1,721,053 research outputs found
Quantitative data on carbon fractions in interpretation of black crusts and soiling on European built haritage
No full textThere is wide recognition of the pivotal role of gaseous multi-pollutants and aerosols in determining the damage encountered on monuments and built cultural heritage in European cities. The main effects of atmospheric pollution on building materials in urban areas are soiling and black crusts formation. Furthermore, anthropogenic pollutants have changed over time, and attention now focuses on the contribution to damage layer formation of particles, particularly soot/carbonaceous ones, whose importance in determining air quality in urban areas is steadily increasing. However, the analytical tools and currently available data remain inadequate to attain a correct approach to black crust characterization and identification of causes of damage: there is a pressing need to discriminate and quantify the pollutant amounts, particularly that of carbonaceous aerosols, which deposit and accumulate on monuments and building surfaces, giving rise to surface blackening. The present work makes a contribution to filling this gap by presenting data on carbon fraction speciation and concentrations, obtained from the application of a specific analytical methodology on black surface layers in different European cities. As well as providing a preliminary data base, the information obtained turn out to offer some insight into past, present and future pollutant sources contributing to the damage on the built heritage
Efficiency evaluation of treatments against rising damp by scale models and test in situ
No full textThe presence of water in masonries is one of the most relevant cause of decay in historic buildings. If water is present, particularly rising damp, degradation processes such as biological growth, powdering due to salt crystallization cycles may arise and be intensified. Treatment against rising damp is therefore generally advised for the protection and preventive conservation of historic buildings. Within this framework, the JPICH Project "Effectiveness of methods against rising damp in buildings: European practice and perspective - EMERISDA" (2014-2017) aimed at a scientifically based evaluation of the effectiveness of different methods against rising damp and at decision support tool definition for a conscious choiceuse of these methods in the practice of conservation. During the present paper the methodology adopted on site for the evaluation of the efficiency of methods aiming at stopping/limiting rising damp on masonries is described. Specifically, results concerning the treatments on masonries with chemical injections (solvent and water based) and with plasters application on scale models and the case study of Agora in Ferrara (Italy) are presented. (C) 2018 Published by Elsevier Masson SAS
Effectiveness of a dehumidifying render system in tackling rising damp: Laboratory, small scale and field tests
No full textIn this research, a commercial 2-layers render system, proposed by the producer for the de-humidification of walls affected by rising damp and salts, has been studied. The research aimed at understanding the moisture and salt transport behaviour of the render system, assessing its ability to favour drying of the wall in comparison to traditional renders, and evaluating it durability in the presence of moisture and salts. Both layers of the render have been characterized in laboratory: composition porosity, pore size distribution, water absorption by capillary and drying behaviour have been measured. The performance of the render system in the presence of moisture and salts has been experimentally evaluated in small scale models and in a field test; this has been done by assessing the moisture and salt content in the render and in the masonry substrate, at different times after the application of the render. Both layers were found to easily transport water and salts, thanks to their high porosity. In the small scale models, the accumulation of salts in the render resulted into efflorescence and moisture spots at the surface due to the hygroscopic behaviour of the salt. No reduction of the moisture content in the walls affected by rising damp was measured after the application of the render. When applied in the field test, the render system did not result in a reduction of the moisture content in the wall in comparison to the previously existing cement-based render
Coltivazione e produzione della pietra ollare nelle Alpi Centrali
No full textLo studio petrografico della pietra olloare rinvenuta in numerosi scavi archeologici medioevali-rinascimentali italiani ha sollecitato lo studio petrografico per l'identificazione delle aree di provenienza. La Val Malenco è una delle aree di probabile approvvigionamento per la diffusa presenza di rocce simili alle litologie dei manufatti archeologici. Lo studio petrografico ha approfondito la caratterizzazione delle rocce metamorfiche ultrafemiche di basso e medio grado e la loro idoneità di impiego per la produzione di manufatti in pietra ollar
Atmospheric deterioration of cement plaster in a building exposed to a urban environment
No full textThe work presents results achieved in a research study on the effects of atmospheric deposition on the cement mortar of the basement in a twentieth-century building located in the city of Ancona (Italy). The degree of damage as a function of the sampling depth is evaluated by combining visual observation, scanning electron microscopy, X-ray diffraction, ion chromatography, differential and gravimetric thermal analysis and the quantitative determination of elemental carbon. Sulphation is found to be the main damage mechanism occurring on the cement mortar constituting the base section of a building since the concentration of sulphate increases from the inner to the outer layer at the expense of the carbonate. The absence of sulphite indicates a direct formation of sulphate, possibly due to the catalytic effect of heavy metals present in the carbonaceous particles of the black crust. Insoluble sulphates, such as ettringite, do not form at the surface, but within a deeper layer of the basement due to its instability to atmospheric carbon dioxide. © 2008 Elsevier Masson SAS. All rights reserved
The Corner Palace in Venice: a case of study on stone damage in urban area
No full textIn order to evidence both the products of damage reactions and the components due to atmospheric deposition, and to identify the pollutant sources, specimens of damaged stone, consisting of surface black crusts with underlying unaltered material, were sampled on the blackened façade of the Corner Palace on the Canal Grande in Venice and submitted to a combination of physico-chemical analytical techniques. The samples were observed in thin section under optical microscope, and the damaged surface was investigated using a scanning electron microscope. X-ray diffractometric analyses, gravimetric and differential thermal analyses, and ion chromatographic analyses were performed in order to identify the main crystalline species, quantify gypsum and carbonate, and measure the anion concentrations, respectively. Finally, the carbon fractions were discriminated and measured following a chemical-thermal methodology specifically developed for damage layer specimens. The data obtained indicate gypsum as the main product of damage processes occurring due to wet and dry SO2 deposition. The burning of fossil fuels produces gases, smoke and particulate carbonaceous matter that deposit on building surfaces and react with the underlying calcareous materials forming the damage layer. Carbonaceous particles have a catalytic effect on CaSO4·2H2O formation and the ensuing surface blackening on building exteriors
Degradation of mortars containing aggregate rich in serpentinites: the case of industrial brick masonry
No full textThe risk of asbestos exposure (European Directive 1999/3/CE) is generally assessed for the C&D waste (Construction and Demolition), for the asbestos cement (eternit) used as building materials (plates, pipes, floor) and for the asbestos textile used for thermal insulation in the industrial sectors and in fire protection barriers. The evaluation of risk for dispersion of asbestos fibres in the atmosphere due to degradation of lime
mortar containing aggregate rich in serpentinite is rarely analysed.
