Assessing the long-term durability and degradation of rocks under freezingthawing cycles

In this research, the degradation rate of physical properties of the Angouran pit bedrock (calc-schist) is first investigated under the specific numbers of freeze-thaw (F-T) cycles. Then, the durability of calc-schist specimens against the FT cycle number (N) is examined considering the mechanical parameters, and using the decay function and half-time techniques. For this purpose, point load strength (IS(50)), second durability index (Id2), Brazilian tensile strength (BTS), and compressive (VP) and shear (VS) wave velocities of calc-schist specimens are measured after 0, 7, 15, 40, and 75 N. For comparing the degradation rate of mechanical properties of available rock types on the Angouran mine walls, these tests are also carried out on the limestone and amphibolite schist specimens beside the calc-schist. According to test results, the exponential regression models are developed between the mechanical parameters of rock specimen's and N variable. Also, the long-term durability of each rock type versus N is studied using the decay function and half-time techniques. Results indicated that the degradation rate differs for the above rock types in which amphibolite schist and calc-schist specimens have the highest and least resistance against the N, respectively. The obtained results from this study can play a key role in the optimal design of the mine's final walls.