干湿循环下混凝土湿度与变形的测量

为考察干湿循环环境下混凝土内部湿度和变形的关系,该文采用自然干燥和液态水湿润的方法,模拟了混凝土的干湿循环环境,试验测定了3个强度等级的混凝土试件在干湿循环下自由变形和内部相对湿度随干湿龄期的变化。试验结果表明:混凝土在干湿循环下表现出干缩湿胀的特性;混凝土水灰比越小,干湿循环下其自由变形和内部相对湿度的变化幅度越小;混凝土干燥阶段内部湿度和变形的变化速率明显低于湿润阶段;混凝土强度等级越高,自干燥作用越明显,相应的变形越大;随着龄期的增长,密封条件下混凝土的变形逐渐超越干湿循环下混凝土变形,并且混凝土强度等级越高,该现象越明显。

Concrete deformation and interior humidity during dry-wet cycles

Cyclic dry-wet conductions were composed on a concrete specimen using drying and wetting processes during the cyclic dry-wet tests to study the relationship between deformation and interior humidity.The deformation and interior humidity of the specimen were continuously measured.The experimental results show that the concrete expands during wetting and shrinks during drying.It higher concrete strengths and lower water to cement ratios reduce the shrinkage during the dry-wet cycles.The rate of the shrinkage variation during wetting is significantly larger than during drying.In addition,as expected,the autogenous shrinkage of concrete is greatly influenced by the concrete strength.Higher strength concretes have greater autogenous shrinkage.