养护制度影响下高性能混凝土早期收缩机理分析

Mechanism analysis of early shrinkage of high performance concrete under influence of curing systems

高性能混凝土早期收缩是其非受力开裂的主要因素之一,养护制度对其早期收缩性能有较大影响,选取适当的养护制度是抑制材料早期收缩的有效方法.文中以常用养护制度为基础,试验研究了不同养护方式和养护时间对高性能混凝土早期收缩的变化规律,定性分析了养护制度对材料收缩的影响机理.研究表明:从抑制混凝土早期收缩的效果依次为养护剂、塑料薄膜和湿草帘;当采用湿草帘养护且养护时间少于7 d,抑制混凝土早期收缩效果不明显;养护可有效降低混凝土早期收缩增加速率,对减少早期收缩有积极意义.试验结果可为实际养护制度的选用提供数据支撑和参考.

The early-age shrinkage is one of the main factors of non-loading cracking in high performance concrete.It has a great influence on the early-age shrinkage of high performance concrete by curing system.The selection of appropriate curing system is an effective method to restrain the early shrinkage of concrete.Based on the common curing system,the variation law of different curing methods and curing time on the early shrinkage of high performance concrete is studied in this paper.The influence mechanism of curing system on the shrinkage of high performance concrete is qualitatively analyzed.The results show that the effect of inhibiting early-age shrinkage of concrete is curing with curing compound,plastic membrane and wet straws in turn.The effect of inhibiting early-age shrinkage of concrete is not obvious when curing time is less than 7 days and by wet straws curing.The increase rate of early-age shrinkage of concrete can reduce effectively by curing and it is positive significance.The test results can provide data support and reference for the selection of actual curing system.