THEORICAL AND EXPERIMENTAL STUDY ON FATIGUE CRACK PROPAGATION LAW OF ULTRA-HIGH TOUGHNESS CEMENTITIOUS COMPOSITE

Based on Paris law of fatigue crack propagation rate, a theoretical and experimental investigation was taken to study the fatigue crack propagation mechanism of ultra-high toughness cementitious composite, which exists the characteristics of strain hardening and multiple cracking. Paris law is applicable for this material, with the two parameters redefined: the covering area of multiple cracks, A, and the composite fracture energy, J. A fatigue crack propagation threshold is found in the experiment. During the whole fatigue progress, there exist three linear stages for the development of crack covering area, in correspondence with the three stages of fatigue deformation. Moreover, the crack propagation rate speeds up with the increases of the maximum fatigue load and the fatigue load range.