Nondestructive Controlled Failure of Concrete based on Elastic-Wave Methods

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Controlled failure of concrete has been studied by applying the elastic-wave methods, which primarily include acoustic emission, impact echo and ultrasonic. Targeting existing concrete structures, nondestructive monitoring, failure mechanisms and damage evaluation have been clarified. Results achieved are summarized, as follows;1. Identification of failure mechanisms of concrete by acoustic emission (AE)AE techniques have been applied to failure process of a variety of cementitious materials. Thus, the failure mechanisms of concrete and concrete structures are clarified.2. Fracture monitoring of concrete structures by nondestructive evaluationMonitoring of cracks and defects has been nondestructively investigated. In particular, applications of the impact echo and ultrasonics are extensively studied. Visualization of internal defects by the SIBIE(Stack Imaging of spectral amplitudes Based on Impact Echo)procedure is practically performed3. Mechanisms of dynamic failure based on elastod … More ynamicsBlasting failure of fiber-reinforced concrete has been theoretically studied, and the effect of resonant vibration on failure modes is clarified. Thus, failure process of concrete can be monitored under impact loading, and dynamic fracturing due to pulse-discharge. The latter technique is substantially applied to fabrication of recycled aggregate.4. Application of fracture mechanics and damage mechanics to controlled failureWith the collaboration of international researchers, fracture mechanics and damage mechanics have been studied in cementitious materials. The SiGMA procedure has been developed for the moment tensor analysis of AE sources(cracks). Visualized presentation of crack location, crack type and crack orientation is now available. Cracking mechanisms at the meso-scale and the macro-scale are clarified by applying the boundary element method(BEM)analysis and AE analysis.5. Nondestructive monitoring for controlled failure in concreteMeasurement techniques based on the elastic-wave methods have been established for controlled failure. Depending on failure modes of concrete from statics to dynamics, proper measuring and analyzing techniques are developed. Less