Alteration dependent physical-mechanical properties of quartz-diorite building stones

The microscopic and geomechanical properties of igneous building stones include the extent of alteration, presence of micro cracks, peak strength, porosity, proportion of detrimental minerals, etc. Porosity has reportedly a devastating impact on the peak strength of igneous rocks. The quartz diorite rock samples in this study were selected from five quarries in Natanz of Iran and were subjected to microscopic and geomechanical investigations. The extent of alteration and the detrimental minerals affecting the strength of the samples were identified from examination of thin sections. Therefore, the geomechanical tests on density, porosity, durability index, the Brazilian, and triaxial tests were conducted following the ISRM standards. The findings from microscopic studies revealed that compared to porosity, alteration has a more intense impact on rock’s peak strength. The results were compared to standard values and a qualitative correlation between strength and microscopic properties was detected revealing the importance of construction stones microscopic studies. The correlation thereupon may be adopted in the exploration, exploitation, and processing of construction stones to avoid heavy expenses and damages to the environment.