Rock Indentation Indices as Criteria in Rock Excavation Technology – A Critical Review

It has been known for thousands of years that materials differ in hardness, quantitative methods of measuring hardness by performing careful indentation experiments only began to be developed during the nineteenth century. At the beginning of the twentieth century, hardness testing machines began to be commercially available. The purpose of this review paper is to present the techniques and advances in Indentation of rocks. Such Rock Indentation is essential for studying the fundamental processes like drilling and cutting operations. The indentation testing is used for characterisation of hardness of rocks. The testing procedure was developed to be in line with other ISRM Suggested Methods. The results show that standardised indentation testing allows for characterisation of mechanical properties of rock and that there is a relationship between the value of the indentation hardens index and the uniaxial compressive strength. And also, rock indentation test is used in the development of models for rock fragmentation process. The review explains the correlation of indentation indices with mechanical properties of rock and the fracturing process of rock during indentation.