Carbonate Rock Evaluation: Petrographic Insights and Geotechnical Implications for Construction Industries in the Salt Range Region, Pakistan

The China-Pakistan Economic Corridor (CPEC) has spurred a massive construction drive in Pakistan, necessitating the exploration of diverse natural aggregate sources to sustain this development. Therefore, this study delves into the petrographic characteristics and mechanical properties of carbonate rocks from the Chichali Gorge (Lockhart and Nammal Formations) and Zaluch Gorge (Amb Formation) in the Western Salt Range, Pakistan. Employing geotechnical analyses adhering to British Standards (BS) and American Society for Testing and Materials (ASTM) standards, various laboratory analyses were conducted. Simple regression analysis unveiled interrelationships among physical parameters. Petrographic scrutiny categorized Lockhart (LFPal) and Nammal (NFEo) Formations as wackestone and Amb Formation (AFPm) as mudstones. Calcite and bioclasts emerged as primary components, shaping the limestones. Petrographic insights elucidated the rocks' engineering traits, establishing correlations between petrography and diverse physical and mechanical properties. Notably, Unconfined Compressive Strength (UCS) and Unconfined Tensile Strength (UTS) exhibited direct associations with calcite content but inverse correlations with porosity and bioclasts. Rocks with higher porosity and water absorption displayed diminished strength, while those with lower porosity exhibited robust strength metrics. Based on these analyses, LFPal and NFEo emerged as pivotal sources for small- and large-scale projects, including CPEC. However, due to their elevated silica content, caution is advised concerning AFPm aggregates. This study provides valuable insights for construction endeavors, ensuring informed material selection for optimal project outcomes in the CPEC framework.