Abstract
Compressive and tensile strengths of commonly being used mortar and mortar specially hardened by adding 1%, 2% and 3% of $CaCl_2$ were compared under the different mixing ratio of mortar and ages to investigate the effect of $CaCl_2$ which is being used as a promotor for coagulation and hardness, on the strength of mortar. The results obtained were as follows: 1. The compressive strength of mortar hardened by addition of $CaCl_2$ was higher than that of commonly being used mortar. The highest compressive strength of mortar was obtained when 2% of $CaCl_2$ were added. 2. The tensile strength of mortar, which was made by adding $CaCl_2$ and aged for seven days, was higher than that of commonly being used mortar. The highest tensile strength of mortar was obtained when 1% of $CaCl_2$ was added and aged for 28 days. And the tensile strength of mortar with 2% of $CaCl_2$ was lower than that of commonly being used mortar. 3. When the amount of $CaCl_2$ added was higher than 3%, the mortar was abruptly hardened and thereby occurred crack was considered lowering strength of mortar. 4. The rich mix was effective for the increasing the compressive and tensile strength before seven days of age and less effective after seven days of age. Therefore, the addition of one to two per cent of $CaCl_2$ would be effective for promoting initial strength of mortar during winter season.
시멘트의 응결(凝結) 경화촉진제(硬化促進劑)로 사용(使用)되는 염화(鹽化)칼슘 첨가량(添加量)이 mortar의 강도(强度)에 미치는 영향(影響)을 연구(硏究)하기 위하여, 보통 mortar를 경화(硬化)시킨 경우와 $CaCl_2$을 1.0%. 2.0%, 3.0% 첨가(添加)하여 경화(硬化)시킨 경우의 압축강도(壓縮强度)와 인장강도(引張强度)를 배합비별(配合比別), 재영별(材令別)로 구분(區分)하여 비교시험(比較試驗)한 결과(結果)를 요약(要約)하면 다음과 같다. 1. 압축강도(壓縮强度)는 염화(鹽化)칼슘을 첨가(添加)한 몰타르가 보통(普通) 몰타르보다 크게 나타났으며, 2.0% 첨가(添加)했을 때 최대강도(最大强度)를 나타냈다. 2.인장강도(引張强度)는 7일(日) 강도(强度)에서 염화(鹽化)칼슘을 첨가(添加)한 몰타르가 보통(普通)몰타르보다 높은 강도(强度)를 나타냈으나, 28일(日) 강도(强度)에서는 1.0% 첨가(添加)한 몰타르가 최대강도(最大强度)를 나타냈고, 2.0% 이상(以上) 첨가(添加)한 경우는 보통(普通)몰타르보다 적게 나타났다. 3. 염화(鹽化)칼슘 첨가량(添加量)이 3.0%이상(以上)일 때는 급결현상(急結現象)이 나타났으며 이로 인(因)한 균열 때문에 강도(强度)는 저하(低下)되는 것으로 사료(思料)된다. 4. 부배합(富配合)에서는 압축(壓縮) 및 인장강도(引張强度)가 재령(材令) 7일(日) 이전(以前)에는 강도증진(强度增進)에 효과(效果)가 컸고 재령(材令) 7일(日) 이후(以後)에는 큰 차이가 없었으므로, 염화(鹽化)칼슘을 1.0%~2.0% 첨가(添加)하여 사용(使用)하면 동기공사(冬期工事)에서 초기강도증진(增初期强度進)을 기(期) 할 수 있을 것으로 생각된다.
(Dept. of Agricultural Engineering, Coll. of Agriculture, Chungnam Natl. Univ.)
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