干燥大温差条件下混凝土界面过渡区的研究

Study on Interfacial Transition Zone of Concrete in Dry Climate and Wide Temperature Change

采用显微硬度仪和扫描电镜,对比研究了干燥大温差气候条件和标准养护条件下混凝土界面过渡区的结构和形态.研究表明:干燥大温差环境使混凝土界面过渡区的宽度增加,显微硬度降低,过渡区水化产物结构疏松,孔隙率高,与骨料的粘结减弱,有明显的微裂缝产生.界面过渡区的劣化是造成混凝土宏观性能下降的内在原因之一.因此,又分析了界面过渡区劣化的原因.

The interfacial transition zone（ITZ） of concrete cured in standard condition and in the dry and wide temperature change environment was studied comparatively. The method of micro- hardness testing and scanning electron microscope（SEM） were used to analyze the ITZ. The re suits show that the dry and wide temperature change environment leads to an increased ITZ width and the values of the micro-hardness are lower than that of the sample cured in standard condition. The microstructure of the hydration products is loose and highly porous, and some micro cracks in the vicinity of the ITZ are observed. The bond between the aggregate and cement paste becomes weak. The formation of the ITZ defects is one of the internal reasons for the degradation of the macro-properties and the causes of deterioration are analyzed.