Processing Technology Of Laminated Bamboo-Bundle Veneer Lumber And Its Application Performance

As a kind of natural biomass gradient composite material, bamboo has advantages ofresurces and performance such as high strength,high toughness,sustainable development and soon. However, it has defects of a lower processing rate, large variability at the same time.Therefore, improving bamboo processing efficiency and the stability of the related products isone of the effective ways to increase the added value of the composite material and also theinevitable trend of the further development and utilization to promote bamboo/woodcomposites. Biomass materials are rich in cellulose, so they are violation targets of fungi,insects and many other kinds of biology. Compared with other materials, biomass materials arevulnerable to the destruction of the environment effect, especially in high temperature, highhumidity, strong storms, and extreme growing conditions. To understand the materialproperties of the environmental effect, the development space of the material, and to give fullplay to its use properties, various performance evaluation for bamboo and composite materialsshould be performed, and the performance evolution laws and natural resistance abilitiesunder the hot and humid environment should be understand too.Dendrocalamus farinosus is taken as the research object. Through debugging and testingof the bamboo brooming device researched by our laboratory independently, the transverseintertwined, and vertical continuous flat veneer were got, which is used as raw material toproduce the Laminated bamboo-bundle veneer lumber(LBVL). The south regionalenvironment with high temperature, high humidity, and strong storms is taken as the researchbackground. Performance and modification technology of termite resistance of Laminatedbamboo-bundle veneer lumber are studied, and the hydrothermal aging characteristics, theabsorbing mechanism and the action of deformation characteristics under uniform load arerevealed, through tests of termite resistance modification, hydrothermal aging, concussion ofdropping hammer, and performance test under uniformly distributed load. The main research results of this paper are summarized as follows:(1)A complete set of processing technology of bamboo brooming is designed, and theoptical image identification is introduced to monitor and evaluate the broom state. The targetbamboo-bunble veneers were optimized and the prediction model between brooming frenquecyand tensile strength decline ratio was got. Laminated bamboo-bundle veneer lumber of stablequality and even density is produced through regular lamination and composition ofbamboo-bundle veneers. and the MOR, MOE and tensile strength of the board with a broomingfrequency of six times is245.8,203.0and21.2MPa, while the thickness swelling rate ofindoor and outdoor is4.8%and7.8%, respectively.The basic performance is superior tobamboo scrimber.(2)The properties of LBVL were significantly influenced by hydrothermal condition.Thehydrothermal aging characteristics of laminated bamboo-bundle veneer lumber can bedescribed according to the Fick's law and thickness expansion model, and the goodness-of-fitof the thickness expansion behavior is greater than0.9. mechanical properties are reduceded bythe hot and humid coupling effect. The retention ratio of the bending strength and thecompression strength are60%and50%at21to60℃(RH99%).(3)Properties of the impact resistance of laminated bamboo-bundle veneer lumber isaffected by the quality of bamboo-bundle veneer, way of the paving, number of layers, densityof the board, the influence of. The total absorption energy of the bamboo/wood compositematerial and laminated bamboo-bundle veneer lumber are105.1J and66.39J, respectively.and the failure modes are mainly layered damage and damage along the fiber direction,respectively. For laminated bamboo-bundle veneer lumber, the energy absorption mechanismare in-plane and out of plane. In-plane strength of bamboo/wood composite restructuringmaterial is poor, and it has a property of layer absorption.(4)Performance under uniformly distributed load of laminated bamboo-bundle veneerlumber is affected by the density, and the deflection(mm) change decreases with the increaseof density. In test conditions of this experiment, the deflection of change of laminated bamboo-bundle veneer lumber of different densities under uniform loading can be preliminaryestimated according to a formula deformation which is introduced the density parameter.Support direction and size effect exist in the performance under uniform load of laminatedbamboo-bundle veneer lumber. The tensile failure on the back of the board easily happen whenthe bamboo fiber direction and the support direction are consistent. The deflection of changedecreased with the board dimensions decreases when single span supporting is adopted.(5)The destroying laws of the termites to laminated bamboo-bundle veneer lumber aresummarized. Termites damage are selective and relevant to cellulose content and surfacehardness level. The more soft basic organization such as bamboo parenchyma cells firstlysuffers termites attack, and the attack path is along the edge of the vascular bundle along thefiber direction. The weight loss rate of moso bamboo is about42.43%. All the damagemorphologies of the samples are along the fiber direction. The weight loss rate of LBVL isabout10.04%. and the modification for laminated bamboo-bundle veneer lumber has goodeffect on termite resistance.