Ability to Glue Portuguese Eucalyptus Elements

Abstract

Portuguese forests have changed in recent years. These changes were mainly boosted by the wildfires that affected a significant percentage of the softwood area. Eucalyptus is actually the dominant wood species in Portuguese forests. This is not a native hardwood, but is being planted mainly for pulp and paper production, and its availability and mechanical performance have made it very present in timber construction in the last 50 years. Within the discussion to substitute imported raw materials, mainly from softwoods, with local hardwoods for the production of engineered wood products, the study of the ability to glue eucalyptus has become a necessity. This paper presents experimental works aimed to assess the ability to glue eucalyptus elements for the production of glued laminated timber (GLT) and cross-laminated timber (CLT). Since this wood species has been known for being difficult to dry, a preliminary study on the dimensional stability under moisture content variation was performed. Then, shear strength tests were made in accordance with ASTM D143. The objective was to correlate those results with the tests performed in the following research step. In this further stage, shear strength tests of the bond line were performed following EN 14080 and EN 16351. The results obtained in all the experiments show that eucalyptus has the potential to be glued and therefore the production of GLT and/or CLT using this local undervalued wood species is potentially of high industrial interest.

Engineering Wood Products from Eucalyptus spp.

“…Apart from E. grandis, Tasmanian Oak (E. regnans/obliqua/delegatensis) and Blackbutt (E. pilularis) have also been glue laminated and their hygroscopic behaviour was examined [86]. Suleimana et al [87] fabricated glue laminated timber from Portuguese Eucalyptus (E. globulus Labill.) and concluded that the E. globulus is suitable to be used in the production of glue laminated timber.…”

Experimental Evaluation of Glulam Made from Portuguese Eucalyptus

“…Moreover, the gluing and delamination properties were measured with PUR adhesive, and it was observed that none of the tried configurations were successful in meeting all the requirements regarding the strength and durability of the glue lines. Nevertheless, glue lines based on MUF adhesive were studied by Suleimana et al [11], who obtained failures that occurred mostly on the wood side and achieved shear strengths of 14 N/mm 2 and 12 N/mm 2 using surface-bonding and edge-bonding specimens, respectively.…”