混凝土早强剂低温性能试验研究

Study on the Propery of Early-strength Agent of Concrete at Low Temperature

从强度、凝结时间、水化热及混凝土工作性、耐久性等方面比较了5种混凝土早强剂在低温环境下的性能差异,综合评价了市售混凝土早强剂的低温使用效果。结果表明:5℃养护下,早强剂使砂浆7 d强度均有一定程度提高,但1 d强度仍比较低,且会使28 d强度倒缩;早强剂的掺入可促进低温下水泥的水化,使水化诱导期缩短,最大放热速率、放热量增大;掺D、E早强剂对混凝土工作性影响不大,满足实际工程施工性能的要求,可一定程度提高混凝土早期强度,但低温早强效果仍有限,且会导致混凝土后期性能下降。

The performance differences of five kinds of commercial concrete early-strength agents at low temperature were compared from the perspectives of compressive strength,setting time,hydration heat,and workability and durability of concrete,and the application effect of the early-strength agents currently on the market was evaluated.The results show that under 5℃curing,the early-strength agent can increase the strength of the mortar to a certain extent,but the strength of 1 d is still relatively low,and it will shrink the strength of 28 d.The incorporation of the early-strength agent can promote the hydration of cement at low temperature,shorten the hydration induction period,and increase the maximum heat release rate and heat release.Adding D and E early-strength agents has little effect on the workability of concrete,which meets the requirements of actual engineering construction performance and can increase the early strength of concrete to a certain extent.However,the effect of low-temperature early-strength is still limited,and adding early-strength agents will cause the later performance of concrete to decline.