Assessment of Petrographic and Physico-Mechanical Properties of Granodiorites for Aggregate Usage: A Comprehensive Case Study from Mayar, Dir (Lower), Khyber Pakhtunkhwa Pakistan

The current study systematically evaluates the granodiorites from the Mayar area through integrated petrographic and physico-mechanical analyses as well as the interrelationship between these parameters to assess their viability as heavyweight aggregates and dimensions stones in civil engineering applications. Field observations indicate that the rock is medium to coarse-grained, hard, and compact, having dark brown and greyish colour on weathered and fresh surfaces, respectively. Petrographic study exhibits that the rocks are euhedral to anhedral, having the dominant concentrations of plagioclase, quartz, K-feldspar, biotite, hornblende, fluorite, and andalusite, with a minor amount of clinopyroxene, muscovite, rutile, and actinolite. The physical and mechanical characterization includes grading, specific gravity and absorption, flakiness and elongation indices, Los Angeles abrasion, and soundness. These analyses demonstrate compliance with standard permissible ranges, confirming their potential as construction materials. Mechanical analysis yields average uniaxial compressive strength (UCS) and uniaxial tensile strength (UTS) 52.96 MPa and 8.54 MPa, respectively, classifying the rock within the moderate to strong category. The above-integrated study reveals that medium-grained granodiorites exhibit higher strength compared to coarse-grained varieties. Plagioclase and mica contents are identified as the dominant controlling factors, whereas quartz and K-feldspar show negligible influence on the strength of the granodiorite. Considering the favourable mechanical properties, excellent and extensive exposure and logistical accessibility of the outcrop, it is concluded that the granodiorite of the Mayar area is recommended for high-load-bearing applications, including Dir- Chitral motorway, CPEC developmental schemes, railway ballast, highways, and dimension stone cladding. Moreover, the quarry byproducts can be utilized as sustainable aggregates in secondary construction applications.