コンクリートスラッジの直接炭酸塩化反応による二酸化炭素固定

Abstract

Concrete sludge is a waste fresh concrete returned from construction sites. Due to its high alkalinity, the waste treatment of concrete sludge is costly and power consuming process; neutralization by using acids is necessary before disposal as solid waste. We have developed a new type of fixation process of carbon dioxide using concrete sludge. By a simple bubbling of carbon dioxide gas into model concrete sludge, a mixture of cement and water, resulted in the formation of calcium carbonate, where calcium concentration and pH decreased with time. The effects of operation conditions including cement/water ratio, bubbling time, CO_2 flow rate, CO_2 partial pressure on the CO_2 fixation performance were examined. The highest fixation ratio was 0.085 mmol/(min∙g-cement), and the highest degree of CO_2 fixation was 91.5%.