Efficiency of the glue line in the treated wood Eucalyptus cloeziana F. Muell for glued laminated (glulam) beams production

The sectors of civil construction, furniture industry, pulp, and paper industry that use wood, seeking new alternatives for a more rational usage of wood while reducing the use limitations. Some examples of new materials are reconstituted wood panels as plywood, chipboard, blockboards, glulam (glued laminated timber), among others. This study aimed at evaluating the efficiency of bonding pieces of chemically preserved with Copper Chrome Arsenate (CCA) Eucalyptus cloeziana wood. Six adhesives were used: MUF (Melamine urea formaldehyde); PVA (polyvinyl acetate); RF (Resorcinol-formaldehyde); TF (Tannin formaldehyde); UF (Urea-formaldehyde; PUR (castor oil-based polyurethane). We evaluated the wood-adhesive interface through photomicrographs, measuring the thickness of the main glue line, shear strength, and percentage of wood flaws. In order to preview the wood-adhesive interface, we withdrew anatomical sections for each position, transverse plane and longitudinal plane of the glued joint, after softening it in hot water. We could not assess the wood-adhesive interface of the lamellas glued with TF, only. CCA contributed negatively to the physical and mechanical properties of wood. The MUF adhesive had the best results, represented by greater penetration of the adhesive into the wood and consequently higher values in the shear and delamination test.