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<bibimport/>
Author:[[user:Hschwarz|Hans-Jürgen Schwarz]]  
authors:[[user:Hschwarz|Hans-Jürgen Schwarz]]  
<br>
<br> <br>  
English Translation by [[user:SLeithaeuser|Sandra Leithäuser]]<br><br>  
Back to [[Fundamentals]] <br>  
Back to [[Fundamentals]] <br>
 
*[[Salts in building substrate and subsoils]] 
*[[Road salts - deicing salt]]
*[[Salts of microbiological origin]] 
*[[Salts Resulting from Restoration Materials]]
 


== Abstract  ==
== Abstract  ==
Salts that cause damages on wall paintings and cultural heritage made of stone, brick or other material originate from the natural alteration circle (chemical, physical and biological alteration of stones, soil formation, rain and ground water) or human activities (emmissions, stock breeding, industrial production, road salt or the pressing of cement). The salts are formed by fortification of ions in the wall or the surface of building parts by leaching out stone, soil, building materials, wet or dry deposition from atmosphere, from the biological metabolism and anthropogenic intervention.
The salts that cause damage to buildings, including wall paintings, and monuments made of stone, brick and other inorganic building materials, can originate from both natural sources or human activities. Natural sources are, for example, salts present in the ground on which the building stands. But they can also be present in the material itself, for example brick or some cements, depending on their manufacture; in stones near flood plains or from the natural stone weathering cycle. They can be brought in by sea spray and wind, for buildings in coastal areas and some microorganisms growing on building materials may generate some. Salts originating from human activities can be linked to emissions from burning fossil fuels, agricultural activities, automotive combustion engines and the use of deicing salts. Historic buildings may also have been used to store salt or gun powder, or even as stables  Over the years, salts will accumulate within or near the surface of the building as water evaporates. Since what migrates within the stone are the ions of the various salts present when water enters the porous system, the accumulation of ions upon water evaporation may result in the formation of different combinations of them,i.e., different salts to the ones entered the material originally.  


== Introduction  ==
== Introduction  ==
Every naturally found water can be seen as a more or less diluted salt solution. This can be secured  by simple measurements of electrical conductivity. Porous building stones, mortars and plasters contain salts in their pore space. Everywhere water flows through porous materials and evaporates on a surface you can find more or less salt efflorescence.<br>
Every natural liquid water can be considered a more or less diluted salt solutions as confirmed by simple electrical conductivity measurements. When water enters porous building materials, such as stone, brick, mortar or plaster, salts will also enter their pore space. As water evaporates at the suface of these materials, salts will accumulate near that area and eventually, some salt efflorescence will result.<br>
Some salts or salt building ions are brought to the monument by humans. These can be alkaline building materials like water glass or portland cement that were used in great quantities in the last century or [[road salt]] in wintertime. Some of the damages that were refered to as a result of acid rain are now known as the result of these building materials. <bib id="Klemm.etal:1999" /> [[Road salt]] is also one of the materials that can be detected on bridges and baseplates, some buildings were even used as salt storages. Every natural material contains a certain amount of salt building ions that can be marginal, but also very high. These can be [[Salts in building materials|building materials]] like natural stone and bricks, adhesives like lime or cement, the building area with its different kinds of soil and the ground- and surface water <bib id="Roesch.etal:1993" />, but also the different coatings and paints on the surface.  
 
