Las sales solubles en el deterioro de rocas monumentales. Revisión bibliográfica

Materiales de Construcción (Impact Factor: 0.96). 09/1994; 44(235). DOI: 10.3989/mc.1994.v44.i235.579
Source: DOAJ


This paper points out the importance of soluble salts in the deterioration/conservation of monumental stones. The most frequent salts in monuments as well as their sources are referred. A review of the damage caused by these salts and the developed mechanisms of deterioration is also included. Finally, the distinctive behaviour of each type of salt and their distribution on the walls of buildings is shown.Se resalta la importancia que las sales solubles tienen en el deterioro/conservación de las rocas monumentales. Se relacionan aquellas sales que con mayor frecuencia aparecen en los monumentos y la procedencia de las mismas. A su vez se lleva a cabo una revisión de los daños originados por dichas sales y de los mecanismos de alteración desarrollados. Finalmente, se indica el diferente comportamiento de cada tipo de sal y su distribución en las paredes de los edificios.

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    • "The deterioration caused by soluble salts is due to continuous hydration and drying cycles or changes in the relative humidity, leading to the appearance of dissolution and crystallization processes of the salts. The pressure exercised by the salts in the interior of the pores can cause their growing, leading to the decohesion of the altered material Taking into account the importance of this alteration agent, there are multiple bibliographical revisions are focused on this subject [1] [2] [3]. "
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    ABSTRACT: Soluble salts are considered a main cause of damage of porous building materials such as rocks, bricks or granites, which were commonly used in the building constructions of the architectural and archaeological heritage. Soluble salts are also responsible for various forms of deterioration such as sand disaggregation and superficial detachments. These problems can be solved by conservation technologies, which are aimed to decrease the salt concentration in rocks (desalination). The present study aimed to investigate the efficiency of electrokinetic techniques for desalination of two different kinds of rocks: granite and sandstone. These rocks were contaminated with NaCl solution, and samples with a thickness of 6 cm were used in the tests. This study compared the percentage of salt removal at different depths (efficacy) and the time needed to get the same percentage removal (effectiveness) achieved in both stones. From the results obtained, it was possible to find those inherent factors to each stone which could have an influence on the efficacy of the treatment. With this technique it was possible to reduce the salt concentration in the granite almost to 100%. However, in the sandstone samples the decreases were not equally high, mainly at the intermediate levels where slight enrichments were observed. The results indicate that although the used technique is efficient for salt removal regardless of the porosimetric distribution of the rock, the better interconnection between the pores in the granite samples (favored a faster desalination process).
    No preview · Article · Jun 2015 · Electrochimica Acta
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    • "A investigação na área da degradação de materiais pétreos utilizados em construções recentes e no património histórico, quando sujeitos à acção do nevoeiro salino, em ambiente costeiro ou em laboratório, registou um aumento significativo nas últimas duas décadas. A necessidade de compreensão dos mecanismos de cristalização do sal e seus efeitos na alterabilidade de diversos tipos de materiais de construção têm levado à publicação de diferentes trabalhos, referindo-se, como exemplo, trabalhos com rochas ornamentais em (Silva & Simão, 2009; Benavente et al., 2007; Silva et al., 2013) e rochas aplicadas em monumentos (Cardell et al., 2003; Winkler, 1997; Grossi & Esbert, 1994). A penetração das soluções salinas na rede de poros, fissuras e fracturas das rochas, a sua permanência à superfície e subsequente cristalização de sal envolve tensões que aumentam os espaços vazios conduzindo à desagregação destes materiais. "
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    ABSTRACT: Stone materials used in the construction of the Spanish Fortress of Bizerte (Tunisia), show a high degree of alteration. Samples of these rocks, calcarenites, were collected and treated with different consolidants. Then, they were subsequently subjected to salt spray test with ventilation, in order to test the effectiveness of the products under these conditions. The results obtained from the samples mass loss and macro and microscopic inspection made possible to compare the performances of the different consolidants. These studies allow to predict the behavior of these stony materials in the field and to decide the best application in the rocks present in monuments, optimizing solutions for conservation and restoration.
    Full-text · Article · Jan 2014 · Comunicações Geológicas
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    • "Salt crystallisation pressures inside the stone generate stress that may cause the stone to crumble (Winkler and Singer 1972; Grossi and Esbert 1994; Rodriguez-Navarro and Doehne 1999; Flatt 2002; Tsui et al. 2003; Coussy 2006). However, in natural conditions, salt crystallisation as sodium sulphate efflorescence is very common. "
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    ABSTRACT: This study assesses the changes on the surface of crystalline stones due to salt crystallisation. Efflorescence was forced to grow on the surface of granite and marbles through 60 cycles of salt crystallisation with sodium sulphate. Changes on surface roughness, gloss and colour were measured every 15 cycles and the specimens were examined with naked eye and SEM. Sodium sulphate produces damage which depends on mineral composition. Results show that granites experience a mechanical decay with an increase in roughness. Peaks of mica can be observed on the surface and cracks widen and grow deeper. Colour and gloss do not show any significant change, although gloss decreases with an increase in surface roughness. In marbles, the decay is mainly chemical. Surface roughness increases due to dissolution of the calcite. White marbles exhibit yellowing. Gloss decreases during the first cycles—as grain boundaries become more visible—but tends to regain almost its initial value as the number of cycles increases. In this case, gloss does not show any relation with surface roughness.
    Full-text · Article · Sep 2012 · Environmental Earth Sciences
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