Reliance of physico-mechanical properties on petrographic characteristics: consequences from the study of Utla granites, north-west Pakistan

The relationship between the mechanical properties and petrographic features of granites from the Utla area, north-west Pakistan, was studied. Three different textural varieties of granites (megacrystic coarse-grained, fine-grained and foliated coarse-grained) were collected. Following a comprehensive petrographic analysis, their uniaxial compressive and tensile strengths as well their physical properties (porosity, water absorption and specific gravity) were determined. The modal concentrations, sizes and shapes of minerals as well as their distribution and alignment were analyzed during the petrographic observations. A detailed investigation utilizing statistical analysis revealed that megacrystic coarse-grained granites are stronger than the other two varieties because of greater variance in the grain sizes of their constituent minerals, their unaligned nature, lower abundances of micaceous minerals, and lower porosity and water absorption values.