Comparación analítica de dos consolidantes comerciales aplicados en areniscas eocenas de monumentos de los siglos XVI y XIX en San Sebastián (norte de España)

The conservation of buildings in the Basque Country made of Eocene sandstone is somewhat problematical, because this type of rock is relatively unstable. This instability is due to the variable content of carbonate cement (0-28%) and the presence of K-feldspar grains (1-13%) which appear to have been dissolved by both diagenetic and environmental processes. We have compared the results of the application of two commercial consolidating products: Sicof SM 296 (product A) and Consistone FS-hA (product B), both ethylsilicates, on Eocene sandstones of the Oquendo Admiral House (16th century) and the Gipuzkoa Provincial Government Palace (19th century), which are both located in the city of San Sebastián (Province of Gipuzkoa, Basque Country, Northern Spain). On the basis of different chemical and physical laboratory tests, together with Scanning Electron Microscopy (SEM) analysis, product A seems to be more efficient in consolidating such Eocene sandstone materials, since it penetrates into the first 8 mm of the rock, occupies very homogeneously even the smallest pore spaces and leaves a certain degree of remaining porosity which allows ventilation of the rock. In contrast, product B seems to be more appropriate for larger pore-sized rocks, because it only penetrates into the first 3 mm of the Eocene sandstone samples due to the thin pores of the matter. Our results demonstrate that the suitability of a commercial product depends not only on its own chemical composition, but also on the textural and lithological features of the rock material upon which it is to be applied.La conservación de los edificios del País Vasco construidos con areniscas del Eoceno es problemática porque este tipo de roca es relativamente inestable debido a su contenido variable en cemento carbonatado (0-28%) y a la presencia de granos de feldespato potásico (1-13%) disueltos tanto por procesos diagenéticos como ambientales. Hemos aplicado dos consolidantes comerciales: Sicof SM 296 (producto A) y Consistone FS+A (producto B), ambos silicatos de etilo, sobre las areniscas de la Casa del Almirante Oquendo (siglo XVI) y el Palacio de la Diputación Foral de Gipuzkoa (siglo XIX), ambos edificios en San Sebastián (País Vasco, norte de España). Los diferentes ensayos físicos y químicos junto con las observaciones al microscopio electrónico de barrido (SEM) revelan que el producto A es más eficiente para la consolidación de este tipo de areniscas, dado que penetra los primeros 8 mm de la roca, ocupa muy regularmente incluso los poros más pequeños y deja un cierto grado de porosidad remanente que permite la aireación de la roca. Por el contrario, el producto B parece más adecuado para rocas con mayor tamaño de poro, dado que sólo penetra los primeros 3 mm. Con ello, queda claro que la eficiencia de un consolidante comercial depende no sólo de su composición química, sino, en gran medida, de las características texturales y litológicas de la roca sobre la que se va a aplicar

Study for the determination of the pathologies in the constituent materials of the Milagros Aqueduct (Mérida)

The conservation of this prime example of national and historical heritage requires a methodology that should be based firmly on modern scientific analysis. In recent years research has moved away from informality and irregularity, and evolved towards the standardization of multidisciplinary techniques. Therefore, any intervention on a historical object should continue to respect developments in scientific methodology and, in doing so, preserve the physical integrity of the object together with its cultural and historical significance. The project has been divided up into five parts. INTROMAC and Fundación Labein (Labein Foundation) have developed phase three: "The material and structural investigation of the Milagros Aqueduct in relation to weathering and appropriate treatments". The building materials of the Milagros Aqueduct in Mérida have been classified according to deterioration, i.e. the characterization of mineralogical, petrographical, petrophysical and petrochemical properties of monument materials. The stony materials are granite in origin. The joint mortars of both stone and brick masonries are lime-based with siliceous aggregates (both with a ratio of 1:3). Roman concrete is a lime mortar with diorite aggregates, with a ratio of 1:1. There are two types of bricks; the original Roman bricks of the aqueduct and replacement bricks from later times.Peer reviewe

Petrography, provenance and alterability of the stone material used for the construction of the St Millán de la CogoIIa Monastery, Yuso (16th to 17th centuries), La Rioja

