The effect of densification on physical and mechanical properties of bamboo Dendrocalamus asper

In this work, the physical and mechanical properties of laminated and densified bamboo elements for use in structural panels were assessed. The physical properties, such as apparent density, water absorption, swelling in radial and tangential directions, the effect of wet-dry cycles on dimensional stability and, surface roughness for un-densified and densified samples before and after wet-dry cycles were studied. Three-point bending tests were also carried out to measure the modulus of elasticity (MOE) and the modulus of rupture (MOR), which was correlated to the fiber distribution profile obtained from image processing of un-densified and densified bamboo samples. In addition, the effect of the bamboo skin (outer layer) on the properties of densified samples was evaluated. The dimensional changes during the wet-dry cycles test started to stabilize after one cycle for un-densified samples and after three to four cycles for the densified samples. The roughness test showed a meaningful variation of surface roughness after one wet-dry cycle for all the samples. The results indicated that densification of bamboo to 34% of densification degree improves both MOR and MOE by up to 81.3% and 36.1%, respectively but sacrifices dimensional stability. Last but not least, it was demonstrated that maintaining the bamboo skin has a positive impact on the all-mentioned analysis and reduces processing steps/costs for the production of high-performance bamboo elements. (AU)