Study of the Edge Effect in Fiber-Reinforced Concrete Cylindrical Molded Specimens Using Computed Tomography

The edge effect is important in the structural design of concrete elements as it may lead to an erroneous estimation of the mechanical response of concrete because of the difference in size between the test specimen and the full-size structure. This study analyses the influence of the pore and fiber distribution on the edge effect under compressive loads. For this purpose, three series of cylindrical specimens of steel fiber–reinforced concrete, with diameters of 75, 100, and 150 mm and a height/diameter ratio of 2 in all cases, were fabricated. Next, computerized tomography scanner was used to obtain the pore and fiber distribution inside the specimens. The images reveal that, near the cylinders’ walls, the pore and fiber content is lower than that in the cores. In addition, the thickness of the ring near the edge, where the microstructure is different, is independent of the specimen size. Moreover, it is determined that the mechanical capacity of the ring is lower than that of the rest of the specimen.