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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 108
PROCEEDINGS OF THE FIFTEENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING
Edited by: J. Kruis, Y. Tsompanakis and B.H.V. Topping
Paper 151

Simulation of Chloride Extraction Tests on Concrete Specimens

J. Nemecek1 and Y. Xi2

1Department of Mechanics, Faculty of Civil Engineering, Czech Technical University in Prague, Czech Republic
2Department of Civil, Environmental and Architectural Engineering, University of Colorado, Boulder, United States of America

Full Bibliographic Reference for this paper
J. Nemecek, Y. Xi, "Simulation of Chloride Extraction Tests on Concrete Specimens", in J. Kruis, Y. Tsompanakis, B.H.V. Topping, (Editors), "Proceedings of the Fifteenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 151, 2015. doi:10.4203/ccp.108.151
Keywords: concrete, reinforcement, corrosion, chloride extraction, diffusion, electromigration.

Summary
This paper is focused on simulations of electromigration tests performed to extract chlorides from concrete samples. The paper shows experimental results and the efficiency of the short-term treatment of the samples in low voltage electric field. The method is applied to both accelerated penetration and extraction procedures. The situation is numerically treated as a diffusion-convection problem. An extended Nernst-Planck equation is introduced for which the finite difference method is applied. Using a combination of the difference schemes needs to be used in order to maintain numerical stability of the calculations. The situation is illustrated in the paper along with identification of the diffusion parameters for penetration and extraction. The physico-chemical process of chloride binding in the porous system is quantified in the paper. It is numerically treated using a simplified approach by introducing an apparent diffusion coefficient which is identified from an extraction test by least squares minimization. Its magnitude was found to be one half of the original diffusion coeficient showing a very high degree of binding. The simulation results agree relatively well with the experimental measurements meaning the short term tests can be effectively modeled using the simplified approach.

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