THE INFLUENCE OF DIFFERENT COMBINATIONS OF Eucalyptus saligna AND Pinus taeda VENEERS IN LVL PANELS

Investigou-se a influ\ueancia do posicionamento de l\ue2minas de madeira de Eucalyptus saligna e Pinus taeda nas camadas de pain\ue9is Laminated Veneer Lumber (LVL). As composi\ue7\uf5es foram manufaturadas em seis diferentes combina\ue7\uf5es de cinco l\ue2minas de 3,2 mm de espessura, coladas com adesivo fenol-formalde\ueddo, resultando em tratamentos compostos de madeira de uma mesma esp\ue9cie e outros com mistura de madeira das duas esp\ue9cies. A avalia\ue7\ue3o dos arranjos propostos foi realizada mediante a caracteriza\ue7\ue3o de propriedades f\uedsicas (teor de umidade e massa espec\uedfica) e mec\ue2nicas (m\uf3dulo de elasticidade \u2013 MOE e m\uf3dulo de ruptura \u2013 MOR), estas verificadas em ensaios de flex\ue3o est\ue1tica flatwise e edgewise. Os resultados obtidos indicaram que, na maior parte das vezes, as diferentes posi\ue7\uf5es das l\ue2minas de maior massa espec\uedfica (nas camadas externas, intermedi\ue1rias e de miolo) influenciaram as propriedades mec\ue2nicas dos pain\ue9is. A influ\ueancia constatada mostrou-se variada para MOE e MOR, em especial quando comparados valores para os ensaios flatwise e edgewise. Em determinadas posi\ue7\uf5es, nas camadas das composi\ue7\uf5es LVL, a presen\ue7a de l\ue2minas de eucalipto resultou em aumentos de rigidez e resist\ueancia. Contudo, os tratamentos constitu\ueddos por l\ue2minas intercaladas de eucalipto e pinus mostraram interessantes performances para uso estrutural, tanto em flatwise quanto em edgewise, por apresentarem valores de MOE e de MOR que permitem distinguilos como de 1\uaa classe, segundo o documento t\ue9cnico norte-americano APA/EWS PRL\u2013501 (2001).This research aimed to investigate the influence of the positioning of Eucalyptus saligna and Pinus taeda wood veneers on layers of laminated veneer lumber (LVL) panels. The compositions were manufactured in six different combinations of five veneers of 3.2 mm thickness, glued with phenol-formaldehyde, resulting in treatments composed of wood of the same species or with a combination of two wood types. The evaluation of the proposed arrangements was performed under the characterization of physical properties (moisture content and density) and mechanical properties (modulus of elasticity \u2013 MOE and modulus of rupture \u2013 MOR) verified in flatwise and edgewise static bending tests. The results obtained indicated that, in most situations, the different positions of the veneers with higher density (in the outer, intermediate and inner layers) influenced the mechanical properties of the panels. The influence detected was varied for MOE and MOR, especially when comparing the flatwise and edgewise test values. In certain positions, on the layers of the LVL compositions, the presence of eucalypt veneers resulted in stiffness and strength increases. However, the treatments formed by interposed veneers of eucalypt and pine demonstrated interesting performances for structural use, in either flatwise or edgewise position, once they present values of MOE and MOR that allow to distinguish them as 1st class, according to the North American standard APA/EWS PRL\u2013501 (2001)