Title:
Modeling Stress-Strain Behavior of Concrete Damaged by Alkali-Aggregate Reaction (AAR)
Author(s):
S. J. Pantazopoulou and M. D. A. Thomas
Publication:
Structural Journal
Volume:
96
Issue:
5
Appears on pages(s):
790-799
Keywords:
alkali-aggregate reaction; concrete; mechanical properties; stress-strain relationships
DOI:
10.14359/733
Date:
9/1/1999
Abstract:
It has been shown by field observation and laboratory testing that the mechanical properties of concrete, such as stiffness, strength, and deformation capacity, are adversely affected by expansion in the material microstructure. Expansion is the overall effect of cracking within the aggregate, at the aggregate-paste interface, and in the matrix, and therefore signifies damage that may have been caused either by stress effects or aggressive chemical activity. This paper pre-sents the development of a simple stress-strain model for concrete that has been damaged by alkali-aggregate reaction (AAR) prior to application of the mechanical load. The approach taken relates the residual stiffness of the material at any level of imposed deformation to the total amount of expansion damage resulting from AAR and from the subsequently applied mechanical load. In evaluating the influence of AAR damage on the initial stiffness and the shape (i.e., rate of softening) of the stress-strain response, the model considers the area-strain in the cross section of the principal compressive strut as the governing state variable. The model was validated using experi-mental data from mechanical tests conducted in the course of this study on a series of concrete specimens that had previously undergone various degrees of expansion due to AAR. The ability of the model to reproduce certain behavioral features of AAR-affected concrete, such as the restraining action of conditioning stress or reinforcement, is evaluated by correlation with published experiments.