Petrography and Mechanical Properties of Dolostone Rocks from Kawagarh Formation Khanpur Area Hazara Basin, North Pakistan

Abstract

The estimation of rock mass strength is a key parameter in geotechnical engineering which is used in the design of geotechnical structures like tunnels, dams, and slopes. Physical characterization was carried out on dolomite rocks from the Kawagarh Formation to explore their potential for utilization as construction and aggregate sources. The Kawagarh Formation will be exposed in Hazara Basin in different sections. A laboratory test was performed per ASTM and ISRM standards to determine uniaxial compressive strength, Brazilian, Schmidt, specific gravity, water absorption, Los Angeles abrasion, and sulfate soundness. The uniaxial compressive strength was determined by using a universal testing machine to crush core samples, The Brazilian test was also performed on a core sample in a horizontal direction, following ISRM and ASTM suggested methods. Schmidt rebound hammer by Schmidt hammer apparatus. While the engineering destructive tests were carried out on aggregate using various apparatus. Mean specific gravity 2.7 to 2.76%, water absorption 0.61 to 0.69% Los Angeles abrasion 14.20%to 16.35% and sulphate soundness values 0.72% to 1.62%. The UCS ranges from 28.64 Mpa to 33.08 Mpa and Brazilian test values range from 6.27 Mpa to 7.26 Mpa and the Schmidt hammer rebound numbers range from 31.31 to 32.26 of the dolomite's rocks. The evaluated mechanical and physical properties were compared with standard specifications for their qualification as construction materials. Petrographic study of the rocks reveals the presence of 93% to 97% dolomite, 3% calcite, 2% sparry calcite, and 2% opaque contents. The presence of calcite contents does not seem to affect the mechanical properties of this dolomite, while pyrite may cause various reactions with water and different solutions can affect mechanical properties. The study indicates that the dolomites of the Kawagarh Formation fall within standard specifications limits and can be used for construction purposes.