The aggregate containing fibrous minerals in light-weight masonry mortars was used in the industrial buildingof ‘900 to reduce the average density and thermal conductivity and to increase the physico-mechanical. The big development of constructions in the 20th century promoted the experimentation of innovative solutions to improve the performance of industrial buildings and in particular the industrial brick masonry chimneys and
furnaces. The use of sand rich in fibrous minerals is one of these innovative technological solutions. It was adopted in the beginning of the 20th century to realize the sugar factory that it was in use until 1968 and that is now the Technological Scientific Pole of University of Ferrara. That sugar factory is a symbol of the industrial history of the Po River Plain, so it is protected by the Italian Ministry of Cultural Heritage (Minghini et al., 2016).
As a result of the petrographic study of the mortars, they were classified as a mixture of lime and cement and an aggregate consisting of silicate sandstones, carbonate and fragments of ophiolite rocks (tholeiitic basalts and serpentinites). Considering the composition of the rocks and the geographic location of the sugar factory, it is possible that the sand was extracted in the Sillaro River area (Benini & Guasti, 1992).
The use of sand rich in fibrous minerals precedes the introduction of the filler and of the asbestos textile in the cements and mortars to improve their technological performance. The study of mortars has shown their high propensity to crack due to salt crystallization, frost stress and biological degradation, so the mortar durability is lower when they are deprived of the protective layer of the plaster
Deterioration of a cement plaster in a 20th century building exposed to urban atmospheric pollutants
No full textOxalate Patinas on Stone Monuments in the Venetian Lagoon: Characterization and Origin
No full textCalcium oxalate patinas have been sampled on architectural elements of two ancient churches located on Torcello Island (Venetian Lagoon) and subsequently analyzed. The site had been selected presenting patinas of exceptional amount and thickness, elsewhere generally found as thin alteration layers covering stone surfaces or within black crusts on monuments in urban environments. Optical and mineralogical analyses suggest that these patinas are not the result of a simple deposition process, but originate as surface "transformations" of the substrate, and are mainly composed of dihydrate calcium oxalate (weddellite) and gypsum. Among the experimental techniques, isotope analyses (C and S) have been specifically carried out aiming at achieving a better understanding of their origin and possible causes of formation. The observed carbon isotopic fingerprint reveals in fact a strong biological fractionation recorded in the oxalate patina (δ13C ranging from -22.3‰ to -28.0‰), almost exclusively attributable to C3 pathway photosynthesis processes. Slightly negative sulfur isotope ratio values seem to be inversely correlated with patina exposure to atmospheric agents and pollutants. The results obtained prove that calcium oxalate originates from a biomineralization process induced by lichen colonization in specific environmental conditions
Characterization of the Stone Masonries and Evaluation of the Environmental Impact in Panamá Viejo: A Contribution for the Conservation of the Monumental Complex
No full textA fundamental step in the best preservation of heritage materials is investigating their chemical and physical characteristics, and understanding how they interact with the surrounding environment. For this reason, the stone masonry of the monumental UNESCO site of Panamá Viejo was subjected to a thorough study to characterize the materials and evaluate their state of conservation. Additionally, potential outcrops were explored in order to identify sites for the supply of raw materials. The methodological approach encompassed mineralogical-petrographic investigations using stereomicroscopy, polarized light microscopy (PLM), X-ray powder diffraction (XRPD), scanning electron microscopy and energy dispersive X-ray spectrometry (ESEM-EDS) and X-ray fluorescence (XRF). The results revealed that the masonries primarily consists of polygenic breccia, basaltic andesite, rhyodacite, tuffite, and rhyolite. In addition, at the potential quarries, breccia and basaltic andesite were identified. The porous structure was studied using mercury intrusion porosimetry (MIP). Possible issues due to salt dissolution/crystallization cycles were considered. Consequently, ion chromatography (IC) was conducted on samples exhibiting alteration patinas to study the presence of soluble salts. In assessing the state of conservation, prevalent forms of deterioration included biological colonization, detachments, material loss, potential salt weathering, and chromatic alteration. In conclusion, the outcomes of this work provide a valuable resource for the current and future preservation of this site
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