Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 54 12 2023 02 20 Determination of fracture parameters of fiber-reinforced cementitious composites containing nano-silica using image processing Determination of fracture parameters of fiber-reinforced cementitious composites containing nano-silica using image processing 4729 4750 4966 10.22060/ceej.2022.21354.7689 FA Hosein Karimpour Civil Engineering Department, Shahid Rajaee Teacher Training University Moosa Mazloom Shahid Rajaee Teacher Training University Journal Article 2022 04 29 Considering that fiber-reinforced cementitious composites have been developed in recent years, it ‎seems necessary to determine their fracture behavior, fix the possible defects of these materials, and ‎facilitate their use in the construction industry. In this study, a new cementitious composite with ‎strain-hardening behavior has been developed. Granulated blast furnace slag has been used as ‎supplementary cement material to reduce the side effects of excessive consumption of cement on the environment. Moreover, Nano silica has been used to increase hydration at early ‎ages due to the low rate of hydration of pozzolanic materials, which leads to low strength at an early age. ‎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. This ‎study's results revealed that adding nano-silica to the amount of 3 wt. % of cement improves the ‎mechanical behavior ‎‎(including compressive strength and bending strength), increases the cohesive ‎toughness, and reduces ‎the brittleness of the fiber-reinforced cementitious composite. Increasing ‎cohesive toughness could be ‎interpreted as an increase in embedded fibers' interfacial frictional ‎bond strength.‎ Considering that fiber-reinforced cementitious composites have been developed in recent years, it ‎seems necessary to determine their fracture behavior, fix the possible defects of these materials, and ‎facilitate their use in the construction industry. In this study, a new cementitious composite with ‎strain-hardening behavior has been developed. Granulated blast furnace slag has been used as ‎supplementary cement material to reduce the side effects of excessive consumption of cement on the environment. Moreover, Nano silica has been used to increase hydration at early ‎ages due to the low rate of hydration of pozzolanic materials, which leads to low strength at an early age. ‎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. This ‎study's results revealed that adding nano-silica to the amount of 3 wt. % of cement improves the ‎mechanical behavior ‎‎(including compressive strength and bending strength), increases the cohesive ‎toughness, and reduces ‎the brittleness of the fiber-reinforced cementitious composite. Increasing ‎cohesive toughness could be ‎interpreted as an increase in embedded fibers' interfacial frictional ‎bond strength.‎ https://ceej.aut.ac.ir/article_4966_30d4e6422cd65c7913bc9ce62e078b79.pdf