Investigation of the effect of saturated conditions and number of measurements on the Leeb hardness test and improved correlations to estimate basic rock properties

Abstract

The Leeb hardness test, which is developed for metallic materials, is a practical and precise test method and therefore its use on rock materials has started to increase in recent years. Since there is not yet a proposed standard method for determining the Leeb hardness on rocks, it was aimed to determine the variation of Leeb hardness on dry and saturated samples, to determine the optimum number of measurements and to reveal the correlation between the optimum number of measurements and rock properties on 26 rock sample groups. A total of 202 samples were tested both in dry and saturated conditions. Leeb measurements were taken as 20 single impacts on a surface of each sample after that basic physical and uniaxial compressive strength (UCS) values of all samples were determined. According to the results of the study, it was determined that the arithmetic mean of taken ten single impacts measurements on a sample was recommended in general use. In saturated conditions, the hardness values were found lower than the dry conditions in various rates under the control of open porosity values. Correlation equations for the prediction of some physical properties and UCS values of rocks have been proposed. The updated test conditions will allow to more effective use of the test method in rapid quality assessment and material characterization of rocks.