A multi-analytical approach to assess the impact of air pollution on cultural heritage : degradation of stones, mortars and bricks

Air pollution is one of the most important causes of surface decay in urban environment. Among the degradation processes due to airborne pollutants, the formation of black crusts is one of the most dangerous one. Currently, emissions from mobile combustion sources are the main agents responsible for pollution, although a significant decrease is expected in Europe within the next decade. The surfaces of architectural heritage in urban environment are exposed to degradation due to the interaction with atmospheric pollutants both in gaseous and in the particulate phase. Monuments located in the historic centres of large cities are subjected to typical anthropogenic emissions. The precise identification of the main substances responsible for the surface degradation phenomena, in particular leading to blackening, erosion of carbonatic matrices and disintegration, is essential for the definition of conservative intervention and maintenance strategies, as well as for the development of emission reduction policies on a larger scale. Black crusts and substrate (stones, mortars or bricks) specimens have been sampled in Milan and Monza from monuments of historical interests and analyzed by a multi-analytical approach including FT-TIR spectroscopy, ion chromatography (IC) and electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). The characterization of the carbon fraction (organic carbon, OC, and elemental carbon, EC) was performed using a new approach based on a thermal protocol and on the use of CHN analysis and thermogravimetric analysis (TGA). This integrated approach has been already applied in some case studies [1-4]. Data acquired on the specimens have been compared with those collected by the regional environmental protection agency (ARPA Lombardia) in order to assess, also through the use of dose-response functions, the degradation phenomenon that occur

The effects of air pollution on cultural Heritage : the case study of Santa Maria delle Grazie al Naviglio Grande (Milan)

Atmospheric pollution causes monuments surface degradation in urban environments. Among the degradation processes the formation of black crusts (BCs) is one of the most dangerous phenomenon. During this process, aerosol particulate matter (PM) can be embedded into gypsum, one of the main crusts constituents, providing the characteristic black colour. EC (elemental carbon) and OC (organic carbon) are the responsible for the yellowing and blackening processes occurring on the surfaces and their quantification in the crusts can provide information on the contribution of atmospheric pollution sources to the degradation products formation. This research study is focused on the characterization of BCs collected from the Church of Santa Maria delle Grazie al Naviglio Grande in Milan, from the point of view of the effects of atmospheric pollution on cultural heritage. The analysed samples consist of mortars and bricks partially degraded and covered with black crusts. Appling different analytical techniques, such as FTIR/ATR, CHN, TGA and IC, the crusts composition has been investigated focusing on the quantification of the carbonaceous fraction. This integrated approach has allowed to identify the sources of pollution responsible for the decay of the different building materials of the church

Characterization of soluble salts on the frescoes by Saturnino Gatti in the church of San Panfilo in Villagrande di Tornimparte (L'Aquila)

During the archaeometric study of the frescoes by Saturnino Gatti in the church of San Panfilo in Villagrande di Tornimparte (L'Aquila), 11 samples of powder and fragments were taken from different panels of the fresco in order to characterize any degradation produced by the presence of salts. The samples were taken in areas where there were evident detachments, exfoliation and saline crystallization (efflorescences). Precisely, 9 samples were taken from panels A, C, D and E and two samples taken from the top part of the vault. The characterization of the samples was performed using two analytical methods such as Ion Chromatography (IC) and FT-IR / ATR infrared spectroscopy. Ion chromatography was used for the quantification of the main ions and to evaluate the presence of soluble salts. Measurements of cationic (Na+, K+, Ca2+, Mg2+ and NH4+) and anionic (NO3-, SO42-, Cl-) species were performed using an ICS-1000 HPLC system equipped with a conductivity detector. The anion analysis was performed with a column of Ion Pac AS14A using Na2CO3 8 mM/NaHCO3 1mM, flow rate = 1.5 mL/min and for the detection a conductivity system equipped with anionic self-healing suppression ULTRA (ASRS-ULTRA). While, the determination of the cations was carried out using a CS12A column (Dionex) and 20mM of methanesulfonic acid (MSA) as eluent at a flow rate = 1.5 mL/min and for the detection a conductivity system equipped with an ULTRA self-healing cationic suppressor (CSRS-ULTRA). Infrared spectroscopy has been used to characterize the mineralogical phases. The apparatus used is a Nicolet 380 (Thermo Electron Corporation) instrument coupled with ATR accessory Smart Orbit equipped with a diamond crystal. The spectra have been acquired in the range 500-4000cm−1 at a resolution of 4cm−1. The results indicate that some, but not all, samples show high concentrations of sulfate and calcium, attributable to probable efflorescence consisting of newly formed gypsum. Furthermore, a good correlation between sodium and chloride was observed, indicating the presence of an efflorescence composed of newly formed sodium chloride. The calcite and silicate bands attributable to the substrate were observed by FT-IR and also gypsum bands were highlighted confirming what observed by the IC technique

