POROUS CERAMIC, WEATHER-RESISTANT POROUS CERAMIC AND THEIR MANUFACTURE

PROBLEM TO BE SOLVED: To prduce a prous ceramic product and a weather-resistant porous ceramic product capable of easily obtaining high strength and high porosity at a low cost. SOLUTION: This manufacture comprises: kneading inorganic aggregate 2 whose particle size is adjusted within a specified range and water glass in a 10 to 20wt.% ratio of the water glass to the aggregate 2 to form a kneaded material; casting the kneaded material into a frame mold up to its every comer while vibrating the frame mold and also, discharging entrained air at the time of casting the material; at the time of vibrating the frame mold, diffusing gaseous carbon dioxide from a diffuser tube that is placed so as to communicate with the frame mold, for a prescribed period of time to separate out jelly-like silicic acid in the cast material by the reaction of carbon dioxide with the water glass; after the lapse of a prescribed period of time, stopping both vibration of the frame mold and the diffusion of gaseous carbon dioxide, drying the resulting cast material for two to three hours and letting it stand still to allow the separation of silicic acid to proceed; then, dipping a formed body of the cast material released from the frame mold into a water repellent 5 to impregnate voids 4 of the formed body with the repellent 5; and thereafter, drying the impregnated formed body to manufacture the objective weather-resistant ceramic product 1 having excellent weather resistance, high strength and high porosity.