An ultrasonic inspection system capable of detecting voids and corroded steel components embedded in prestressed concrete structures

An ultrasonic system has been developed which detect voids, voids in ducts, major cable breaks and severe corrosion damage. Transducers are employed that generate a broad range of frequencies. The system operates by investigating the changes that occur in the different frequency bands as the signal traverses through the concrete. The central hypothesis of the signal processing methodology is that different wavelengths will be reflected with different energies depending upon the size, geometry and acoustic impedance of the defect encountered. By partitioning the reflected signal into discrete frequency bands and by comparing the magnitudes of their energies, it is possible to derive information relating to the position, size and nature of the defect