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The implementation of analytical techniques able to certify food quality and origin in a fast and non-destructive way is becoming a widespread need in the agri-food sector. Among the physical non-destructive techniques, X-ray fluorescence (XRF) spectrometry is often used to analyze the elemental composition of biological samples. In this study, X-ray fluorescence (XRF) elemental profiles were measured on tomato samples belonging to different geographical areas in Sicily (Italy). The purpose of this investigation was aiming to establish a protocol for in-situ measurement and analysis able to provide quality assessment and traceability of PGI agri-food products, specifically sustaining health safety and self qualifying bio-chemical signature. In detail, sampling was performed in one of the most tomato productive area of south-eastern Sicily (Pachino district), characterised by a relative higher amount of Organic Carbon and Cation Exchange Capacity, and compared with samples from other growing areas of Sicily, falling in Ragusa province and Mt. Etna region. Experimental data were analyzed in the framework of multivariate analysis by using principal component analysis and further validated by discriminant analysis. The results show the presence of specific elemental signatures associated to several characterizing elements. This methodology establishes the possibility to disentangle a clear fingerprint pattern associated to the geographical origin of an agri-food product. [ABSTRACT FROM AUTHOR]

Due to the surprising lack of knowledge concerning raw materials and production technology employed to make mosaics after the twelfth century, an archaeometric investigation was carried out on the materials constituting the mosaic decoration of the South aisle wall of Monreale Cathedral (Italy), taking advantage of a conservation intervention. In this work, fallen coloured or gilded glass tesserae to be repositioned were studied by means of a combination of a molecular technique (Raman spectroscopy) and an elemental one (portable X-ray Fluorescence, pXRF); also, efflorescences affecting the general conservation state and samples of the respective bedding mortar were analysed with the former technique and with X-ray diffraction (XRD). The raw materials used and, consequently, the different compositions characterizing gilded vs. coloured glass tesserae were highlighted with the vibrational spectroscopy; chromophores and trace elements were detected by pXRF. This complementary approach allowed to disclose clues about glass-manufacturing technique and raw materials. The nature of the salts was also ascertained through Raman spectroscopy and XRD, for the benefit of the conservation procedure, and connected to the mortars' composition. [ABSTRACT FROM AUTHOR]

This paper presents the results obtained from the thermal analysis of a set of geomaterials (clays, pyroclastic materials, and industrial recycled materials) to be used as raw materials for the synthesis of geopolymers, specifically designed for the conservation of Cultural Heritage (CH) buildings, particularly in seismic hazard zones such as Sicily. X-ray diffraction and gas volumetric analysis (calcimetry) were applied to this set of raw materials in order to characterize the materials from the chemical and structural point of view. Thermogravimetric analysis (TG), TG coupled to Fourier transform infrared spectroscopy (TG-FTIR), and differential scanning calorimetry were used to characterize their thermal behavior. The statistical treatment of the thermogravimetric data by principal component analysis and hierarchical clustering analysis highlights the direct relation between the thermal data and the material composition that will be exploited for the selection of the best materials to obtain geopolymers specifically designed for the conservation of CH buildings. [ABSTRACT FROM AUTHOR]

In this contribution a non-destructive approach has been used aiming at investigating the chemical composition of 35 ceramic items belonging to the collections of the Regional Aeolian Museum "Luigi Bernabò Brea" in the Lipari Island (Sicily, Italy). Different vessel types have been selected for analysis, including aryballoi, kotylai, olpai, anforiskoi, oinochoai, and alabastra, belonging to the "Proto-Corinthian and Corinthian" ware classes. The items, dating back to the period comprised between the early eighth and the first half of the sixth century BC, come from two different archaeological sites in the province of Messina (Sicily), specifically the Istmo necropolis of Milazzo, in the northern Sicilian coast, and the acropolis and necropolis of Lipari, in the Aeolian islands. The chemical characterization of ceramics, carried out through portable X-ray fluorescence spectroscopy (pXRF), aimed at gaining information on the production area of examined items whose autoptic analysis pointed to Corinthian imports. The possibility of carrying out experimental investigations on the most ancient materials from the archaic necropolis of Milazzo and on fragments from Lipari, albeit limited to pXRF investigations, allowed to enrich the knowledge on the Corinthian production exported to western areas as well as to discriminate, no longer based solely on autoptic observations and stylistic evaluations, between Corinthian productions and "local" imitations. [ABSTRACT FROM AUTHOR]

