Influence of the interfacial transition zone between a steel inclusion and cement-based composite on the fracture response of a bent specimen

The influence of the interfacial transition zone (ITZ) between a steel inclusion and fine-grained cement-based composite on fracture behaviour of the specimen with the inclusion is investi-gated. Three-point bending fracture tests were conducted and the mechanical fracture properties of the composite were evaluated based on the results of the tests. The numerical analysis of the fracture test was performed and related to the experimental data obtained during crack propa-gation, and the microstructure of fracture surfaces. The crack propagation conditions were assessed based on the criterion of the average value of tangential stress calculated over certain distance in dependence on the polar angle (GMTS criterion). We concluded that the fracture toughness of the interface KIc, ITZ is equal to 33 % of the fracture toughness of matrix KIc, MTX. The poor fracture properties of ITZ are responsible for the reduction of load-bearing capacity of whole specimen with inclusion in comparison to the sample without the inclusion.