Numerical model of Ca(OH)2 transport in concrete due to electrical currents

Title: Numerical model of Ca(OH)2 transport in concrete due to electrical currents
Author(s): T. Koster, W.H.A. Peelen, J.A. Larbi, M.R. de Rooij, R.B. Polder
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: 299 - 306
Total Pages: 8
Nb references: 3
Language: English

Abstract: A mathematical model is being developed to describe a repair method in concrete, called cathodic protection (CP). The model is in principle also useful to describe electrodeposition in concrete, e.g. the process of re-precipitation of Ca(OH)2 invoked by an electrical current. In CP the current is sent from an external anode to the reinforcement inside the concrete. This model is implemented using the numerical software package Comsol Multiphysics. The model is based on the Nernst-Planck equations and the electroneutrality condition considering the ionic species Na+, OH-, and Ca2+ and the solid Ca(OH)2. The mathematical model makes it possible to predict the location where Ca(OH)2 precipitates when a certain current density is used. This could be of great use for controlled crack repair in concrete and for electrochemical re-alkalisation. This paper presents the qualitative behaviour of dissolution and reprecipitation of Ca(OH)2 in CP. It discusses model calculations and preliminary experimental results. Experiments for a more complete validation of the model are in process.

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