Volcanic rocks have been used for building activity by the inhabitants of important cities located on the slopes of Mt. Etna, Italy. In this paper, the potential use of volcanic residues (code 20 03 03—"Municipal waste" residues from road cleaning in the European Waste Catalogue (EWC)) for the production of alkali activated material, especially devoted to the restoration of buildings belonging to the Baroque Sicilian architecture, was investigated. In particular, large volcanic pyroclastic deposits of recent eruptions considered waste materials were studied and a volcanic paleo-soil, locally named ghiara, widely used for mortars and plaster production in XVII–XVIII century with good pozzolanic features, was also considered. Both volcanic materials were activated using different mixtures of NaOH and Na2SiO3. Furthermore, formulations with different amount of metakaolin addition (10–25 wt%) were prepared due to low reactivity of volcanic materials and to allow the activation at room temperature. X ray diffraction revealed the formation of small quantities of zeolites as a result of the alkali activation process. The mechanical-physical results evidenced that the mechanical strength is strongly dependent on the metakaolin amount (10–38 MPa); accessible porosity average 25% and an average pore diameter of 0.06 µm; water absorption range 9–15%, eluates conductivity in the range 20–350 µS/m. These results confirm the occurring of alkali activation and the good potential for these pyroclastic wastes for valorization in the restoration field. [ABSTRACT FROM AUTHOR]

The investigation on the reticulation degree of volcanic alkali-activated materials, AAMs, were experimentally determined in terms of chemico-physical properties: weight loss after leaching test in water, ionic conductivity and pH of the leachate and compressive strength. Artificial neural network (ANN) was successfully applied to predict the chemical stability of volcanic alkali-activated materials. Nine input data per each chemico-physical parameter were used to train each ANN. The training series of specific volcanic precursors were tested also for the other one. Excellent correlations between experimental and calculated data of the same precursor type were found reaching values around one. The evidence of strong effect on chemical stability of the alkaline activator SiO2/Na2O molar ratio as well as the Si/Al ratio of precursor mixtures on the reticulation degree of ghiara-based formulation with respect to volcanic ash-based materials is presented. It must be noted that such effect was much less pronounced on the compressive strength values, appearing more insensitive the molar ratio of the alkaline activator. The comparison of the ANN results with more conventional multiple linear regression (MLR) testifies the higher prediction performance of the first method. MLRs results, less significant, are useful to confirm the powerful capacity of ANNs to identify the more suitable formulation using a set of experimental AAMs. This study, as few others, on the correlation between chemical stability and compressive strength of AAMs provide a great contribution in the direction of durability and in-life mechanical performance of these class of materials. [ABSTRACT FROM AUTHOR]

The results of a petrographic and geochemical study carried out on archeological grindstones allow to provide new constraints on protohistoric commercial exchanges over the Mediterranean area. Eleven grindstones, discovered in an archeological site located in Milazzo (Messina, Sicily) and dated from the Early Bronze Age, have been investigated by geochemical and petrographic techniques. The raw materials are mainly volcanic rocks characterized by calc-alkaline and K-alkaline affinities with volcanic arc geochemical signature. Only one sample, made of basalt belonging to the Na-alkaline series, shows an intraplate signature. The comparison with the available literature data for similar rocks allowed constraining the volcanic origin of the exploited lavas. While the intraplate-type raw material came from Mt. Etna Volcano (Sicily), the arc-type volcanic rocks are mostly trachyandesites, basaltic andesites, and one rhyolite. Although most of them come from the Aeolian Arc, a provenance of some samples from the Aegean Arc cannot be excluded. This last region could represent the most probable provenance area for the rhyolite sample. [ABSTRACT FROM AUTHOR]

