International Concrete Abstracts Portal

Title: Detection and Quantification of Distributed Damage in Concrete Using Transient Stress Waves

Author(s): Keith Kesner, Mary J. Sansalone, and Randall W. Poston

Publication: Materials Journal

Volume: 101

Issue: 4

Appears on pages(s): 318-328

Keywords: alkali-silica reaction; concrete; stress; test

Date: 7/1/2004

Abstract:
The feasibility of using transient stress waves to detect and quantify cracking caused by distributed damage mechanisms, specifically alkali-silica reactivity (ASR) or delayed ettringite formation (DEF) was evaluated. Numerical studies were used to determine how distributed damage in concrete plates affects propagation of impact-generated stress waves. It was found that distributed damage produces significant and quantifiable changes in the waveforms and spectra obtained from impact-echo results. To verify the results obtained in the numerical simulations and to develop correlation between changes in impact-echo signals and the actual amount of damage, impact-echo tests were performed on a specially prepared plate specimen made from concrete modified to produce distributed cracking over time. The amount of damage in the plate was determined periodically using images obtained from samples removed from the plate and subjected to neutron radiography. A correlation between the amount of damage in the samples and changes in impact-echo signals was established. The correlation was verified in a field study in which impact-echo tests were carried out on and core samples taken from concrete box beams experiencing cracking caused by distributed damage mechanisms.