WEATHERING. SALT MIGRATION AND DISINTEGRATION DUE TO SALTS. A HYPOTHESIS

SALTVITTRING. SALTVANDING OCH SALTNEDBRYTNING. EN HYPOTES

Conventional moisture physics does not satisfactorily explain disintegration of brickwork and concrete due to salts. When films of salt dry out, the edges (menisci) dry faster than the inner zone, causing salt to migrate towards the edges. For this to occur, salt concentration must be sufficiently high, moisture content differences and gradients must exist, quantity of salt in pore volume must not exceed a certain value otherwise conditions inside the pore may stabilise, the pore must not be completely filled by either salt or salt solution, and the material must be wettable in order that menisci which initiate salt transport may be formed. The salt formations at the edges are of very fine porous structure. Especially about the dew point, pronounced structural and therefore volumetric changes occur. A suggested secondary disintegration mechanism is adsorption of salt onto the damaged substrate, resulting in increased concentration and further disintegration. Salt structures on material surfaces may be ideal crystals, needle structures or other microporous structures formed in discontinuous processes, amorphous structures or combinations of these. Disintegration can be prevented by reducing pore volume, achieving stable moisture conditions in the pore system, achieving stable temperature conditions (to prevent fluctuations about dew point). (TRRL)

  • Availability:
  • Corporate Authors:

    Swedish Council for Building Research

    St Goergansgatan 66, Box 27063
    S-11230 Stockholm,   Sweden 
  • Authors:
    • Puehringer, J
  • Publication Date: 1983

Language

  • Swedish

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: 159 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00387205
  • Record Type: Publication
  • Source Agency: Swedish National Road and Transport Research Institute (VTI)
  • ISBN: 91-540-3892-8
  • Report/Paper Numbers: R22:83 Monograph
  • Files: ITRD, TRIS
  • Created Date: Aug 30 1984 12:00AM