Fatigue deformation behavior and fiber failure mechanism of ultra-high toughness cementitious composites in compression

Abstract

Ultra-high toughness cementitious composites (UHTCCs) belong to a family of fiber-reinforced cementitious composites with strain-hardening behavior under tension. Such composites have potential application in structures sustaining fatigue loads. In this paper, the compressive fatigue deformation behavior of UHTCC under various stress levels S (S = 0.90, 0.85, 0.80, 0.75, 0.70 and 0.65) was investigated. It is found that the stress level has little influence on the cyclic creep curve of UHTCC, while the fatigue failure strain increases as the stress level decreases. The failure strains at different stress levels obey the two-parameter Weibull distribution, and a probabilistic model is proposed to consider the effect of stress level on the fatigue failure strain. Using X-ray computed tomography and a scanning electron microscope, three fatigue-induced failure modes of polyvinyl alcohol fibers in UHTCC are found and the possibility for further improvement of the compressive fatigue performance is discussed.