An effective stone desalination method for cultural heritage
| Autor: | Fort González, Rafael, Álvarez de Buergo, Mónica, Ergenç, D., Feijoo, J. |
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| Rok vydání: | 2019 |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | Historic building materials are usually loaded with soluble salts which can originate from different sources, including groundwater, sea spray, and road deicing. Some of these sources can be reduced; however, the salt formation cannot be completely eliminated once in the masonry when it penetrated inside the pore system. The cleaned masonry is subjected to salt successively. Therefore instead of quarantine the decay effect; more sustainable remedies should be concerned in other words preventive conservation should be found straightaway. Weathering related to salt crystallization frequently occurs in porous building materials. Moreover due to extreme climatic conditions this damage is anticipated to increase (Nijland et al. 2009). When salts crystallize on the material surface as efflorescence, they grounds only aesthetical harm. However, they generally crystallize inside the material as sub-florescence leading to high pressure, and consequently loss of material (Espinosa-Marzal and Scherer 2013). The exerted pressure on the pore walls, when salts crystallize, is directly related to the supersaturation of the pore water. Besides, the habit of salt crystals can affect the conservation of building stone (Espinosa-Marzal and Scherer 2013). For several decades, research has been done to understand the salt induced deterioration mechanism and to decrease its harmful effect (Rodriguez Navarro et al. 1999; Flatt et al. 2017). Recently crystallization modifiers have been investigated to mitigate the decay by direct application to building material and by favor of mortar (Gupta et al. 2012). Encouraging preliminary results were gathered from previous studies (Lubelli, 2006; Granneman et al. 2018). In this study, we present the desalination efficiency of aerial lime mortars with addition of potassium ferrocyanide modifier at different conditions. It was added (5% of binder), and the mixes were applied as joint mortar between sandstone cubes contaminated with NaCl. The desalination efficiency of the mortars was followed in dry and wet atmospheric conditions. The former was cured at laboratory and the latter was carried out by placing the sandstones bonded with mortar in contact with tap water in order to simulate the capillarity rise of groundwater and infiltration of rain water after a waterless period. Results showed that the modifier hindered movement of salts into the mortar during hardening. Therefore, compared to control samples, better mortar-sandstone adherence was observed. In both conditions, dry and wet, NaCl content was almost completely reduced. The dendritic form chloride salt crystallized mainly as efflorescence which enabled its removal easier. |
| Databáze: | OpenAIRE |
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