Comparative Study of Methods Used to Estimate Ionic Diffusion Coefficients Using Migration Tests

Ionic diffusion coefficients are estimated rapidly using electromigration tests. In this paper, electromigration tests are accurately simulated by numerically solving the Nernst–Planck (NP) equation (coupled with the electroneutrality condition (EN)) using the finite element method. Numerical simulations are validated against experimental data obtained elsewhere (E. Samson et al., 2003; H. Friedmann et al., 2004). It is shown that migration due to the non-linear electric potential completely overwhelms diffusion due to concentration gradients. The effects of different applied voltage differences and chloride source concentrations on estimations of chloride diffusion coefficients are explored. The authors show that: the pore fluid within concrete and mortar specimens generally differs from the curing solution, lowering the apparent diffusion coefficient, primarily due to interactions of chloride ions with other ions in the pore fluid, and that the variation of source chloride concentration strongly affects estimation of diffusion coefficients in non-steady-state tests; however, this effect vanishes under steady-state conditions. Most importantly, a comparison of diffusion coefficients obtained from sophisticated analyses (i.e., NP–EN) and a variety of commonly used simplifying methods to estimate chloride diffusion coefficients allows for identification of those methods and experimental conditions where both approaches give good estimates for chloride diffusion coefficients. Lastly, it is demonstrated why simultaneous use and monitoring of current density and fluxes are recommended for both the non-steady and steady-state migration tests.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00088846
• Supplemental Notes:
  • Abstract reprinted with permission from Elsevier
• Authors:
  • Narsilio, G A
  • Li, R
  • Pivonka, P
  • Smith, D W
• Publication Date: 2007-8

Language

• English

Media Info

• Media Type: Print
• Features: Appendices; Figures; References; Tables;
• Pagination: pp 1152-1163
• Serial:
  • Cement and Concrete Research
  • Volume: 37
  • Issue Number: 8
  • Publisher: Elsevier
  • ISSN: 0008-8846
  • Serial URL: http://www.sciencedirect.com/science/journal/00088846

Subject/Index Terms

• TRT Terms: Coefficients; Concrete construction; Corrosion; Durability; Durability tests; Reinforced concrete bridges; Structural deterioration and defects
• Uncontrolled Terms: Chloride ingress; Electromigration; Ionic diffusion
• Subject Areas: Highways; Materials; I32: Concrete;

Filing Info

• Accession Number: 01076968
• Record Type: Publication
• Files: TRIS
• Created Date: Sep 27 2007 7:07AM