Suchergebnisse

14 pp.- Publicado en el libro "Ciencia, Tecnología y Sociedad" dentro del programa Maternas financiado por la Comunidad de Madrid, en colaboración con la Asociación Restauradores sin Fronteras. ; [ES] Los materiales pétreos se utilizan por ser materiales resistentes de gran durabilidad, aunque se ven afectados por los efectos del paso del tiempo. Esta alteración natural es lenta y el daño se produce durante largos períodos de tiempo. Sin embargo, a lo largo de las últimas décadas el proceso de degradación ha aumentado de manera espectacular, hasta el punto de que monumentos que han permanecido sin cambios durante siglos o incluso miles de años se encuentran en un estado que pone en peligro la posibilidad de preservarlos para generaciones futuras. En los últimos cien años, la humanidad ha creado otro factor de riesgo para la preservación del patrimonio arquitectónico: la contaminación atmosférica. El deterioro causado en los materiales por este agente es muy elevado y hace que la conservación y el mantenimiento de las fachadas de los edificios sea un proceso sea muy costoso. Con el fin de reducir los efectos nocivos sobre nuestro patrimonio, deben tomarse medidas preventivas; la conciencia política y social es una de las más recomendables formas de lograr una reducción en la contaminación atmosférica en nuestras ciudades. ; [EN] Stone materials are used because they are resistant materials of great durability, but they do suffer the effects of the passage of time. This natural alteration is slow and damage occurs over long periods of time. Nevertheless, over the last few decades the process of degradation has increased dramatically, to the point where monuments that had remained unchanged for centuries or even for thousands of years are now in a state which jeopardises the possibility of preserving them for future generations. Over the last hundred years, mankind has created another risk factor for the preservation of the national monument and architectural heritage: air pollution. The deterioration caused by this agent on materials is extensive and makes preserving and maintaining the facades of buildings a very costly process. In order to reduce harmful effects on our heritage, preventive measures must be taken; social and political awareness is one of the most highly recommendable ways to achieve a reduction in air pollution in our cities. ; Proyecto Maternas financiado por la Comunidad de Madrid. Referencia S-0505/MAT-0094 ; Peer reviewed

Granite is found in many world heritage monuments and cities. It continues to be one of the most widely used stones in today's construction, given its abundance, uniformity and durability. Quarrymen traditionally cut this rock along its orthogonal slip planes, where splitting is easier. Ranked by ease of splitting, these planes are rift, grain and hardway. Granite is traditionally quarried along the rift plane where coplanar exfoliation microcracks coalesce developing a flat surface. This splitting surface minimizes the cost and effort of subsequent hewing. Rift plane was predominantly used on the fair face of ashlars in heritage buildings worldwide. Determining the petrographic and petrophysical behaviour of these three orthogonal splitting planes in granite is instrumental to understanding decay in ashlars and sculptures. The decay of building granite is different in each splitting plane. Alpedrete granite was the stone selected for this study based on the orientation and distribution of exfoliation microcracks and the characterisation of their implications for the anisotropy of petrophysical properties such as ultrasonic wave propagation, capillarity, air permeability, micro-roughness and surface hardness. Inter- and intracrystalline microcrack length and spacing were also measured and quantified. The findings show that the splitting planes in Alpedrete granite are determined by the orientation of exfoliation microcracks, which as a rule are generally straight and intracrystalline and determine the anisotropy of the petrophysical properties analysed. Splitting planes are the orientation that should be applied when performing laboratory tests for the petrographic and petrophysical properties of building granite. ; This study was funded by the Regional Government of Madrid, Spain, in the framework of the GEOMATERIALS-2CM [S2013/MIT-2914] programme. ; Peer reviewed

