Title:
Using Impact-Echo to Assess Tendon Ducts
Author(s):
Barbara J. Jaeger, Mary J. Sansalone, and Randall W. Poston
Publication:
Concrete International
Volume:
19
Issue:
2
Appears on pages(s):
42-46
Keywords:
cantilever beams; corrosion; grout; nondestructive tests; precast
concrete; repairs; sonic tests;
DOI:
Date:
2/1/1997
Abstract:
As part of an evaluation of a multispan, precast concrete segmental bridge, the nondestructive testing method of impact-echo was utilized to locate voids in grouted tendon ducts. Impact-echo is based on the use of transient stress (sound) waves. A short duration mechanical impact produced by tapping a small steel ball against a concrete surface generates low frequency stress waves that propagate into the structure and are reflected by flaws or external surfaces. A discussion of characteristic impact-echo responses is presented. The field study involved the use of a commercially available impact-echo system, and testing was carried out on all cantilever beams during a full site investigation.