The paper attempts to explain the phenomenon of a static strength increase due to the previous cyclic loading. Finite Element Method simulation of the potential strengthening mechanism is presented. The crack growth is controlled by the energy criterion used in the linear fracture theory. A wedge splitting test has been performed in order to determine the critical energy release rate of the tested mixture GIC. It was observed that the appearance of additional cracks in the material may lead to an increase of its strength. Analysis of the tensile stress distribution allows for a qualitative explanation of the observed phenomenon.