Electrochemical impedance spectroscopy of sand of varied particle size and water content using the three-electrode system

The EIS behavior, corrosiveness, and seepage structure of sand of varied water content were studied by means of electrochemical impedance spectroscopy under the three-electrode system. The results show that the effect of void geometry on the impedance modulus disappears at the high frequency range. However, the impedance modulus is greatly affected by the pore geometry and the effect is greater for standard sand with increased randomness when the frequency is under 5 Hz. The pore structure of standard sand increases Re by an order of magnitude and the increase is more obvious when water content is low. By contrast, Rt decreases with increasing water content. The corrosiveness of the sand system increases with increasing water content. The electrochemical process of a wet sand system shifts from a kinetic control process to a material transfer control process as frequency changes from a high to a low range. The hydraulic radius, a parameter of the seepage structure, fluctuates between 0.01 and 0.03 mS. The magnitude of W, showing a change in tortuosity T, fluctuates between 10^-5 and 10^-6