A proposal of high strength wooden nail for environmentally friendly building

在这项研究中，我们调查了压缩木材或竹子钉子作为房屋建筑紧固件的可能性及其对自动钉子机的适应性。木钉有以下几个优点：1。回收或刮除时不需要与木头部件相匹配。重复使用时，可与木质火焰或板材一起用木材机械切割。既不会造成金属污渍，也不会因水汽凝结而损坏。它足够轻，在承重和抗震设计上具有优势。将竹子劈成12至16块，交替定向，向外和向内，用粘合树脂压缩，将竹条的曲率弯曲成扁平的形状。竹条在压缩过程中相互约束，实现了更大的变形而不断裂。通过53%的竹材压缩(Madake)，在静曲强度为1.45g/cm~3的条件下，可获得400 Mpa以上的高强度材料，钉头对提高板材与火焰的抗拔性能具有重要作用。因此，我们尝试用偏置头来塑造钉子。此外，刺穿基材后钉点处的压缩回复率增加，达到与紧固相同的效果。作为将长维管束鞘与竹条分离的前处理，我们尝试了碱处理、蒸煮、蒸汽爆破及其组合。结果表明，竹钉的密度在1.33~1.43g/cm~3之间，抗弯强度和静曲强度分别超过40 Gpa和400 Mpa。与普通钢钉相比，竹钉具有较高的硬度、屈服强度和最大强度，但韧性较低。

In this research, we investigate the possibilities of compressed wood or bamboo nails as fastener in house construction and its adaptability to automatic nailer. Wooden nails have some points of advantage as follows :1. It does not have to assort from wooden part when recycling or scraping.2. It can be cut by wood machinery together with wood flame or panels when reusing.3. It causes neither the stain by metal nor the damages by moisture condensation.4. It is enough light to have an advantage in withstand load and seismic-resistant design.Splitting bamboo culms into 12 to 16 pieces, alternatively orienting, to outer and inner directions, compressing them with adhesive resin, the curvature of the strips is bent into flat form. The bamboo strips restrain each other during compression, which achieved greater deformation without breakage. A wide bamboo flat board can be obtained.We could obtain high strength material more than 400Mpa in MOR at density of 1.45g/cm^3 by 53% compression of bamboo (Madake).Nail head is important to increase withdrawal resistance when the panels joint to the flame by nails. Thus, we try to shape the nail with offset head. Furthermore, it increases by recovery of compression at nail point after piercing through the base material resulting in the same effect as clenching.As a pre-treatment to separate the long vascular bundles sheath from bamboo strips, we have tried the alkali treatment, steaming, steam explosion, and their combinations. As an example of the results, density of the products was around 1.33-1.43g/cm^3. The MOE and MOR exceeded 40GPa and 400MPa, respectively.The higher stiffness, yield and max strength, but lower toughness can be observed in bamboo nail compared to steel common nail.