PETROGRAPHIC INVESTIGATION OF LIMESTONE OF THE LAKI FORMATION USED IN CONSTRUCTION SECTOR FROM JAMSHORO AND THATTA DISTRICTS, SINDH, PAKISTAN

Abstract

Limestone belonging to the Laki Formation is well exposed at Nooriabad, Jhampir, and Makli Hills.  Representative samples of the Laki Formation limestone were collected from different locations such as Jamshoro, Bolhari, Makli Hills, and Nooriabad. The four crush plants i.e. Afridi Crush Plant and New Hazara Crush Plant (Makli, Thatta District), Shah Rahim Crush Plant and Bhatti Crush Plant (Nooriabad, Jamshoro District) were selected for sampling. The Petrographic investigation as per ASTM- C295-03 (1) was performed using standard thin sections. The megascopic and microscopic study results reflect no hindrance in using the studied limestone. For cement concrete, this limestone can be used for the low-strength concrete and aggregate base course and sub-base. Variation in lithology, stratification and non-homogeneity was observed, however, the aggregate from the New Hazara crush plant is found fractured in nature and therefore, its use as concrete material is not suggested. The studied limestone of all crushed plants does not show any potential for Alkali Silica Reaction (ASR) and Alkali Carbonate Reaction (ACR). Based on the present study, it is concluded that the studied limestone of the Laki Formation from the above-mentioned locations is suitable for construction purposes and industrial use. For cement concrete, this limestone can be used for the low strength concrete and pavement (sub-base & base coarse) as well as aggregate base course. In the stockpile of crushed aggregate on crusher plants, the chalky limestone was found to be less stable and less durable.