Archaeological Glass Research Articles

Transparency at its best: neutrons probing archaeological glass finds from Romania

This paper demonstrates the suitability of Prompt Gamma Activation Analysis (PGAA) technique for the compositional study of ancient glass finds, illustrating this idea by presenting and commenting the chemical composition of 41 Roman glass fragments discovered in archaeological excavations at Tomis, Histria, and Beidaud, Romania. According to typological and stratigraphic criteria, most finds were dated to the 1st-4th centuries AD. The PGAA measurements were performed at the Budapest Neutron Centre (BNC), Hungary. Regardless of their color (or the lack of it), most of the analyzed vitreous items have compositional traits often encountered in coeval glass artefacts discovered at various sites all over the Roman Empire. The sample set turned out to include several examples of Foy Série 2.1 and a single HIMT glass item, in agreement with the later chronological attribution of the corresponding fragments. This study provides some information about the chemistry of the Roman glass finds unearthed during the archaeological research performed in the region of the western Black Sea coast.

Analyzing the Physicochemical Characteristics of an Archaeological Glass Collection from Mexico City, Mexico

Este trabajo es un estudio preliminar de análisis químico-físico de 20 fragmentos de vidrio arqueológico de la Ciudad de México, mediante microscopio electrónico de barrido (MEB) con emisión de rayos X, hasta ahora no realizado en el país. El contenido de óxidos y particularidades físicas de las muestras permitió delimitar que: diecisiete coincidieron, relativamente, con los componentes identificados en vidrios europeos previos al siglo XVIII y tres posteriores a éste. Las características físicas microscópicas fueron diversas y manifestaron adherencias resultantes del entorno que genera su degradación. Lo anterior abre un panorama de análisis de contenido de óxidos y mecanismos de degradación del vidrio que permitirá avanzar en la comprensión del proceso de producción de este material en nuestro país. ___________ This paper is a preliminary study detailing the results of a chemical-physical analysis executed on 20 fragments of archaeological glass from Mexico City. The analysis was carried out using scanning electron microscopy (SEM) and X-ray microanalysis, two techniques not previously applied in Mexico, for this purpose. The content of oxides and the sample’s physical characteristics allowed us to determine that approximately seventeen coincided with the types of components identified in European glass before the 18th century. The other three were identified as having come from a later period. The physical characteristics on the microscopic level were diverse and showed adhesions resulting from the effects of environmental degradation. This facilitates analysis of oxide content and mechanisms of glass degradation that will allow us to further our understanding of this material’s production process in our country moving forward.

British glass consumption during World war one in the Ypres Salient (Belgium): an archaeological contribution

ABSTRACT Glass finds are a common feature of archaeological excavations in the context of World War One (WWI). In spite of this, only little attention is paid to this material category. The main aim of this article is therefore to explore the type of information that can be gained from the study of glass and to emphasise the importance and added value of well-developed research into material finds at WWI sites. The study itself is based on a traditional material culture study of the British Army’s use of glass in the Ypres Salient, Belgium, during WWI. As a foundation for the study, 5 different archaeological glass finds were examined and statistically analysed. Combined with data from commercial archaeological research, this provided insights into the glass containers used and their contents, the spatial distribution of these objects and the chronological trends in their use.

Beads of Alexandria: Non‐invasive analysis of glass from Roman, Late Antique and Islamic Kom el‐Dikka, Egypt