Uniaxial compressive strength (UCS) is the most used parameter to measure rock strength. However, restrictions in sampling large volume of material, the need of very large set of results and onsite characterisation of UCS non-destructively are requirements in many scientific and engineering investigations. The estimation of UCS from a single non-destructive or minimally invasive technique (NDT) may result incomplete because each NDT is sensitive to different compositional and textural factors. This paper combines open porosity, P-wave velocity, Leeb hardness and micro-drilling resistance force to estimate USC for a wide range of carbonate sedimentary rock types with different petrographic characteristics. Results reveal that mineralogical composition significatively affects micro-drilling resistance force profiles and P-wave velocity values, especially for quartz-bearing rocks. In addition, texture controls substantially the reproducibility of tests sensible to rock surface properties, such as Leeb hardness and micro-drilling resistance force. Fifteen simple and multiple expressions for UCS are fitted. Linear expressions have shown better coefficients of determination (R2) than non-linear equations because of the linearity shown by individual parameters. Curve fitting improves as the number of petrophysical parameters increase in the multiple linear regression analysis. The best correlation is found when the equation incorporates all the mechanical parameters obtained non-destructively as well as open porosity (R2 = 0.910). Leeb hardness is always the most significant variable of the fitted regressions and its addition into multiple linear equations causes an increase of R2. Open porosity also improves R2 whereas drilling force and P-wave velocity have a lower statistical weight in the expressions. The UCS estimation from all NDT, without considering open porosity, shows a good correlation (R2 = 0.899), which presents the advantage that they can be obtained non-destructively with portable equipment and can provide a numerous set of results at relatively low cost. ; This work was supported by the Spanish Government [grant number RTI2018-099052-B-I00] and Regional Government of Madrid (Spain) [Top Heritage, grant number S2018/NMT-4372].

Published online: 05 Jan 2018. ; The color patterns generally found on the façades of architecturally sensitive buildings have an adverse impact on their aesthetics, to the detriment of their identity and potential economic value. A quantitative and qualitative study was conducted of the perception of aesthetic decay in the limestone on a heritage building. The study assessed building aesthetics between two façade cleaning operations, conducted in 1984–1986 and 2006–2008. Based on the calculation of the final or total soiling index, by means of in situ lightness measurement and three architectural design variables, the color distribution of the façades was quantified in 2006 and a model was developed to monitor façade soiling over time. The proposed model, a tool for planning preventive façade maintenance on architecturally sensitive buildings, advocates for sustainable cleaning operations. Its premise that periodic cleaning should only be conducted in areas where the limestone is affected by aesthetic decay redounds to minimised intervention and lower building management costs. ; This study was funded by the Regional Government of Madrid, Spain and the European Social Found [Geomaterials (S2009/MAT_1629) and Geomaterials 2 (S2013/MIT_2914) Programmes] and by the Complutense University of Madrid research group "Petrology applied to heritage conservation" [ref. 921359]. ; Peer reviewed

A study of the stability of calcium carbonate polymorphs formed as a result of the carbonation process from an alcoholic colloidal solution of nanocrystals of Ca(OH)2 in low relative humidity (RH) conditions (33% and 54% RH) is presented in this research. The crystalline behavior, the time dependence of nucleation and the phases' transformations as a result of exposure to low humidity conditions are evaluated. The carbonation process is slow, starting with the nucleation of amorphous calcium carbonate, associated to an amorphization process that affects both the portlandite (Ca(OH)2) and the initial unstable CaCO3 polymorphs. The excess of alcohol in the solution decreases the surface tension and the nucleation is accelerated by the fast evaporation of the solvent, which avoids the particles to diffuse to their lowest energy sites, giving smaller particles with lower crystallinity as RH decreases. ; Government of the Community of Madrid (Spain), the GEOMATERIALES (S2009/MAT-1629/GEOMATERIALES) and CONSOLIDER-TCP (CSD2007-0058) programmes and to the JAE-Doc CSIC contract. ; Peer Reviewed

Pothole formation and development may be influenced by joint sets and other heterogeneities within bedrock, as well as by hydraulics. Previous research indicates that most potholes found in rivers of the mountainous Spanish Central System exhibit preferred orientations associated with dominant joints and correlate more strongly with variations in substrate resistance than with hydraulics. Weathering and erosion weaken rock surfaces, which leads to decreased mechanical resistance. We start from the hypothesis that different mechanisms of pothole formation may create around the pothole a distinctive signature in terms of ultrasound pulse velocity and surface hardness. We develop a conceptual model and test it using potholes for which we know the mechanism of formation, demonstrating that the spatial and statistical distributions of dynamical mechanical properties and surface hardness of a pothole may provide insight into its genesis. Copyright © 2016 John Wiley & Sons, Ltd. ; This research was partially funded by Geomateriales 2 programme (S2013/MIT-2914) funded by the Regional Government of Madrid (Spain). ; Peer reviewed

