Phd Degree / Doktora
Permanent URI for this collectionhttps://hdl.handle.net/11147/2869
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Doctoral Thesis Properties of Lime Binders and Aggregates of Roman Mortars in Western Anatolia(Izmir Institute of Technology, 2021) Taşcı, Burcu; Böke, HasanIn this study, the characteristics of Roman lime mortars taken from a wide area in Western Anatolia were determined in order to understand whether there was a common production technology of lime mortar in the Roman Empire by making a comparison between Europe and Western Anatolia. For this purpose, opus caementicium and opus signinum mortars were collected from twenty-six archaeological sites in Western Anatolia. Basic physical properties, raw material compositions, mineralogical and chemical compositions, mechanical, microstructural, and hydraulic properties of mortars, pozzolanicity and geochemical characteristics of aggregates were identified by SEM-EDS, MIP, XRD, TGA, FTIR analyses, and point load tests. Results showed Roman lime mortars were compact, low dense, and high porous materials. Opus caementicium mortars were grayish with the use of crushed stones, however opus signinum mortars were light brownish due to the use of crushed bricks/tiles. Opus caementicium mortars were used in various types of structures, while opus signinum mortars were generally used in water-related structures. Lime/aggregate ratios of mortars varied between 1:4-3:2 parallel to ideal lime/aggregate written in Roman sources. Despite using high calcium lime in the production of mortars, the compressive strengths of mortars were found compatible with NHL3.5 type of lime due to the use of pozzolanic aggregates which were produced from rhyolite and dacite (silicic rocks). These results indicated that the properties of Roman lime mortars were similar in Western Anatolia and other regions of the Roman Empire. This finding can be evidence of common lime mortar technology produced using similar local sources throughout the Roman Empire.Doctoral Thesis Long-Term Protection Efficiency of Biodegradable Polymer Treatments on Limestone(Izmir Institute of Technology, 2019) Kaplan, Zişan; Böke, Hasan; Sofuoğlu, Aysun; İpekoğlu, BaşakSynthetic polymers can be replaced by biodegradable ones as adhesive, water repellents and consolidants in stone conservation to preserve historic buildings from further deterioration. In this study, the long-term stabilities of two biodegradable polymers, polyhydroxybutyrate (PHB) and poly-l-lactide (PLA) and an acrylic polymer (Paraloid B72), which are commonly used in conservation works of artefacts, were evaluated on limestone through an UV lamp-weathering chamber. Chemical and morphological changes induced by accelerated weathering test were followed by Fourier Transform Infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) analysis. The protection efficiencies of the polymers were determined by following the changes in the color, capillary water absorption and static contact angle on the limestone surfaces in accordance with CEN standards developed by the European Committee of Standardization (CEN) for conservation of cultural property. PHB, PLA and Paraloid B72 coatings significantly increased hydrophobicity, decreased capillary water absorption and caused negligible change in the color of the limestone. All polymers showed chemical, physical and optical changes under accelerated weathering conditions. Paraloid B72 decomposed by the reduction of molecular weight, decomposition of ester group and formation of gamma lactones and hydro peroxides. PHB and PLA decomposed with formation of CO2 and hydro peroxide, hydrolysis of ester groups and reduction of the molecular weight. Chemical changes cause to etching, holes, voids, cracks and slight color differentiations on the coatings by chain scission, breaking of polymer bonds and formation of volatile gaseous products. Protection efficiencies of the PLA and PHB polymers almost same as that of the widely used acrylic polymer Paraloid B72. However, PLA and PHB seem to be promising polymers as protective agents due to their reversibility and biodegradability, low chromatic changes, good hydrophobic behavior and good stability to weathering in reducing the effects of outdoor exposure on limestone surfaces.