摘要
混凝土在长期的使用过程中,由于环境中CO2的进入,在一定的相对湿度下形成碳酸,导致水泥的水化产物与碳酸发生反应而破坏水泥石的结构,同时导致水泥石发生碳化收缩。论文综合分析了混凝土各种收缩及其机理,在此基础上,提出了混凝土发生碳化收缩的3种机理:碳酸钙对毛细孔的细化及水分的散失导致凝胶表面张力增加而产生收缩、钙矾石发生碳化反应后绝对体积的减小而产生的体积收缩,以及在碳化后期C-S-H凝胶结构的转换而导致体积的收缩。
Carbonic acid was formed at a certain relative humidity for a long time due to the carbon dioxide into the concrete, which leads to a chemical reaction between hydration products and carbonic acid, and break the structure of hardened cement paste, meanwhile resulted carbonated shrinkage.Varies of concrete shrinkages and their shrinkage mechanisms were analyzed in the paper, and on the basis,3 kinds of mechanisms of carbonated shrinkage of concrete were presented： pore size of capillary porosity changed more smaller for calcium carbonate, and the lost of moisture leads to the increasing the surface tension of gel producing the shrinkage,the decreasing of the absolute size of ettringite which resulted in the contraction of volume,the changed of the structure of C-S-H gel during the later period of carbonation which generated the volume shrinkage.
出处
《工程质量》
2014年第8期31-35,共5页
Construction Quality
关键词
混凝土
碳化收缩
机理
concrete
carbonated shrinkage
mechanism
