缓凝剂对补偿收缩胶凝体系水化放热的影响

采用等温量热法,研究了酒石酸和硼酸这2种缓凝剂对掺氧化钙型膨胀剂与氧化钙-硫铝酸钙复合型膨胀剂的水泥净浆的诱导期结束时间、主放热峰出现时间及其最大放热速率、不同时间累计放热量等方面的影响.结果表明:与掺膨胀剂水泥净浆相比,缓凝剂均明显推迟补偿收缩胶凝材料体系的诱导期结束时间和主放热峰出现时间,减少最大放热速率和24 h内累计水化热,72 h总水化热略低.对氧化钙型膨胀剂水泥体系,硼酸比酒石酸缓凝效果好.

Influence of Retarder on Hydration Heat Process of Cement Paste Mixed with Expansive Agent

The effects of retarder on the hydration heat process of cement paste mixed with expansive agent were studied using a differential calorimeter, two types of retarders were used as followings:tartaric acid and boric acid, two types of expansive agents were used as followings: calcium hydroxide expansive agent and calcium sulphoaluminate hydrate-calcium hydroxide expansive agent.The terminal time of induction period, the time of the appearance of the temperature peak and maximum rate of hydration heat evolution, the heat of hydration at different ages were investigated.The results show that the two retarders can postpone the terminal time of induction period and the time of the appearance of the temperature peak in cement paste mixed with expansive agent, reduce the maximum rate of hydration heat evolution and the total hydration heat of 24 h, the total hydration heat of 72 h is slightly low, compared with cement mortar mixed with expansive agent.The retarding effect of boric acid is better than tartaric acid in cement paste mixed with calcium hydroxide expansive agent.