Evaluation of mode I failure of concrete in a splitting test using acoustic emission technique

A splitting test was performed to generate a well-defined crack surface in a concrete cube. Using acoustic emission technique the formation of micro cracks was observed and correlated with the stress distribution during the test. Subsequent to the experiment the topography of the crack surface was evaluated, using a process of stepwise grinding and digitalization of photographs of cross-sections of the cube. Inversion of the amplitudes of the spatial displacement distribution yields a system of equivalent moments for selected acoustic events, the so-called moment tensor. Analysis of the moment tensor allows a fracture mechanics based interpretation of failure and gives information about the stress field within the specimen. A comprehensive 3D visualization combines all this information and allows for a broad understanding of the failure process.