Development of lightweight wood-cement composite board using microballoon of fine pulvernized volcanic glass(micro-Shirasu-balloons)

为了制备轻质木材-水泥复合板，将不同部位的微细硅胶气球掺入水泥刨花板中。人们预计，气球的加入不仅会使它们变得更轻，还会改善一些性能。因为气球是细粉化火山玻璃的燃烧产物，具有极低的密度、低导热系数、低吸湿性、高熔点、高耐热性和不燃性。在水泥/木屑比(木比)：2.0、2.5气球/水泥比(气球比)：0~0.5目标密度：0.6~1.2板材尺寸：350×350×15 mm的条件下，试板的物理测试和观察结果如下：(1)当气球比较高时，木材比为2.5的高密度板不能控制目标厚度。(2)板材表面状况明显改善。当气球比为0.1和0.2时，密度在0.8以上的板材的弯曲性能和内粘合质量均得到改善。即使密度为0.8的板材的抗折强度也达到了《高密度水泥刨花板JIS》的要求。(4)当气球比为0.1及以上时，板材的24小时厚度膨胀率显著降低，尤其是在密度较高的板材中。(5)当气球比为0.3及以上时，密度为1.2的板材的导热系数降低了5~10个百分位数。当气泡比大于0.2时，密度分别为1.0和0.8。(6)所有受试板材均表现出较高的耐火性，达到JIS内饰面材料不燃等级2的要求。

In order to make lightweight wood-cement composite board, various parts of micro-Shirasu-balloon were mixed into cement-bonded particleboard. It was expected that the addition of the balloon would not only make them lighter, but also improve some properties. Because the balloon is the burning product from fine pulvernized volcanic glass and possesses very low density, low thermal conductivity, low hygroscopicity, highly melting point, highly heat resistance and incombustibility. Boards for test were made at the mixture ratio under the conditions as follows :Cement/wood chip ratio(Wood ratio) : 2.0,2.5Balloon/cement ratio(Balloon ratio) : 0-0.5Target density : 0.6-1.2 Board size : 350x350x15mmResults were summarized from physical tests and observation of the boards made as follows :(1)Target thickness could not be controlled in higher density board of the wood ratio of 2.5 at higher Balloon ratio.(2)Surface condition of the boards was improved remarkably, especially in lower density boards.(3)Bending properties and internal bond quality were improved in the boards of the density of 0.8 and more at lower ballon ratio of 0.1 and 0.2. Even the board with the density of 0.8 met the requirements of JIS of High Density Cement-Bonded Particleboard in bending strength. But, those properties decreased in the boards of the balloon ratio less than 0.2.(4)Thickness swelling after 24h soaking test was reduced remarkably in the boards at the balloon ratio of 0.1 and more, especially in higher density boards.(5)Five to ten percentile reduction of thermal conductivity was recognized in the boards of the density of 1.2 at the balloon ratio 0.3 and more, and of the density of 1.0 and 0.8 at the balloon ratio 0.2 and more.(6)All of the boards for test showed high fire resistance and met the requirements of the JIS incombustibility grade 2 of Internal Finish Material.