Beside natural imissions by volcanoes (H<sub>2</sub>S, HCl, HF, SO<sub>2</sub> etc.), particulate material from sea (NaCl etc.)<bib id=Steiger.etal:1994b/><bib id=Steiger.etal:1997/><bib id=Steiger.etal:2002/><bib id=Becker.etal:2005/>, anthropogenic immissions become more and more important. The extraction of resources, generation of energy, traffic and much more produce a great number of damaging salts. The most  familiar substances are sulphur dioxide (with the secondary product sulphate)<bib id=Wittenburg.etal:1993/>  and nitrogen oxides (with the secondary product nitrate). It is still quite unknown, how ozone (O<sub>3</sub>) and the large number of organic compounds participate in the destruction of cultural goods. Immissions mostly reach the objects by dry or wet deposition <bib id=Steiger.etal:1989/> by rainwater or fog, but also by fortification on the building site.
Some salts are introduced into the buildings or monuments by human activity. These may result from the use of [[Salts in restoration materials|consolidants and/or cleaning agents]] such as alkaline materials, such as water glass [[Salts in building materials|building materials]]; some Portland cement in mortars, as well as historical use of the buildings for storage of salt or gun powder, or as stables. Some damages previously attributed to air pollution are now known to be due to the use of these materials <bib id="Klemm.etal:1999" />. [[Road salts - deicing salt| Deicing salts]] should be added to the list of these materials, especially since they are still in use mostly for roads, bridges and tunnels, affecting these structures and the foundations of buildings near them. Other sources for damaging salts can be fertilizers and some detergents that are introduced through ground and surface water. Finally, cleaning interventions based on the use of alkaline materials followed by an acid rinse, can leave soluble salts behind. This cleaning approach is mostly used for brick masonry in some countries, although there are records of their application on stone facades.  
 
Many building materials are contaminated with salt-forming ions, varying from low to high concentrations. These can include natural stone or man-made ones, such as brick, lime, cement and mortars. The [[Building substrate and subsoils| soil substrate and subsoil consistency]], as well as the ground- and surface water contribute to this contamination  <bib id="Roesch.etal:1993" />. So do natural emissions by volcanoes ((H<sub>2</sub>S, HCl, HF, SO<sub>2</sub> etc.) and sea- water aerosols (mostly NaCl but other salts as well), <bib id="Steiger.etal:1994b"/><bib id="Steiger.etal:1997"/><bib id="Steiger.etal:2002"/><bib id="Becker.etal:2005"/>, but anthropogenic activities are becoming the most important contributors to salt contamination.  


Nitrates and organic salts like oxalates mostly have a [[Microbiological provenance of salts|microbiological provenance]]. While nitrates are transported into the object by humidity, oxalates are originated on the spot and stay there due to their low solubility.  
Among these are the industrial and traffic emissions, which produce a great number of aggressive substances, such as sulfur dioxide (at the origin of sulfates) <bib id="Wittenburg.etal:1993"/> and nitrogen oxides (originating nitrates), are the most common ones. It is still not fully understood, how ozone (O3) and the large number of organic compounds released participate in the deteroration mechanism of building materials. [[Immissions]] mostly reach the objects through dry or wet deposition <bib id="Steiger.etal:1989"/>  by rainwater or fog, but also through accumulation in the subsoil.


Other sources for damaging  salts can be fertilisers or detergents  that are introduced by ground and surface water.
Nitrates and organic salts such as oxalates mostly are of [[microbiological origin]]. While nitrates are transported into the object by humidity, calcium oxalates are usually formed in situ by microorganisms, where they remain due to their low solubility.


== Literature ==
== Literature ==
<bibprint />
<biblist/>


[[Category:Origin of Salt]] [[Category:InProgress]]
[[Category:Origin of Salt]] [[Category:approved]][[category: Schwarz,Hans-Jürgen]]

Latest revision as of 14:57, 17 November 2022

Author:Hans-Jürgen Schwarz
English Translation by Sandra Leithäuser

Back to Fundamentals


Abstract[edit]

The salts that cause damage to buildings, including wall paintings, and monuments made of stone, brick and other inorganic building materials, can originate from both natural sources or human activities. Natural sources are, for example, salts present in the ground on which the building stands. But they can also be present in the material itself, for example brick or some cements, depending on their manufacture; in stones near flood plains or from the natural stone weathering cycle. They can be brought in by sea spray and wind, for buildings in coastal areas and some microorganisms growing on building materials may generate some. Salts originating from human activities can be linked to emissions from burning fossil fuels, agricultural activities, automotive combustion engines and the use of deicing salts. Historic buildings may also have been used to store salt or gun powder, or even as stables Over the years, salts will accumulate within or near the surface of the building as water evaporates. Since what migrates within the stone are the ions of the various salts present when water enters the porous system, the accumulation of ions upon water evaporation may result in the formation of different combinations of them,i.e., different salts to the ones entered the material originally.