A catalogue of the stone material employed for the construction of the San Millán de la CogoIIa Monastery (Yuso) has been undertaken. The characterization of the rocks has enabled us to explain the provenance of the most part of the stones from several quarries very close to the monastery. We have also compared the different degree of alteration of the stone material. Whereas the brecciated limestones from Jurassic age employed for the construction of all the main walls and columns of the monastery, have a very resistant behaviour to weathering, the Tertiary sandstones and coarse-crystalline evaporites (gypsum) were destined to archs, archivolts, cornices and ornamental pieces and appear largely affected by dissolution processes showing a high degree of decomposition, particularly in the northern and western façades of the building. The evaporitic material has been specially conflictive with respect to the restoration works carried out the last year on this historic monaster

Resultados de SEM/EDX en morteros de restauración aplicados a areniscas del Eoceno de Gipuzkoa utilizadas en la construcción de edificios

The restoration of buildings made of sandstones is a critical problem in the Basque Country, because the wide use of Eocene sandstones that appear as a constructing material very frequently affected by weathering processes. The impossibility to recuperate the original material sometimes leads to complete or even replace the masonry stones with mortars which should have the same physical properties and visual appearance than the original stones. Our research is focused to find the better mortars for the Eocene sandstones, and even to synthesize a mortar having the same resistance to weathering than the original sandstone. In order to improve the research, the first step was to accurately know the intimate textures of several types of mortars for furtherly test their physical behaviour under different experimental techniques in the laboratory. We have compared the textures of three commercial mortars (A, B and C) and a fourth one synthesized by Teusa. The mortar A is an amorphous arid-free alite-mortar, whereas the B and C are composed by quartz, alite and calcite. From all the four studied mortars, the A seems to be the most appropriate to rejoin the Igueldo sandstone masonry stones, without exclude its use for completion. The B and C mortars are suitable for completion because their composition and texture is very similar to that of Eocene sandstones. Finally, the uncommercialized Teusa mortar is thought to have by the moment an excessively resistant behaviour when compared to Eocene sandstones. Being relatively-close the textures of all the four studied mortars, we think that both organic additives or catalysts together with the ratio high-Ca-lime/white-cement should play an important role in the final properties of the mortar

S.E.M. Applications to the study of the damage and restoration of historic buildings: the Oquendo House (16th century) and the Deputation Palace (19th century) (San Sebastián, Basque Country)

The studies on the deterioration and restoration of buildings have increased in the last decades. The role of Scanning Electron Microscopy (S.E.M.) as a tool for textural studies of both damaged and restored rocks is important since it enables to us to identify both the style of penetration of consolidating products inside altered rocks and the solidification textures into pore spaces. We have compared the results of the application of the products Sicof SM 296 and Consistone FS+A on Eocene sandstones of the Oquendo House and of the Deputation Palace, both buildings at San Sebastián city. As observed from S.E.M. and different laboratory tests, the Sicof SM 296 seems to be the most efficient consolidating product for the restoration of such Eocene sandstone materials since it occupies even the smallest pore spaces very homogeneously and leaves a certain degree of remaining porosit

Chemical and mineralógica! study of restoration mortars applied to the Eocene sandstones of Gipuzkoa used for building construction

We have chemically and mineralogically analysed four commercial mortars (A, B, C and D) and a fifth one (synthesised by Teusa) by means of X-ray fluorescence and X-ray diffraction techniques. The mortar A is an amorphous arid-free alite-mortar, whereas the B and C are composed by quartz, alite and calcite. The mortar D is particularly special because of its composition of calcite and zincite together with minor amounts of quartz. The establishment of the precise chemical and mineralogical composition of mortars is an essential tool to enlighten the suitability of each type of mortar when applied to a particular rock for building. Most mortars have alite, quartz and calcite, appearing portlandite after 28 days of hardening. The low cristallinity of the mortar A, together with its chemistry suggests the presence of pozzolan. The mortars B and C have variable amounts of quartz as arid, being the C enriched in Ti, which appears as rutile. Probably the presence of Ti is to color the product. Mortar D is enriched on zincite that becomes simonkolleite after hardening, most probably due to reaction with the binding liquid that is added. The Teusa mortar has been synthesised in four different varieties by modifying the proportions ofhigh-Ca lime, white cement and grey cement. All the four varieties recorded the quartz as the main component together with alite, portlandite and calcit