Behaviour of carbon fiber reinforced cement composites in direct tension

The effect of carbon fibers on the tensile strength of cement paste matrix was experimentally and analytically investigated. The tensile strength values were obtained using the cementitious composites axial tensile technique (CCATT) [1,2]. The addition of 1, 1.5, 2, and 3 volume percent of polyacrylonitrite-based (PAN) carbon fiber to a cement matrix results in an increase in the uniaxial tensile strength of 32, 42, 48 and 56 percent, respectively. A predictive model based on the rule of mixtures is developed. The model accounts for the tensile strength of composites with short and randomly dispersed carbon fibers. In addition, the developed equation of the tensile strength accounts for the orientation and the length of fibers, the specimen geometry and the effectiveness of the reinforcement with increasing fiber content. The developed constitutive model compares satisfactorily with experimental results and it can be used as a practical tool for approximating the tensile strength of CFRC composites.