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The study of external renderings in the scope of conservation and restoration has acquired in the last years great methodological, scientific and technical advances. These renderings are important elements of the built structure, for besides possessing a protection function, they possess often a decorative function of great relevance for the image of the monument. The maintenance of these renderings implies the conservation of traditional constructive techniques and the use of compatible materials, as similar to the originals as possible. The main objective of this study is to define a methodology of conservative restoration using strategies of maintenance of renderings and traditional constructive techniques. The minimum intervention principle is maintained as well as the use of materials compatible with the original ones. This paper describes the technique and products used for the consolidation of the loss of cohesion. The testing campaign was developed under controlled conditions, in laboratory, and in situ in order to evaluate their efficacy for the consolidation of old renders. A set of tests is presented to evaluate the effectiveness of the process. The results are analysed and a reflection is added referring to the applicability of these techniques. Finally the paper presents a proposal for further research. KeywordsLime mortars; techniques of restoration; consolidation; lime water. ResumoO estudo dos revestimentos exteriores tem vindo a adquirir, nos últimos anos, avanços metodológicos, científicos e técnicos. Estes revestimentos são elementos importantes da estrutura edificada, pois para além de terem uma função protectora apresentam também muitas vezes uma função decorativa relevante para a imagem do edifício. A manutenção destes revestimentos implica a conservação das técnicas construtivas tradicionais e o uso de materiais de restauro compatíveis e o mais similar possível ao original. Uma das principais formas de degradação é a perda de coesão, que consiste na perda da resistência mecânica das camadas de reboco devido à perda ou à alteração da ligação entre partículas, provocando diversas anomalias, tais como: desagregação e pulverulência. Estas anomalias não podem ser reparadas com as técnicas actuais da construção, que prevêem a sua substituição por novos revestimentos, perdendo-se a história dos materiais e da tecnologia da construção. O principal objectivo deste estudo é definir uma metodologia de restauro conservativa, usando estratégias de manutenção dos revestimentos e das técnicas construtivas tradicionais, onde haja uma intervenção mínima, utilizando materiais compatíveis com os originais. Escolheu-se a técnica de consolidação como método para a preservação destes revestimentos. Neste artigo descreve-se a técnica e os produtos utilizados para a consolidação da falta de coesão, apresenta-se um conjunto de ensaios para avaliar a respectiva eficácia, analisam-se os resultados obtidos e em conclusão faz-se uma reflexão sobre a aplicabilidade destas técnicas. Mediante os resultados obtido...

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Many historical buildings with renders based in air lime still exist in Portugal. These old mortars have proved to be durable and reliable materials. However, new lime mortars prepared nowadays to be used in conservation practice, often present low strength in comparison with cement mortars. This paper presents a study of the viability of improving the performance of lime mortars through the use of different nature aggregates (Tagus River siliceous sand and crushed calcareous sand) as well as different size distributions, varying the filler contents. For that purpose a set of mortars with volumetric proportion of 1:3 (lime:aggregate), using siliceous sand from Tagus river or calcareous sand and including different volume percentages of aggregate replacement by filler (0% of incorporation, 5% of incorporation, 10% of incorporation), were prepared. An evaluation of the main characteristics of this set of mortars was made in terms of: i) hygric behaviour (water absorption by capillarity), and ii) mechanical resistance (flexural and compressive strength and elastic modulus). This study aims to assess the viability and possible advantages of using calcareous aggregate in lime mortars and to evaluate the possibility of improving characteristics through a better compaction obtained by the incorporation of different ratios of filler.

This paper intends to characterize the floor mortar layers (nucleus, rudus and statumen) of the high imperial mosaics of the domus integrated in the Museum of Archeology D. Diogo de Sousa, the oldest roman housing testimonies known in Braga, Portugal. It offers an important archaeological and historical contextualization and first chemical characterization attempt on the mortars. The study of 13 mortar samples was carried out at a chemical level through X-ray fluorescence spectroscopy (XRF). All samples presented low lime content when compared to similar studies. A high chemical similarity between nucleus mortars (opus signinum) and chemical composition differences between rudus and statumen mortars was determined, confirmed by statistical analyses. Their composition was distinctly related to the stratigraphic position of each floor mortar layer, following Vitruvius’ model, and to the external conditions and treatments (e.g., capillary rise with soluble salts and application of chemical treatments), to which they were submitted.

This investigation intends to study and characterize the mortars and bricks from walls and floors used in the funerary nucleus of the archaeological site of Dr. Gonçalo Sampaio Street (Braga, Portugal), associated with the Via XVII necropolis of the Bracara Augusta Roman city. The diversity of the funeral structures and their exceptional state of conservation make this sector of the necropolis an unprecedented case and a reference site in the archaeology of Braga, a determinant for its conservation and musealization. Nineteen mortars samples were analysed by X-ray Fluorescence. The results showed clear chemical composition differences among coating and floor mortars (CFM), masonry mortars (MM) and bricks (B) groups of samples. The chemical affinity between CFM from the V to IV centuries, CFM from the IV to V centuries, MM from brick walls (IV–V centuries), MM from stone walls (V–VII centuries) and B from the IV to V centuries samples were confirmed by statistical analyses. Their composition was distinctly related to the use of different raw materials, according to their chronological context; in mortars, according to their function in the structures; and in some samples, from contamination.

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