Numerical modelling of chloride ingress into saturated concrete

Title: Numerical modelling of chloride ingress into saturated concrete
Author(s): T.Q. Nguyen, V. Baroghel-Bouny, P. Dangla, P. Belin
Paper category : conference
Book title: 2nd International RILEM Symposium on Advances in Concrete through Science and Engineering
Editor(s): J. Marchand, B. Bissonnette, R. Gagné, M. Jolin and F. Paradis
Print-ISBN: 2-35158-003-6
e-ISBN: 2351580028
Publisher: RILEM Publications SARL
Publication year: 2006
Nb references: 6
Language: English

Abstract: Chloride ions are an important deteriorating factor, which governs the durability of reinforced-concrete structures under marine environments or exposed to de-icing salts. It is then of crucial importance to describe chloride penetration into concrete through models based on fundamental physico-chemical relationships rather than on empirical formulas. A multi-species model based on the Nernst-Planck equation has thus been developed by using a volume finite method. The model makes it possible to simulate migration under electrical field or diffusion tests and to predict chloride penetration through saturated concrete. The determination of the effective chloride diffusion coefficient consists here in measuring the penetration depth by using a colorimetric method. The experimental results are analyzed by using the proposed numerical model. The effective diffusion coefficient thus determined allows to correctly reproduce the chloride penetration depth measured experimentally. The effect on the migration results of various parameters such as the pore solution composition or the experimental conditions is also discussed. Then, a new approach for the determination of chloride binding, based on non-steady state diffusion tests, is proposed. The binding isotherm is identified by numerical inverse method from a single experimental total chloride concentration profile obtained at a given exposure time and from Freundlich’s formula. In order to determine the initial pore solution compositions, the method of Taylor that describes the release of alkalis from cement and alkali sorption by the hydration products is used. Finally, with these parameters (effective chloride diffusion coefficient, binding isotherm, initial pore solution compositions), prediction of kinetics of chloride penetration or total chloride concentration profiles has been performed. The method is validated by comparing the numerical simulations to experimental results obtained on various types of concretes and conditions (diffusion test under non-steady state conditions and marine site).

Keywords: Chloride, durability, multi-species, predictive model, concrete

Online publication: 2006-08-02
Classification: 3.1 Theme 1: Numerical Models: from Microstructure to Transport Properties and Durability
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2351580028.037