中文摘要：

初始微裂纹的存在对高强混凝土的宏观性能和耐久性等均有重要影响。微裂纹定量分析的前提是对微观分析试样进行浸渍染色,而常用的真空环氧浸染法、伍德合金真空高压浸染法等由于制备试样过程中需要真空、干燥等环节,不可避免地引入了人工微裂纹,影响结果的准确性。采用常温常压下即可实施的荧光流体置换法对高强混凝土进行浸渍染色,基于数字图像处理技术对试件内部不同类型的初始微裂纹结构特征参数进行了定量研究。结果表明,在未承受荷载之前高强混凝土基体内部分布有一定数量的初始微裂纹,其中骨料微裂纹占初始微裂纹的长度比、面积比在53%以上;初始基体微裂纹中以过渡区微裂纹为主;骨料、砂浆和过渡区微裂纹的宽度并无明显差异。

英文摘要：

Initial microcracks play an important role in the macro properties and durability of high strength concrete （ HSC ）.The precondition for quantitative microcrack analysis of HSC was the impregnation and dyeing process for the microscopic specimens.Both the vacu- um-epoxy-impregnation method and vacuum-high-pressure-impregnation method with wood-metal had inevitable influences on the original microcrack pattern in concrete because of the vacuum and drying procedures, so either method was not suitable to study initial microcracks in HSC.In this study quantitative microcracks analysis wass made for high strength concrete cured in the standard curing room for two years based on fluorescent fluid replacement method and digital-image-processing（DIP ） techniques.Results showed that aggregate mi crocracks maked up over 53% in length or in area of the initial microcracks （composed of aggregate microcracks and matrix microcracks ） in HSC and the Interfacial Transitional Zone （ITZ） microcracks,which maked up over 94% in length or in area,were the major part of the initial matrix microcracks （composed of ITZ microcracks and mortar microcracks ）.It also showed that there were no obvious differences among the aggregate microcracks, mortar microcracks and ITZ microcracks.