The weathering and weatherability of Basílica da Estrela stones, Lisbon, Portugal
Published:January 01, 2007
C. A. M. Figueiredo, L. Aires-Barros, M. J. Basto, R. C. Graça, A. Maurício, 2007. "The weathering and weatherability of Basílica da Estrela stones, Lisbon, Portugal", Building Stone Decay: From Diagnosis to Conservation, R. Přikryl, B. J. Smith
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This paper presents a study of stone decay on the Basílica da Estrela, the most famous 18th century monument in the city of Lisbon, Portugal. It was built with Jurassic and Cretaceous limestones from the surroundings of Lisbon. Different approaches were used to establish the typology, causes and processes of the major weathering forms. Limestone samples from ancient quarries, salt efflorescences and disintegrated stone material from the interior of the church were characterized by chemical, mineralogical and petrographical analyses. Limestone physical properties related to fluid percolation were also determined. Detailed surveys of stone decay phenomena were carried out on the monument. Textures of grey-level images representative of the weathering forms were analysed by image analysis through covariance and granulometry operators. An HIDSPEC computational hydrogeochemical model, phase and graphical diagrams, and multivariate statistical analysis were used for water–rock interaction studies. Physical weathering forms prevail inside the church. The yellow Cretaceous limestone is the most deteriorated stone. This observation compares well with its intrinsic properties. The weathering is determined by the stone structures, such as stilolytes and fossils, and architectural features (geometry and surface finish). Soluble salts such as trona and thenardite were only found in a very small area inside the church.
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Building Stone Decay: From Diagnosis to Conservation
Stone buildings and monuments from the cultural centres of many of the world's urban areas. Frequently these areas are prone to high levels of atmospheric pollution that promote a variety of aggressive stone decay processes. Because of this, stone decay is now widely recognized as a severe threat to much of our cultural heritage. If this threat is to be successfully addressed it is essential that the symptoms of decay are clearly identified, that appropriate stone properties are accurately characterized and that decay processes are precisely identified. It is undoubtedly the case that successful conservation has to be underpinned by a comprehensive understanding of the causes of decay and the factors that control them. The accomplishment of these demanding goals requires an interdisciplinary approach based on co-operation between geologists, environmental scientists, chemists, material scientists, civil engineers, restorers and architects. In pursuit of this collaboration, this volume aims to strengthen the knowledge base dealing with the causes, consequences, prevention and solution of stone decay problems.