Performance of glulam beams produced with free-formaldehyde adhesive and underexploited rubber wood treated with preservatives solutions of chromated copper borate and pyrethroids

Abstract

The release of formaldehyde may cause serious human health problems. Free-formaldehyde adhesives is increasingly well regarded by industry, since some adhesives are effective in providing of good mechanical properties even when the object of study is treated wood. This study proposes to evaluate the properties of rubber wood treated with chromated copper borate (CCB) and pyrethroid to produce glued laminated (glulam) timber using different types of adhesives as a binder. The modulus of elasticity (MOE) of the rubber wood pieces was investigated and predicted in this study before the glulam beams production. Glulam beams were glued with: polyurethane (as a free-formaldehyde adhesive) and resorcinol–formaldehyde, in the presence or absence of preservative treatment. Each beam was composed by three wood pieces. In total, 30 glulam beams were produced, 15 for each type of adhesive (60 mm thickness, 60 mm wide and 1200 mm length). Rubber wood treated with CCB showed a significant increase in pH. The glulam beams with polyurethane did not present statistical difference from those produced with resorcinol–formaldehyde for MOE and MOR. The MOE values of the beams glued with polyurethane were 6124.66 and 5768.93 MPa for the treatment with CCB and pyrethroid, respectively. The glulam beams samples showed the same efficiency in shear strength test for both adhesives. The results indicate that polyurethane adhesive could be used as a possible alternative for glulam beams production.