AbstractWritten sources indicate that Alexandria in Egypt was a leading producer of Roman glass. Furthermore, archaeological finds have provided evidence for the local production of drawn glass and gold‐in‐glass beads, which were distributed throughout the world. In this study, we present an analysis of the chemical composition of more than two hundred glass objects from the Roman (2nd–3rd/4th century ce) and Late Antique (4th/5th–7th century ce) glass bead workshops located at Kom el‐Dikka in Alexandria. This study is based on the results of portable X‐ray fluorescence (pXRF) analyses carried out on raw glass, bead semi‐products, products and waste from both periods. Additionally, the glass chemistry of some Islamic (8th–12th century ce) beads found at the site has been analysed.Despite the limitations of the method, the vast majority of samples exhibited compositions confirming their general dating and Egyptian origin. Remarkably, a single bead was made of high‐alumina glass and appeared to be an import from India, possibly a remnant of the Indo‐Pacific glass bead route that connected Red Sea ports and Europe in Late Antiquity. In addition, we offer a new analytical approach to the method that has potential to enhance the value of pXRF in the analysis of archaeological glass.

A comparative and experimental study to evaluate the use of nanocontainer solutions for removing polymeric coatingsfrom glass artifacts

Purpose The purpose of this study is to evaluate the effectiveness of nanocontainer solutions in removing deteriorated and aged polymers commonly used in coating and consolidating archaeological glass. Design/methodology/approach This study focused on characterizing glass surfaces coated with two commonly used polymeric materials in archaeological glass preservation. Furthermore, the study evaluates the elimination of these coatings from the surfaces by using innovative aqueous systems composed of micellar solutions (MS) and oil-in-water (O/W) Texapon-P microemulsions (TEX). Glass samples coated with selected polymers were subjected to thermal and photochemical aging to simulate natural degradation conditions. This study aimed to evaluate the effectiveness of nanocontainer aqueous systems compared to acetone (Ac), a conventional solvent commonly used for removal procedures. The characterization procedures involved transmission electron microscopy, USB digital microscopy, scanning electron microscopy, color alteration and gravimetric measurement. Findings The findings indicate that the effectiveness of novel techniques using aqueous nanocontainer systems is quite promising when considering a “green approach” to preserving cultural heritage. Microscopic examination demonstrated the efficacy of MS in effectively removing acrylic and vinyl polymers from the glass surface. Furthermore, TEX proved effective in removing polyvinyl acetate (PVA) over Paraloid B72 (B-72). In addition, the measurement of color alteration values revealed a decrease after using MS compared to the standard sample before applying the polymers, with values of ΔE = 1.48 and 1.82 for B-72 polymer and PVA, respectively. Originality/value This research provides nanocontainer solutions for removing aged polymers from the glass surface. This makes the current study a promising step for treating archaeological glass.

Evaluation of Cleaning Soiled Deposits and Crusts from Archaeological Glass Using Laser Treatment with Ag/Au Nanoparticles

The study aims to evaluate the effect of silver and gold nanoparticles during the laser cleaning process of glass artifacts. It is the first time that nanoparticles have been used to clean antique glass, as far as the authors are aware. In the context of this study, work was done on glass samples extracted from excavations that suffer from dense layers of corrosion products, soil deposits, brittle, easy to break, and cannot bear pressure. To characterize the investigated glass shards and assess the cleaning procedure, a variety of analytical techniques, including the transmission electron microscope (TEM), digital microscope, stereomicroscope, scanning electron microscope (SEM-EDX), X-ray diffraction (XRD), and color change measurement, have been used. The XRD analysis revealed different minerals such as ferrosilite, hillebrandite, and jacobsite, in the black corrosion layer, and calcite, syngenite, and arcanite in the white crust layer. The results of the microscopic examination employed in the evaluation procedure demonstrated that using Ag NPs with laser perfectly removed the tough crust layers without scratching the surface. The cleaned surface became smooth, homogenous and more transparent. The elemental analysis results by (SEM-EDX) revealed a significant reduction in the proportion elements of the (Al, Fe, p, and Mg) in the corrosion layer and their loss in the cleaned areas. Measurement of color change indicated that laser-treated glass samples with the addition of Ag NPs gave higher (ΔE*), confirming the influential role of this method in cleaning archaeological glass. It was also observed that the effect of Ag NPs with Laser assistance decreases the required time for the cleaning process. Thus the heat generated by the laser-treated was reduced, so the laser-treated with Ag NPs is recommended for use in the archaeological glass cleaning process.

