Effects of Hydrothermal Environment on the Deformation of the Thin Bamboo Bundle Veneer Laminated Composites

To overcome warping in thin bamboo bundle veneer laminated composites(TBLC),their hydrothermal deformation characteristics were systematically investigated in this study.It was found that TBLCs accelerated the release of internal stress in the thickness direction in a hydrothermal environment,which increased their warpage.TBLCs showed increased warpage in the width and diagonal directions upon increasing the temperature.The warpage of Type E increased by 155.88%and 66.67%in the width and diagonal directions,respectively,when the temperature increased from 25
C to 100
C.The symmetrical TBLC with cross-lay-up and odd layers displayed better hydrothermal stability.We revealed that the deformation of the TBLCs could be regulated under the synergistic effect of water and temperature.These results provide a scientific basis for improving the uniformity of bamboo bundle composite materials and for developing thin bamboo bundle fiber composite materials with designable structures and controllable performance.

Effects of characteristic inhomogeneity of bamboo culm nodes on mechanical properties of bamboo fiber reinforced composite

Dendrocalamus farinosus and Phyllostachys heterocycla bamboo logs were subjected to a novel treat- ment process for the preparation of bamboo fiber mats （BFMs）, and the obtained BFM were used to fabricate bamboo fiber reinforced composite （BFRC）. We studied the mechanical properties of the BFRCs manufactured from the mats with and without bamboo nodes. The pres- ence of nodes in BFM greatly reduced tensile strength, compressive strength, modulus of elasticity, and modulus of rupture of the BFRCs, while the BFRCs fabricated from BFMs with nodes possessed higher horizontal shear strength. Therefore, the nodes in bamboo culms were an important factor in the uniform distribution of mechanical properties, and BFMs should be homogeneously arranged to reduce the impact of nodes on the mechanical strengths of BFRCs.

Analysis and characterization of microstructures of a TiO_2/bamboo charcoal composite and modified poplar veneer

A type of TiO/bamboo charcoal composite made by a dip-dry method was loaded onto wood veneer with a vacuum- pressure method in order to prepare modified poplar veneer. The pore structure parameters and surface morphology of the TiO2/ bamboo charcoal composite were determined and analyzed by means of a porosimetry analyzer and SEM. The results show that the surface morphology of the composite does not change after being loaded with nano TiO2. However, its specific surface area （359.814 m^2·g^-1）, pore volume （0.317 cm^3.g^-1） and average pore diameter （3.526 nm） increased; particularly the cumulative volume of pores was increased by 65.83%. In addition, the distribution range of the pores was wider than that of the bamboo charcoal. Combining the SEM of unmodified and modified poplar veneer, the results of X-ray photoelectron spectroscopy revealed that actually some TiOz compounds, i.e., 4.08%, are imbedded in the modified poplar veneer.

Engineered Wood/Bamboo Laminated Composites for Outdoor Hydrophilic Platforms:Structural Design and Performance

Landscape designers increasingly prefer to use wood/bamboo-based composites for outdoor hydrophilic platforms owing to their natural surface texture,high performance,and sustainability to facilitate extensive interaction between people and water and enable the full range of ecological functions of water resources.In this study,four laminated composite(LC)structures were designed and manufactured using fluffed bamboo and wood veneers.Their surface textures,profile densities,water resistances,and mechanical properties were then evaluated.The type of fluffed veneer of the surface layer determined the texture of the LC surface.The specific structures of fluffed bamboo and wood veneer laminations were found to affect the LC profile density variability,water resistance,and mechanical properties owing to the differences in the strength and interfacial properties of bamboo and wood fibers.Finally,the water resistance and mechanical properties of all four LCs were found to be much higher than the highest level specified in GB/T 20241-2006 for“laminated veneer lumber”and GB/T 30364-2013 for“bamboo scrimber flooring”,indicating that they are promising materials for structures and flooring,particularly for outdoor hydrophilic platforms.

Experimental and Theoretical Study on Bonding Properties between Steel Bar and Bamboo Scrimber

To further verify the feasibility of newly designed reinforced bamboo scrimber composite(RBSC)beams used in building construction,the bonding properties between steel bar and bamboo scrimber were investigated by anti-pulling tests.Results indicated that the anti-pulling mechanical properties were significantly correlated to the diameter,thread form and buried depth of steel bar,forming density of bamboo scrimber as well as the heat treatment of bamboo bundle.There were two failure modes for anti-pulling tests:the tensile fracture and pulling out of steel bar.Both the ultimate load and average shear strength of anti-pulling specimen could be increased greatly with the ribbed bar,high forming density of bamboo scrimber and un-heated bamboo bundle.Furthermore,a theoretical calculation model of the bonding interface between steel bar and bamboo scrimber was developed.Based on the theoretical calculation model,the change laws of normal stress of bamboo scrimber,and shear stress of glue layer along the buried depth of steel bar were revealed.This study is beneficial for the safety application of RBSC beams in building construction.

Flexural and Impact Resistance of FRC/Bamboo Laminate

The flexural and impact resistance of a newly developed FRC/bamboo laminate have been investigated. The laminate considered in this study was combined with reformed bamboo plate and extruded fiber reinforced cementitious (FRC) sheet. Innovated from the raw bamboo, reformed bamboo showed high tensile strength and high strength to weight ratio. It can not only remarkably strengthen the FRC sheet but also reduce the total weight of the laminate. Flexural and impact load, broken energy, deflection and duration were measured. Test results showed that the flexural strength value for the laminate can be improved to greater than 90 MPa, while the impact resistance is increased more than 10 times for the laminate when compared with the FRC sheet only.