早期养护方式对高性能混凝土塑性开裂的影响

Influence of Early-curing Method on High Performance Concrete's Plastic Cracking

高性能混凝土比普通混凝土更容易发生塑性收缩开裂,适宜的早期养护措施是防止或减免高性能混凝土塑性开裂的重要途径。通过早期抗裂试验研究了几种养护方式以及养护起始时间对高性能混凝土塑性开裂的影响。结果表明:在干燥、高温、大风环境中,高性能混凝土浇筑后如果不及时进行养护,混凝土表面很容易产生较大面积的塑性开裂;养护起始时间对混凝土是否发生塑性开裂以及开裂程度的影响很大,混凝土浇筑成型抹面后应在1 h内对混凝土表面进行覆盖养护,才能有效防止或避免塑性裂缝的产生;覆盖塑膜养护与涂刷养护剂养护的防裂效果相近;在混凝土终凝时覆盖湿毯及时补水,能够有效抑制裂缝的产生和发展。

The high performance concrete is more prone to plastic shrinkage cracking than ordinary concrete, and the ap- propriate early-curing measures are the important way to prevent and reduce the high performance concrete＇ s plastic cracking. Through the early-crack resistance tests, the effects of the several maintenance ways and maintenance starting time on the high performance concrete＇ s plastic cracking are studied here. The test results show that in a dry, high-tem- perature and wind environment, if the high performance concrete after pouring is not in a timely curing, the concrete sur- face is easy to produce the plastic cracking in a relatively large areas; The influence of the maintenance starting time on the plastic cracking and cracking 1 hour after the concrete pouring of the concrete is very big, and the concrete curing should be carried out within with the surface coverage method, so as to effectively prevent or avoid the plastic cracks; The anti-cracking effect of plastic-film curing is close to that of curing agent; The producing and development of cracks could be restrained effectively with the wet blanket covering for filling water in time when the concrete finally setting.