引气和非引气混凝土冻融损伤微裂纹扩展规律研究  

Microcrack development in freezing-thawing-damaged concrete with and without air-entrainment

作　　者：李曙光[1] 陈改新[1] 鲁一晖[1] 

机构地区：[1]中国水利水电科学研究院,流域水循环模拟与调控国家重点实验室,北京100038

出　　处：《水利学报》2013年第S1期80-86,共7页Journal of Hydraulic Engineering

基　　金：国家重点基础研究计划(973计划)(2013CB035901);中国水利水电科学研究院科研专项(结集1321;1246)

摘　　要：基于真空荧光环氧浸渍染色法和数字图像处理技术,对经受不同程度冻融损伤的非引气混凝土、引气混凝土(含气量5%)试件基体内部不同类型的微裂纹(砂浆裂纹、过渡区微裂纹)的结构特征参数进行了详细定量分析。结果表明,随着冻融损伤程度的增大,无论引气混凝土还是非引气混凝土,其内部微裂纹的长度密度、面积密度和最大裂纹宽度等均在逐渐增大;冻融循环过程引起的微裂纹以过渡区微裂纹为主,砂浆微裂纹为辅;砂浆微裂纹和过渡区微裂纹的宽度并无明显差异。研究结果还显示,在同样的冻融损伤度下,引气混凝土基体微裂纹的密度要低于非引气混凝土。Most of the concrete structures in North China are suffering freezing-thawing(FT)damage. It'sof great significance to study the microcrack developing process to reveal the essence of FT damage in con-crete. In this paper a thorough investigation based on vacuum-epoxy-impregnation method and digital-image-processing technique was made on the microcrack structures, including mortar microcrack and InterfacialTransition Zone(ITZ) microcrack,in non-air-entrained and air-entrained concrete suffering different FTdamage degrees. The results show that the length density,area density and maximum width of matrix micro-cracks in both types of concrete increase with the increase of FT damage degree. The ITZ microcracks arethe major part of the matrix microcracks caused by FT in non-air-entrained and air-entrained concrete. Noobvious differences are found between the width of mortar microcracks and ITZ microcracks. At the samedamage degree,the microcrack density in air-entrained concrete is smaller than non-air-entrained concrete.

关 键 词：混凝土 冻融损伤 微裂纹扩展 数字图像处理 引气 

分 类 号：TU528.45[建筑科学—建筑技术科学]