Marble hydrophobicity tuned by Si-based coatings

Hydrophobic polymers applied on stone materials increase their durability against undesired weathering processes [1]. The achievement of a certain degree of surface hydrophobicity (reducing the water permeation) constitutes one of the main research focuses [2]. Herein, two commercial Si-based resins (e.g. Alpha\uaeSI30 and Bluesil\uaeBP9710), directly applied on Carrara marble substrates and a silanization process, by using trichloromethylsilane (TCMS), were adopted. Contact angle measurements were carried out to evaluate the hydrophobic features. Hence, since only in the case of TCMS a good hydrophobicity was achieved (\uf071 around 150\ub0), two commercial polysiloxane-based additives (e.g. TegoPhobe 1500N and TegoPhobe 1650) were added respectively to Alpha\uaeSI30 and Bluesil\uaeBP9710, according to their chemical compatibility. These auxiliary substances allowed to decrease the wettability features of marble. Furthermore, since all the investigated coatings could be used as stone materials protective agents, water capillary absorption and vapor permeability tests were performed. Also, in this case, TCMS revealed to be the most performing one among the adopted silane-based resins, thanks to the drastic reduction of absorbed water and the decrease of vapor permeability within the threshold value of 50%. Finally, the coatings stability was evaluated by accelerated ageing tests. References [1] Cappelletti G., Fermo P., Pino F., Pargoletti E., Pecchioni E., Fratini F., Ruffolo S.A., La Russa M.F., On the role of hydrophobic Si-based protective coatings in limiting mortar deterioration, Environ Sci Pollut Res, 22 (2015) 17733\u201317743. [2] Cappelletti G., Fermo P., Camiloni M., Smart hybrid coatings for natural stones conservation, Progress in Organic Coatings 78 (2015) 511\u2013516

A multi-analytical survey for the identification of the red and yellow pigments of coloured sherds discovered in the Monte d’Oro area (Rome)

The aim of the study was the characterisation of the pigments utilised on the painted sherds found during an excavation performed by the Soprintendenza Archeologica and just approximately assigned to a historical period between the first century B.C. and the first century A.D. The analytical survey here presented meant to provide archaeologists with useful information on the painting materials to better contextualise the findings from an artistic and historical point of view. The investigation procedure comprehended the use of SEM-EDX technique and Raman, infrared and visible reflectance spectroscopies, paying most attention to portable instrumentation diagnostic performances. The study carried out on a selection of the red, and yellow sherds highlighted the presence of cinnabar, litharge, red and yellow ochre also blended among themselves or possibly utilised overlapping more painting layers. Furthermore, it is to notice the presence of gold decorations on some fragments that denotes certain care for details and opulence in the adornment

Experimental and numerical analysis of short sisal fiber-cement composites produced with recycled matrix

"Published online: 02 Jan 2017"The proper use of renewable or recycled source materials can contribute significantly to reducing the environmental impact of construction industry. In this work, cement based composites reinforced with natural fibers were developed and their mechanical behavior was characterized. To ensure the composite sustainability and durability, the ordinary Portland cement matrix was modified by adding metakaolin and the natural aggregate was substituted by 10% and 20% of recycled concrete aggregate. Compression and splitting tensile tests indicated that mechanical strength did not seem to be affected by recycled content. Flat sheets were cast in a self-compacted cement matrix and bending tests were performed to determine the first crack, postpeak strength and cracking behavior of the composites. The use of short sisal fiber as reinforcement of recycled cement matrices results in a composite with multiple cracking and increment of strength after first crack. The modeling of composites using finite element method allowed to determine the tensile stress-strain behavior of material and to design possible applications of this new sustainable material.This research was supported by CAPES (PVE Program: Project 047/2012) and CNPqinfo:eu-repo/semantics/publishedVersio

