Correlation of Uniaxial Compressive Strength with Indirect Tensile Strength (Brazilian) and 2nd Cycle of Slake Durability Index for Evaporitic Rocks

In engineering applications of rock materials, predicting the uniaxial compressive strength (UCS) is essential, particularly in the preliminary stage of a project. The UCS of rock materials is profoundly affected by the rock type, porosity, grain size, water content, etc. The rigor and cost of sampling as well as sample preparation are more than those of the Brazilian (indirect tensile strength, ITS) and 2nd cycle of slake durability index (I_d2) tests. Therefore, ITS or I_d2 values can be used to predict the UCS value of rocks through correlation. In this study, evaporitic rocks from Al Ain, United Arab Emirates (UAE) were examined. Forty-eight representative rock blocks were collected, while avoiding anisotropy effects of thinly bedded rocks along with the gypsiferous layers. The relations between UCS and ITS and UCS and I_d2 were estimated with representative empirical equations. Results reveal moderate correlation between them. Moreover, Student’s t and F tests show that there is a significant correlation between UCS and ITS and I_d2. Further, the fit between the predicted and measured values was evaluated in terms of the 1:1 line, a good index to confirm the reliability of the empirical relationship. Finally, the study demonstrates that ITS or I_d2 can estimate the UCS of evaporitic rocks within a certain correlation coefficient, R.