عنوان مقاله [English]
The improvement of compressive-tensile strength of concrete has a great importance in the construction industry. In this study cubic samples constructed in dimension of 150 × 150 × 150 mm with different amounts of macrosynthetic and polymeric fibers by means of seven mix designs. The volumetric content of macrosynthetic fibers consist of 0.1 and 0.15% and also 0.2, 0.3 and 0.35% volumetric polypropylene fibers was used. Compressive and spliting tests were performed using a 200 tons servo-control device. For each sample, stress-strain, load-displacement, absorbing energy, ductility and crack patterns were investigated. In order to digital image correlation analysis (DIC) imaging the samples during tests. Strain variations were also calculated on the surface of the specimens using DIC. Finally, FEM was modeled and the results of the mentioned methods were compared with each other. The results of this study showed that the presence of fibers in concrete has a significant effect on crack reduction, displacement increase and absorbing energy compared to conventional concrete. In addition, displacement at the failure moment in tension and pressure for fiber concrete was more than the controls sample. Thus, according to the observations, although the addition of the fibers reduces compressive and tensile strength, it is evident from the results that by choosing the optimal amount, this decrease in comparison with the positive effects of the fibers would be neglected. Finally, comparing FEM and DIC with each other showed an acceptable match that given the low cost and high speed of analysis in FEM and DIC methods, it is possible to combine these two methods as a useful tool for analysis of surface strains.
The absorbing energy is directly related to the amount of fiber used in the test. The fibers have a controlling effect on the cracks of the samples so that they reduce the depth and length of the cracks. However, it should be noted that the number of cracks has increased.