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Identification of Issues and Opportunities for LVL from NZ Eucalypts

By Steve Riley, October 2016.

Download SWP-T015 (pdf)

Executive summary

Information on the opportunities and possible issues for LVL made from eucalypts available or likely to be available in NZ is reviewed and summarised. While it is generally agreed that eucalypt will make good feedstock for LVL despite being mostly planted for pulp production, there is a paucity of information available especially for the species in question. This combination of positive signals mixed with paucity of published information and data extends from big the issues, such as peeling, drying and gluing, down to specific detail such as shear strength, impact bending, water absorption and swelling behaviour.

Opportunities

  • The medium-density eucalypts should easily meet the demand for high stiffness product.
  • Eucalypt veneers could be used to stiffen pine or other low-density species LVL.
  • LVL from early thinnings is a possibility to be investigated.
  • There is a possibility that eucalypt LVL may also be superior to softwood LVL in long term performance and thickness swelling.

Issues

  • Poor gluing reputation of eucalypts appears confined to high-density tropical eucalypts
  • The following require investigation:
    • The best eucalypt log pre-steaming practice before peeling is unknown
    • Shear properties - an instance of poor shear strength has been reported for Eucalyptus nitens LVL.
    • Collapse. While collapse-prone eucalypts like nitens meet strength and stiffness requirements, it is not certain that it is achieved through the likely increased glue usage for collapsed veneers or whether higher stiffness grades could have been achieved with non-collapsed veneers.
    • Drying - while few drying problems are reported there is certainly a lack of information in this area, and this could affect profitability.
    • There is sparse information on water absorbency, swelling, shear and impact bending. This needs to be remedied in an engineered product.

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