Offer the equations required to measure the compressive strength of rocks and concretes, using the new "Twist-off" test and compare it with standard methods

In engineering works, especially in geological sciences, civil engineering and mining engineering, before or after the construction of structures, there are cases where it is necessary to determine the strength of stone or concrete. In this regard, changes in the use of the structure (change in load), unfavorable operating conditions, lack of time, lack of access to laboratory equipment and structural damage are among the reasons for assessing the strength of materials in situ. There are several methods for testing materials that are either destructive or have expensive and imported equipment. In this paper, using the new "Twist-off" test, the strength of 9 different types of stone and concrete with eight different strength classes has been measured. Also, while comparing the results with standard methods, calibration diagrams and equations required to convert the results of the "Twist-off" test to the compressive strength of the mentioned materials are presented. According to the results, to measure the compressive strength of ordinary concrete using twist-off test, the relationship y = 19.27x0.67 with a coefficient of determination of about 0.95 can be used. Also, for the rocks used in this research, by using the equation y = 27.87x0.52, the compressive strength of the mentioned rocks can be determined by using the twist-off test with an accuracy of 94%.