Analysis of stone alterations in traditional architectural structures in Gaziantep province and modeling using the terrestrial laser scanning

Gaziantep province has been home to many civilizations throughout history and, due to its strategic location, has been an important settlement area where various cultural influences intersect. Stone structures such as inns, bathhouses, castles, and fountains, especially those built during the Ottoman period, are among the most important elements that make up the historical fabric of the city. Although the stone material used in these structures was preferred for both its architectural aesthetics and durability, over time it has been subjected to various types of alterations due to environmental and structural factors. In this context, the main objective of the study is to identify the types of alterations observed in Gaziantep's historical stone structures, determine the causes of these alterations, produce data supported by chemical analyses, and document the current state of the structures with high accuracy using terrestrial laser scanning systems. The study examined a total of 24 stone structures located in the center of Gaziantep province, consisting of 14 houses, 7 bathhouses, 1 kastel, and 2 fountains. The alterations occurring in these structures were examined under four main headings: physical, chemical, biological, and anthropogenic. Physical alterations stem from temperature differences, humidity changes, and freeze-thaw cycles, while chemical alterations are mostly caused by atmospheric pollutants, salt crystallization, and the effects of water. Biological alterations originate from microorganisms and vegetation, while anthropogenic alterations result from unconscious human interventions, incorrect restoration practices, and environmental neglect. Within the scope of the research, chemical analyses were performed on samples taken from the stone surfaces of the structures using an XRF device, thereby enabling the detailed identification of the chemical compositions causing the alterations. Furthermore, the structures were digitally documented in three dimensions using terrestrial laser scanning technology, and the spatial distribution of alterations on stone surfaces was determined with the help of orthophoto images. These documents provided the basis for preparing analytical survey drawings and provided scientific support for intervention decisions prior to restoration. In conclusion, it is of great importance to correctly diagnose alterations in historic stone structures, analyze their causes using scientific methods, and develop conservation strategies accordingly. Although this study was conducted specifically in Gaziantep, it offers a comprehensive approach that can serve as an example for similar historic stone structures. Regular monitoring, appropriate material selection, and qualified restoration practices are vital requirements for the sustainable preservation of historic structures.