Hybrid oriented strand boards made from Moso bamboo (Phyllostachys pubescens Mazel) and Aspen (Populus tremuloides Michx.): species-separated three-layer boards

Five sets of three-layer OSB were made from aspen and/or Moso bamboo strands in the following three configurations: Aspen strands in the surface and core layers; Moso strands in the surface and core layers; and Moso strands in the surface and aspen strands in the core. Boards containing Moso strands in the surface layers had two sub groups: (1) all strands contain a node in the middle, and (2) all strands are node free (internode). All 30 boards were comprised of 50 % w/w surface furnish and 50 % core furnish, fabricated to 737 mm 9 737 mm 9 11.1 mm. Standard mechanical (thickness, density, surface and core density) and strength properties [internal bond (IB), flexure, lateral nail withdrawal resistance (LNR)], and water resistance [2 and 24 h thickness swell (TS) and water absorption (WA)] were assessed. Complete replacement of the aspen in the surface layers with internode Moso strands resulted in over 45 % greater MOR. Panels made with Moso surface layers met CSA O437.0 (2011) minimum requirements TS/WA without the need for wax addition, possibly because no densification of the surface material was observed. Due to high variance in LNR, effects of board type and core composition were not statistically significant, but LNR of boards exceeded CSA O437.0 minimum requirements. Moso bamboo surface OSB were low in MOE which is consistent with unadulterated tissue being high in bending strength and fracture toughness but low in specific stiffness. The presence of nodes in the bamboo strands significantly reduced the strength properties of OSB, a problem which could be mitigated by minimising the incidence of nodes in the strands, particularly those used in the surface layers.