Determination of the Fracture Toughness Parameters of Cement Composite Using Specimens with Rounded Notch

The fracture mechanics parameters are used in different applications to formulae the classic criteria of failure as well as in computational models to analyze the concrete structures and other brittle materials. The parameters are determined using the specimens with notches. The study for assessing the influence of the notch curvature in specimen on fracture mechanics parameters, e.g. critical stress intensity factor, critical crack tip opening displacement and fracture energy, was performed on cement mortar as a typical quasi-brittle material. The U-shaped notches with a depth of 30 mm were formed during molding the specimens. The radius of notch curvature was changed in the range from 0.15 mm to 30.0 mm. The results obtained demonstrated that the notch curvature radius has a significant effect on the level of maximum stress and the parameters describing the cement composite resistance to cracking. Therefore, the experimental determination of the fracture characteristics requires a strict definition of the test conditions.