Utilization of Chinese fast-growing trees and the effect of alternating lamination using mixed-species eucalyptus and poplar veneers

Abstract

Over the past few decades, the sustainable forest area in China has increased remarkably, with 2400 million cubic meters of eucalyptus produced in 2018 in Guangxi which is the largest plantation area in China. In this study, the effect of alternating lamination using soft poplar veneers and hard eucalyptus veneers, on the mechanical properties of laminated veneer lumber (LVL), was examined. Eucalyptus and poplar veneers were imported from China to Japan to manufacture the LVL. For both eucalyptus and poplar veneers, the pith side (innerwood) sheets were lighter in density than the bark side (outerwood) sheets. The specific Young’s modulus of alternating LVL with hard eucalyptus veneers and soft poplar veneers was smaller than that of the mono-species LVL of eucalyptus and poplar. Strain distributions were obtained with the compression test by using the digital image correlation method. Normal strains showed that the hard eucalyptus layer behaved as a thin plate, whereas the soft poplar layer mitigated the movement of the hard eucalyptus layer. Alternating lamination decreased the variation in the elastic modulus of LVL made from fast-growing species. Therefore, the soft layers mitigated the movement of the hard layers, which had large variations in mechanical properties.