End reinforcement of wood member using short-cut carbon fibers

Short-cut carbon fibers were used to adhesively reinforce the end of a pine (Pinus spp.) wood member. The test specimens were fabricated with an epoxy resin content of 150 or 250 g/m², fiber content of 120 or 170 g/m², pressing pressure of 0.10 MPa and pressing time of 24 h. In addition, the dispersion degree of short-cut carbon fibers in adhesive was examined. It was found that the dispersion degree increased with decreasing fiber length. Carbon fibers greatly improved the shear strength of bond layers between wood ends. The tensile strength of short-cut carbon fiber reinforced plastic (CFRP) increased with increasing fiber length. However, there was almost no difference in the tensile strength of CFRP made of 2, 3 and 5 mm long fibers. The tensile strength of a wood member with reinforced end was twice as high as or more than that of unreinforced ones. High shear strength of bond layers between wood ends could be obtained at fibers content of 170 g/m² and resin content of 250 g/m². It could be suggested that the reinforcement technology of using short-cut carbon fibers is a feasible way to improve the tensile strength of the end of a wood member.