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 are 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 arc 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 arc given.