竹-橡胶木复合正交胶合木的制备和性能

Journal of Forestry Engineering Manufacture and performance of new cross-laminated timber made from bamboo and rubber wood

以锯材为基本单元的正交胶合木是具有广泛应用前景的重型木结构建筑材料。为减少对国外树种的进口和依赖,首次采用竹篾层积材与橡胶木2种本土层板原料,以相同制备工艺(胶黏剂为单组分聚氨酯,施胶量为180 g/m^(2),冷压时间1 h,压力为1.0 MPa),在大幅面压机上压制尺寸为2400 mm×1200 mm×96 mm的三层竹木复合正交胶合木(cross-laminated timber,CLT)以及另外3种不同复合形式的CLT(纯木CLT、木竹复合CLT、纯竹CLT),通过对竹木复合CLT强轴方向的抗弯弹性模量、抗弯强度、胶层剪切强度、层间剪切强度和浸渍剥离率等性能的评估和不同复合形式CLT弯曲性能差异的分析,研究国内树种与竹材制备足尺竹木复合CLT的可行性。结果表明:采用单组分聚氨酯制备的竹木复合CLT,其干态和真空加压状态下的强度、木破率以及浸渍剥离率均符合ANSI APA PRG 320-2019“Standard for performance-rated cross-laminated timber”中使用环境1的要求;抗弯性能和剪切性能测试值均能达到以上标准和LY/T 3039—2018《正交胶合木》标准中E2等级性能的要求。上述试验研究和分析为竹木复合CLT在建筑工程中的应用提供了设计参考及理论依据。

During the global industrialization process of manufacturing cross-laminated timber(CLT),attempts have been made to efficient utilize the low-cost local wood species.CLT is a panel product obtained by gluing sawn lumber or structural composite lumber to form a large dimensional prefabricated products for building wall,floor,and roof applications.However,there is a relative shortage of timber resources in China,and with the implementation of the national natural resource protection policy,the supply of domestic timber has been insufficient,so most of the dimension timber used in the domestic production of CLT has been imported from abroad.In order to overcome this situation and reduce the carbon emission during transportation,in this study,the laminated bamboo and Grade H18 rubber wood were selected as lamination materials to manufacture bamboo-wood composite CLT,which is a novel technique.Using the same processing parameters(one-component polyurethane adhesive with a glue application rate of 180 g/m^(2),1 h cold pressing time,and 1.0 MPa pressure)to manufacture three-layer bamboo-wood composite CLT and three other structures of CLT(pure wood CLT,wood-bamboo composite CLT,and pure bamboo CLT).The feasibility of manufacturing full-size bamboo-wood composite CLT from domestic species and bamboo was investigated by evaluating the panel s modulus of elasticity,modulus of rupture,interlaminar shear strength,block shear and delamination percentage in the major strength direction and analyzing the differences in bending properties for different composite forms of CLT.The results showed that the average shear strength of the bamboo-wood composite CLT under dry condition was 3.25 MPa,which was decreased to 1.15 MPa under wet condition.It was demonstrated that the bonding quality of the bamboo-wood composite CLT was sensitive to the change of environmental humidity.In the using of Environment#1,both bonding quality and delamination percentage of the bamboo-wood composite CLT could meet the requirements specified in ANSI APA PRG 320-2019 and LY/T 3039-2018 standards in dry or wet condition.Bamboo-wood composite CLT beams were tested by the method of out-of-plane four-point bending,and the cross-section strain in the middle of the span was uniformly and symmetrically linear-distributed along the height direction.Therefore,it could be considered that the bending deformation of CLT beams followed the plane section assumption with a large span-height ratio.The modulus of elasticity and modulus of rupture of the bamboo-wood composite CLT were 9631 and 44.7 MPa,respectively.Both bending and shear performances could meet E2 grade requirements in the above standards.Thus,it is feasible to manufacture the bamboo-wood composite CLT with rubber wood and laminated bamboo for its engineered applications.