Introduction[edit]

Every natural liquid water can be considered a more or less diluted salt solutions as confirmed by simple electrical conductivity measurements. When water enters porous building materials, such as stone, brick, mortar or plaster, salts will also enter their pore space. As water evaporates at the suface of these materials, salts will accumulate near that area and eventually, some salt efflorescence will result.

Some salts are introduced into the buildings or monuments by human activity. These may result from the use of consolidants and/or cleaning agents such as alkaline materials, such as water glass building materials; some Portland cement in mortars, as well as historical use of the buildings for storage of salt or gun powder, or as stables. Some damages previously attributed to air pollution are now known to be due to the use of these materials [Klemm.etal:1999]Title: Schwefelisotopenanalyse von bauschädlichen Sulfatsalzen an historischen Bauwerken
Author: Klemm, Werner; Siedel, Heiner
Link to Google Scholar
. Deicing salts should be added to the list of these materials, especially since they are still in use mostly for roads, bridges and tunnels, affecting these structures and the foundations of buildings near them. Other sources for damaging salts can be fertilizers and some detergents that are introduced through ground and surface water. Finally, cleaning interventions based on the use of alkaline materials followed by an acid rinse, can leave soluble salts behind. This cleaning approach is mostly used for brick masonry in some countries, although there are records of their application on stone facades.

Many building materials are contaminated with salt-forming ions, varying from low to high concentrations. These can include natural stone or man-made ones, such as brick, lime, cement and mortars. The soil substrate and subsoil consistency, as well as the ground- and surface water contribute to this contamination [Roesch.etal:1993]Title: Damage to Frescoes caused by sulphate-bearing salts: Where does the salt come from?
Author: Rösch, Heinrich; Schwarz, Hans-Jürgen
Link to Google Scholar
. So do natural emissions by volcanoes ((H2S, HCl, HF, SO2 etc.) and sea- water aerosols (mostly NaCl but other salts as well), [Steiger.etal:1994b]Title: Determination of wet and dry depostion of atmospheric pollutants on building stones by field exposure experiments
Author: Steiger, Michael; Dannecker, Walter
Link to Google Scholar
[Steiger.etal:1997]Title: Sea Salt in Historic Buildings: Deposition, Transport and Accumulation
Author: Steiger, Michael; Behlen, Andreas; Neumann, Hans-Herrmann; Willers, U.; Wittenburg, Christian
Link to Google Scholar
[Steiger.etal:2002]Title: Immissionsbelastung durch salzbildende Stoffe und Wirkung auf mineralische Baustoffe
Author: Steiger, Michael; Behlen, Andreas; Wiese, Utz
Link to Google Scholar
[Becker.etal:2005]Title: Luftschadstoffe und Natursteinschäden
Author: Becker, Karl-Heinz; Brüggerhoff, Stefan; Steiger, Michael; Warscheid, Thomas
Link to Google Scholar
, but anthropogenic activities are becoming the most important contributors to salt contamination.

Among these are the industrial and traffic emissions, which produce a great number of aggressive substances, such as sulfur dioxide (at the origin of sulfates) [Wittenburg.etal:1993]Title: Ein Vergleich von Schwefeldioxid-Depositionsgeschwindigkeiten auf Naturwerksteine aus verschiedenen experimentellen Ansätzen (Comparison of sulfur dioxide deposition velocities on building stones from different experiments)
Author: Wittenburg, Christian; Mangels, Henning; Wolf, Falk; Steiger, Michael; Bothmann, Thomas; Dannecker, Walter
Link to Google Scholar
and nitrogen oxides (originating nitrates), are the most common ones. It is still not fully understood, how ozone (O3) and the large number of organic compounds released participate in the deteroration mechanism of building materials. Immissions mostly reach the objects through dry or wet deposition [Steiger.etal:1989]Title: Variability of aerosol size distributions above the North Sea and its implication to dry deposition estimates
Author: Steiger, Michael; Schulz, Michael; Schwikowski, Margit; Naumann, K.; Dannecker, Walter
Link to Google Scholar
by rainwater or fog, but also through accumulation in the subsoil.

