Key mechanical properties of cross-banded laminated veneer lumbers manufactured from blending spotted gum and hoop pine veneers

Abstract

The main objective of this study was to investigate the key mechanical properties of cross-banded laminated veneer lumbers (LVL-C) manufactured from blending veneers recovered from sub-optimal native forest spotted gum and plantation hoop pine logs. The recovered veneers were separated into three grades based on their dynamic modulus of elasticity (MOE). Additionally, the spotted gum veneers were visually graded to evaluate whether a relationship exists between the MOE-based and visual grades. In total, six 12-ply reference LVL and six mixed-species 12-ply LVL-C panels were manufactured and analyzed for (i) flatwise and edgewise bending performance; (ii) bearing and tension strength perpendicular to the grain; and (iii) longitudinal-tangential shear strength. Little correlation was found between MOE-based and visual grades for the spotted gum veneers. The LVL- C showed flatwise and edgewise MOE up to 24% and 13% lower, respectively, than the reference mixed-species LVL. The flatwise and edgewise modulus of rupture were up to 39% and 19% lower, respectively. On average, the tensile and bearing strengths of the LVL-C were considerably higher than the hoop pine LVL and mixed-species LVL, with the former being approximately three times higher. The manufactured LVL-C showed markedly higher bending properties and tensile strengths than commercial LVL-C products.