Physico-Mechanical and Petrographic Appraisal of Carbonate Rocks as Construction Aggregate: A Case Study from Lesser Himalaya, Pakistan

Owing to the exceptional role of crushed rock aggregates in construction, their prospective reserves fulfilling qualitative and economic parameters should be identified to meet their ever-increasing demand. This research aims to unlock new sources of high-quality construction materials, thereby optimizing concrete performance and meeting the requirement for sustainable building materials. The study investigated the physicomechanical and petrographic properties of Jurassic, Cretaceous, and Eocene limestones of the Kawagarh Formation (KF), Samana Suk Formation (SSF), and Margalla Hill Limestone (MHL) along the Abbottabad–Nathiagali roadside section, as per the American Society for Testing and Materials (ASTM) and British Standards Institute (BSI). The results of geotechnical investigations are flakiness and elongation index (19.6–34.85% and 17.53–31.2%), specific gravity (2.64 to 2.67), water absorption (0.34–0.63%), unconfined compressive strength (41.72–80.65 MPa), loss angeles abrasion value (15.63–19.08%), impact value (15.38–19.36%), and the soundness (0.9–1.97%). These results showed values within the acceptable range according to ASTM and BSI standards. Petrographically, the KF is classified as mud and wackestone, the SSF was mainly classified as wacke-packstone and grainstone, while the MHL was classified as bioclastic wacke and packstone. The dominancy of micrite matrix favors the strength of aggregate, whereas porosity, microfractures, stylolites, and allochems adversely affect the mechanical properties of rock aggregates. Based on reserve estimation, the studied sections possess significant exploitable reserves and are feasible for quarry operations. The studied rocks can be utilized to produce high-strength concrete, optimizing its performance and quality.