ACOUSTIC TOMOGRAPHY AND REFLECTION IMAGING FOR STRUCTURAL CONCRETE

THE RESEARCH INVOLVES ACOUSTIC TOMOGRAPHY AND REFLECTION IMAGING OF CONCRETE CONDITIONS USING STRESS WAVE ENERGY TO DETECT FLAWS SUCH AS VOID, HONEYCOMB, CRACKING, AND WEAK CONCRETE IN CONCRETE TEST WLL MODELS. A KEY ASPECT OF THE RESEARCH IS THE IMPLEMENTATION OF A RAPID SCANNING ULTRASONIC STRESS WAVE ENERGY SYSTEM THAT CAN BE USED TO GENERATE AND MEASURE COMPRESSION AND SHEAR WAVE ENERGY. ANOTHER COMPONENT OF THE RESEARCH INVOLVES THE ADAPTATION OF TOMOGRAPHIC VELOCITY AND REFLECTION/DIFFRACTION IMAGING METHODS FROM GEOPHYSICS FOR EVALUATION OF STRUCTURAL CONCRETE CONDITIONS INCLUDING BOTH FLAW DETECTION AND REINFORCEMENT LOCATION. THE IMAGES INDICATE BOTH ZONES OF LOW VELOCITY AND REFLECTORS/DIFFRACTORS THAT CORRESPOND TO ANOMALIES (FLAWS). THE USE OF MULTI-MODE COMPRESSION AND SHEAR WAVE ENERGY TO DETECT AND BETTER IMAGE ANOMALIES IS ANOTHER INNOVATION OF THIS RESEARCH. THE IMAGING RESULTS ARE OBTAINED FOR VARIOUS FLAW SIZES AND COMPARED AGAINST CONVENTIONAL NONDESTRUCTIVE TESTING METHODS SUCH AS ULTRASONIC PULSE VELOCITY AND IMPACT ECHO. SURFACE REFLECTION, VERTICAL SEISMIC PROFILING (ADJACENT SIDES), AND CROSSHOLE SEISMIC (OPPOSITE SIDES) ARE ALL INVESTIGATED FOR CURVED RAYPTH CONDITIONS WITH TOMOGRAPHIC AND REFLECTION FORWARD AND BACKSCATTER IMAGING ANALYSES.