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Title: Impact of the associated cation on chloride binding of Portland cement paste

Well hydrated cement paste was exposed to MgCl{sub 2}, CaCl{sub 2} and NaCl solutions at 20 °C. The chloride binding isotherms for free chloride concentrations ranging up to 1.5 mol/l were determined experimentally. More chlorides were found to be bound when the associated cation was Mg{sup 2} {sup +} or Ca{sup 2} {sup +} compared to Na{sup +}. The chloride binding capacity of the paste appeared to be related to the pH of the exposure solution. In order to explain the cation dependency of the chloride binding a selection of samples was investigated in detail using experimental techniques such as TG, XRD and SEM–EDS to identify the phases binding the chlorides. The experimentally obtained data were compared with the calculations of a thermodynamic model, GEMS. It was concluded that the measured change in chloride binding depending on the cation was mainly governed by the pH of the exposure solution and thereby the binding capacity of the C-S-H.
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [3] ;  [4] ;  [1]
  1. Department of Structural Engineering, Norwegian University of Science and Technology (Norway)
  2. (Italy)
  3. Department of Engineering and Applied Sciences, University of Bergamo (Italy)
  4. SINTEF Building and Infrastructure, Trondheim (Norway)
Publication Date:
OSTI Identifier:
22475490
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cement and Concrete Research; Journal Volume: 68; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CALCIUM CHLORIDES; CAPACITY; CATIONS; COMPARATIVE EVALUATIONS; CONCENTRATION RATIO; ISOTHERMS; MAGNESIUM CHLORIDES; MAGNESIUM IONS; PH VALUE; PORTLAND CEMENT; SCANNING ELECTRON MICROSCOPY; SODIUM CHLORIDES; SODIUM IONS; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY