CHARACTERIZATION OF CONCRETE CONDITION USING ACOUSTIC TOMOGRAPHIC IMAGING

RESIDUAL LIFETIME EVALUATION OF EXISTING NUCLEAR FACILITIES REQUIRES DETAILED INFORMATION REGARDING CONDITION OF CONTAINMENT AND SUPPORT STRUCTURES. CURRENT NONDESTRUCTIVE METHODS FOR SUBSURFACE EVALUATION OF REINFORCED CONCRETE USE COMPLEX EQUIPMENT AND RELY HEAVILY ON INTERPRETATION BY THE OPERATOR. A RESEARCH EFFORT IS PROPOSED TO EXAMINE THE USE OF COMPUTERIZED TOMOGRAPHIC IMAGING FOR LOCATING SUBSURFACE FEATURES IN REINFORCED CONCRETE STRUCTURES. ACOUSTIC PULSE VELOCITY DATA WILL BE USED AS THE BASE INFORMATION FOR IMAGE RECONSTRUCTIONS. THE APPROACH WOULD PROVIDE A CROSS-SECTIONAL IMAGE OF THE MASS BEING INVESTIGATED, SHOWING THE VELOCITY DISTRIBUTION THROUGHOUT THE INTERIOR OF THE CONCRETE. THE IMAGE OF CONCRETE CONDITION CAN BE ANALYZED AND USED AS A BASIS FOR DETERMINING THE INTERNAL CONCRETE CONDITION AND THE NECESSITY OF REPAIRS. A NUMBER OF INTIAL PROBLEMS WILL BE ADDRESSED, PERTAINING TO DETERMINATION OF APPROPRIATE STRESS WAVE PARAMETERS AND OPTIMIZATION OF DATA GATHERING TECHNIQUES. A MASS CONCRETE SPECIMEN WILL BE CONSTRUCTED TO INCORPORATE FEATURES OF INTEREST, SUCH AS REINFORCING STEEL, DENSITY VARIATIONS, CRACKS, AND VOIDS. THE MAIN PORTION OF THE STUDY WILL CONCENTRATE OF DETERMINING THE ABILITY OF ACOUSTIC IMAGING TECHNIQUES TO IDENTIFY THE PRESENCE AND LOCATION OFSUCH FEATURES.