In-grade Testing of Norfolk Island pine ('Araucaria heterophylla') to Enable Characterisation for use as a Structural Timber

Abstract

This study investigates the structural properties of Norfolk Island pine ('Araucaria heterophylla' - referred to previously as 'A. excelsa or 'A. robusta') to enable characterisation of the timber. The timber is used on Norfolk Island as a structural and decorative timber. Better utilisation needs to be made of the timber by determining its structural properties. These are determined by in-grade testing. No significant testing has been done in the past on Norfolk Island pine. It has previously been provisionally graded based on small, clear specimens. This project involved testing full-size, randomly selected, locally-produced timber. The work was undertaken in accordance with AS4063:1992 (a joint Australian/New Zealand standard). The results indicated higher shear and compressive strengths but lower bending and tensile strengths and modulus of elasticity. The timber is weakest in tension. The presence of knots had a significant effect on the results. Knot reduction by way of improved silvicultural techniques and/or knot excision/re-jointing will substantially improve utilisation of the species. Careful selection of timber members will be needed for specific loading applications.