冻融作用下超高性能混凝土细观结构损伤研究  

Research on damage of microstructure of ultra-high performance concrete under freeze-thaw action

作　　者：张燕燕 ZHANG Yanyan(School of Architectual Engineering,Zhengzhou Business University,Zhengzhou 451200,China)

机构地区：[1]郑州商学院建筑工程学院,河南郑州451200

出　　处：《混凝土》2023年第10期221-224,共4页Concrete

摘　　要：研究了超高性能混凝土在冻融作用下的损伤。对含钢纤维和不含钢纤维的超高性能混凝土进行了冻融试验。采用压汞法(MIP)、扫描电镜(SEM)和X射线计算机断层扫描对冻融试验前后超高性能混凝土基体的微观结构进行了检测。结果表明,超高性能混凝土由于其致密的微观结构,具有很好的抗冻融性能。在冻融作用后,超高性能混凝土基体中砂浆界面处出现裂纹并容易萌生裂纹;压汞法结果还表明,超高性能混凝土基体在冻融作用后出现了裂纹;超高性能混凝土在冻融作用后X线CT可见缺陷数量增加。砂浆界面开裂的原因是团聚体和膏体的热膨胀系数的不匹配。超高性能混凝土中的钢纤维抑制了基体裂缝的扩展,提高了超高性能混凝土的冻融性能。The purpose of this study is to study the damage of ultra-high performance concrete under freeze-thaw action.The freeze-thaw test of ultra-high performance concrete with and without steel fiber was carried out.The microstructure of ultra-high performance concrete matrix before and after freeze-thaw test was investigated by means of mercury injection(MIP),scanning electron microscopy(SEM)and X-ray computed tomography.The results show that the ultra-high performance concrete has good freeze-thaw resistance because of its compact microstructure.After freeze-thaw action,cracks appear at the sand paste interface in the ultra-high performance concrete matrix and crack initiation is easy.The results of mercury injection also show that cracks appear in the ultra-high performance concrete matrix after freeze-thaw action.The number of defects visible on X-ray CT of ultra-high performance concrete increased after freeze-thaw action.The reason of mortar interface cracking is the mismatch between the thermal expansion coefficient of aggregate and paste.The steel fiber in ultra-high performance concrete inhibits the expansion of matrix cracks and improves the freeze-thaw performance of ultra-high performance concrete.

关 键 词：超高性能混凝土 冻融作用 钢纤维混凝土 

分 类 号：TU528.01[建筑科学—建筑技术科学]