Investigation of size effect on concrete samples with and without fibers

In this study, the effect of shape and size of concrete samples with and without fibers on compressive strength was investigated. For this reason, different concrete mixtures were prepared in three groups. In the first group, mixtures were prepared based on the water/cement ratio (0,5, 0,6, 0,65 and 0,7) without using any chemical or mineral additives. In the second group, mixtures with different compressive strengths (C12, C16, C25, C30, C35, C40 and C50) were prepared. In the third group, the mixtures were prepared by adding steel fiber at different rates into the C25 and C35 mixtures. By using these mixtures, cylindrical samples with different diameters (10, 12 and 15 cm) and heights (10, 15, 20, 25 and 30 cm) with a l/d ratio between 3,5 and 0,67 were obtained. In addition to these samples, cube samples of different sizes (7,1, 10, 12, 15 and 20 cm) and prism samples of 10x10x50 cm were also produced. In addition to these samples, 10x10x50 cm prism samples were also produced in order to find the bending strength of steel fiber mixtures. Axial compressive strength and bending tensile strength tests were performed on all samples at the age of 28th day. As a result of the experiments, comparisons were made between the results of the compressive strength of the cylinder and cube samples of different sizes and the compressive strength of the standard sample. In the light of the findings, it was seen that the sample shape and length change had a definite effect on the compressive strength. Keywords: Concrete, Compressive Strength, Size Effect, Shape Effect, Fiber Reinforced Concrete