Do We Need a Standard Concrete Fracture Mechanics Test?

Fracture mechanics has allowed scientists and engineers to understand brittle fracture and to determine the conditions that cause a crack to grow in an brittle manner and lead to failure of the structure. In this paper we consider the information that fracture mechanics provides, especially that which is not obtained from a simple test of strength. Fracture mechanics provides a measure of toughness, the extent to which a material can undergo deformation without fracturing. For a linear elastic material, the measurement and interpretation of fracture toughness is fairly straightforward. Concrete is not such a material; it is rather described as quasi-brittle, and only recently has research led to the development of fracture mechanics tests suitable for such quasi-brittle materials. We show in this paper that fracture toughness provides considerable information about concrete over and above what we can learn from strength. We also show how the practicing engineer can benefit from the use of fracture criteria in design. However, fracture specifications will not be developed until there is a standard test method. Researchers have now developed tests that are suitable as standards. Therefore, we conclude that a need exists for a standard test and that it is time to begin its consideration.