Assesment of chloride binding isotherm
Title: Assesment of chloride binding isotherm
Author(s): V. Baroghel-Bouny, T.Q. Nguyen, P. Dangla, P. Belin
Paper category : conference
Book title: International RILEM Symposium on Concrete Modelling - ConMod '08
Editor(s): E. Schlangen and G. De Schutter
Publisher: RILEM Publications SARL
Publication year: 2008
Pages: 733 - 743
Total Pages: 11
Nb references: 36
Abstract: In this paper, two methods of assessment of chloride binding isotherms of cementitious materials in saturated and isothermal conditions are proposed.
One of the methods is based on numerical inverse analysis performed by means of a multispecies transport model. This model involves the species Cl-, OH-, Na+ and K+, and is based on the Nernst-Planck equation. In this case, Freundlich’s equation is used to describe globally the chloride binding isotherm.
In the second method, physical adsorption onto C-S-H and formation of Friedel’s salt by chemical reactions are addressed separately. The chemical reactions are assumed as instantaneous and independent of the chloride concentration. The chloride binding isotherm can thus be described by an analytical formula, which includes two components. The physical and the chemical components involve respectively the C-S-H content and the residual content of equivalent aluminates of the material, at the considered age. These contents are derived here from an analytical hydration model.
The numerical and analytical binding isotherms thus obtained, as well as experimental data, are compared together, for various cementitious materials. In addition, the influence of the choice of the binding isotherm on the chloride penetration prediction (e.g. the total chloride concentration profile) performed by means of a multi-species transport model in saturated and isothermal conditions is investigated.
Online publication: 2009-06-15
Publication type : full_text
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