Estimating the brittleness values of carbonated rocks with Shore, Schmidt, and Leeb hardness values

There is not a defined standard method for determining the brittleness of rocks. Prediction of rock brittleness using rebound based hardness test methods is widely used in the characterization of rocks because they are non-destructive, inexpensive, and easy to apply. Rock surface hardness can also be used to predict the physical and mechanical properties of rocks. In this study, hardness values of 12 different carbonated rocks were determined on the same specimens using 3 different methods. C-2 type Shore Scleroscope, L-type Schmidt hammer, and Leeb hardness test device are rebound based hardness tests. The aim of the study is to determine the most suitable rebound hardness test method, that can be used to estimate the four different brittleness values recommended, by considering the compressive and tensile strength values in the literature. Relationships between the hardness values obtained using three different test methods and four different brittleness values were analyzed. It was observed that each method can be interchangeable. It was determined that the rebound based hardness tests could be used in predicting two of the four different brittleness values, which are widely used in the literature but cannot be used in estimating the other two. The strongest relationships were obtained from Leeb hardness values, followed by Shore hardness values and Schmidt hardness values, respectively. The best method to estimate the two brittleness indexes of rocks was determined as Leeb hardness. Besides, Shore hardness and Schmidt hardness methods also had strong relationships between the two brittleness indexes.