大体积补偿收缩混凝土中膨胀剂的使用效能

Factors Influencing the Efficiency of Expansive Agent in Massive Shrinkage-compensating Concrete

在模拟大体积混凝土内部温度变化过程的条件下,研究了混凝土的水胶比、掺合料种类和掺量以及养护条件对补偿收缩砂浆的限制膨胀率的影响;探讨了补偿收缩混凝土中延迟钙矾石生成的可能性.结果表明:处于大体积混凝土内部环境中的膨胀剂仍能有效发挥作用;补偿收缩砂浆的限制膨胀率基本上随水胶比减小而增加,掺加矿物掺合料使限制膨胀率显著降低.养护条件,特别是湿度对膨胀剂膨胀性能的发挥有至关重要的影响,在一定条件下补偿收缩混凝土会发生延迟钙矾石生成的现象.

The effect of waterbinder ratio, kinds and use level of mineral admixtures and curing conditions on the restrained expansion rate of shrinkagecompensating mortars cured under the conditions simulating the temperature and humidity variation process in the massive concrete was investigated. The possibility of delayed ettringite formation in the shrinkagecompensating concrete is discussed. Expansive agent acts efficiently in the massive concrete. The restrained expansion rate of shrinkagecompensating mortars increases with the decrease of waterbinder ratio of mortars. Addition of mineral admixtures results in remarkable decrease of restrained expansion rate. Curing conditions, especially humidity, exhibit very important influence on the efficiencies of expansive agent. Delayed ettringite formation can take place in shrinkagecompensating concrete in some situations.