INVESTIGATING THE EFFECT OF FIBER ON COMPRESSIVE AND SPLITTING TENSILE BEHAVIOR OF CONCRETE VIA EXPERIMENTAL TESTS, DIGITAL IMAGE ORRELATIONS

The improvement of compressive and tensile strength of concrete has a great importance in the construction industry. In this study, cubic samples constructed in a dimension of 150times150times150 mm containing different amounts of macro-synthetic (0.1 and 0.15 vol.%) and polymeric fibers (0.2, 0.3, and 0.35 vol.%) by means of seven mix designs. Compressive and splitting tests were performed using a universal testing machine. For each specimen, stress-strain and load-displacement behaviors, absorbing energy, ductility and crack patterns were investigated. In order to analyze the strain variations on the surface of the specimens digital image correlation (DIC) was applied. Moreover, finite element method (FEM) was conducted to evaluate the experimental results. The results of this study show that the presence of fibers in concrete has a significant effect on reducing size and number of cracks, and increases displacement compared to conventional concrete. In addition, displacement at the failure moment in tension and pressure for fiber contained concrete was more than the control specimen. According to the observations, addition of the fibers reduces compressive and tensile strength. However, it is so obvious from the results that by choosing the optimal amount, this reduction would be neglected in comparison with the positive effects of the fibers. Finally, the results indicate an acceptable agreement between the FEM and DIC evaluations. Therefore, considering the low cost and high speed of analysis with FEM and DIC methods, it is possible to combine these two methods as a useful tool to determine the surface characteristics of such specimens.