Mixed glued laminated timber of poplar and Eucalyptus grandis clones

The authors investigated the properties of small-sized joint-free laminated beams (80 mm in width, 115 mm in height and 2 m in length) composed of 7 mechanically graded laminations of poplar (Populus x euramericana, 'Neva' clone) and eucalyptus (Eucalyptus grandis, '7', '329', '330' and '358' clones) in different combinations. Tests were carried out in order to determine their modulus of elasticity, bending strength and shear modulus; the bonding reliability was also evaluated by means of delamination and shear tests in the glue lines. The beams composed using the '330' eucalyptus clone, by its own or in combination with poplar, showed outstanding mechanical performance and the best structural efficiency. In addition the bonding quality, also at the interface between the two species, proved to be excellent. The results, separately for each clone of E. grandis, in terms of absolute values and structural efficiency, are shown and discussed.