Engineering Characterization of Lockhart Limestone for Construction Applications: An Integrated Geomechanical, Petrographic, and Geochemical Approach

ABSTRACT This study presents an integrated geo mechanical, petrographic, and geochemical assessment of Lockhart Limestone to evaluate its suitability for construction applications and cement production in Pakistan. A 75 m thick exposure was systematically investigated through field logging, laboratory testing, and petrographic analysis. All tested geomechanical properties confirm to standards established by the British Standards Institution, the American Society for Testing and Materials, and the International Society for Rock Mechanics and Rock Engineering. Uniaxial compressive strength (UCS) ranges from 25 to 188 MPa (mean = 106 MPa), reflecting significant lithofacies-controlled heterogeneity. Petrographic analysis reveals a calcite-dominated fabric (>75 %) with minimal reactive phases (dolomite < 8 %, quartz <3 %), explaining negligible alkali–silica reactivity (expansion = 0.056 %). Geochemically, high calcium oxide content (53.7 wt. %) and low impurities, confirm suitability as a cement raw material. A robust empirical model developed from 30 paired point-load and UCS tests enable reliable strength prediction for routine quality control.