Building stones are frequently subjected to very intense degradation due to salt crystallization, often responsible for strong modifications of their pore network. These effects have a great influence on the mechanical properties and durability of the materials, and on the penetration of water. Therefore, the quantification and visualization of water absorption into the pore network of degraded stones could provide useful information to better understand the weathering process. In this study, neutron radiography has been used (1) to monitor and visualize in two dimensions the capillary water uptake in a Sicilian calcarenite widely used as building and replace stone (namely Sabucina stone) and (2) to quantify the water content distribution, as a function of time and weathering degree. Additionally, traditional experiments based on gravimetric methods have been performed, following the standard recommendations. Results demonstrated a change in the physical properties of Sabucina stones with the intensification of the degradation process, with severe effects on the capillary imbibition dynamics. The water penetration depth at the end of the experiment was substantially higher in the fresh than in the weathered stones. The water absorption kinetics was faster in the weathered samples, and the amount of water absorbed increased with the number of weathering cycles. Good agreement between classical and neutron imaging data has also been evidenced. However, neutron radiography has allowed retrieving additional spatial information on the water absorption process, and to better understand how salt weathering affects the petrophysical properties of the studied stone and how it influences then the stone response against water. [ABSTRACT FROM AUTHOR]

In this work, the results of a Raman campaign for studying seventeenth-century Sicilian frescoes, by using two portable Raman systems, equipped with different excitation sources (785 and 1064 nm), are proposed. The measurements were performed with the aim to provide an in situ diagnostic analysis of the wall paintings (in terms of colorants and preparation layer) and to support the conservators in the framework of the ongoing restoration. The combined use of the two Raman spectrometers has given a complete overview on the artist palette and on the state of preservation of frescoes, also informing us about the technique employed by the painter. Natural pigments as hematite, vermillion, goethite, lead red, lead white and carbon-based black pigments have been identified. Additionally, the application of a transitional Romanesque-Renaissance frescoes method has been noticed by the systematic combined presence of calcite and gypsum in the substrate. Finally, the analyses have highlighted the presence of degradation products, mainly related to alteration of lead-based pigments. [ABSTRACT FROM AUTHOR]

The excavations at Mount San Paolillo (Catania, Italy) led to the discovery of a Prehistoric site that still represents the most important evidence of Middle and Late Bronze Age settlement in this area. During the excavations, archeologists located a hut, a store for ceramic storage vessels, and a pottery workshop, all of which provided a large quantity of heterogeneous ceramics with apparent typological parallels in other areas of Sicily, such as Syracuse, Augusta, and Messina. A large number of specimens were selected in order to cover all the macroscopic types and the main classes. The results identified four petrographic fabrics. Most of the ceramics are characterized by abundant tempers consisting of volcanic rock fragments and occasionally of grog. Only a few samples contained common fine-grained quartz. The groundmass ranges from non-micaceous to very micaceous. In some cases, there is evidence of mixed clays. Analysis of the chemical composition of the ceramics revealed the existence of two groups with low and high CaO contents. The high FeO content (more than 8.7 wt%) is probably due to the use of temper from altered pyroclastic rocks which are of local provenance as SEM-EDX data suggest, even if petrographic and chemical results suggest that different raw materials may have been used. The data provided by these archeometric analyses have made a significant contribution to the study of Middle and Late Bronze Age pottery from the Catania area, by offering insights into the methods, production processes, and high technical level of the prehistoric craftsmen. [ABSTRACT FROM AUTHOR]

