AshEse Journal of Physical Science
Vol. 1(1), pp. 001-008, April, 2015
© 2015 AshEse Visionary Limited
Full Length Research
Muhammad Arif1, Ihtisham Islam2,3* and Muhammad Rizwan2
1Department of Geology, University of Peshawar, Peshawar, Pakistan
2National Centre of Excellence in Geology, University of Peshawar, Peshawar, Pakistan.
3Shaheed Benazir Bhutto University Sheringal, Dir Upper, Pakistan.
Received March, 2015; Accepted April, 2015
The granitic rocks of the Kumrat area (upper Dir group of Kohistan Batholith) have been investigated in terms of their petrographic features and mechanical properties. Field observation and petrographic studies of representative samples reveal that the Kumrat granites are sub-equigranular to inequigranular, coarse to medium grained and without any preferred orientation. They essentially consist of plagioclase, quartz and alkali feldspar (exclusively orthoclase) with accessory amounts of biotite, muscovite, sericite, an opaque ore mineral and trace amounts of apatite. Chlorite observed in the studied samples is undoubtedly secondary mineral.The quartz grains are mostly strained and display strong undulose extinction. As a part of present study, some of the mechanical and physical properties including uniaxial compressive strength (UCS), uniaxial tensile strength (UTS), shear strength, specific gravity, porosity and water absorption of samples representing different textural varieties of Kumrat granites were also determined. The average UCS values for coarse and medium grained varieties are 49.15 and 58.50 respectively. On the basis of UCS values, the coarse grained and medium grained varieties fall in the category of moderately strong and strong rocks respectively. Correspondingly the values of their specific gravity, porosity and water absorption are within the range permissible for their use as construction material. A detailed investigation of petrographic features and mechanical properties reveals that the medium-grained granites are stronger than the coarse-grained ones, probably because of their relatively finer grain size. Elaboration of the relationship between physico-mechanical properties and petrographic characteristics is needed.
Key words:Granitic rocks, petrography, mechanical properties.