Micromechanics-based investigation of fatigue deterioration of engineered cementitious composite (ECC)

This paper reports fatigue deterioration of engineered cementitious composite (ECC), a unique high-performance fiber-reinforced concrete featuring high ductility. Sources of fatigue dependency in ECC microscopic constituent properties were discovered experimentally. These fatigue-dependent fiber and fiber/matrix interface properties were incorporated into a novel multi-scale mechanics-based analytical model to reveal the influences of fatigue dependency on the fiber-bridging and fatigue crack propagation in ECC. The flexural stress-fatigue life (S-N) of ECC were predicted and compared with experimental results. It was found that several fatigue-induced changes of microscopic constituent properties contribute to the fatigue deterioration of fiber bridging of ECC. As a result, saturation of multiple cracks (and thus strain capacity) of ECC was much reduced under fatigue. The flexural fatigue model incorporating the fatigue-dependent fiber-bridging constitutive model developed in this study could be used to predict the flexural stress-fatigue life of ECC and the resulting S-N curve agreed well with experimental results.