地熱水から回収したシリカの高強度セメント用混和材適用評価試験

概要

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Silica recovered from Sumikawa geothermal brines by reaction with cationic precipitant was examined to the industrial application as admixtures to high strength cements. The silica deposits from brines consist of > 90 % silica and H2O with minor amounts of Al, Ca and Na. They were converted to silica fume (spherules of 1 to 10 m in diameter) by heating at 180°C in a spray-dryer. Then, the products were heated up to 900°C and sintered in an oven for 2 hours. During this process, the zeta potentials of the products drastically changed from positive to negative values at 300°C in calcination temperature. The sintered products were mixed with cement and the strength of the hardened body exceeds > 100 N/mm2. These results show that the fumed silica converted from excess silica in geothermal brines can be applied as admixtures to high strength cements.
2003-02-25