A. Faircloth, B. P. Gilbert, C. Kumar, W. Leggate, R. L. McGavin
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引用次数: 0
Abstract
To be commercialised, glued laminated timber must typically conform to a strict bond integrity assessment. While the associated testing protocols vary slightly from standard to standard, the general method consists of a series of swelling (water immersion) and shrinkage (drying) cycles. The approach is independent of the species and adhesive type. Those cycles strain the gluelines to a level depending on the species’ moisture uptake, timber dimensional movement and modulus of elasticity, as well as adhesive layer elasticity. High density and high modulus of elasticity materials frequently fail within the glueline regions rather than within the timber and therefore fail the bond integrity assessment. To better understand the mechanisms that lead to glueline failure, glulam samples were manufactured using three prominent Australian commercial timbers of various densities (Radiata pine—Pinus radiata, Southern pine—Pinus caribaea/Pinus elliottii, and Spotted gum—Corymbia citriodora) and two structural adhesive types (resorcinol formaldehyde and polyurethane). Using advanced measurement techniques (digital image correlation and strain gauges), the response of the different species and adhesive types to moisture swelling and shrinkage, as well as times at which glueline separation occurs, were captured. A relationship was observed between moisture uptake and delamination percentages with spotted gum producing significantly higher levels of delamination and significantly lower moisture uptake values, compared to both Radiata pine and Southern pine. While the polyurethane glued samples on average produced higher levels of delamination, the digital image correlation data indicates that the time at which this delamination occurs is later than the samples glued with resorcinol formaldehyde.
期刊介绍:
European Journal of Wood and Wood Products reports on original research and new developments in the field of wood and wood products and their biological, chemical, physical as well as mechanical and technological properties, processes and uses. Subjects range from roundwood to wood based products, composite materials and structural applications, with related jointing techniques. Moreover, it deals with wood as a chemical raw material, source of energy as well as with inter-disciplinary aspects of environmental assessment and international markets.
European Journal of Wood and Wood Products aims at promoting international scientific communication and transfer of new technologies from research into practice.