Bond integrity of aramid, basalt and carbon fiber reinforced polymer bonded wood composites at elevated temperature

Wood is one of natural composites and characterized as a renewable resource with great environmental benefits in construction and building industry. Since its mechanical properties are highly sensitive to environmental humidity and temperature, the key issues for wood application are reliability and durability. Fiber reinforced polymer (FRP) is a good candidate to strengthen/retrofit wood structures with superior mechanical properties. The bond integrity between FRP and wood is critical for structural integrity. It becomes more serious when FRP bonded wood is exposed to elevated temperature since the thermal responses of FRP and wood are quite different, exacerbating the integrity of composite. The residual performance of various FRP and the bond after elevated temperature exposure, ranging from 80 to 210 °C, have been investigated through macroscale single shear fracture test and microstructure characterizations. Moreover, the deterioration mechanism of aramid, basalt and carbon FRP bonded wood at elevated temperature has been revealed. The findings presented in this study can be adopted for evaluation of durability and thermal performance of FRP strengthened wood structures in high temperature service condition, and provide fundamental insight on the enhancement of composite through fiber selection or polymer modification to achieve better fire resistance of strengthened wood structures.