Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
4 results
Search Results
Now showing 1 - 4 of 4
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: 1Citation - Scopus: 1Plaster Characteristics of Byzantine Wall Paintings in Western Anatolia(Institute of Metals Technology, 2022) Şerifaki, Kerem; Böke, HasanIn this study, the execution technique and material characteristics of the plaster layers of Byzantine wall paintings from three archaeological sites (Anaia, Olympos and Aigai) from western Anatolia were examined for the purpose of their conservation. Throughout the study, mineralogical and chemical composition of the plaster layers were determined with a scanning electron microscope coupled with an X-ray energy dispersive system (SEM-EDS) and X-ray diffraction analyses (XRD). Reflected light microscopy (RLM) and SEM studies conducted on polished cross-sections of samples revealed the stratigraphy and microstructural properties of the plaster layers of the Anaia Church (4th–12th centuries), Baºpýnar Church (13th century) in Olympos and a Byzantine settling and the Chapel (13th century) in Aigai. Throughout the research, pure lime and aggregates in the plasters of Aigai, as well as magnesium-rich lime and straw in the plasters of Anaia and Baºpýnar were determined. The plasters from the Anaia and Baºpýnar Churches exhibit characteristics similar to the samples from the post-iconoclastic period due to a similar raw-material use. In the samples from Aigai, plastering techniques such as marmorino, intonachino and cocciopesto, indicating earlier periods, were observed. As a result of this study, it was concluded that the number and characteristics of the plaster layers from the paintings had been applied intentionally in accordance with the technique of the painting. Plaster characteristics of the wall paintings in western Anatolia from the Byzantine period were found to be similar to the ones in Ýstanbul, the Balkans, Crete and Cyprus. The results of this study will guide the conservation efforts of the wall paintings.Article Citation - WoS: 3Citation - Scopus: 3Microstructural Characteristics of Mortars Prepared by Hot Lime Mix(Union of Croatian Civil Engineers and Technicians, 2020) Şerifaki, Kerem; Uğurlu Sağın, Elif; Böke, HasanThe effect of lime characteristics and hot lime mix method on hydraulic, microstructural and mechanical properties of mortars is determined by producing mortars from quicklimes of two different marbles and two limestones. Results of SEM-EDS, XRD and TGA analyses reveal that the porous microstructure of mortars and spongy texture of calcite crystals are the indicators of the hot lime mix method. This study shows that characteristics of limestones used for the production of limes, as well as the preparation method, directly affect hydraulic, mechanical and microstructural properties of mortars.Article Citation - WoS: 8Citation - Scopus: 8Reducing Marble-So2 Reaction Rate by the Application of Certain Surfactants(Springer Verlag, 2003) Böke, Hasan; Gauri, K. LalSulfur dioxide (SO2), prevalent in the modern urban environment of industrial countries, attacks calcite (CaCO3) in marble. As a result, a gypsum (CaSO4.2H2O) crust is produced at rain-sheltered surfaces while areas exposed to rain experience accelerated erosion. We have investigated the effect of certain surfactants as protective agents against SO2 attack. We report that the anions oxalate (C2O4-2) and oleate (C17H33COO-) from solutions of their highly soluble alkali salt species are able to replace carbonate (CO3-2) in calcite producing less reactive substrate of oxalate and oleate of calcium. Experiments to measure the protection obtained by these treatments were carried out in the laboratory and field conditions at nearly 1 ppm and 10 ppb SO2 concentrations, respectively. We found that these treatments provided significant protection to marble exposed in sheltered areas, up to 30% reduction of reaction rate by treatment with 2 × 10-4 M sodium oleate and up to 14% by a 2 × 10-3 M with potassium oxalate solutions, but become ineffective over long term exposure when applied to surfaces exposed to rain. Carrara marble was used in the reported study. Ion chromatography was the analytical tool, which allowed precise measurements of ionic concentrations of these salts, the amount of their uptake by marble, and the thickness of the gypsum crust. X-ray diffraction allowed determination of the new minerals formed at the marble surface by the treatment with surfactants.