Self-cleaning photocatalytic coatings based on TiO nanoparticles obtained by sol-gel techniques at two different pH values (1.3-10.6) have been investigated on carbonatic stone. The selected material is the yellowish lithofacies of Palazzolo Formation calcarenite, commonly named Pietra di Noto, widely used in the Baroque monuments of the Noto Valley (Sicily, Italy). SEM-EDS, XRD and Raman investigations were carried out to characterize the TiO nanoparticles (mainly nanocrystalline anatase) obtained by the acid and basic nanosols and the corresponding coatings on pietra di Noto. To evaluate the effects of the treatments at two different pH values, changes in the stone color appearance, water absorption by capillarity and the behavior for salt crystallization were measured. The photocatalytic activity of the coatings was evaluated under UV irradiation, by monitoring methyl orange and methylene blue dye degradation as a function of time. The results highlight the compatibility of both treatments with respect to the properties of the calcarenite stone, showing no chromatic changes, no alteration of physical properties, an improvement in the resistance to salts crystallization and the good photocatalytic activity on both dyes. The experimental data suggest that the basic coating has to be preferred for carbonatic stones for its harmlessness and better performances in terms of self-cleaning action and protection against water and salts. Graphical Abstract: Self-cleaning photocatalytic coatings based on TiO, obtained by sol-gel at two different pH values, are applied on Pietra di Noto carbonatic stone. TiO nanoparticles and coatings are characterized by SEM, XRD and Raman. The photocatalytic activity of the coatings is evaluated under UV irradiation, by monitoring methyl orange and methylene blue dye degradation as a function of time. The basic coating is suitable for carbonatic stones for its harmlessness and better performances in terms of self-cleaning action and protection against water and salts.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Blackening and disaggregation of exposed surfaces of stone monuments are well-known effects of stone decay taking place in polluted urban environments all over the world. This paper aims to assess the contribution of natural and anthropogenic sources of total suspended particulate (TSP) causing permanent damage (black crusts) to the stone monuments of Catania (Sicily), one of the most popular 'cities of art' of southern Italy. Atmospheric pollution of Catania, a typical Mediterranean coastal town, is mainly contributed by vehicle exhaust emissions rather than industrial ones. Episodically, the city also suffers gaseous and ash emissions (plumes) from the nearby Mount Etna volcano. Thus, to discriminate between natural and anthropogenic contributions to stone decay on Catania monuments, black crusts and TSP were sampled within the urban area and subjected to specific analytical procedures (optical microscopy, X-ray powder diffraction, Fourier transformed infrared spectroscopy, scanning electron microscopy equipped with energy dispersive spectrometry, ionic chromatography and dual inlet mass spectrometry). Mineralogical, chemical and isotopic characterization of black crusts and TSP provided new insights concerning the partition of sulfate sources in this particular urban context. The influence of Mount Etna emissions on both TSP and black crusts compositions was shown. Nevertheless, the key role of anthropogenic sources in the total sulfate budget was confirmed, while sea spray and volcanic emissions were found to make subordinate contributions. Quantitative data useful for the identification of the threshold pollution levels for preventive conservation of Catania monuments were obtained. [ABSTRACT FROM AUTHOR]

We report on a non-destructive study of Sicilian ceramic fragments of cultural heritage interest, classified as 'proto-majolica' pottery and dating back to the twelfth to thirteen centuries AD. The analytical approach used is based on the employment of two totally non-invasive spectroscopic techniques: X-ray fluorescence (XRF), using a portable energy-dispersive XRF analyser, and X-ray absorption spectroscopy, using synchrotron radiation as a probe (SR-XAS). XRF measurements allowed us to collect elemental and spatially resolved information on major and minor constituents of the decorated coating of archaeological pottery fragments, so providing preliminary results on the main components characterizing the surface. In particular, we assigned to Fe and Mn the role of key elements of the colouring agent. With the aim of obtaining more detailed information, we performed SR-XAS measurements at the Fe and Mn K-edges at the Italian BM08 beamline at the European Synchrotron Radiation Facility (Grenoble, France). The experimental data were analysed by applying principal component analysis and least-squares fitting to the near-edge part of the spectra (X-ray absorption near-edge structure) to determine the samples' speciation. From the overall results, umber, a class of brownish pigments characterized by a mixture of hydrated iron and manganese oxides, has been ascribed as a pigmenting agent. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Noto is an important Baroque urban center in south-eastern Sicily, which was completely reconstructed after the severe earthquake of 1693. Most of its monuments and historic buildings were built in Pietra di Noto stone, a pale cream calcarenite, quarried in outcrops located near the city. This stone, still currently used as building material, is undergoing many forms of alteration and degradation, which cause significant damage to monuments. In this study, three commercial protective products were tested on some Noto calcarenite samples from quarries, with the aim of assessing their protective effectiveness. In particular, petrographic analyses by optical microscopy were carried out for textural characterization of the stone materials. Capillary water absorption, porosimetric and colorimetric procedures, UV radiation and salt crystallization aging tests were performed to better evaluate interactions between protective products and substrate. [ABSTRACT FROM AUTHOR]

This paper presents new petro-chemical data on some typical mortars found in many buildings in the historic city centre of Catania (Eastern Sicily). Extensively used in the architecture of the city from the second half of the nineteenth century until the mid-twentieth century, these mortars are characterised by a particular aggregate locally known as “ agghiara” or “ ghiara”. This is the product of thermal transformation induced by the heating undergone by palaeo-soils, originally rich in organic matter, covered by lava flows, which change their colour to reddish nuances. The volcanic origin of ghiara is a peculiar feature of the Etnean area. Mixed with lime, it gives to mortars an intense reddish colour, as well as hydraulic properties, which are comparable with those of the historically used pozzolana. This work aimed at complete characterisation of these ghiara mortars, for providing information on several important technological aspects. In order to get information on used raw materials, sampling of some ancient underground quarries, located both in the historic city centre and at the periphery, was also performed. Results led to the complete characterisation of the selected ghiara mortars and yielded information on some technological features and the composition of both newly formed and secondary phases, these latter due to alteration processes. The hydraulic properties of mortars have been related to the occurrence of amorphous phases within the ghiara aggregate, which were identified by means of SEM morphological observations. These phases, formed during the “firing” process of palaeo-soils, react with lime producing hydraulic compounds (C–S–H and C–A–H), which are responsible for the mortars durability. [ABSTRACT FROM AUTHOR]

