The Impact Echo (IE) method is used for rapid flaw detection and thickness evaluation of concrete and masonry structural materials. The method is normally applied to plate-like objects such as slabs and walls, but is also used on columns, mat foundations, and beams. The method requires access to only one side for testing, and can measure not only flaw location, but also depth. This method is used extensively for slab thickness profiling without the need to drill, core or excavate.

A variation of the impact echo principle for use on large areas and for high resolution imaging is the Impact Echo Scanning (IES) method. The IES method is based on the Olson Engineering patented technology of a rolling transducer and automated impactor for near-continuous Impact Echo based thickness and flaw scanning of structural concrete and pavements.

Literally thousands of tests can be performed per hour when "imaging" of internal concrete conditions is required. Examples of applications include slab thickness profiling and flaw detection, pavement testing, and for the location of ungrouted sections of post-tensioning ducts in bridge structures. A paper on IES as applied to PT duct void location is available here.