BEHAVIOR OF CARBON-FIBER REINFORCED CEMENT COMPOSITES IN DIRECT TENSION

The effect of carbon fibers on the tensile strength of cement paste ma trix was experimentally and analytically investigated. The tensile str ength values were obtained using the cementitious composites axial ten sile technique (CCATT) [ 1, 2]. The addition of 1, 1.5,2, and 3 volume percent of polyacrylonitrite-based (PAN) carbon fiber to a cement mat rix 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 add ition, the developed equation of the tensile strength accounts for the orientation and the length of fibers, the specimen geometry and the e ffectiveness of the reinforcement with increasing fiber content. The d eveloped constitutive model compares satisfactorily with experimental results and it can be used as a practical tool for approximating the t ensile strength of CFRC composites.