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 determine the compressive or tensile strength of rocks. In this research, by performing uniaxial compression strength (UCS) test, block punch test (BPT), cylindrical punch test (CPT) and Brazilian test (BT) 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 rock blocks used were mainly collected from the Gachsaran Formation outcrops at four reservoir dam sites under construction (as well as from two points of the Aghajari Formation) in Iran. Regression analysis was used to study the correlations between UCS and 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 had high determination coefficients, and therefore BPT and CPT results can be used to predict compressive strength and tensile strength of rock with the same high reliability. In this study, we present specific correlation relationships for different mineral compositions of sulfate rocks, and present the conversion factors of BTS–CPI–BPI to UCS and CPI–BPI to BTS.