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Putsfasader i kustmiljö - En undersökning av havsnära putsfasader i västra Skåne

Hasselqvist, Fredrik and Bråvall, Johan (2009) In Examensarbete (LTH Ingenjörshögskolan vid Campus Helsingborg)
Civil Engineering - Architecture (BSc)
Division of Building Materials
Abstract
Of rendered façades in coastal environment Rendered coastal-facing façades have been observed to be in worse condition than those facing away from the coastline in the same environment. This leads to the hypothesis that salt water accelerates the deterioration of render, either by salt blasting or through other forms of weathering processes. Since salt does not react with common render components, no form of chemical degradation is considered in this report. Compared to the rest of Sweden, the coastal area of western Scania is more exposed to driving rain. Thus, the rendered façades of that region are exposed not only to driving rain, but also concomitant spray from the sea caused by the wind of those rains. Render in its simplest form... (More)
Of rendered façades in coastal environment Rendered coastal-facing façades have been observed to be in worse condition than those facing away from the coastline in the same environment. This leads to the hypothesis that salt water accelerates the deterioration of render, either by salt blasting or through other forms of weathering processes. Since salt does not react with common render components, no form of chemical degradation is considered in this report. Compared to the rest of Sweden, the coastal area of western Scania is more exposed to driving rain. Thus, the rendered façades of that region are exposed not only to driving rain, but also concomitant spray from the sea caused by the wind of those rains. Render in its simplest form consists not only of ballast and water, but also limestone, cement, or a lime-cement mixture as a binder. In order to examine the accuracy of the salt water acceleration hypothesis, there are two separate requirements - first, the façades facing the sea need to be more worn than the façades facing away from the sea, and second, these façades need to be shown to contain salt. 10 year old buildings in a close-to-shore environment are examined with respect to, inter alia, type of render, distance to, and altitude above the sea. Damage to the façades have been documented through photographs, and descriptions of general observations were carried out. Within a time frame of 10 years, façades facing the sea displayed clear degradation, while the façades facing away from the sea lack visible degradation. Examples meeting the first requirement include Västra hamnen in Malmö and Norra hamnen in Helsingborg. However, while the first of the two requirements of the hypothesis is met, laboratory samples taken from properties in Norra hamnen of Helsingborg, demonstrate that salt is completely missing in the façades, which means that the second of the two requirements have negative results for the buildings covered in the study.
Though, all render samples had organic binders. Therefore the negative results could be due to the surfaces inability to absorb water. Clearly, coastal façades facing towards the sea in western Scania are more worn than opposing façades in the same environment. However, the cause of this is not investigated further in this report. Due to lab results, salt blasting may be excluded as a factor for the deterioration of the render on buildings in the neighbourhood Holger Danske in Norra hamnen of Helsingborg, where the sampling occurred. Further studies are suggested in order to obtain a more clear idea of the influence of salt water on rendered façades. To falsify the hypothesis, total absence of salt deposition needs to be demonstrated in rendered façades set facing the sea with favourable conditions for absorption. A thick lime render on thermal insulation is deemed to satisfy such conditions, as a result of its high ability to absorb water and sufficiently weak yield strength. Results should also be compared to a cement-lime-based render with high yield strength, and with a render without favourable conditions, such as a thin render which lacks absorption. (Less)
Abstract (Swedish)
Kustnära putsade fasader ställda mot havet har av rapportförfattarna observerats vara i sämre skick än fasader med riktning inåt landet i samma miljö. Detta leder till hypotesen att saltvatten påskyndar nedbrytningen av kalk/cementbruk genom saltsprängning eller annan form av vittringsprocess.
Ingen form av kemisk nedbrytning är rimlig då salt inte reagerar med putsens vanliga beståndsdelar.
Svenska västkusten, inklusive västra Skåne, är mer utsatt för slagregn än resten av landet. Ett sådant klimat innebär mycket vind, vilket även leder till mer vågor och stänk från havet. Byggnader nära kusten utsätts således av påfrestningar från dessa. Putsbruk består i sin enklaste form, förutom vatten och ballast, av kalk, cement, eller kalkcement... (More)
Kustnära putsade fasader ställda mot havet har av rapportförfattarna observerats vara i sämre skick än fasader med riktning inåt landet i samma miljö. Detta leder till hypotesen att saltvatten påskyndar nedbrytningen av kalk/cementbruk genom saltsprängning eller annan form av vittringsprocess.
Ingen form av kemisk nedbrytning är rimlig då salt inte reagerar med putsens vanliga beståndsdelar.
