Effect of multiple matrix cracking on crack bridging of fiber reinforced engineered cementitious composite

Abstract

In the present paper, a modified micromechanics based model that describes the crack bridging stress in randomly oriented discontinuous fiber reinforced engineered cementitious composite is developed. In the model, effect of multiple matrix cracking on fiber embedded length, which in turn influencing fiber bridging in the composite, is taken into consideration. First, crack spacing of high strength-low shrinkage engineered cementitious composite was experimentally determined by photographing the specimen surface at some given loading points during uniaxial tensile test. The diagram of average cracking spacing and loading time of each composite is obtained based on above data. Then, fiber bridging model is modified by introducing a revised fiber embedment length as a function of crack spacing. The model is verified with uniaxial tensile test on both tensile strength and crack opening. Good agreement between model and test results is obtained. The modified model can be used in design and prediction of tensile properties of fiber reinforced cementitious composites with characteristics of multiple matrix cracking.