Nitrates and organic salts such as oxalates mostly are of microbiological origin. While nitrates are transported into the object by humidity, calcium oxalates are usually formed in situ by microorganisms, where they remain due to their low solubility.

Literature[edit]

[Becker.etal:2005]Becker, Karl-Heinz; Brüggerhoff, Stefan; Steiger, Michael; Warscheid, Thomas (2005): Luftschadstoffe und Natursteinschäden. In: Siegesmund, Siegfried; Auras, Michael; Snethlage, Rolf (eds.): STEIN. Zerfall und Konservierung, Edition Leipzig, 35-45.Link to Google Scholar
[Klemm.etal:1999] Klemm, Werner; Siedel, Heiner (1999): Schwefelisotopenanalyse von bauschädlichen Sulfatsalzen an historischen Bauwerken, Wiss. Mitt. Inst. Geol. TU Bergakademie FreibergLink to Google Scholar
[Roesch.etal:1993]Rösch, Heinrich; Schwarz, Hans-Jürgen (1993): Damage to Frescoes caused by sulphate-bearing salts: Where does the salt come from?. In: Studies in Conservation, 38 (4), 224-230, UrlLink to Google ScholarFulltext link
[Steiger.etal:1989]Steiger, Michael; Schulz, Michael; Schwikowski, Margit; Naumann, K.; Dannecker, Walter (1989): Variability of aerosol size distributions above the North Sea and its implication to dry deposition estimates. In: Journal of Aerosol Science, 20 (8), 1229-1232Link to Google Scholar
[Steiger.etal:1994b]Steiger, Michael; Dannecker, Walter (1994): Determination of wet and dry depostion of atmospheric pollutants on building stones by field exposure experiments. In: Zezza, Fulvio; Ott, Heinrich; Fassina, Vasco (eds.): The conservation of monuments in the Mediterranean Bassin: Stone and Monuments: Methodologies for the Analyses of Weathering and Conservation, , proceedings of the 3rd international symposium, Venice, 22-25 June 1994, , 171-178.Link to Google Scholar
[Steiger.etal:1997]Steiger, Michael; Behlen, Andreas; Neumann, Hans-Herrmann; Willers, U.; Wittenburg, Christian (1997): Sea Salt in Historic Buildings: Deposition, Transport and Accumulation. In: Moropoulou, A.; Zezza, F.; Kollias, E.; Papachristodoulou, I. (eds.): 4th International Symposium on the Conservation of Monuments in the Mediterranean - Proceedings, , 325-335.Link to Google Scholar
[Steiger.etal:2002]Steiger, Michael; Behlen, Andreas; Wiese, Utz (2002): Immissionsbelastung durch salzbildende Stoffe und Wirkung auf mineralische Baustoffe. In: Institut für Steinkonservierung Mainz (eds.): Salze im historischen Mauerwerk, IFS, Mainz, 1-10.Link to Google ScholarFulltext link
[Wittenburg.etal:1993]Wittenburg, Christian; Mangels, Henning; Wolf, Falk; Steiger, Michael; Bothmann, Thomas; Dannecker, Walter (1993): Ein Vergleich von Schwefeldioxid-Depositionsgeschwindigkeiten auf Naturwerksteine aus verschiedenen experimentellen Ansätzen (Comparison of sulfur dioxide deposition velocities on building stones from different experiments). In:: VDI-Berichte 1060 (Materialien in ihrer Umwelt), , 383-392.Link to Google Scholar