ESTIMATING THE HARDNESS AND ABRASION PROPERTIES OF IGNEOUS ROCKS FROM CERCHAR INDENTATION DEPTH (CID

Abstract

The most known and applied method for determining the abrasivity of rocks is the Cerchar Abrasivity Index (CAI). Properties of rocks such as abrasive mineral content, density, strength, and degree of cementation are the main factors affecting abrasivity, and these parameters likewise control their hardness properties. In this study, the average scratch depth formed on the rock surface after the CAI test was determined and it was investigated whether this calculated new parameter had the properties to represent the rock. Measurements were taken from four points along the scratch line formed on the surface with the help of a comparator and the average value was defined as the Cerchar Indentation Depth (CID). Measurements have shown that igneous rocks have CID values in the range of 0.01 mm-0.68 mm. Apart from the CID parameter, nine different properties (hardness, abrasivity, and physical) of fifty igneous rocks were tested. Statistically significant results were obtained by establishing relationships between CID and other rock mechanics tests. In CAI tests, it has been shown that CID measurements can be determined very sensitively if well-leveled core samples with parallel lower and upper surfaces are used. It has been determined that the CID value is directly related to the investigated rock properties and can be used as very useful experimental data in estimation studies.