Morphometric characterisation is particularly relevant in the study of geomorphological heritage. 3D modelling techniques have been proven as very useful tools to recognise, characterise and valorise geomorphosites. Bedrock rivers account for one of the most outstanding aspects within geomorphological heritage due to the amount of distinctive and attractive geomorphological features associated to them and the high preservation of sculpted forms. Digital elevation models (DEMs) have made it increasingly possible to establish accurate morphometric indices and establish clearer connections between forms and processes. This paper reviews different methodologies to obtain DEMs on bedrock rivers. This review goes from DEM analysis at multiple spatial scales to introduce optical microrugosimeter as the latest technical development to facilitate micromorphometric analysis. Micromorphometric analysis opens the scope for improving the knowledge we have on trans-scale issues in bedrock rivers. Micromorphometric analysis also opens a new layer of information that enriches the public's valuation of geodiversity of geomorphosites by increasing its didactic and interpretative potential. ; This work was supported by Geomateriales 2 (S2013/MIT-2914) and Top Heritage (P2018/NMT-4372) programmes from the Regional Government of Madrid (Spain). ; Peer reviewed

Nondestructive in situ analysis of materials is highly desirable in cultural heritage studies, because it precludes the need for intensive sampling. The present study focused on the usability of Raman spectrometers, which can provide such analysis, in the identification of conservation treatments applied to stone materials forming part of the architectural heritage. Two products commonly used to conserve stone monuments, an ethylmethacrylate copolymer and an ethyl orthosilicate, were analyzed with a Raman spectrometer, both as supplied and after application to limestone. The main conclusion was that portable Raman analyzers can detect the presence and—in some cases—identify the nature of products on stone substrates. The latter is not always possible due to product-stone substrate interaction. The study clearly showed that a product and substrate database is needed for portable Raman spectroscopy to be usable in the analysis of conservation products, both before and after application to stone substrates. ; This research was funded by the Spanish Government's CONSOLIDER-INGENIO 2007 (CSD2007-0058) project and GEOMATERIALES (S2009/MAT-1629/GEOMATERIALES), a project sponsored by the Regional Government of Madrid. ; Peer Reviewed

The effect of high relative humidity (90% and 75% RH) on phase transformation and stability of CaCO3 polymorphs has been studied based on the structural and morphological changes from a colloidal solution based on Ca(OH)2 nanocrystals. Carbonation process has been confirmed indicating differences in nucleation and stability of CaCO3 polymorphs as a function of RH. Local fluctuations in the water/alcohol ratio significantly affect the precipitation/dissolution of anhydrous and hydrated polymorphs that are reflected in the particle size. Changes in lattice parameters and particle size are related to surface tension fluctuations, release of residual water and time of exposure. These results highly contribute to evaluate the stability of the Ca(OH)2 nanoparticles in high humidity conditions. ; This work was supported by the Government of the Community of Madrid (Spain), the GEOMATERIALES (S2009/MAT-1629/GEOMATERIALES) and CONSOLIDER-TCP (CSD2007-0058) programmes and by the JAE-Doc CSIC contracts. ; Peer Reviewed

