Analysis of the manufacturing parameters of glued laminated timber elements in the response of gluing quality based on NBR 7190-6

Abstract

This study aimed to evaluate manufacturing parameters and their impact on the quality of gluing glulam elements. Three stages of research were carried out with Eucalyptus grandis and Pinus elliottii timbers, using different adhesives, analyzing the percentage of delamination and the shear strength of the glue lines. Different bonding pressures were tested with commercial adhesives, quantifying the rupture modes in the bonding zone, different proportions of natural adhesive in the glulam elements and different lamella thicknesses with a two-component polyurethane adhesive. Results indicated that pressures of 0.7 MPa for Pinus and 1.2 MPa for Eucalyptus were in line with the Brazilian standard. Significant differences were observed in the shear strength between Pinus’s outer and inner lamellae. The natural adhesive showed good shear strength, but problems with delamination. The thickness of 3.5 cm showed better bonding quality. The recommendations of NBR 7190-6 proved to be effective in controlling the quality of the bonding of glulam.

Keywords
Glued laminated timber; Gluing quality; Shear at the glue line; Delamination; Gluing pressure