Evaluation of thermographic techniques for the detection of subsurface delaminations in concrete bridge substructures

Abstract

This thesis presents both an analytical and an experimental evaluation of the feasibility of using infrared thermographic techniques to detect subsurface damage in concrete. Various methods of artificial heating, required to effectively apply this technique, are presented. Four major conclusions are reached in this study. 1) Normal ambient diurnal atmospheric temperature changes are not generally sufficient to produce a measurable response in bridge substructures. 2) Heating by an infrared heat source is a technically viable artificial method provided some type of surface preparation is made to assure uniform emissivity. 3) Hot air heating is a viable technical alternative which does not require surface preparation prior to the application of heat. However, this method does require some type of enclosure to produce a hot air pocket. 4) Artificial heating methods based on heating blankets are not a feasible method due to local nonuniform heating effects.