Fracture Analysis of Mortar‐Aggregate Interfaces in Concrete

Deformation and failure behavior of concrete is influenced by the characteristics of mortar‐aggregate interfaces. Recently, the interest in the study of the role of mortar‐aggregate interfaces in material behavior has increased particularly because of the need for the development of high‐performance cementitious materials. Presently, there is a need for the development of a fracture mechanics‐based approach for the characterization of interface fracture properties. In this paper, novel fracture models arc presented to quantify the fracture properties of the mortar‐aggregate interfaces. Sandwich specimens are used to develop the fracture toughness curves of the mortar‐aggregate interfaces in concrete. Also, a criterion based on energy release‐rate concepts is considered to study the crack‐penetration‐versus‐crack‐deflection scenarios in the interface regions of concrete modeled as a two‐phase composite. The tests indicate that the interface fracture toughness is markedly increased with the increase in the effects of shear loading relative to that of tensile loading. The interface fracture toughness values determined from the sandwich models are correlated with the results from a numerical‐experimental study of a concrete composite consisting of an aggregate inclusion embedded in a mortar matrix. Finally, recommendations for further study are given.