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Title: The impact of sulphate and magnesium on chloride binding in Portland cement paste

The effect of magnesium and sulphate present in sea water on chloride binding in Portland cement paste was investigated. Ground well hydrated cement paste was exposed to MgCl{sub 2}, NaCl, NaCl + MgCl{sub 2}, MgSO{sub 4} + MgCl{sub 2} and artificial sea water solutions with a range of concentrations at 20 °C. Chloride binding isotherms are determined and pH of the solutions were measured. A selection of samples was examined by SEM-EDS to identify phase changes upon exposure. The experimental data were compared with calculations of a thermodynamic model. Chloride binding from sea water was similar to chloride binding for NaCl solutions. The magnesium content in the sea water lead to a slight decrease in pH, but this did not result in a notable increase in chloride binding. The sulphate present in sea water reduces both chloride binding in C–S–H and AFm phases, as the C–S–H incorporates more sulphates instead of chlorides, and part of the AFm phases converts to ettringite.
Authors:
 [1] ;  [2] ;  [3] ;  [1]
  1. Department of Structural Engineering, Norwegian University of science and Technology, Trondheim (Norway)
  2. (Norway)
  3. Department of Civil Engineering, Technical University of Brno, Brno (Czech Republic)
Publication Date:
OSTI Identifier:
22395926
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cement and Concrete Research; Journal Volume: 65; 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:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; ISOTHERMS; MAGNESIUM; MAGNESIUM CHLORIDES; MAGNESIUM SULFATES; PORTLAND CEMENT; SCANNING ELECTRON MICROSCOPY; SEAWATER; SODIUM CHLORIDES; SOLUTIONS; THERMODYNAMIC MODEL