Layer Properties of Oriented Strandboard

It is well known that the density varies through the thickness of oriented strandboard, with the face being much denser than the core. Hence, the modulus of elasticity and the strength should vary through the thickness. To determine the variation in these properties through the thickness of the panel, a commercial oriented strandboard panel was sliced into fifteen layers to obtain specimens for tension and compression testing. Using multiple saw blades and spacers mounted on an arbor in a milling machine, thin specimens were obtained both perpendicular and parallel to panel length. The specimens were tested in tension using straight-sided specimens and non-bonded tabs. The compression specimens were tested using an apparatus developed to prevent buckling.

For specimens cut parallel to the panel length, the face layers had moduli of elasticity and strengths approximately an order of magnitude greater than the core. For specimens cut perpendicular to the panel length, the modulus of elasticity and strength were relatively uniform through the thickness of the panel. This was due to a combination of density changes and strand orientation. The denser faces, with the strands oriented perpendicular to the applied load in testing, had approximately the same strength as the less dense core, where the strands were aligned with the applied load.

These layer properties were related to the vertical density profile with evidence of a strong linear relationship. The layer properties were also employed to predict panel properties and compared to the strength and stiffness values obtained from full thickness bending tests. This study has successfully established a method to relate the vertical density profile to panel properties.