Title:
Impact-Echo Studies of Interfacial Bond Quality in
Concrete: Part II - Effects of Bond Tensile Strength
Author(s):
Juinn-Ming Lin, Mary Sansalone, and Randall Poston
Publication:
Materials Journal
Volume:
93
Issue:
4
Appears on pages(s):
318-326
Keywords:
bond (concrete to concrete); bonding; concretes; impact tests;
nondestructive tests; stresses.
DOI:
10.14359/9817
Date:
7/1/1996
Abstract:
This paper and a companion paper summarize the results of a feasibility study in which the impact-echo method was used to determine interfacial bond quality in layered concrete structures, such as in bridge decks with overlays or at the interface between repair concrete and the concrete in the structure being repaired. In this context, bond quality involves both the tensile strength and the amount of unbonded fraction of area at an interface. This paper focuses on how bond tensile strength affects impact-echo results. Results obtained from numerical (finite element), experimental, and field studies are presented. The numerical studies were used to quantify the stresses in the waves generated by elastic impact to determine whether these waves could be used as a measure of bond tensile strength. Experi-mental and jield studies were performed to study impact-echo results obtained from a layered concrete plate with a variety of interface condi-tions varying from strongly-bonded to delaminated as well as conditions produced by removal of concrete by jackhammering and hydrodemolition. The pulloff test method was used to determine bond strengths in both the experimental and field studies. The results showed that the stresses gener-ated by short-duration (20 - 100 us), elastic impacts are much too small to serve as a measure of bond tensile strength.