Impact Echo & Impact Echo Scanning

To determine the condition and thickness of concrete, wood, stone, and masonry structural members when voids, honeycomb, and/or cracks are suspected, ACER can before an investigation using Impact Echo (IE) technology. IE investigations can also be performed to predict the strength of early age concrete if the member thickness is known. Lastly, the IE method will provide information on the depth of a flaw or defect, in addition to mapping its lateral location and extent.

In typical Impact Echo investigations, the hammer or impactor is used to generate compressional waves that reflect back from the bottom of the tested member or from a discontinuity. The response of the system is then measured by the receiver placed next to the impact point. Only one relatively smooth and clean surface needs to be accessible for receiver placement and hammer or solenoid impact.

The Impact Echo Scanning (IES) system is designed for large area investigations of shallow voids, debonding/delamination, cracking or honeycomb often found between an overlay on a bridge deck or surrounding dense rebar mats. Performed at slow walking speeds, test results are obtained every inch (25 mm) in a line and multiple lines can be combined for 2-D to 3-D displays of concrete thickness and locations of internal void, honeycomb, cracking, delamination, etc. The scanning method is capable of determining bottom echo thicknesses up to ~ 40 inches (1 m). IES is commonly used in locating post-tensioning (PT) cables used in reinforcing various structures and determining duct grout condition. The scanning technology allows tracing of the PT cables through slabs and beams. An advantage of the IES method is that only one side of the structure needs to be accessible for testing.