Unravelling the role of iron and manganese oxides in colouring Late Antique glass by micro-XANES and micro-XRF spectroscopies

This research aims to understand colouring technologies in 5th–7th centuries glass imported to Atlantic Britain by correlating the iron (Fe) and manganese (Mn) ratios and oxidation states with colour. Despite having a similar matrix chemical composition and concentrations of Fe and Mn oxides, these vessels display different colours (from green to yellow/amber, sometimes with purple streaks). Colour changes can be induced by controlling the reduction-oxidation reactions that occur during glass production, which are influenced by the raw materials, furnace and melt atmosphere, and recycling. To evaluate these parameters, reference glasses were prepared, following the composition of Late Antique archaeological glass recovered from Tintagel (UK) and Whithorn (UK). A corpus of archaeological and experimental glass samples was analysed using bulk Fe and Mn K-edge x-ray absorption near edge structure (XANES) spectroscopy, micro-XANES and micro x-ray fluorescence (μ-XRF) at beamline ID21, at the European Synchrotron Radiation Facility. Fe and Mn XANES spectra of the archaeological glass indicate that Fe and Mn are in a similar oxidation state in all the yellow samples, predominantly Fe3+ and Mn2+. No detectable difference in Mn and Fe oxidation state occurs in the purple streaks compared to the yellow glass bulk but μ-XRF maps of the distribution of Fe and Mn show that Mn is more concentrated in the purple streaks. This indicates that the purple colour of the streaks is mainly due to a higher Mn/Fe ratio and persistence of more oxidised manganese in the purple areas, even though it is difficult to detect. Many archaeological fragments appear pale green in transmitted light but amber in reflected light. XANES studies detected the presence of surface layers where manganese is more oxidised. This layer is believed to scatter transmitted and reflected light differently and might be responsible for the optical features of the archaeological glass.

Elegant robustification of sparse partial least squares by robustness-inducing transformations

Robust alternatives exist for many statistical estimators. State-of-the-art robust methods are fine-tuned to optimize the balance between statistical efficiency and robustness. The resulting estimators may, however, require computationally intensive iterative procedures. Recently, several robustness-inducing transformations (RIT) have been introduced. By merely applying such transformations as a preprocessing step, a computationally very fast robust estimator can be constructed. Building upon the example of sparse partial least squares (SPLS), this work shows that such an approach can lead to performance close to the computationally more intensive methods. This article proves that the resulting estimator is robust, by showing that it has a bounded influence function. To establish the latter, this article is first to formulate SPLS at the population level and therefrom, to derive (classical) SPLS's influence function. It also shows that the breakdown point of the resulting regression coefficients can approach 50% when properly tuned. Extensive Monte Carlo simulations highlight the advantages of the new method, which performs comparably and at times even better than existing robust methods based on M-estimation, yet at a significantly lower computational burden. Two application studies related to the cancer cell panel of the National Cancer Institute and the chemical analysis of archaeological glass vessels further support the applicability of the proposed robustness-inducing transformations, combined with SPLS.

Glassmaking remains from the 12th to 14th centuries CE glass workshop in Boshan, Shandong Province, China

Many glass furnaces producing K2O-CaO-SiO2 glass were excavated in Yanshen Town, Zibo city, Shandong province, dating to the Jin to Ming Dynasties, a large-scale glass-making center recorded in historical sources. According to the typological study of ceramics, the workshop which produced the studied samples dated from the Jin to the Yuan Dynasties (12th to 14th centuries CE), and is one of the earliest archaeological glass workshops found in China. The workshop yielded many semi-finished glass fragments, final products, and glass crucible fragments. We conducted chemical and micro-structural analysis by LA-ICP-AES and SEM-EDS, determining that the glass recipe included feldspar, quartz, nitrate, fluorite, colorants, and probably calcite. These minerals match those in the glass recipes recorded in the historical literature. Glass making comprised at least two steps, namely the pre-melting of raw materials into a semi-finished glass, to which more fluxes were then added to make the final glass products or ingots.