The Cathedral of St. Giorgio in Ragusa Ibla (Sicily) is one of the most important Baroque monuments of eastern Sicily. The restoration of the monument underway has put forward notable questions regarding the stone materials used and their state of degradation. The façade appears to be made mainly of a creamy white calcarenite, and of mortars and plasters. However, detailed analysis has highlighted a more complex use of the raw material. The mortar and plaster have a different composition in regards to their architectural use while the natural stone material is distinguished not only by a creamy-white calcarenite but also by a dark coloured bituminous calcarenite (pitch rock), which now appears whiter because of superficial chromatic alterations. This process was reproduced in the laboratory using an accelerated aging technique on samples of bituminous calcarenite, which allowed the cause of the alternation to be identified as photo-oxidation of the asphaltenes. Following this process of photo-oxidation, other forms of chromatic alterations affected the façade (brown–orange-coloured patinas). FTIR, Scanning Electron Microscope and thin section microscopic observation allowed the characterization of also the products of this process to be carried out, highlighting the complex mechanism which the processes underwent. [ABSTRACT FROM AUTHOR]

The Cathedral of St. Giorgio in Ragusa Ibla like the majority of historic buildings in the Ragusa area is constructed mainly from locally outcropping calcarenite belonging to the Ragusa Formation. Through the years, the cathedral has undergone diverse restoration procedures using different protective products , the nature of which was determined by means of Fourier transform infrared spectroscopy (FT-IR) and gas chromatography coupled with mass spectrometry (GC–MS). Regardless of these interventions, the materials used today are still subject to diverse forms of alterations and degradation (alveolitation, differential degradation, decohesions, chromatic alterations and the formation of biological patinas correlated to lichen activity), which cause considerable damage to the façade. In this paper, three protective products were tested on the calcarenite of the Ragusa Formation taken from a quarry: a fluorurated elastomer , a fluorurated anionic polyurethane and linseed oil. The protective efficiency was determined, after undergoing UV radiation aging by means of capillary water absorption, porosimetric and colorimetric procedures. The results highlighted a good and persistent protective capability of both the elastomer and the fluorurated polyurethane, whereas, the linseed oil not only provoked strong chromatic variations but also quickly lost its hydro-repellant capacity with aging. [ABSTRACT FROM AUTHOR]

An archaeometric study of the stone materials employed in the Late Baroque historical monuments of the ancient city centre of Catania was carried out. Lithological maps of a selection of monuments, transferred to a digital format, revealed that the stone materials are both magmatic and sedimentary rocks, the colours of which are matched in a peculiar type of bichromy. Particular attention focused on sedimentary rocks, which consist of various types of limestone quarried near the city of Syracuse (Hyblean Plateau, south-eastern Sicily). Carbonate rocks were characterised in terms of mineralogy, petrography and geochemistry, by studying rock samples from both monuments and historical extraction sites. Results showed that, although only one name was historically attributed to the above lithotypes (i.e. “Pietra di Siracusa‘’), they were quarried from many locations and, as they belong to various geological formations, they therefore exhibit great variety. In order to examine the durability of Hyblean limestones employed in works of cultural heritage interest, salt crystallisation tests were carried out according to standard procedure norms (UNI EN 12370 () Determination of resistance to crystallisation of salts, 6p). Results are consistent with the forms of deterioration observed in the monuments, and highlight the close relationship between textural characteristics and damage. Our purpose is to provide a basic tool, which may be useful both for conserving monuments of cultural heritage and for their restoration. [ABSTRACT FROM AUTHOR]

