Anisotropy attenuation of reconstituted bamboo lumber by orthogonal layup process

Abstract

Current reconstituted bamboo lumber materials have significant anisotropy as the strength along the fiber is much stronger than that perpendicular to the fiber, which will bring a lot of mechanical limitations in actual applications. A new kind of cross laminated bamboo (CLB) was designed and four-point bending properties of this CLB were investigated. Flexural mechanical properties of the CLB and traditional parallel bamboo strand lumber (PBSL) were tested both parallel to and perpendicular to the fiber direction to explore the effect of the cross-laminated structure in reducing the anisotropy of bamboo products. The ratio of the parallel strength (0°) to the transverse (90°) is reduced from 8.32 of the PBSL to 1.52 of the CLB in bending. A laminated composite theory with strain failure criterion was developed and consistently predicts the flexural failure of the CLB. With balanced mechanical properties in all directions, the new CLB could be widely applied as plated structures in building engineering.