Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Moisture fixation in concrete treated with a water repellent agent
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
(English)In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873Article in journal (Other academic) Submitted
National Category
Building Technologies
Identifiers
URN: urn:nbn:se:kth:diva-6302OAI: oai:DiVA.org:kth-6302DiVA: diva2:10980
Note
QS 20120327Available from: 2006-10-25 Created: 2006-10-25 Last updated: 2012-03-27Bibliographically approved
In thesis
1. Impregnation of concrete structures: transportation and fixation of moisture in water repellent treated concrete
Open this publication in new window or tab >>Impregnation of concrete structures: transportation and fixation of moisture in water repellent treated concrete
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Water repellent agents, today mainly consisting of alkylalkoxysilanes, are often used on concrete to prolong the service life of the structure. This is accomplished by protecting the reinforcement bars from chlorides or by changing the moisture content inside. When the concrete is treated with a water repellent agent the properties of the surface layer turn from hydrophilic to hydrophobic and thereby water droplets are stopped from entering, still allowing water vapour to pass through. This property change can reduce chloride ingression and stop heavy rain from penetrating through the surface layer.

This thesis presents results concerning how the moisture transport and fixation in the surface layer of the concrete is affected by a water repellent treatment. It also presents an investigation in which the effective penetration depth and the factors that influence it are studied. The methods used covers uni-dimensional transport of moisture using the so called cup method, measurements on moisture fixation using climate boxes with saturated salt solutions, penetration depth by cracking samples and spraying water on them, and field tests in a harsh tunnel environment.

The moisture diffusion coefficient for a water repellent treated concrete is close to constant and not nearly as dependent on the relative humidity (RH) as for untreated concrete. Unlike untreated concrete, where capillary suction plays an important role for the moisture transport at high RH, the vapour transport is the dominant transport mechanism even at high RH for water repellent treated concrete.

The moisture fixation is affected by a water repellent treatment and the effect is clearest at high moisture levels. There is, however, a certain amount of moisture present in a concrete treated with a water repellent agent. It can also be seen that the main reason for this is that the capillary porosity is affected by the treatment to a relatively high degree while the gel porosity to a large extent remains unaffected.

The three most important factors for the penetration of any water repellent agent into concrete is time, porosity and degree of saturation. An empirical equation is derived that gives an idea on how much these factors affect the efficient penetration depth of the water repellent agent.

Measures prolonging the service life of a concrete structure will lead to savings of natural resources and thus both economical and environmental savings for the community. The aim with the PhD-project is to develop explanation models to the promising results that have been obtained from the empirical research during the last decade and by doing this also create a better knowledge about when and how to apply a water repellent agent in order to benefit as much as possible from the product. The results presented in this Lisenciate thesis will be used as input in these models in the planned second phase of this project.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. x, 38 p.
Series
Trita-BKN. Bulletin, ISSN 1103-4270 ; 84
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-4160 (URN)
Presentation
2006-10-13, Sal L1, KTH, Drottning Kristinas väg 30, Stockholm, 13:10
Opponent
Supervisors
Note
QC 20101117Available from: 2006-10-25 Created: 2006-10-25 Last updated: 2012-02-21Bibliographically approved

Open Access in DiVA

No full text

Authority records BETA

Silfwerbrand, Johan

Search in DiVA

By author/editor
Johansson, AndersJanz, MårtenSilfwerbrand, Johan
By organisation
Civil and Architectural Engineering
In the same journal
Materials and Structures
Building Technologies

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 75 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf