| 摘要 |
<p>PURPOSE:To smoothly obtain the titled cement board having excellent strength without hindrance of hardening at a low cost by using a mixture of chip selected by a specified method, cement and water as main component. CONSTITUTION:After chip of a coniferous tree such as pine, white cedar, Japanese cedar, etc., is immersed in water, allowed to stand at room temp. for >=10min, alcohol such as methanol, ethanol, isopropanol is added and mixed to the immersed liquid directly or to the separated supernatant indirectly. At that time, when the chip is or contains Japanese larch, the liquid becomes opaque. Therefore, the liquid is tested whether the color of the liquid changes or not, and when the color changes only the chip without color change is sorted out. Then, a mixture of 20-30pts.wt. sorted chip other than Japanese larch and 80-70pts.wt. cement is added and mixed with 40-60pts.wt. water basing on 100pts.wt. the mixture, press-molded at 20-40kg/cm<2> pressure with a roll press, etc., and hardened.</p> |
