This study explores the thermal behavior of four widely used Iranian granites - Khoramdareh, Nehbandan, Natanz, and Taibad - under temperatures ranging from 20°C to 1050°C. The investigation focused on the evolution of microcracks and their impact on key physical properties such as porosity, water absorption, and P-wave velocity in both dry and saturated conditions. Using fluorescence microscopy, linear microcrack density (LMD), microcracks type, and width were analyzed in detail. At 300°C, all granite samples showed an increase in inter-crystalline microcracks, leading to elevated porosity and water absorption. At 600°C, the quartz phase transition at 573°C resulted in volumetric expansion, causing a temporary decrease in porosity and an increase in P wave velocity. For example, the dry P wave velocities at 600°C were 4.77 km/s for Taibad, 4.71 km/s for Khoramdareh, 3.84 km/s for Natanz, and 5.12 km/s for Nehbandan. Above 750°C, trans-crystalline microcracks became dominant, significantly increasing porosity and water absorption while reducing P wave velocity. Nehbandan granite suffered structural failure at 600°C, whereas Natanz exhibited the highest LMD at 750°C, indicating severe internal damage. The study highlights the importance of microcracks evolution and mineralogical transformations, particularly quartz phase transitions, in controlling granite's thermal stability. Three critical thresholds (300°C, 600°C, and 750°C) were identified as turning points in the deterioration process. Additionally, this research introduces a novel methodological approach, combining fluorescence microscopy with physical testing to achieve detailed characterization of thermal damage. By extending the temperature range up to 1050°C, the study provides valuable insights into granite performance in fire-prone and heat-exposed environments.
Nejati, S. , Khamehchiyan, M. and Nikudel, M. Reza (2025). Thermal Effects on Microcracking and Physical Characteristics of Khoramdareh, Natanz, Nehbandan, and Taibad Granites. Geopersia, (), -. doi: 10.22059/geope.2025.390516.648809
MLA
Nejati, S. , , Khamehchiyan, M. , and Nikudel, M. Reza. "Thermal Effects on Microcracking and Physical Characteristics of Khoramdareh, Natanz, Nehbandan, and Taibad Granites", Geopersia, , , 2025, -. doi: 10.22059/geope.2025.390516.648809
HARVARD
Nejati, S., Khamehchiyan, M., Nikudel, M. Reza (2025). 'Thermal Effects on Microcracking and Physical Characteristics of Khoramdareh, Natanz, Nehbandan, and Taibad Granites', Geopersia, (), pp. -. doi: 10.22059/geope.2025.390516.648809
CHICAGO
S. Nejati , M. Khamehchiyan and M. Reza Nikudel, "Thermal Effects on Microcracking and Physical Characteristics of Khoramdareh, Natanz, Nehbandan, and Taibad Granites," Geopersia, (2025): -, doi: 10.22059/geope.2025.390516.648809
VANCOUVER
Nejati, S., Khamehchiyan, M., Nikudel, M. Reza Thermal Effects on Microcracking and Physical Characteristics of Khoramdareh, Natanz, Nehbandan, and Taibad Granites. Geopersia, 2025; (): -. doi: 10.22059/geope.2025.390516.648809
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