Svenska västkusten, inklusive västra Skåne, är mer utsatt för slagregn än resten av landet. Ett sådant klimat innebär mycket vind, vilket även leder till mer vågor och stänk från havet. Byggnader nära kusten utsätts således av påfrestningar från dessa. Putsbruk består i sin enklaste form, förutom vatten och ballast, av kalk, cement, eller kalkcement som bindemedel. I syfte att undersöka hypotesens riktighet ställs två separata krav. Dels måste fasader i riktning mot havet visas vara mer slitna än fasader ställda från havet, och dels måste fasaderna påvisas innehålla salt. Tio år gamla hus i aktuell miljö undersöks med avseende på bland annat avstånd till och höjd över havet samt putstyp. Skador på fasaderna har dessutom dokumenterats i form av fotografier och beskrivningar. Exempel på områden i vilka man inom tidsramen för 10 år kan observera tydlig nedbrytning på fasader med riktning mot havet, samtidigt som fasaderna ställda från havet saknar skador, är Västra hamnen i Malmö samt Norra hamnen i Helsingborg. Med andra ord uppfylls det första av de två kraven ställda i hypotesen. Laboratorieundersökning av prover tagna från fastigheter i Norra Hamnen i Helsingborg visar dock att salt helt saknas i fasaderna, vilket medför att det andra delkravet inte uppfylls för byggnaderna som omfattas av laboratorieundersökningen. Samtliga prover togs från fasader utförda med konstruktionen organisk tunnputs på cellplast. En sådan konstruktion har ej förmågan att suga upp vatten och saltavlagring är därmed mindre trolig.
Klart står alltså att kustnära fasader med riktning mot havet i västra Skåne är mer slitna än motstående fasader i samma omgivning. Vad detta beror på fastställs dock inte i denna rapport. Saltsprängning kan till följd av resultaten från laboratorieundersökningen uteslutas som faktor för byggnaderna i kvarteret Holger Danske i Norra Hamnen i Helsingborg där provtagning skett.
För att få en klarare uppfattning om saltvattnets inverkan på putsade fasader föreslås vidare mer storskaliga studier med mer tydligt avgränsade undersökningar. (Less)
Please use this url to cite or link to this publication:
author
Hasselqvist, Fredrik and Bråvall, Johan
supervisor
organization
year
type
M2 - Bachelor Degree
subject
keywords
Bo01, salt, putsfasader, nedbrytning, kustklimat, Norra hamnen Helsingborg
publication/series
Examensarbete (LTH Ingenjörshögskolan vid Campus Helsingborg)
report number
THID-09/5132
ISSN
1651-2197
language
Swedish
additional info
Detta examensarbete är utfört vid Avd. Byggnadsmaterial, Lunds tekniska högskola.
id
1464591
date added to LUP
2009-08-19 00:00:00
date last changed
2018-10-18 10:07:36
@misc{1464591,
  abstract     = {Of rendered façades in coastal environment Rendered coastal-facing façades have been observed to be in worse condition than those facing away from the coastline in the same environment. This leads to the hypothesis that salt water accelerates the deterioration of render, either by salt blasting or through other forms of weathering processes. Since salt does not react with common render components, no form of chemical degradation is considered in this report. Compared to the rest of Sweden, the coastal area of western Scania is more exposed to driving rain. Thus, the rendered façades of that region are exposed not only to driving rain, but also concomitant spray from the sea caused by the wind of those rains. Render in its simplest form consists not only of ballast and water, but also limestone, cement, or a lime-cement mixture as a binder. In order to examine the accuracy of the salt water acceleration hypothesis, there are two separate requirements - first, the façades facing the sea need to be more worn than the façades facing away from the sea, and second, these façades need to be shown to contain salt. 10 year old buildings in a close-to-shore environment are examined with respect to, inter alia, type of render, distance to, and altitude above the sea. Damage to the façades have been documented through photographs, and descriptions of general observations were carried out. Within a time frame of 10 years, façades facing the sea displayed clear degradation, while the façades facing away from the sea lack visible degradation. Examples meeting the first requirement include Västra hamnen in Malmö and Norra hamnen in Helsingborg. However, while the first of the two requirements of the hypothesis is met, laboratory samples taken from properties in Norra hamnen of Helsingborg, demonstrate that salt is completely missing in the façades, which means that the second of the two requirements have negative results for the buildings covered in the study.
Though, all render samples had organic binders. Therefore the negative results could be due to the surfaces inability to absorb water. Clearly, coastal façades facing towards the sea in western Scania are more worn than opposing façades in the same environment. However, the cause of this is not investigated further in this report. Due to lab results, salt blasting may be excluded as a factor for the deterioration of the render on buildings in the neighbourhood Holger Danske in Norra hamnen of Helsingborg, where the sampling occurred. Further studies are suggested in order to obtain a more clear idea of the influence of salt water on rendered façades. To falsify the hypothesis, total absence of salt deposition needs to be demonstrated in rendered façades set facing the sea with favourable conditions for absorption. A thick lime render on thermal insulation is deemed to satisfy such conditions, as a result of its high ability to absorb water and sufficiently weak yield strength. Results should also be compared to a cement-lime-based render with high yield strength, and with a render without favourable conditions, such as a thin render which lacks absorption.},
  author       = {Hasselqvist, Fredrik and Bråvall, Johan},
  issn         = {1651-2197},
  keyword      = {Bo01,salt,putsfasader,nedbrytning,kustklimat,Norra hamnen Helsingborg},
  language     = {swe},
  note         = {Student Paper},
  series       = {Examensarbete (LTH Ingenjörshögskolan vid Campus Helsingborg)},
  title        = {Putsfasader i kustmiljö - En undersökning av havsnära putsfasader i västra Skåne},
  year         = {2009},
}