| 摘要 |
PURPOSE: To produce a water-permeable block excellent in water permeability and strength, which is never clogged even if used for a long period and with the deterioration of permeability reduced. CONSTITUTION: This water-permeable block consists of a surface layer 1 having 25-50% porosity and a base layer 2 having a lower porosity than the surface layer. The permeability coefficient of the block is controlled to >=1×10<-2> cm/sec, the flexural strength to >=30kgf/cm<2> , the compressive strength to >=160kgf/cm<2> , the Mohs hardness of the surface of the surface layer to >=6 and the slide resistance when wetted to >=40. A base-layer material prepared by admixing a binder with a mixture of the inorg. aggregate having 1.5-2.5mm average grain diameter and paste is fed into a die and pressed at 0.5-50kgf/cm<2> pressure, then the surface-layer material formed by admixing a binder with a mixture of an inorg. aggregate having 0.5-2mm average grain diameter and paste is placed thereon, pressed at 0.5-50kgf/cm<2> pressure and formed, and the obtained formed body is fired at 900-1300 deg.C to produce the objective block.
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