Damage Evaluation of Concrete Test Specimens Related to Failure Analysis

Abstract

Mechanical degradation of concrete is studied on compact tension (CT) test specimens. The proposed concept for providing a description of the actual damage, and thus a description of the overall mechanical behavior of a test specimen, consists of three basic steps: acquiring knowledge of the mechanical behavior of the homogenized material, evaluating the actual pattern of damage, and adapting a numerical analysis of the specimen on the basis of the foregoing information. The paper shows how acoustic emission processing is adapted to the evaluation of the actual pattern of concrete damage. The damage is located by measuring the difference in the times of arrival of the acoustic emission signals, generated from a single damage mechanism and detected by an array of transducers surrounding the zone to be evaluated. The degree of damage is then estimated by performing a selective location according to signal amplitude, and three damage zones are distinguished: a microcracked area, a macrocracked area, and an area that may be regarded as an open crack.