混凝土早龄期受力对后期性能的影响

Influence of preload concrete on its latter performance

本试验通过测试早龄期混凝土受力后养护28天强度及其他性能,来研究早期受力混凝土对长期性能的影响。试验中,采用高强混凝土(设计强度等级C80)和普通强度混凝土(设计强度等级C40)来分析和比较两者的异同。在龄期分别为8小时,12小时,1天,2天,3天时,在混凝土圆柱体试块上施加一定的静力(分别为混凝土当时强度的30%,50%,70%),持荷,然后在实验室条件下,将部分试件放入养护室养护,部分放在空气中养护。到龄期28天,测其各项力学性能,如抗压强度,应力———应变全曲线。在此试验基础上,考虑抗拉性能方面,在龄期为12小时,1天和3天,测试普通混凝土梁受静力荷载(混凝土当时抗折强度的70%),同样养护28天后其力学性能。采用四点弯曲试验方法。在试验中,每组混凝土试件都有参考试件。这样,我们研究了静力大小、养护条件和荷载作用时间对早龄期受力混凝土后期性能的影响,同时考察了混凝土的自愈性能。试验结果证明了混凝土的自愈功能,而且混凝土受力时间及其后期的养护条件比受力大小对早龄期受力混凝土后期性能影响要大。

In this paper,the influence of early loading on young concrete on the longterm performance was investigated by testing the 28 days characteristics of the loaded concrete specimens.Both high strength concrete and normal strength concrete were chosen.Bring certain static load(30%,50% and 70% of compressive strength)to bear on young concrete cylindrate specimens at ages of 8hours,12hours,1days,2days and 3days,then cure some loaded specimens in air and some in curing room,wait to test their 28days mechanical properties,such as compressive strength,complete stressstrain curve.In terms of tension,normal strength beam specimens subjected to 70% of flexural strength at ages of 12hours,1day and 3days were chosen and four points loading method was adopted.The 28days flexural strength and forcestrain curve were obtained of loaded specimens both cured in air or in curing room.Of course,the referential specimens were tested simultaneously.By this way,the effects of static load level,curing condition and age at time of loading on young concrete were studied and the concrete autogenous healing capacity was observed.The results show that the concrete has the autogenous healing ability and age at time of loading and the following curing condition influence on longterm performance of loaded concrete are more than the preload level.