The Church of the Assumption of Our Lady, in Valdemorillo (Madrid, Spain) is almost entirely built with granitoids. The studies and analyses were focused on the oldest part of the building (Ghosts Corner), which will be restored and rehabilitated in the near future. Homogeneous monzogranite is the predominant granitoid used in the Ghosts Corner, followed by granitic porphyry, porphyrytic monzogranite, gneiss and leucogranite. The original quarries that supplied homogeneous monzogranites for the first construction stages correspond to blocks present in the monument's surroundings. Quarries that supplied the granitic porphyries correspond to the dykes located to east–southeast of Valdemorillo, which are oriented N–S in relation to their intrusion direction. The combined use of ultrasonic velocity and Schmidt hammer techniques allowed, first, selection of the most representative blocks and ashlars for sampling. This reduced sampling to a minimum, but yielded representative results for the whole building. Second, the combined values were used to compare results for the building stones of the church to rocks from the surrounding quarries. Stones from the building showed lower ultrasonic and Schmidt hammer values, and higher porosity and water saturation values compared to the original quarry rocks. The anisotropy indices are directly related to the decay processes in the stone: spalling of homogeneous monzogranite and grain disintegration in granitic porphyries. Finally, the methods applied are inexpensive, easy to use and non-destructive techniques, very advisable properties when working with built heritage. ; This study was financed by the Heritage General Directorate of Comunidad de Madrid (Regional Government of Madrid). The authors are also grateful to the MATERNAS programme (Durability and Conservation of Natural Traditional Materials for Architectural Heritage), which is also financed by Comunidad de Madrid (0505/MAT/94), to the CONSOLIDER programme (Technologies for the preservation and revalorisation of Cultural Heritage, CSD2007-0058) and to the Research Group financed by the Complutense University of Madrid "Alteration and Conservation of heritage stone materials (ref. 921349). ; Peer reviewed

Attached files: Extended abstract (3 pages) and PDF-PPT Presentation (24 slides).-- Communication presented at: 7th International Symposium on the Conservation of Monuments in the Mediterranean Basin, Water and Cultural Heritage (Orléans, June 6-9, 2007). ; The former Workers Hospital was designed by architect Antonio Palacios in the Northern enlargement of Madrid at the beginning of the 20th century. The building and its surrounding wall are mostly built with limestone masonry. It remained abandoned almost during 25 years, and the Government of Madrid purchased the property at the beginning of the eighties of the last century. It commissioned the building restoration, and the works were carried out between 1984–1986. ; The main decay forms that exist on the stone façades are related to soiling processes, with the development of black crusts in some specific areas. The main causes responsible for this soiling are the urban environment that surrounds the Hospital -with intense traffic-, the façades and the wall design with many set backed elements that makes very difficult their washing by rain water, the rusticated finishing ashlars and the own passage of time. ; This work has been carried out as part of a Special Intramural Project, supported by the Spanish Council for Scientific Research. We would like to thank the architect of the Regional Ministry of Culture José María la Calle and the companies Proliser and FTB the facilities and assistance provided, and to the Regional Government of Madrid for the financial support Durability and Conservation of Natural Traditional Materials of the Architectural Heritage (MATERNAS_CM, 0505/MAT/0094). ; Peer reviewed

A consolidating product based on nanoparticles of slaked lime (Ca(OH)2) dispersed in isopropyl alcohol was exposed under different relative humidities (RH), 33%, 54%, 75% and 90% during 7, 14, 21 and 28days. The characterization of the calcium hydroxide nanoparticles and the formed calcium carbonate polymorphs have been performed by Micro Raman spectroscopy, Transmission Electron Microscopy (TEM), Environmental Scanning Electron Microscopy (ESEM) with Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD). Precipitation and transformation of calcium carbonate polymorphs strongly depend on the relative humidity (RH). Higher RH (75%-90% RH) gives rise to amorphous calcium carbonate and monohydrocalcite, calcite, aragonite and vaterite, faster carbonation and larger particles sizes with higher crystallinity compared to lower RH (33%-54% RH) that gives rise mainly to portlandite and vaterite, slower carbonation and smaller particle sizes with lower crystallinity. © 2010 Elsevier B.V. ; This study was funded by the Government of the Community of Madrid by GEOMATERIALES (S2009/MAT-1629) and CONSOLIDERTCP (CSD2007-0058) and to the JAE-Doc CSIC contracts for supporting P. López-Arce and L.S. Gómez-Villalba to develop this work. ; Peer Reviewed

