Mode I fracture energy of Australian native hardwood spotted gum at various moisture contents

Abstract

While there is an industry drive to use Australian hardwood spotted gum (Corymbia citriodora) boards in the manufacturing of glulam beams, such beams frequently fail the delamination requirements in the Australian and New-Zealand standard AS/NZS 1328.1 (1998). Delamination likely occurs due to (a) the difficulty in gluing this species and (b) the combination of large shrinkage coefficients and high moduli of elasticity of the material, resulting in large moisture-induced stresses developing in the gluelines during the wetting and drying cycles of the delamination test. The paper forms part of a research aiming at finding mechanical solutions to reduce the moisture-induced stresses in the gluelines, allowing spotted gum glulam beams to pass the delamination requirements and land on the market. Especially, this paper introduces the reader to the overall project and focuses on measuring the Mode I fracture energy of the spotted gum material in the tangential-longitudinal crack system and of the glueline between spotted gum boards at 8%, 12% and 16% moisture contents. The relationship between the Mode I fracture energies and moisture content are then discussed and analysed statistically to determine whether fracture energy is sensitive to the moisture content for the analysed range. © 2023 13th World Conference on Timber Engineering, WCTE 2023. All rights reserved.