Geotechnical and Petrographic Assessment of Kamila Amphibolites from Kuza Drushkhela, Swat (KP), Pakistan: Evaluating Their Feasibility as Concrete Aggregates in Construction Applications

The growing demand for high-quality, locally available construction materials has intensified interest in evaluating alternative rock sources for aggregate production. This study examines the potential of Kamila Amphibolites, extensively exposed in Kuza Drushkhela of the Matta region, District Swat, Khyber Pakhtunkhwa, Pakistan, for use as coarse aggregates in concrete and other structural applications. The study area lies within the southern portion of the Kohistan Island Arc, a terrain dominated by medium- to high-grade metamorphic rocks. Representative samples, including both aggregate and bulk rock specimens, were systematically collected and subjected to comprehensive petrographic and geotechnical investigations. Petrographic analysis identified Amphibole, Epidote, Hornblende, and Plagioclase as the principal mineral phases, displaying predominantly anhedral to subhedral textures with minor mica and accessory minerals. Engineering evaluation followed ASTM, AASHTO, BS, and National Highway Authority (NHA) standards. The determined properties include specific gravity (3.015 g/cm³), water absorption (0.270%), bulk density (3.031 g/cm³), soundness (1.022%), flakiness index (12.10%), uniaxial compressive strength (63.83 MPa), and Los Angeles abrasion value (9.84%). These results are within the acceptable range for high-performance construction aggregates. The findings demonstrate that Kamila Amphibolites possess the requisite strength, durability, and physical characteristics, confirming their suitability for concrete manufacturing and large-scale civil engineering works.