基于粗骨料含量的混凝土早龄期收缩调控

Control on early-age shrinkage of concrete from coarse aggregate content aspect

试验研究了粗骨料体积分数在0~50%范围内增大时对混凝土早龄期收缩以及内部相对湿度的影响规律。试验结果显示:混凝土早龄期内部相对湿度和收缩发展均呈典型的两阶段发展特征。混凝土第I阶段收缩、自收缩和干燥收缩均随着粗骨料体积分数增大而减小,其中干燥收缩受粗骨料的约束程度最为明显。早期收缩中,低强混凝土以干燥收缩为主,高强混凝土以自收缩为主,中等强度混凝土的干燥收缩和自收缩二者相当。粗骨料含量对同水胶比系列混凝土的内部相对湿度发展的影响可以忽略。

Effect of volume fraction of coarse aggregate within the range of 0 to 50% on the development of intemal relative humidity and shrinkage in early-age concrete was studied experimentally.The experimental results show that the development of internal relative hu- midity and shrinkage of early-age concrete follows a two-stage developing law respectively.The first stage shrinkage, autogenous shrinkage and drying shrinkage of concrete is decreased with the increase of coarse aggregate volume content.Drying shrinkage is more significantly influenced by the addition of coarse aggregate compared to that of autogenous shrinkage.Drying shrinkage for low-strength concrete, auto- genous shrinkage for high-strength concrete, both drying and autogenous shrinkage for medium-strength concrete is individually found to be the principal part of early-age total shrinkage.The effect of coarse aggregate content on the internal relative humidity is ignorable.