Examine the Correlation between Physico-Mechanical properties of Selected Granite rocks in Ondo State, Nigeria

Abstract

This research examines the correlation between physico-mechanical properties of some selected granite rocks in Ondo State, Nigeria. Samples were collected at Zibo FM Quarry, Aaye and Samchase Quarry, Itaogbolu and tested in the laboratory for the determination of rock density, hardness, and strength. An average density of between 2.57g/cm3 and 2.67g/cm3 was recorded. Schmidt hammer and Rockwell hardness machine wereused for the determination of rock samples hardness. An average uniaxial compressive strength of rock sample was estimated from the values obtained from Schmidt hammer rebound value. The Hardness test varies from 115.90MPa to 185.00MPa (classified to have high strength) while the average Rockwell hardness varied from 45.1HRA - 57.32HRA. The average point load index ranges from 7.402MPa - 7.505MPa classified to have very high strength. Multiple regression analysis using computer-aided solution (Statistical Package for Social Sciences - SPSS) was used to analyze data obtained from the laboratory and field tests. Five parameters were input into the multiple regression analysis to generate the models. Two parameters which are Schmidt hammer rebound value and Rockwell hardness value out of five parameters are dependent variables, while point load index, uniaxial compressive strength, and density are independent variables. The result of the models developed shows positive correlations – an indication that the hardness of rock gives a significant contribution in drilling bit selection.

Keywords: Rock density, Schmidt hardness, Rockwell hardness, uniaxial compressive strength, point load strength, and SPSS