Finger-jointing of green Eucalyptus globulus L. wood with one-component polyurethane adhesives

Abstract The use of glued finger joint in green wood, directly from the sawing process, would open the possibility to obtain glued timber from small-sized wood, achieving an efficient use of the original raw material. The gluing of finger-jointed green wood, with moisture content above the fibre saturation point, may improve the efficiency and the manufacturing process of glulam or joinery. This may be especially beneficial for a hardwood such as Eucalyptus globulus L., which is a globally important forest resource, but is a challenging wood to dry. This article presents a study on the possibility to develop finger joints with wood in green state. To compare them, conventional finger joints on dry wood and solid boards without end joints were also manufactured. Cold-setting and fast-curing commercial one-component polyurethane adhesive systems were used. Finger-jointed samples were tested to determine mean and characteristic values (5th percentile) of density, bending strength and modulus of elasticity, and the results were analysed and discussed. Green-glued joints showed no statistically significant differences compared to the solid boards and improved strength properties with respect to dry-glued joints.