Date

2018

Author

Sırt Çıplak, Elif

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Traditional conservation methods for the preservation of historical stones including applications with inorganic and organic polymers are often inadequate and results in introduction of new deterioration problems to historic structures. At this point, consolidating a stone by re-creating a structure similar to original microstructure of stone is a new approach developed to ensure the maximum compatibility by comparison to the traditional conservation techniques. In this study it was aimed to develop a sustainable and an eco-friendly repair material, biological mortar (BM)/infill, to be used in conservation interventions for healing micro-cracks (<1 mm) in travertines of historical monuments. This new repair material contains an environmental strain of a known bacteria species. In this context, bacterial isolation and identification were carried out from thermal spring water resources in Pamukkale Travertines (Denizli). Bacillus cereus, already known to have high calcite production capacity, was selected for BM development studies within isolated strains. Upon specifying all components of BM in details, mortar set up was performed in defined proportions and applied to micro-cracks of artificially aged test stones. Performance of this repair material was examined through physical, physico-mechanical, microstructural analyses, and other evaluation criteria. Consequently, a strong bond between the grains and matrix of BM was determined in relation with the calcite production activities of B. cereus. Moreover, in all samples where BM application was performed, interface of biological mortar and original material showed continuous and coherent structure. Hence, biological mortar and production substructure developed in this study, could be used for remediation of micro-cracks and micro-voids in historical travertine structures such as sculptures, ornaments, capitals, and elements. In future studies, to increase the rate and concentration of bacterial calcite precipitation in mortar, some parameters in the experimental procedure could be improved by adding specific enzymes or macromolecules having potential to induce nitrogen cycle pathways to the nutritive medium, using large fermenters that could yield high quantities of bacteria, using multiple bacterial populations that might also increase the amount of calcite production and identifying genes related with the mineral production process and with the adjustment of these genes, bringing out large quantities of macromolecules that might induce calcite precipitation.

Subject Keywords

Historic buildings, Historic buildings, Travertine., Bacteria., Mortar., Calcite.

URI

http://etd.lib.metu.edu.tr/upload/12622634/index.pdf
https://hdl.handle.net/11511/27781

Collections

Graduate School of Natural and Applied Sciences, Thesis