EFFECTS AND CONTROLS OF PETROGRAPHIC CHARACTERISTICS ON GEO-MECHANICAL PROPERTIES OF CHHIDRU FORMATION WESTERN SALT RANGE, PAKISTAN

Abstract

The strength of a rock mass is the key parameter in geotechnical engineering which can be used for designing structures i.e. dams, buildings, roads and tunnels etc. Mechanical characterization of limestone of Chhidru Formation was carried out to explore its potential for utilization as aggregate material or dimension stone. Investigation of the effect of petrographic characteristics on mechanical properties and its application needs to be carried out as it is accessible in Western Salt Range. This work is also important because of inadequate published work on Chhidru Formation in terms of geotechnical assessment. Laboratory test were performed in accordance with ASTM and ISRM standards to determine Uniaxial Compressive Strength Test (UCS), Uniaxial Tensile Strength Test (UTS), Schmidt Rebound Hammer Test (SRH), Point Load Test (PLT), Specific Gravity (SG) and Water Absorption Test (WA). Average values calculated for SG is 2.60% and WA 0.46%. The UCS ranges from 44.50 MPa to 53.36 MPa with a mean value of 48.41 MPa and UTS values ranges from 9.185 MPa to 15 MPa with a mean value of 12.88 MPa and SRH average values ranges from 38.66 to 44.00 of the studied samples. The evaluated mechanical and mineralogical properties were compared with standard specifications of ASTM and ISRM for their significance as construction materials. Petrographic study of the rocks revealed the presence of calcite, bioclast and hematite in the samples. The study indicates that the average calcite content is 73.6 % and average bioclast content is 10.8%. Chhidru Formation falls within standard specification limits and can be used for construction purposes and utilized as aggregate sources in construction industry.