Fracture toughness for high-strength concrete

It is known that high-strength concrete tends to be more brittle or less tough than normal strength concrete. Yet, there is no acceptable method available to quantify the brittleness of normal strength or high-strength concrete. It seems reasonable to use the concepts of linear elastic fracture mechanics to quantify fracture toughness, since these have been successfully applied to metals. In this paper, the concepts of linear elastic fracture mechanics are summarized. It is shown that a single fracture parameter, such as the critical stress intensity factor, cannot be simply applied to quasi-brittle material like concrete. A two-parameter fracture model is presented. The two parameters can be calculated from an (ASTM-type) notched-beam test. This model accurately predicts fracture toughness, as well as split cylinder strength and modulus of rupture strength of high-strength concrete.