Research for the Detecting Method of Concrete Structure Internal Defects with Spherical Embedded Ultrasonic Transducer

As a nondestructive detecting method, ultrasonic detection has been widely adopted in concrete structure detections. This approach would not damage the structural integrity, and could fulfill most of the detecting requirements of various concrete structures. However, for mass concrete and complicated concrete structural elements, there are still many problems of detection to be solved, such as the operating position of detection could not be achieved easily for technicians, especially in some narrow spaces, or the volume of elements might be quite large so that the detecting distance is far beyond the effective detecting distance of traditional transducers. After researching the technical performances of traditional ultrasonic transducers and ultrasonic detecting method, a brand new type of ultrasonic transducer adopted spherical piezoelectric ceramic chips has been developed. The transducer could be embedded inside concrete structure, and motivate or receive ultrasonic signal in all directions pair with external or internal transducers. Testing with the embedded transducers would not be limited by on-site conditions or other enviorenmental conditions. The transducer could be used in realtime systems for monitoring or detecting internal compactness situation of concrete elements. The technical characteristics of spherical transducer have been verified by a series of experiments in laboratory. Moreover, the detecting method with spherical transducer has been proposed, which could be used in the inspection for mass concrete and complicated structural concrete elements. Meanwhile, the appropriate technical schemes for reactor containment of nuclear power plant have been designed and has already been applied in nuclear power plant.