Earticle

Materials such as concrete, rocks, and masonry are often used for structures and their quality is usually verified by compression strength tests on core specimen. However, their quality is not uniform for the entire structure and local defects such as cracks, delamination, voids, honeycombing cannot easily be detected in compression tests on core specimen. In this case, impact-echo method can be used to determine the location and size of defects of materials of structures on site. It is simple enough for on-site tests and yet has relatively good accuracy. It can also be used to measure the thickness of concrete or rocks. This study provides a brief description of the method, test equipment, and two case studies describing its applicability. One of its applicability is to estimate the integrity of large rocks on site and the other applicability is to determine the location of the defect of a sheath grouting of a prestressed-concrete girder bridge.