Physico-mechanical and petrographic insights of Lockhart Limestone, sections of Islamabad, Pakistan

Abstract

This paper investigates the physico-mechanical and petrographic attributes of the Palaeocene Lockhart Limestone, which were measured, sampled and described from the Rumli and Shah Allah Ditta sections of Islamabad, Pakistan. Petrographic analysis shows that the limestone is categorised mainly into mudstone and wackestone microfacies and the dominant presence of the micrite matrix favours the strength of the rock, whereas veins, microfractures and porosities adversely affect the stability of the rock. Unconfined compressive strength (UCS) and point load test (PLT) analyses show that the limestone samples that have the lowest porosities partnered with bioclasts present the highest UCS and PLT values, and the higher porosities partnered with bioclasts correspond to the lowest values of UCS and PLT. The physico-mechanical analyses reveal that the limestone aggregates are within the limits of the respective standards for utilisation in wearing, coating and cement concrete. The limestone of both sections can be utilised for geotechnical purposes such as crushed material and aggregate sources. Simple regression analysis was employed, and based on these correlations, the limestone of the studied formation is designated as moderately strong and recommended for road or bridge construction.