The results of punch, Brazilian, and uniaxial compressive strength experiments on sulfate rocks with complex mineral composition

Punch testing with different approaches has been used to know the compressive or tensile strength of rocks. In this research, by performing UCTs, BPTs, CPTs, BTs experiments and petrological studies, for the first time, the correlation between the results of these experiments and the mineral composition of sulfate rocks was investigated. The used rock blocks are mainly collected from the Gachsaran Formation outcrops at the four under construction reservoir dam sites (as well as from two points of the Aghajari Formation) in Iran. The regression analysis was used to study the correlations between UCS with block punch index (BPI) and cylindrical index (CPI) and Brazilian tensile strength (BTS) as well as BTS and CPI-BPI. By extracting 254 correlation equations, it was found that if the rock samples were taken from a specific geological point, the predominant correlation relationships were linear and with high determination coefficients, and therefore, the results of BPTs and CPTs can be used to predict compressive strength and tensile strength of rock with the same high reliability. In this study, for different mineral compositions of sulfate rocks, while presenting specific correlation relationships, the converting factors of BTS-CPI-BPI to UCS and CPI-BPI to BTS are presented.