Application of the MSR Impact-Echo system for crack detection in concrete dams

Concrete dams suffer from many forms of deterioration and specifically the presence of internal cracks. Presently, the borehole technique is used to evaluate the orientation of the cracks and the mechanical properties of the concrete. High costs are associated to this method as well as the need to extrapolate results between adjacent boreholes. Nondestructive testing is seen as a possible solution for reducing high inspections costs and increase the precision of crack location. This thesis presents the theoretical and practical aspects of a nondestructive method called the Miniature Seismic Reflection (MSR Impact-Echo) system. The system can evaluate a crack profile and determine the quality of concrete from one test surface. The objective of the research is to extend the capabilities of the system to crack detection in large scale concrete structures. Results are presented with respect to inclined crack detection, the minimum crack thickness detectable, and tests performed on a section of a concrete gravity dam. The experiments are part of a long term research project between McGill University and the "Institut de Recherche en Electricite d'Hydro-Quebec (IREQ)".