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15. An integrated model to predict the relations between electrical double layer properties and chloride ingress in cement-based materials



Title: 15. An integrated model to predict the relations between electrical double layer properties and chloride ingress in cement-based materials
Author(s): Y. Elakneswaran, T. Nawa, K. Kurumisawa
Paper category : conference
Book title: NUCPERF 2009 - Long Term Performance of Cementitious Barriers and Reinforced Concrete in Nuclear Power Plants and Waste Management
Editor(s): V. L'Hostis, R. Gens, C. Gallé
Print-ISBN: 978-2-35158-072-1
e-ISBN: 978-2-35158-087-5
Publisher: RILEM Publications SARL
Publication year: 2009
Pages: 135 - 142
Total Pages: 8
Nb references: 14
Language: English


Abstract: The mechanisms of the transport of species into the cementitious material have lately received a great deal of attention in durability problems. Hydrated cement acquires an electrical charge when it contacts with polar medium and leads to formation of Electric Double Layer (EDL). In this study, the significant influence of EDL properties on ionic transport through cement-based materials was investigated. Hardened cement paste shows net positive surface charge due to ionization of surface sites and adsorption ions from pore solution. EDL properties such as surface charge significantly influence not just on ionic adsorption but also on ionic diffusion. An integrated modelling approach employing phase - equilibrium model, surface complexation model, and multicomponent diffusion model was developed using PHREEQC to simulate the ionic ingress through cement-based materials. A comparison of predicted and experimental chloride profile is presented for hydrated cement paste. The surface charge influence is much higher on ionic transport in gel pore as compared in other pores. Chloride is being held in chemical combination as Friedel`s salt and also bound mainly by adsorptive action of cement hydrates. Finally, an influence of pozzolanic materials on chloride binding (chemical as well as physical) and diffusion is discussed.


Online publication: 2009-11-16
Publication type : full_text
Public price (Euros): 0.00