A study for the analysis of pigments from ancient Egyptian artefacts

Like all pigments, those of the Egyptian period require their own analysis to be identified and thus understood. There are several testimonies and numerous studies that confirm the vast number of colours that the ancient Egyptians had at their disposal to decorate their works of art and strong also was the symbolic meaning they associated with each different hue. In ancient Egypt the ritual and social use of colour was the result of theological speculations, and each different hue had a precise cultural value. In general, the palette of the Egyptians consisted mainly of white, red, yellow, blue, green and black. To obtain the colouring substances, the pigment was first ground and then diluted with water or, also depending on the support, with oils, egg whites, gum arabic or resins. The aim of the present work is to investigate the nature of sixteen samples of three ancient Egyptian artifacts, identify the pigments used and highlight the possible presence of organic materials. The sample set is composed of fragments from three different artifacts from a private collection. The first six samples come from an anthropomorphic sarcophagus belonging to the period between the XXVI and XXX dynasties. The next seven samples come from a wooden fragment of another sarcophagus placed chronologically during the Late Period (664-332 BC). Finally, the last three samples come from a red container, better defined as a cylindrical wooden ciborium from the Roman imperial period (I-III century AD). The chemical characterization of the fragments was performed by using a multi-analytical approach. A first observation of the painting and an initial characterization of the chemical elements present in the pigments was carried out by SEM-EDX (Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy) analysis. Subsequently, investigations were carried out using molecular techniques such as ATR-FTIR (Attenuated Total Reflectance Infrared) and Raman spectroscopies to identify the nature of the pigments. Finally, the samples were further investigated by using VIL (Luminescence Induced by Visible light) analysis, a technique that proved particularly useful in the identification of Egyptian blue. As a result of the analyses carried out, inorganic pigments of different nature were found, and the presence of various organic substances, including polysaccharides, protein material and oils, was ascertained. On the first artifact, the presence of Egyptian blue, red ochre, green earth and calcium carbonate were recognized, whereas, on the sarcophagus fragment, yellow ochre, green earth, chrysocolla, Egyptian blue, red ochre, calcium carbonate and carbon black were found. Lastly, in the third artifact, mainly organic products and the red pigment realgar were identified. Therefore, this work made it possible to characterize the palette used to paint the three artifacts. In addition, the employement of organic binders for pigment application was highlighted. Finally, the identified colours were found to be compatible with what is reported in the literature for analogous artifacts, and some preliminary information about the presence of organic substances, both in the pictorial layers and in the sample coming from inside the ciborium, was achieved

Efficiency of an air cleaner device in reducing aerosol particulate matter (PM) in indoor environments

Indoor air quality (IAQ) in household environments is mandatory since people spend most of their time in indoor environments. In order to guarantee a healthy environment, air purification devices are often employed. In the present work, a commercial household vacuum cleaner has been tested in order to verify its efficiency in reducing the mass concentration and particle number of aerosol particulate matter (PM). The efficiency has been tested measuring, while the instrument was working, PM10 (particles with aerodynamic diameter less than 10 μm), PM2.5 (particles with aerodynamic diameter less than 2.5 μm), PM1 (particles with aerodynamic diameter less than 1 μm), and 7 size-fractions in the range between 0.3 and >10 μm. Measurements have been carried out by means of a portable optical particle counter instrument and simulating the working conditions typical of a household environment. It has been found that the tested commercial device significantly reduces both PM concentrations and particle number, especially in the finest fraction, i.e., particles in the range 0.3-0.5 μm, allowing an improvement of indoor air quality

Efficiency of an Air Cleaner Device in Reducing Aerosol Particulate Matter (PM) in Indoor Environments

Abstract: Indoor air quality (IAQ) in household environments is mandatory since people spend most of their time in indoor environments. In order to guarantee a healthy environment, air purification devices are often employed. In the present work, a commercial household vacuum cleaner has been tested in order to verify its eciency in reducing the mass concentration and particle number of aerosol particulate matter (PM). The eciency has been tested measuring, while the instrument was working, PM10 (particles with aerodynamic diameter less than 10 m), PM2.5 (particles with aerodynamic diameter less than 2.5 m), PM1 (particles with aerodynamic diameter less than 1 m), and 7 size-fractions in the range between 0.3 and >10 m. Measurements have been carried out by means of a portable optical particle counter instrument and simulating the working conditions typical of a household environment. It has been found that the tested commercial device significantly reduces both PM concentrations and particle number, especially in the finest fraction, i.e., particles in the range 0.3\u20130.5 m, allowing an improvement of indoor air quality

The hydrophobicity modulation of glass and marble materials by different Si-based coatings

Hydrophobic polymers applied on hydroxylated surfaces increase their durability against undesired weathering processes. The achievement of a certain degree of surface hydrophobicity (reducing the water permeation) constitutes one of the main research focuses. Herein, two commercial Si-based resins (e.g. Alpha\uaeSI30 and Bluesil\uaeBP9710), directly applied on both glass and Carrara marble substrates, and a silanization process by using trichloromethylsilane (TCMS) were adopted. Contact angle measurements together with hysteresis determination and Surface Free Energy (SFE) were carried out to evaluate the hydrophobic features. Hence, since only in the case of TCMS a good hydrophobicity was achieved (\uf071 around 150\ub0), two commercial polysiloxane-based additives (e.g. TegoPhobe 1500N and TegoPhobe 1650) were added respectively to Alpha\uaeSI30 and Bluesil\uaeBP9710, according to their chemical compatibility. These auxiliary substances allowed to decrease the wettability features of either glass or marble. Furthermore, since all the investigated coatings could be used as stone materials protective agents, water capillary absorption and vapor permeability tests were performed. Also in this case, TCMS revealed to be the most performing one among the adopted silane-based resins, thanks to the drastic reduction of absorbed water and the decrease of vapor permeability within the threshold value of 50%. Finally, the coatings stability was evaluated by accelerated ageing tests