せき板存置期間が高強度コンクリートの強度性状と耐久性に及ぼす影響
中庸熱ポルトランドセメントを用いた高強度コンクリートによって現場内で製作するプレキャストコンクリート部材(サイトPCa部材)を想定し、強度発現性などの面で不利な低温でかつ乾燥状態にある冬期において、せき板存置期間が躯体の品質(強度性状や耐久性)に及ぼす影響を明らかにするため、実大柱を模擬した試験体による実験を行った。その結果、せき板存置期間は強度発現性には影響せず、また耐久性に及ぼす影響もほとんどなく、JASS 5に規定される普通ポルトランドセメントを用いた高強度コンクリートの湿潤養生期間と同等としてよいことが明らかになった。
The Effect of the Sheathing Removal Time on the Strength and Durability of High-Strength Concrete
The effect of the sheathing removal time on the strength and durability of high-strength concrete made with moderate-heat Portland cement was studied using full-scale specimens in a cold and dry environment. In the experiments, the concrete's setting time, temperature, compressive strength, length change, carbonation and pore volume were measured. From the experiments, the following conclusions were derived. 1) The strength of the concrete core specimen was not affected by the sheathing removal time. 2) The removal time had little effect on carbonation after about 34 hours had passed from the time the concrete was cast. 3) The removal time had little effect on length change once the concrete had set. 4) High-strength concrete made with moderate-heat Portland cement had almost identical strength properties and durability as concrete made with ordinary Portland cement.