コンクリートスラッジ中の残存固形物を用いた高炉セメントモルタルの養生条件が圧縮強度と塩分浸透性に与える影響

抄録

　This study investigated the potential use of residual solids, obtained by dewatering fine calcium carbonate produced through the injection of carbon dioxide into concrete sludge suspended in water using a filter press method, as a mortar admixture. The compressive strength of mortar mixes containing Type B equivalent cement (which is a 60:40 blend of ordinary Portland cement and blast furnace slag fine powder) combined with differing ratios of residual solids containing fine calcium carbonate (25, 50, 75, and 100 mass%) was then tested. Compressive strength tests were conducted under both water curing and steam curing conditions. The results indicated a 12.7% increase in compressive strength at 25% replacement under water curing, whereas steam curing led to a decrease in strength with increasing replacement ratios. Moreover, salt penetration tests confirmed superior durability of the water–cured specimens, with the 25% replacement mixture exhibiting significantly higher resistance compared with the control specimen. These findings demonstrate that residual solids containing fine calcium carbonate from concrete sludge can serve as an effective partial substitute for blast furnace slag powder.