Glass beads from a Scythian grave on the island of Khortytsia (Zaporizhzhia, Ukraine): insights into bead making through 3D imaging

AbstractFour glass beads from a Scythian burial on the island of Khortytsia (Southern Ukraine) were subjected to 3D imaging using micro-CT and photogrammetry. The aim was to reconstruct the process used to produce and decorate the beads by detecting and interpreting the traces left by the technological processes on the bead surface and in the glass body. It turned out that all the beads were obtained by winding hot glass around the mandrel. The distribution, size and shape of the bubbles in the glass matrix revealed by the micro-CT scans and the features observed during a thorough examination of the photogrammetric models allowed us to follow the movements of the bead maker during the formation of the bead body and its decoration, highlighting several details of the production processes such as the number of the superimposed layers and the direction of the rotation of the mandrel during both the formation of the body and the decoration of the bead. Some information about the tools also emerged, with particular reference to the shape of the mandrel, the possible use of a releasing agent and how tools were used to decorate the surface or to remove the beads from the mandrel. According to the archaeological classification, the beads considered here belong to three different types, that are considered chronological indicators of the fourth century BCE and are found in archaeological sites spread over an area extending for several thousand kilometers from the Black Sea coast to the Ural Mountains. This work enriches the knowledge of the micromorphology of beads found in Eastern Europe, which is rarely discussed in the scientific literature on the archaeological glass beads.

An experimental study for using nano-alumina to improving mechanical properties of epoxy resin for assembling glass artifacts

Purpose This study aims to assess the efficacy of nano-alumina (nano-Al2O3) in improving the performance of epoxy adhesives used to assemble archaeological glass. The conservators face a significant problem in assembling this type of artifact. Therefore, the assembling process is considered one of the important stages that must be taken care of to preserve these artifacts from damage and loss. Design/methodology/approach To evaluate the stability of adhesives, the samples were subjected to artificial aging under varying environmental conditions. Some investigative techniques and mechanical testing were used in this study to evaluate the selected materials. It includes a transmission electron microscope, X-ray diffraction, visual assessment, digital microscope, scanning electron microscopy (SEM), color change and tensile strength test. Findings The visual evaluation and the digital microscope results showed that the epoxy/nano-Al2O3 greatly resisted artificial aging. Although slight yellowing was present, it did not significantly affect the general appearance of the samples. On the other hand, the pure epoxy sample showed cracks of different sizes on its surface due to aging, as evidenced by SEM examination. Furthermore, epoxy/nano-Al2O3 has a better tensile strength (11.27 MPa) and slight color change (ΔE = 2.06). Originality/value The main objective of the experimental study was to identify appropriate adhesive materials that possess key properties such as non-yellowing and improved tensile strength by conducting various tests and evaluations. Ultimately, the goal was to identify materials that could serve as effective adhesives for assembling the archaeological glass.

