# Experimental Evaluation of Gluam Made from Portuguese Eucalyptus
###### Abstract  
Engineered wood products (EWPs) have evolved over time to become a popular and sustainable alternative to traditional lumber by offering design flexibility, increased strength, and improved quality control. This work analyzes the potential of Portuguese eucalyptus wood (_Eucalyptus globulus_) to produce glued-laminated timber (gululam) for structural applications. Currently, this hardwood is used for less noble applications in Portugal's construction industry. To promote the use of this species of timber in construction, an experimental campaign was conducted to characterize its compression parallel to the grain and bending strength. The results demonstrated that this hardwood presents a compression parallel to the grain strength of 73 N/mm\({}^{2}\) and a bending strength of 151 N/mm\({}^{2}\) with a global value of elastic modulus equal to 24,180 N/mm\({}^{2}\). Based on those strength values obtained from the gulam produced with eucalyptus, one can conclude that the test results presented here are higher than the ones declared by the current gulam made of softwoods; thus, additional studies are encouraged. gulam; hardwoods; eucalyptus; experimental evaluation +
Footnote †: journal: Applied  
0000-0001-4800-058  
Portuguese forests present a high percentage of hardwoods, with eucalyptus being the most representative species. In this context, it will be interesting to study the possibility of using eucalyptus to produce gplum, thereby adding value to the Portuguese forests. It is possible to find German producers of gplum, which is made of beech from the black forest; however, to our knowledge, the only producers of gplum made from eucalyptus are located in Galicia, Spain, where the presence of this species is also important. Eucalyptus seeds were first introduced in Spain in the 1800s [6], and their woods have been used in different areas, from mercanaries to carpentry and buildings. Most of the gplum is produced using softwoods; however, the use of some hardwoods was previously mentioned in EN 14080 [7]. Unfortunately, _Eucalyptus globulus_ was not mentioned by this standard as a possible species to use in the production of gplum. [PERSON] et al. [8] presented a summary of studies conducted on the different uses of eucalyptus species worldwide, with special emphasis on engineered wood products (EWP), such as gplum, cross-laminated timber (CLT), fiberboards, oriented strand boards (OSBs), laminated vener timber (LVT), and other particleboards and plywood. It was demonstrated that gplum was the application least studied. In Brazil, gplum beams made from _Eucalyptus urogandis_ have been tested and obtained values for bending strength in the range of 57-94 N/mm\({}^{2}\), with an elastic modulus in the range of 17,800-20,100 N/mm\({}^{2}\), a compression strength parallel to the grain between 65 and 75 N/mm\({}^{2}\), and a bond line shear strength of 10-12 N/mm\({}^{2}\)[9], which suggested that the species had great potential to be applied in gplum industries owing to its high mechanical properties. Despite this lack of information, [PERSON] and [PERSON] [10] evaluated the use of _Eucalyptus globulus_ as an engineered material, achieving characteristic values of 115 N/mm\({}^{2}\) and 83 N/mm\({}^{2}\) for bending and compressive strength parallel to the grain, respectively. 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 [PERSON] 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. In Spain, solid and gplum elements made of _Eucalyptus globulus_ have been evaluated and characterized by [PERSON] et al. [12], for use in timber grid shells.