Mino Yogyo Co., Ltd.

Tatsushi Kachi

Fumikazu Tanemura

Yoshiharu Kajita

Shigetoshi Ohta

Tohru Honda

A water-permeable ceramic material is made of a porcelain particulate material as the principle component, one or more primary binders selected from starch adhesives, organic binders, clay and water glass, and one or more secondary binders selected from frit, glaze and glass powder. The principal component is selected from one or more porcelain materials including a fired mixture of pottery stone, kaolin and feldspar; porcelain wastes, and other porcelain materials such as road-surfacing porcelain color aggregates, and is classified to have a particles are of relatively high bulk density and very low porosity. The mix is shaped by a pressing machine to a tabular or tubular form suited to the specific use of the final product. The pressure of the pressing machine is adjusted to an amount of 30-200 kg/cm.sup.2. After shaping, the resultant compact is sintered at a temperature up to the melting point of the porcelain particles to produce the ceramic material. The ceramic material has a continuous porous structure which provides an effective water-permeable property. The individual particles have interstices therebetween having an average pore diameter of at least 0.1 mm; the composite material has an apparent porosity of 10-53%, a water permeability of at least 50 ml/min.cm.sup.2, and a normal incident absorptivity of at least 65% within or throughout the frequency range of 500-5,000 Hz.

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Tokyo, Japan

Tatsushi Kachi