Development of a new test method for determining the tensile strength (proportional limit) of fibrous concrete under biaxial bending stress

Although concrete has a high compressive strength, it is very brittle due to very low tensile strength and deformation capacity. Some features of this material may need to be improved by various methods. One of these methods to improve the mechanical properties of concrete is to add fiber to the mixture. In this study, various tests were carried out using the triangular plate method and the three-point beam bending test available in the literature to determine the flexural tensile strength of steel fibre reinforced concretes. By comparing the obtained results, it has been discussed whether the proposed triangular plate method can be used to determine the flexural tensile strength of fibre reinforced concretes. Within the scope of the study, triangular plate and beam samples containing steel fiber with hooks at both ends at the ratio of 0%, 0.3%, 0.6% and 0.9% of the concrete volume were prepared. The slump-flow value of the mixtures was obtained as fresh state properties. On hardened concrete, compression test, triangular plate test and three -point bending tests were performed. In addition, the energy absorption capacity of the samples were determined. No significant relationship was observed between the addition of steel fiber to concrete mixtures and the compressive strength. However, as the fiber ratio increased, the ultimate load, tensile strength, energy absorption capacity and ductility significantly increased. Considering these test results, two test methods were compared.