Evaluation of fracture processes under shear with the use of DIC technique in fly ash concrete and accurate measurement of crack path lengths with the use of a new crack tip tracking method

The paper proves how the innovative optical and contactless DIC technique can be used for the examination of fracture processes in concrete with fly ash under shear loading. Critical stress intensity factor K-IIc and the characteristics of the cracks occurring in the loaded specimens were investigated by two measuring devices. A new proposed concept allowed to assess the fracture toughness of the composite by the direct testing of the material with an initial defect, i.e. directly in the crack propagation area. The article also presents an original, sophisticated solution for measuring the actual length of crack path (ALCP) in the material with the use of the crack tip tracking (CTT) method. The measurement of the ALCP, using the CTT method, allowed to prove that unmodified concrete are characterised by greater brittleness, whereas composites made on the basis of the binary binder behave as quasi-plastic materials in the fracture process.

Automated summary

The paper discusses the use of innovative optical and contactless DIC techniques to examine fracture processes in concrete with fly ash under shear loading. It investigates the critical stress intensity factor K-IIc and crack characteristics in loaded specimens, proposing a new concept for assessing fracture toughness of composites. It also presents a sophisticated solution for measuring actual crack path length (ALCP) and demonstrates the different brittleness and quasi-plastic behavior of unmodified concrete versus composites based on binary binders during the fracture process.