Fracture toughness on compact tension specimen as a quality parameter for cement stone

A series of tests of compression strength and fracture toughness of hardened cement paste (cement stone) was carried out. The compression strength was tested on cubes with side lengths of 10, 20, 30 and 40 mm. Fracture toughness was measured on compact tension (CT) specimens with dimensions commonly used in metallurgy; two different thicknesses were used (h x l x b: 50 x 48 x 3 mm³ and 50 x 48 x 8 mm³). A particularly stiff piezo‐controlled test frame was used as testing device. The different thicknesses of the specimens allow the investigation of a possible size effect in toughness. In a Weibull statistical evaluation, the scatter of the strength results is compared with the scatter of the measured toughnesses. It could be shown that the fracture toughness results are as reliable as the strength results and the method is a useful addition to the research on fracture of binders.