Conservation and Restoration of Cultural Heritage / Kültür Varlıklarını Koruma ve Onarım
Permanent URI for this collectionhttps://hdl.handle.net/11147/23
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Article Characterization of Yellow Patina on Stone Surfaces by Instrumental Analysis Including Libs(Taylor & Francis, 2022) Badur, Fulya; Aras, Nadir; Yalçın, Şerife; Böke, HasanYellow patina formed on the stone surfaces of historical buildings, monuments, and archaeological structures due to weathering is considered a value of the building in the conservation of cultural heritage studies. Although yellow patina layers can be easily distinguished on white marble surfaces, it is not possible to distinguish them on the yellow travertine surfaces with the naked eye. It should be taken into account in yellow travertines as well as marble surfaces before conservation treatments of the stone. In this study, mineralogical and chemical compositions and the thicknesses of yellow patina layers formed on yellow travertine and marble surfaces in Aizanoi, Aphrodisias, and Hierapolis archaeological sites in Turkey were analyzed in order to constitute a conservation approach in the archaeological sites. In this respect, XRD, FT-IR, SEM-EDX, and LIBS were used in the determination of compositions and thicknesses of yellow patina. Although LIBS analysis is a more convenient method to investigate patina layers on stone surfaces, this technique is not as well known as the others. Yellow patina layers contained calcium oxalate in the form of whewellite (CaC2O4.H2O). Their thicknesses were between 15 and 100 μm and should be protective against weathering on travertine and marble surfaces. Highlights LIBS analysis seems to be the most convenient micro-destructive method to estimate the thickness of the yellow patina layers on the marble and yellow travertine surfaces. The determination of the thickness of the yellow patina is critical to keep irreversible cleaning interventions, especially for the yellow travertines due to their similar colors. Yellow patina is mainly composed of calcium oxalate with clay minerals and organic compounds.Article Citation - WoS: 27Citation - Scopus: 28Lime Mortar Technology in Ancient Eastern Roman Provinces(Elsevier, 2021) Uğurlu Sağın, Elif; Duran, Hasan Engin; Böke, HasanNatural pozzolanic aggregates were discovered during the Roman era and have been widely used in hydraulic mortar production. Despite the claims of ancient treatises, the properties of pozzolans and the technology of hydraulic lime mortars were well known and applied in the eastern provinces of the Roman Empire. In this study, the characteristics of lime mortar at the ancient sites of Aigai and Nysa located in Western Anatolia were investigated to elicit the technology applied. The raw material compositions of the mortars, the hydraulic properties of the binders, and the mineralogical and chemical compositions of the natural pozzolans used were determined via X-ray diffraction, X-ray fluorescence spectroscopy, scanning electron microscopy coupled with energy dispersive spectroscopy, and thermogravimetric analysis. The major and trace element compositions of the natural pozzolans were evaluated via multivariate statistical analysis to determine whether the same local raw material resources were used in their manufacture. The analytical results indicated that the Roman mortars were hydraulic, stiff, and durable materials due to the use of natural pozzolanic aggregates mostly comprising dacite. Although the aggregates had similar mineralogical compositions, multivariate statistical analysis revealed that their chemical compositions were clearly distinguishable, indicating the use of different sources of raw materials. Thus, it was inferred that similar pozzolan resources were known and deliberately used to produce hydraulic mortars in the eastern ancient Roman provinces.