The project focuses on fracture of quasi-brittle silica-based materials. It combines analytical and soft-computing methods, programming, numerical analysis (FEM, physical discretization) and a wide range of experimental techniques. Procedures determining pure material values of fracture parameters independent of the test geometry and specimen size (specimen free boundaries) will be developed and experimentally verified. These values can serve as relevant inputs for structural analyses using nonlinear fracture mechanics and as the real basis for the material failure classification. Determination of fracture parameters is based on the relationship between the energy dissipated in the fracture process zone (FPZ) and its volume. The FPZ size and shape will be constructed using approaches: i) Multi-parameter linear elastic fracture mechanics, ii) Classical non-linear fracture models, iii) Plasticity/damage theory. Predicted failure intensity in the FPZ, its shape and the crack opening will be measured by using radiographic methods in the volume of solids and optical ones on their surface.