This article reports on a compositional investigation of stone patinas: thin colored layers applied for protective and/or aesthetic purposes on architectural or sculptural substrates of cultural heritage. The analysis and classification of patinas provide important information of historic and artistic interest, as their composition reflects local practices, the availabilities of different materials, and the development of technological knowledge during specific historical periods. Model patinas fabricated according to traditional procedures and applied onto limestone, and a historic patina sample from the main façade of the San Blas Monastery in Lerma (a village in the province of Burgos, Spain), were analyzed by laser-induced fluorescence and Fourier transform Raman spectroscopy. The results obtained demonstrate the ability of these two analytical techniques to identify the key components of each formulation and those of the reaction products which result from the chemical and mineralogical transformations that occur during aging, as well as to provide information that can aid the classification of different types of patinas. ; This work has been funded by the Madrid Regional Government project Geomateriales (S2009/Mat-1629) and by the Ministerio de Ciencia e Innovación under projects CTQ2010-15680 and CONSOLIDER CSD2007-00058. ; Peer Reviewed

For hundreds of years, two types of granite (Zarzalejo and Alpedrete) from the Madrid region, Spain, have been extensively used as building stones. Fresh specimens of both stone types have been sampled from their respective quarries and subjected to sodium sulphate salt crystallization test (SCT). The resulting physical and chemical weathering patterns have been characterized by polarized light optical and environmental scanning electron microscopy. Water absorption under vacuum conditions and mercury intrusion porosimetry techniques were used to determine the pre- and post-SCT porosity and pore size distribution. The following non-destructive techniques were performed to assess stone durability and decay: ultrasound velocity (US) and surface roughness determination (SR) of intra- and inter-granular quartz, feldspar and biotite minerals at the centre as well as at the corners and edges of specimen surfaces. Before the SCT, US values were lower and SR values higher in Zarzalejo (ZAR) than Alpedrete (ALP) granite. After SCT, the US values declined while SR rose in both types of granites, with greater average differences in ZAR than ALP for both parameters. Feldspar and biotite and their inter-granular contacts were found to be the weakest and therefore the most decay-prone areas of the stone.The initial SR parameters were generally higher and rose more steeply after SCT at the corners and around the edges of the specimens.While behaviour was found to be similar in the two types of granite, variations were greater in ZAR, the less durable and more decay-prone of the two. Surface roughness measurement of mineral grains in granite stones is a very useful, in situ, non-destructive technique for quantifying salt crystallization-mediated physical and chemical weathering. The resulting quantification of decay and of related durability provides insight into the future behaviour of this type of stone, commonly used in historic buildings. © 2010 Elsevier B.V. ; This study was funded by the Government of the Community of Madrid under the MATERNAS project (Ourability and conservation of traditional natural materials in heritage architecture) (MATERNAS CM 0505jMATj0094) and the Spanish Ministry of Science and Innovation as part of the Consolider-Ingenio 2010 programme (CS02007-0058). ; Peer Reviewed

Slaked lime (Ca(OH)2) nanoparticles were exposed at 33% and 75% relative humidity (RH) to consolidate dolostone samples used in historical buildings. Non-destructive techniques (NDT) were applied to determine the chemical, morphological, physical and hydric properties of the stone samples, before and after 20 days treatment. Morphological and mineralogical characterisation of the nanoparticles was performed. 75% RH favors the consolidation process studied under Environmental Scanning Electron Microscopy (ESEM-EDS), spectrophotometry, capillarity, water absorption under vacuum, ultrasound velocity, Nuclear Magnetic Resonance (imaging and relaxometry) and Optical Surface Roughness analyses. At 75% RH the nanoparticles fill the pores and inter-crystalline dolomite grain contacts but do not favor calcite re-crystallization as it occurs at 33% RH. The ESEM, XRD and TEM analyses under 75% RH reveal the fast transformation of portlandite (Ca(OH)2) into vaterite (CaCO3), monohydrocalcite (CaCO3 · H2O) and calcite (CaCO3), and eventually the physical and hydric properties of the stones significantly improve. New insights are provided for the assessment of consolidation effectiveness of porous carbonate stones with calcium hydroxide nanoparticles under optimum RH conditions combining several NDT. ; This study was funded by the Government of the Community of Madrid under the project "Durability and conservation of traditional natural materials in heritage architecture" (MATERNAS CM 0505/MAT/0094) and the Spanish Ministry of Science and Innovation as part of the Consolider-Ingenio 2010 programme (CSD2007-0058) ; Peer reviewed