In the quest for historical Lisbon through 17th century Millefiori glass

Being Lisbon one of the world’s most important trading port and a place where historical documents attest the presence of at least four glass furnaces working between the 16th and 17th centuries, the authors decided to investigate one of the most luxurious coeval glass decorative techniques (millefiori) found in Lisbon to try to understand the trade route and raw-materials provenance of these artefacts.For this work, two Lisbon archaeological contexts were selected: Largo do Chafariz de Dentro (LCD) and Santana Convent (LCS) due to their significant amount of interesting millefiori fragments (eight fragments) and the presence of production waste (one in LCD and three in LCS). The analysis, comparison and discussion of glass production waste (PW) and archaeological glass artefacts will be carried out for the first time.For this work, macroscopic and microscopic observations were combined with the chemical characterization of colourless and coloured glass to make the morphological characterization and to determine which raw materials were employed in its production. The chemical characterization was made by using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to obtain the major, minor and trace elements composition, including rare earth elements (REE).The chemical composition of the selected samples revealed that all the millefiori glasses are of soda-lime-silica type (part of them made with Levantine ashes and the other part with barilla) while the glass type of PW is was not attributed.Regarding the Lisbon millefiori glass fragments, there is a notable relation between the concentration of major components associated with the silica source, namely SiO2, Al2O3 and TiO2. Moreover, upon analysing the geochemical patterns exhibited by the production waste found in LCS context and comparing it with the pick-up glass fragments, a consistent trend emerges, implying that both were made by using either the identical silica source or, at the very least, a closely related silica source. For this reason, the possibility of a Portuguese local production may be proposed, especially when some decorative patterns are clearly from Portuguese inspiration (e.g. caravel and cross of Christ), while the authors admit that more data analysis is still required to prove this hypothesis.

Robust adaptive variable selection in ultra-high dimensional linear regression models

We consider the problem of simultaneous variable selection and parameter estimation in an ultra-high dimensional linear regression model. The adaptive penalty functions are used in this regard to achieve the oracle variable selection property with simpler assumptions and lesser computational burden. Noting the non-robust nature of the usual adaptive procedures (e.g. adaptive LASSO) based on the squared error loss function against data contamination, quite frequent with modern large-scale data sets (e.g. noisy gene expression data, spectra and spectral data), in this paper, we present a new adaptive regularization procedure using a robust loss function based on the density power divergence (DPD) measure under a general class of error distributions. We theoretically prove that the proposed adaptive DPD-LASSO estimator of the regression coefficients is highly robust, consistent, asymptotically normal and leads to robust oracle-consistent variable selection under easily verifiable assumptions. Numerical illustrations are provided for the mostly used normal and heavy-tailed error densities. Finally, the proposal is applied to analyse an interesting spectral dataset, in the field of chemometrics, regarding the electron-probe X-ray microanalysis (EPXMA) of archaeological glass vessels from the 16th and 17th centuries.

Cluster analysis for the selection of potential discriminatory variables and the identification of subgroups in archaeometry

In this article, three variable selection methods based on Gaussian mixture models were compared to find a subset of variables that provided the “best” clustering. The use of an appropriate transformation for compositional data, whose geometric space is the Simplex, is emphasized. The comparison revealed the ability of the models to cluster data in multiple phases, showing to be more convenient to select the relevant variables than to perform an analysis based on 2D plots or by simultaneously including all the available variables in a multivariate analysis. Once the informative variables for the clustering were obtained, we used a method called Databionic Swarm (DBS). This method uses unsupervised machine learning, taking advantage of emergence and swarm intelligence applied to find natural chemical groups in the input data space. DBS can visualize high-dimensional distances in the projection through a 3D topographic map with hypsometric tints. The results were compared in terms of accuracy, both in the selection of the variables and in the classification, using a supervised accuracy index for clustering and two unsupervised indexes (the Heatmap and the Silhouette plot). The concepts and methods were illustrated by applying them to two published archaeological glass data sets. The first set consisted of 245 Romano-British glass vessels and the second set of 180 glass vessels from the 15th-17th century in Antwerp. In these applications, it was found that the methods for the selection of variables increased the accuracy of the classification compared to traditional methods.

Localised extended (“vermiform”) features formed during glass dissolution

Studies on glass durability are important to our understanding of the likely long term behaviour of vitrified nuclear wastes, natural and archaeological glasses; there has, however, been little in the way of systematic reporting of features associated with localised chemical attack on such glasses. Durability experiments performed in water at 90 °C from 28 d to 672 d on glass monoliths of 5 different compositions: 3 basaltic compositions; an inactive version of the 25 wt% loaded UK mixture Windscale (MW25) glass and the International Simple Glass (ISG) all yielded locally extended or vermiform alteration features. Similar features are seen on all glasses at all dissolution times studied. The number of features and whether they were filled by alteration products or not was dependant on glass composition. The majority of features have quite simple geometries but lesser numbers of more complex morphologies are seen. The location of these features is thought to be most probably linked to residual damage arising from the monolith production providing sites for locally accelerated dissolution. Despite being sites of localised accelerated dissolution the impact of these features on the total surface area is calculated to be limited. Hence the surface area term used to calculate normalised mass losses and normalised loss rates will not be greatly in error as a result of these features.

