Scientific Paper

Grade verification of SA pine — bending, modulus of rupture, modulus of elasticity, tension and compression


The last verification of SA pine timber strengths was done in the early 1980s. Uses of the pine logs and the rotation periods have changed. This investigation was undertaken to verify the visual grade 5 grading rules of SANS 1783-2 (1997) on 36 x 111 mm specimen sizes. Qualified timber graders identified forestry areas with low-density SA pine. Four sawmills were randomly chosen as being representative of the forestry in those areas. Bending, tension and compression tests were done in accordance with the ISO standard test methods. It was found that only one of the sawmills came close to making the grade strength. The combined strength from all the sawmills indicated that these would only make a grade 4. It is thus suggested that sawmills that do only visual grading, in accordance with SANS 1783-2 (1997), draw random specimens that can be tested in-house for strength or by an independent testing laboratory to ensure that their timber meets the requirements of a grade 5.

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