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Comparison of chloride models: the importance of surface concentration



Title: Comparison of chloride models: the importance of surface concentration
Author(s): C. Andrade, F. Tavares, M. Castellote, I. Petre-Lazars, M.A. Climent, G. Vera
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: 16
Language: English


Abstract: Modelling of chloride penetration into concrete has been developed extensively during the last few years due to the need to predict evolution of existing structures and try to design more resistant elements. These models are based in assuming diffusion as the main mass transport mechanism, but they differ: a) in the boundary or initial conditions, b) in considering more than one penetration mechanism or c) in the “age factor” taken for the evolution of variables. As not calibration at long term has been possible yet, the suitability of the different models cannot be verified. A manner to overcome long term uncertainty is to compare the different models available in order to gain understanding, with the comparison of their predictions.
A comparison among different available models is given in present paper. The models selected are five numerical and three analytical including the standard “error function”. The exercise made consisted in having a profile at a certain age, to predict a second age profile that is experimentally known. The profiles predicted by the different models where compared by a method consisting in comparing the areas between real and predicted profile.
The results indicate that it is not the D value applied which makes the differences between the models, but the value of the Surface Concentration, Cs, assumed at the second age. If the Cs is well predicted by the model, the D value results of minor comparative importance. The risk of failure in the prediction is higher as higher is the difference between real and predicted Cs.

Keywords: chlorides, models


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: 10.1617/2351580028.015


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