Effect of network connectivity on behavior of synthetic Broborg hillfort glasses

AbstractThere is wide industrial interest in developing robust models of long‐term (>100 years) glass durability. Archeological glass analogs, glasses of similar composition, and alteration conditions to those being tested for durability can be used to evaluate and inform such models. Two such analog glasses from a 1500‐year‐old vitrified hillfort near Uppsala, Sweden have previously been identified as potential analogs for low concentration Fe‐bearing aluminosilicate nuclear waste glasses. However, open questions remain regarding the melting environment from which these historic glasses were formed and the effect of these conditions on their chemical durability. A key factor to answering the previous melting and durability questions is the redox state of Fe in the starting and final materials. Past work has shown that the melting conditions of a glass‐forming melt may influence the redox ratio value (Fe+3/∑Fe), a measure of a glass's redox state, and both melting conditions and the redox ratio may influence the glass alteration behavior. Synthetic analogs of the hillfort glasses have been produced using either fully oxidized or reduced Fe precursors to address this question.In this study, the melting behavior, glass transition temperature, oxidation state, network structure, and chemical durability of these synthesized glass analogs is presented. Resulting data suggests that the degree of network connectivity as impacted by the oxidation state of iron impacted the behavior of the glass‐forming melt but in this case does not affect the chemical durability of the final glass. Glasses with a lower degree of melt connectivity were found to have a lower viscosity, resulting in a lower glass transition temperature and softening temperature, as well as in a lower temperature of foam onset and temperature of foam maximum. This lower degree of network connectivity most likely played a more significant role in accelerating the conversion of batch chemicals into glass than the presence of water vapor in the furnace's atmosphere. Future work will focus on using the results from this work with outcomes from other aspects of this project to evaluate long‐term glass alteration models.

Data from Multiple Portable XRF Units and Their Significance for Ancient Glass Studies.

X-ray fluorescence spectroscopy is a non-destructive technique employed for elemental analysis of a wide range of materials. Its advantages are especially valued in archaeometry, where portable instruments are available. Considering ancient glass, such instruments allow for the detection of some major, minor, and trace elements linked to the deliberate addition of specific components or to impurities in the raw materials of the glass batch. Besides some undoubted advantages, portable XRF (p-XRF) has some limitations that are addressed in this study. The performance assessment of four different p-XRF units and the reconciling of their output were conducted. The results show the limitations in cross-referencing the data obtained from each unit and suggest procedures to overcome the issues. The p-XRF units were tested on the set of Corning reference glasses and on a small set of archaeological glasses with known composition. The compatibility of the output was assessed using multivariate statistical tools. Such a workflow allows us to consider data from multiple sources in the same frame of reference.

