Study of the effect of the fibers' orientation on the post-cracking behavior of steel fiber reinforced concrete from wedge-splitting tests and computed tomography scanning

The correlations between fiber orientation and residual tensile strength and fracture energy in steel fiber-reinforced concrete are analyzed with Computed Tomography (CT) Scanning, Digital Image Processing (DIP) software, and the Wedge Splitting Test (WST). A mixture containing 2% by volume of steel fibers was performed to cast a total of six prisms measuring 150 x 150 x 600 mm. Then, two cubes with 150 mm edges and a mini-prism measuring 50 x 50 x 150 mm were cut from each prism. The two cubes were subsequently prepared for the WST by sawing a groove and a notch on one face. The groove and the notch were sawn on the front face of one cube and on the side face of the other cube from each prism. All the specimens were held in a curing room at 20 degrees C and at 100% humidity. The mini-prisms were scanned using a micro CT-Scan and their fiber orientation obtained with DIP software. Additionally, all the cubes were subjected to the WST and the residual tensile strength and fracture energy were obtained. A comparison of the results from both the CT-Scan and the WST revealed strong correlations between fiber orientation, on the one hand, and the values of both residual tensile strength and fracture energy, on the other hand. Finally, a set of empirical formulas are proposed on the basis of the results. (C) 2018 Elsevier Ltd. All rights reserved.