Impact-Echo Strikes Home

by Randall W. Poston, (M.ASCE), Vice President; KCI Technologies, 8832 Rixlew Lane, Manassas, VA, 2210-3733,
Keith E. Kesner, (M.ASCE), Project Engineer; KCI Technologies, 8832 Rixlew Lane, Manassas, VA, 2210-3733,

Serial Information: Civil Engineering—ASCE, 1995, Vol. 65, Issue 6, Pg. 60-62

Document Type: Feature article


Diagnosing flaws without destroying the structure is the first step to cost-effective repairs. Impact-echo is one of the more successful nondestructive evaluation (NDE) methods that have been developed recently to probe the internal condition to structural concrete. In the impact-echo technique, a transient stress pulse is introduced into the test object by mechanical impact on the surface and monitored by a displacement transducer placed close to the point of impact. Speed of the wave measurement is a function of concrete density, aggregate type, moisture content and other factors, and is established in an area of known sound concrete before testing is done on unknown areas. In concrete plates such as slabs, the impact-echo response reflects the plate bottom or any internal cracks or flaws. Examples are given of tests done on a concrete slab, bridge, building balcony and other structures. A sidebar discusses tests being done with mobile equipment on concrete pipe.

Subject Headings: Concrete | Concrete structures | Concrete pipes | Concrete bridges | Wave measurement | Slabs | Plates

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