تحلیل ویژگیهای فنی آجر در بناهای تاریخی کاشان.

Objective: Self-sufficiency and reliance on natural materials are fundamental principles of Iranian architecture, with brick being a locally abundant material in Iran. Over time, brick buildings require retrofitting, restoration, and enhancement. To gain a deeper understanding of brick and its retrofitting, it is essential to analyze historical bricks and incorporate past experiences in brick making. This research aims to examine the technical characteristics of bricks used in the historical buildings of Kashan city across different time periods. Five brick samples from these historical structures have been selected for analysis. Method: The research employs a quantitative approach based on field studies and laboratory experiments. The experiments are categorized into three groups. The first group comprises basic tests, including density, specific gravity, moisture content, and water absorption. The second group encompasses mechanical tests, focusing on compressive and bending strength. The third category involves chemical tests conducted through X-ray Diffraction (XRD) analysis. Results: The tests revealed that the specific weight of the samples ranged from 1.6 to 2.14 grams per cubic centimeter, while water absorption varied between 9.3 and 18.5 percent. The compressive strength was found to be between 53.12 and 195.27 kg/cm², and the bending strength ranged from 11.62 to 125.83 kg/cm². The findings indicate that basic characteristics significantly influence mechanical properties. As specific weight and volume density of the samples increase, their internal pore structure diminishes, leading to reduced moisture content and lower water absorption. Furthermore, higher sample density correlates with increased compressive and bending strength. The predominant chemical composition in the samples was quartz, while the presence of gypsum contributed to decreased mechanical resistance. In contrast, higher levels of quartz, anorthite, and albite enhanced the resistance of the samples Conclusions: The physical and mechanical characteristics of brick samples remain relatively stable over time. Consequently, it appears that the resistance parameters are more influenced by the quality of the raw materials, sample density, and production methods rather than the age of the samples. [ABSTRACT FROM AUTHOR]