Determination of fracture parameters of fiber-reinforced cementitious composites containing nano-silica using image processing

Due to the increasing development of fiber-reinforced cementitious composites, studying their fracture behavior is necessary for the possibility of widespread use in the construction industry. In the present study, a new cementitious composite with strain hardening behavior has been fabricated. To reduce the adverse environmental problems, part of the cement has been replaced with pozzolanic materials such as blast furnace slag. Due to the fact that composites with high pozzolanic materials have lower strength at early ages than composites produced with ordinary cement, nano-silica has been used to solve this problem. Therefore, in this study, the effect of adding nano-silica on the fracture behavior of cementitious composites has been discovered. The double-k fracture method (DKFM) has been used to analyze the fracture behavior at different stages of specimen failure, i.e., crack initiation and stable and unstable crack propagation. In addition, the digital image correlation technique has been used to find the initial crack load and the crack opening displacement at different loading stages. The results show that the addition of 3% nano-silica positively affects compressive and flexural strength. In addition, it increases the toughness of the fiber bridging and reduces the brittleness of the composite.