Compositions of early Islamic glass along the Iranian Silk Road

The composition of archaeological glass reflects the geochemical nature of its raw materials. To determine the origins and distribution of early Islamic glasses from Iran, a set of 169 glass samples from five different sites was analysed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of 58 elements. The glasses were classified into six different plant ash glass groups, three of which were attributed to a Mesopotamian origin, while three further groups are presumed to represent regional Iranian productions. The ratios of MgO/CaO and K2O/P2O5 of the different groups reflect variations in the plant ash component. Minor elements Cr, Ti, Zr, La and Th and their ratios proved effective in distinguishing the base glass types. Mapping their frequency across the Iranian plateau revealed the relative movement of glass and likely source areas. The decline in the frequency of glass types with elevated Cr/La ratios east of the Zagros Mountain range confirms that elevated Cr/La ratios together with an augmentation of the magnesium levels are features of Mesopotamian glass production apparently inherited from the geochemical environment of the Euphrates and Tigris river valleys. Some exceptionally clean Mesopotamian glasses made from a quartz-rich silica with low levels of accessory minerals are consistent with ninth-century glass from Samarra, which was evidently traded widely along the Silk Road network. No evidence of local glass production was detected in Nishapur. The Iranian groups were produced from a quartz-rich silica source, high in thorium but with different zirconium contents resulting in different Th/Zr ratios. Aluminium concentrations tend to increase from west to east, with the highest values found among glass assemblages from Central Asia.

Sand and Pebbles: The Study of Portuguese Raw Materials for Provenance Archaeological Glass

Portuguese archaeological excavations dated to the 17th century onwards are extremely rich in glass artefacts, with this being a reality from the north to the south of the territory. Contrasting with this reality, no glass production locations from this period have been discovered or excavated so far, which makes the provenance attribution a challenging endeavour. One specific archaeological location, the Monastery of Santa Clara-a-Velha in Coimbra, held one of the largest glass archaeological assemblages dated to the 17th century unearthed in Portugal so far. Due to the large variety of objects’ shapes, glass colours and decorative features, this assemblage is a valuable candidate to hold glass artefacts produced in Portugal. Lacking archaeological excavation on glass furnaces in Portugal, the study of glassmaking raw materials is the most promising research line to investigate the provenance of glass circulating in Portugal. In this study, sand and pebbles from six different locations in the north/centre of Portugal were collected and melted to produce glass samples. The resulting glass samples were chemically characterised using LA-ICP-MS, to obtain the composition of the samples in major, minor and trace elements. The obtained results were compared with the composition of 37 historical samples from the Monastery of Santa Clara-a-Velha previously studied. Additionally, the thermal properties of selected synthesised glasses were analysed by Differential Scanning Calorimetry, allowing new insights on melting temperatures and glass workability. Results indicate that three artefacts with stylistic features attributed to a Portuguese production were locally made with sands collected in Coimbra.

АРХЕОЛОГІЧНІ СТЕКЛА – МОДЕЛЬ ДЛЯ ОЦІНЮВАННЯ СТІЙКОСТІ ОСКЛОВАНИХ РАДІОАКТИВНИХ ВІДХОДІВ

This article presents the possibility of usage of the archaeological glasses to predict the behavior of radionuclides incorporated into the glass matrix, under the conditions of the underground storage during prolonged contact with the groundwater. Archaeological glasses, whose age is more than two thousand years old, selected from the cultural horizon of the archaeological reserve "Olvia" were examined. A gel layer was formed on the surface of the glass prolonged contact with the soil, on the outer surface of which layered aluminosilicates are formed. The formation of a protective layer of the glass occurs by the mechanism of the incongruent dissolution. It has been experimentally established that alkaline and alkaline earth cations (Na, Ca), partially silicon and iron, are intensively removed into the soil during leaching from the glass, with the practical immobility of aluminum. Simulation of glass fracture was performed in Soxhlet extractors under conditions of continuous exposure to hot water (t = 75–80 °C) saturated with carbon dioxide for 6 months. The change in the rate of components removal from the glass is connected with an increase in the thickness of the "locking" gel layer, the thickness of which increases over time. Cyclic changes in the dissolution rate of the glass are connected with the partial destruction of the gel layer due to the increase in thickness of the gel layer and, accordingly, a decrease in the adhesion of the gel to the glass. The results of the aluminosilicate (archaeological) glasses fracture study and their comparison with the results of the borosilicate glasses fracture study indicate that archaeological glasses can be a model for the predicting of the behavior in natural conditions of the glass matrices intended for radioactive waste volume reduction for centuries.