关键词: 水泥基复合材料, 微观结构, 轴向拉伸疲劳, 数字成像技术

Abstract:

In this paper, the uniaxial tensile cyclic loading test was carried out on engineered cementitious composites (ECC) specimens using a fatigue testing machine to investigate the fatigue pattern and the damage reason of the ECC.

The results show that the damage pattern of ECC specimens is related to its cumulative axial deformation rate. At the initial stage of loading, the cumulative axial deformation amplifies significantly with the number of cyclic loads increasing, and then enters a stable deformation phase. Further loading will result in a rapid increase of the cumulative axial deformation and eventually leads to fracture of the specimen. The crack width of ECC development, shows a trend of low in the middle and high at both ends. ECC specimens will not rapidly crack after the initial cracking in the cyclic loading process, mainly because the fibers are still tensile and can continue to withstand cyclic loading. Microscopic analysis of the fiber-matrix interface reveals that the fibers are well bonded to the matrix and can dissipate energy as a whole, which is the main reason for the high fatigue performance of ECC.

Key words: engineered cementitious composites (ECC), microstructure, axial tensile fatigue, digital imaging technology