【摘要】 采用光学显微镜对经历不同周次疲劳荷载作用而破坏的混凝土试件内部疲劳裂缝进行了观察,并对粘结裂缝和基体裂缝的长度进行了统计。观察和分析结果显示界面区预先存在尺寸细小的微裂缝,由初始微裂缝引发的粘结裂缝既存在于粗集料与砂浆的界面区,也存在于水泥石与细集料之间的界面区;基体裂缝可以由邻近的细集料与水泥石之间粘结裂缝贯穿而形成,也可以存在于水泥石中;疲劳裂缝的数量随试件破坏前所承受的荷载循环次数(即疲劳寿命)的增加而增多;粘结裂缝占疲劳裂缝的多数,且其相对数量有随疲劳寿命的增长而增加的趋势。更多还原

【Abstract】 Inner fatigue cracks of failed concrete specimens were examined by optical microscope,bond crack and matrix crack were identified and quantitative assessed too.Observation and results showed that bond crack originates from preexisting microcracks either in the interface transition zone between coarse aggregates and mortar or in the interface zone between fine aggregates and bulk cement paste.Matrix crack could be formed in bulk paste only or by connection of bond crack between fine aggregate and bulk cement paste;specimens which subjected to a larger number of cycles of load before failure crack more extensively than those failed after a few number of cycles of load;the amount of bond crack increased with the increase of the number of cycle to failure.更多还原