The recent discovery of the Sphinx Room, belonging to the Domus Aurea Esquiline wing, thanks to the framework given by the project "Non-destructive analytical studies at Parco Archeologico del Colosseo (Rome, Italy)", allowed to perform an analytical campaign, both in situ and on micro-fragments. The first aim was to contribute to the overall comprehension of the Domus Aurea complex and to contextualize the newly-discovered room inside this extraordinary imperial architecture by means of an archaeometrical characterisation of the painting materials. The palette, composed of Egyptian blue, green earths, iron- and lead-based red, orange and yellow, calcite, carbon-based black, allowed to compare the Sphinx Room to Corridor 92 and Room 114 of Domus Aurea and to other sites in Rome. Furthermore, the employ of an organic binder in some spots can be put forward based on spectroscopic results, which does not exclude a wider use of the a fresco. Furthermore, a complementary methodological strategy was designed, in order to achieve a complete characterization of the materials. In addition to the well-known combination of portable X-ray fluorescence and portable/laboratory Raman analyses, Infrared Fourier Transform Spectroscopy was used, both in situ (Diffuse Reflectance) and in the lab (Attenuated Total Reflectance). The results confirm the suitability of this approach for the characterization of Roman wall paintings, where both inorganic and organic materials are simultaneously present. [ABSTRACT FROM AUTHOR]

Apulia (southern Italy) is typified by widespread outcrops of rocks exploited in the last centuries in historical architectures and religious constructions, as building and decorative stone. Today, as in the past, these stones represent an important source for region economy and prestige, due to their uses for modern works, restoration of local medieval churches and also exporting abroad. Among these, a noteworthy and still poorly known material is the Carovigno stone. In this paper, firstly an overall view on the, mineralogical and petrophysical features of the stone was reached through a multianalytical approach based on several investigation procedures and techniques, including ultrasonic test, X-ray diffractometry, scanning electron microscopy, optical microscopy, mercury intrusion porosimetry. In order to simulate decay phenomena, the Carovigno stone samples were processed to three different ageing tests: cycles of thermal treatments at different high temperatures, cycles of heating-cooling and cycles of exposure to decahydrate sodium sulphate and sodium chloride saline solutions. During and after each ageing processes, mineralogical transformations and petrophysical changes were evaluated. Results suggested that the Carovigno stone is a fine-grained calcarenite, pure or nearly pure, characterized by high porosity and, consequently, very notable thermal stress resistance. Conversely, the type and amount of porosity causes stone predisposition to salt crystallization decay. [ABSTRACT FROM AUTHOR]

Geopolymers have been recently proposed for restoration of built heritage to substitute traditional mortars. Local materials and industrial wastes from the Italian region Sicily showed their potential as low-cost aluminosilicate sources for the preparation of geopolymers. Here, a set of Sicilian clays was studied by Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC), and its mineralogical composition was evaluated by X-ray diffraction (XRD). The raw materials were used to prepare geopolymers by alkaline activation with or without the addition of silicate. The thermal degradation profile of the final materials was studied by TGA and compared with that of the precursors, and the energetics of dehydration were investigated by DSC. Two statistical analyses (made by Principal Component Analysis) were performed on the TG data of raw materials and geopolymers and on the TG data of geopolymers and their mineralogical composition, respectively. The last analysis in particular showed a correlation between the mineralogical composition of the materials and the samples' thermal properties. Additional studies of samples subject to accelerated aging by UV irradiation and exposure to acetic acid vapors highlighted the different effects of these two agents on the samples’ stability.Graphical abstract: Geopolymers have been recently proposed for restoration of built heritage to substitute traditional mortars. Local materials and industrial wastes from the Italian region Sicily showed their potential as low-cost aluminosilicate sources for the preparation of geopolymers. Here, a set of Sicilian clays was studied by Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC), and its mineralogical composition was evaluated by X-ray diffraction (XRD). The raw materials were used to prepare geopolymers by alkaline activation with or without the addition of silicate. The thermal degradation profile of the final materials was studied by TGA and compared with that of the precursors, and the energetics of dehydration were investigated by DSC. Two statistical analyses (made by Principal Component Analysis) were performed on the TG data of raw materials and geopolymers and on the TG data of geopolymers and their mineralogical composition, respectively. The last analysis in particular showed a correlation between the mineralogical composition of the materials and the samples' thermal properties. Additional studies of samples subject to accelerated aging by UV irradiation and exposure to acetic acid vapors highlighted the different effects of these two agents on the samples’ stability. [ABSTRACT FROM AUTHOR]