The Ion Mobility of Deteriorating Salts in Masonry Materials of Different Moisture Content

  1. Prof. F. H. Wittmann
  1. Anja Buchwald and
  2. Christian Kaps

Published Online: 23 DEC 2005

DOI: 10.1002/3527606211.ch22

Materials for Buildings and Structures, Volume 6

Materials for Buildings and Structures, Volume 6

How to Cite

Buchwald, A. and Kaps, C. (2000) The Ion Mobility of Deteriorating Salts in Masonry Materials of Different Moisture Content, in Materials for Buildings and Structures, Volume 6 (ed F. H. Wittmann), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, FRG. doi: 10.1002/3527606211.ch22

Editor Information

  1. ETH Zürich, Institut für Baustoffe, Werkstoffchemie und Korrosion, ETH Hönggerberg, HIF E12, 8093 Zürich, Switzerland

Author Information

  1. Bauhaus-Universität Weimar, Professur Bauchemie, Germany

Publication History

  1. Published Online: 23 DEC 2005
  2. Published Print: 20 APR 2000

Book Series:

  1. EUROMAT 99

ISBN Information

Print ISBN: 9783527301256

Online ISBN: 9783527606214

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Keywords:

  • transport phenomena;
  • durability;
  • deteriorating salts;
  • masonry materials of different moisture content;
  • ion mobility of deteriorating salts

Summary

The existence and movement of water and damaging salts are at the origin of numerous types of decay observed in masonry. Salt migration can be subdivided at least into two processes based totally on different mechanisms. Ions of dissolved salts can be transported with the migrating water. The second transport mechanism is the ion diffusion driven by a concentration gradient. In practice this mechanism comes into play to remove dissolved ions from salt containing masonry by application of a compress. For the calculation of the duration of such a desalination process the knowledge about salt diffusion coefficient is necessary. The diffusion coefficient of the ion pair of Na+ and SO42− in fully saturated brick material were recently presented [1]. Nevertheless in reality the water saturation is much less than 100 %. Therefore diffusion measurements were carried out to determine the influence of the degree of water saturation on the observed diffusion coefficient of salt ions in brick and mortar material. Additionally to this the impedance spectroscopy were used as an independent method to measure the ion mobility and therefore the diffusion coefficient of these and other materials also.