Mechanical properties of a novel laminated veneer bamboo using curved cross-sectional strips

Laminated veneer bamboo is a green and sustainable building material with better mechanical properties and lower discreteness than raw bamboo. Normal laminated veneer bamboo (NLVB) is usually made of flat-sawn bamboo strips, which needs to slice the curved cross-sectional bamboo strips into rectangular section. Nevertheless, the outer bamboo wall with rich vascular bundles is cut off, reducing the mechanical properties of laminated veneer bamboo. In this regard, a novel curved laminated veneer bamboo (CLVB), directly using curved cross-sectional bamboo strips, was investigated in this work. The failure modes, stress-strain relationships and load-displacement curves of CLVB material were studied and compared with NLVB material through tensile, compressive, shear and bending tests. Otsu algorithm was used to identify the proportion of vascular bundles. In addition, the microscopic morphology of the adhesive layer and vascular bundle was observed by scanning electron microscope (SEM). Finally, the energy consumption of the specimen was calculated to compare the differences of large deformation in bending test. The results showed that the CLVB and NLVB exhibited similar failure modes in tensile, shear and bending tests, but had different failure modes in compressive test. It was demonstrated that the CLVB showed significant enhancements in the strength and modulus when compared to the NLVB. Specifically, the proportion of cross-sectional vascular bundles in the CLVB was 1.22 times larger than that of the NLVB, contributing to the better mechanical performance of fiber-loaded specimens. In addition, the CLVB had superior bonding performance with a continuous and obvious adhesive layer in the SEM observation, while the adhesive layer of NLVB was discontinuous and irregular. Compared with CLVB, NLVB consumed more energy consumption due to the extra fiber dissociation of bending specimens. In short, CLVB performed better mechanical properties, showing its great potential as an alternative material to engineered bamboo.