Mechanical Propetries And Brooming Processing Of Bamboo-culm

Bamboo is the most important forest resources in China second only to timber, andbamboo-culm is the important part of processing and utilization which is composed ofinternode part and bamboo joint. In order to more scientific and reasonable to play goodcharacteristics of bamboo to be used common building, Moso bamboo and Dendrocalamusfarinosus were used as experimental materials. The mechanical properties of bamboo-culm areresearched which can be directly used in the architecture. And In order to solve those cannot bedirectly applied in building, the bamboo-culm brooming processing equipment has beendeveloped, which can improve the utilization rate of bamboo, produce good performance ofbamboo qualitative engineering materials, thus achieve the goal of utilize bamboo resourceeffectively.Main results are summarized as follows：1The mechanical properties of bamboo-culm1) The longitudinal compressive strength, longitudinal shearing strength, transversebending strength and ring stiffness of bamboo-culm increase with stem from bottom to top;while the failure load of biaxial compression decrease. The mechanical properties of4-year-oldbamboo-culm are better than that of6-year-old bamboo-culm overall.2) The variation of mechanical properties between bamboo-culm and bamboo strip wassimilar, both can reflect the change trend with different age and position.3)6-year-old Moso bamboo-culm are better than that of5-year-old Dendrocalamusfarinosus bamboo-culm, such as longitudinal compressive strength, longitudinal compressiveand shearing failure loads. Moreover the ring stiffness and failure load of6-year-old Mosobamboo-culm is respectively3times and4.5times of the5-year-old Dendrocalamus farinosusbamboo-culm.4) The bamboo joint has not effectively improve the longitudinal compressive strengthand compressive. While can improve radial compression of bamboo-culm is about2.3times that of the without bamboo joint. Using hose clamps may improve the mechanical property ofbamboo-culm, but the holes make reduce its performance, both of them are affected its thestyle of failure.5) The sizes of tensile samples has no remarkable influence on the result of tensileproperties, but with the increase of specimen size the machining precision increases and thetensile test success rate decreases. Therefore the size of bamboo tensile properties test can be(280×10×t) mm,“t” may best be from4mm to6mm.6) The biaxial compressive strength of bamboo-culm under ultra-low temperature is thehighest，followed by low temperature, constant temperature and humidity, boiling, and airdrying.2The brooming processing and utilization of bamboo-culm1) With the increase of brooming processing times, the tensile property of bamboo bundledecreasing at first, then increasing, and then decreasing. And on different brooming processing,the mechanical properties of laminated board would be in different, Among them, using thesixth times broom processing bamboo bundle can produce optimum performance board.2) In the same layer, with the increase of the lay-up direction, the bending strength,bending modulus, compression strength and horizontal shear strength of laminated board hasbeen in decline, but a positive influence on its connection performance.3) An analysis of the range of the hot-pressing process test results shows that hot-pressingtemperature has the largest effect on every quality index of the product, hot-pressing time asless，and hot-pressing pressure has the least. The technology of Cold-Hot-Cold pressing isbetter than Hot-Hot pressing, but its hot-pressing cycle is much higher than the Hot-Hotpressing.4) With density increase, the mechanical properties enhances gradually, while physicalproperties increasing at first, and then decreasing. The experiment proved that add a certainproportional poplar veneer to bamboo bundle which is the raw material can improve themechanical properties of laminated bamboo bundle board at low density, and its MOE could beefficiently improved by putting the bamboo bundle veneer in the surface layer. 5) The outdoor horizontal shear strength of laminated bamboo bundle board is less thanindoor horizontal shear strength. After weting cycles, the mechanical properties of board are alldecreased, especially boiling-freezing-drying treatment, but the board still has high physicaland mechanical properties.To sum up, The mechanical properties of bamboo-culm were evaluated syntheticallycomprehensive to provide reference in the construction engineering, materials bamboooptimization, structural design. Bamboo bundle can be made of bamboo by broomingprocessing technology. It not only improve utilization of bamboo, but also produce high qualityboard which can achieve the180E level and65V-55H level of structural laminated veneerlumber. Bamboo element shape, lay-up, hot-pressing, and board density are closely related withthe physical and mechanical properties of laminated bamboo bundle board. To make goodunderstanding of those factors will have directive significance to optimize the structure andproperties of the board.