Recent advances in the determination of ionic diffusion using migration test results

Title: Recent advances in the determination of ionic diffusion using migration test results
Author(s): E. Samson, J. Marchand, P. Henocq, P. Beauséjour
Paper category : conference
Book title: International RILEM Symposium on Concrete Modelling - ConMod '08
Editor(s): E. Schlangen and G. De Schutter
Print-ISBN: 978-2-35158-060-8
e-ISBN: 978-2-35158-076-9
Publisher: RILEM Publications SARL
Publication year: 2008
Pages: 65 - 78
Total Pages: 14
Nb references: 18
Language: English

Abstract: Since the introduction of ASTM C1202, the so-called “rapid chloride permeability test”, accelerated methods based on the application of an external electrical potential have been commonly used to evaluate ionic diffusion properties of saturated hydrated cement systems.
In some cases, these tests are integrated in a quality control program and results simply serve to assess the variability of a concrete from one production to another. In other cases, current data are analyzed to estimate the ionic diffusion coefficients of the material. Although the calculation method tends to vary from one laboratory to another, most approaches share a common feature. They all tend to be based on the assumption that ions move so quickly throughout the hydrated cement paste pore structure that chemical reactions can be neglected in the analysis. This hypothesis is quite convenient since it contributes to simplify considerably the analysis. In the present paper, a series of experimental test results clearly demonstrate the invalidity of this assumption, particularly in the cases of chloride ions. A new approach to analyze current data is then presented. This method allows taking into account the transport of all species and the influence of chemical reactions that may occur during the experiment. A series of numerical tests also emphasize the dominant role of the initial pore solution on the analysis.

Online publication: 2009-06-15
Publication type : full_text
Public price (Euros): 0.00

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