analysis of the glow discharge results shows that, during the solid-liquid composite process of copper-steel, the element C in steel has a great influence. As the temperature rises, the segregation of C intensifies seriously; the peak of the C content moves toward the copper side and its value is gradually increases. The segregation of C would reduce the melting point of the steel and cause irregular fluctuations of the diffusion of Cu in low carbon steel. Therefore, a relatively lower molten copper temperature is more conducive to the preparation of copper-steel composite materials.