Experimental research on mechanical properties of granite in chemical dissolution under freeze-thaw cycles

The variation of mechanical properties of granite under uniaxial compression after being soaked in different chemical solutions (water, NaOH solution and HNO₃ solution) and subjected to different freeze-thaw cycles is experimentally studied. The damage mechanism of granite subjected to chemical soaking and freeze-thaw cycles is analyzed according to the micro mechanism and chemical mechanism. In addition, a damage variable is defined in terms of which the damage degree of granite can be analyzed quantitatively. The test results show that for all the chemical solutions (water, NaOH solution and HNO₃ solution), with the increase of freeze-thaw cycles, the relative Young’s modulus decreases by exponential function, the loss rate of the peak stress increases by power function, and the axial peak strain changes by Guass function. With the increase of freeze-thaw cycles, the damage and deterioration of granite in HNO₃ solution is larger at a smaller number of freeze-thaw cycles than that at a larger number of freeze-thaw cycles, while an opposite phenomenon is found for granite soaked in NaOH solution. The process of freeze-thaw damage is essentially a process in which the granite is damaged gradually by thermal stresses, meanwhile, the chemical damage produced by chemical dissolution together with the freeze-thaw damage can give mutual effects on the damage and deterioration of granite.