Effects of Postlayup Borate Treatment on Appearance and Flexural Properties of Douglas-Fir Glued Laminated Beams
Abstract Preservative treatments are required whenever glued laminated beams are exposed outdoors. Treatments can be either water-based systems applied to individual laminations prior to layup or o...
The potential of improving wood preservative penetration into glued wood products bonded with one-component polyurethane by discontinuous adhesive bondline design
As a vast majority of glued wood products are intended for outdoor use or for building construction, impregnation with different agents is important for ensuring proper performance. It has been shown that the impregnation prior to gluing has several disadvantages, therefore the possibility of carrying out impregnation after gluing is analysed in the present research. Impregnation efficiency as well as the effect on the bond quality is evaluated for the one-component polyurethane glued wood specimens. The results showed that the impregnation with Cu preservative after gluing did not affect the shear strength of the glued wood specimens, but did significantly restrict Cu preservative penetration due to the adhesive bondlines. Considering the results, the possibility of improving the impregnation efficiency was also investigated. By using specific adhesive application designs, which cover the bondline only partially, it was possible to improve the impregnation efficiency. However, the Cu distribution was inhomogeneous and the improvement was noticeable only up to the second bondline. The partial adhesive application design also affected the bond strength of glued wood specimens, which resulted in a decrease both in dry and wet state. However, the reduction was not so sever as to cause delamination during three consecutive wetting and drying cycles.
Preparation and performance evaluation of swine manure bio-oil modified rubber asphalt binder
Abstract In order to study the effect of the preparation process of swine manure bio-oil modified rubber asphalt binder on the rheological properties of the binder, the matrix asphalt and asphalt rubber were used as the control group, and swine manure bio-oil modified rubber asphalt binders were obtained by three preparation processes. Then the rheological properties of five binders were evaluated by rotational viscosity, DSR, MSCR and BBR tests. The results show that the addition of swine manure bio-oil to asphalt rubber is beneficial to the workability, but cause negative effect on its high temperature performance, fatigue performance and low temperature crack resistance. The preparation method of premixing bio-oil and rubber powder can reduce the degradation of high-temperature performance of asphalt rubber caused by addition of swine manure bio-oil to a certain extent. The fatigue properties of the three bio-binders are close, and the critical temperature is less than 25 °C. The process of premixing bio-oil and rubber powder will increase the creep stiffness and reduce the low-temperature performance. However, the low-temperature performance of the binder obtained by this process is still better than that of the matrix asphalt and can meet the requirements of use. Therefore, it is recommended to use the preparation process of premixing bio-oil and rubber powder to prepare swine manure bio-oil modified asphalt rubber.