Feasibility of glued laminated timber beams with tropical hardwoods

Abstract

18The tests revealed the influence of wood properties and manufacturing parameters on joint 19 resistance. In fact, the results showed that specific gravity and the shrinkage coefficientgreatly 20 influenced the gluing step. Indeed, wood with a medium specific gravity needed more adhesive 21 and more pressure than wood with a high specific gravity. In addition, planning and lamella 22 thicknesswere found to affect glue joint resistance. In this study, the bondability of hardwoods for glued laminated timber beams was 5 assessed in French Guiana using local wood species. The aim was to establish 6 gluing parameters affording good mechanical properties to glued laminated beams 7 manufactured in a tropical climate. Wood and adhesive properties 18In French Guiana there are almost 1,500 species listed, but wood properties and 19 industrial constraints impose a strict choice of species for glulam manufacture. 20The most important physical wood properties are specific gravity, wood Bonding durability tests 4To assess bonding efficiency, delamination and block shear tests were used in this Delamination 8The delamination test is used to assess the resistance of the glue joint after ageing 9 cycles including strong variations in wood moisture content. As wood dimensions 10 vary during use depending on changes in ambient humidity, delamination assesses 11 the resistance of the glued assembly under those variations. Depending on the 12 service classes for which the end-product is to be used, different delamination test Delamination was measured to an accuracy of 0.1 mm. This value was compared 27 to the upper limit allowed by the European standards, i.e. 10% for tropical 28 hardwoods. 30 Block shear strength and wood failure. 31The block shear test is used to assess the shear mechanical resistance parallel to Experimental procedure 21In this study, 92 glulam beams composed from three wooden slats were 22 manufactured and tested. Depending on the lamellae thickness (e), the size of the 23 beams was 3ex100x700 mm³. Beams were manufactured from boards, air-dried in 24 the local atmosphere until they had reached a balanced moisture content MC. The 25 balanced MC observed on the guianensis species was 14, 16 and 17% (± 2%) for

Effects of adding nano-clay (montmorillonite) on performance of polyvinyl acetate (PVAc) and urea-formaldehyde (UF) adhesives in Carapa guianensis, a tropical species

“…However, the effect of nanoparticle incorporation on the performance of adhesives used with tropical wood is still unknown. While the behavior of adhesives with nanoparticles is relatively well understood in temperate countries, in regions of high temperature and high humidity, such as in tropical countries, it can create many problems [14]. Furthermore, tropical species have high specific gravity and high contraction coefficients…”

Micro- and Nanofibrillated Cellulose (MNFC) from Pineapple (Ananas comosus) Stems and Their Application on Polyvinyl Acetate (PVAc) and Urea-Formaldehyde (UF) Wood Adhesives

“…Considering pineapple residues' availability, the aim of this work was to produce and characterize nanocellulose from pineapple stems and determine the effect of adding this material on two commercial woody adhesives: urea-formaldehyde (UF) and polyvinyl acetate (PVAc). While the behavior of adhesives with nanocellulosic material from crops has been explored with certain success in temperate countries, there is no information regarding their performance in tropical countries [9,10] or in general tropical wood adhesion [11]. The adhesives were applied to the following tropical species: Vochysia ferruginea, Cordia alliodora, and Gmelina arborea (main wood produced in Costa Rica from fast-growth plantation), and their shear strength was evaluated.…”

Caracterización mecánica por ondas de esfuerzo de la madera laminada de tres especies angiospermas

“…Esta tecnología reduce además defectos naturales en la madera sólida, como son nudos y fisuras estructurales (NADIR;NAGARAJAN, 2014). Así, la madera laminada puede ser una alternativa para sustituir a la madera sólida (BOURREAU et al, 2013). La hipótesis de la investigación es que el tratamiento de laminado incrementa la densidad aparente y el módulo dinámico de la madera.…”