What is surface resistivity?

What is Surface Resistivity?

Surface resistivity is the resistance experienced by an electric current leaking along the surface of a coating/insulation material. It can also be defined as the resistance that exists between two parallel electrodes contacted by a surface. The electrodes need to be separated by a distance equal to the contact length of the electrodes. The four ends of the electrodes form a square; therefore, resistivity is measured in ohms, sometimes in ohms/square.

The surface resistivity was calculated as the quotient of the potential gradient and the unit V/m and the current A/m per unit electrode length. This is generalized as the ratio of DC voltage drop per unit electrode length to current per unit width.

Surface resistivity determines the conductivity of any given material. The higher the surface resistivity, the lower the conductivity of the material because there will be low leakage current. To understand this clearly, find below an example of a surface resistivity test. This test is used to estimate the permeability of hardened concrete.

process:

Find a practical sample of any size, although a 4-inch sample is recommended.

The sample is placed between two electrodes and a voltage is applied to the electrodes for 60 seconds.

Measure resistance.

Calculates the surface resistivity and gives the apparent value.

When calculating the data, you will need to calculate the surface resistivity and express its units appropriately. Reminder to you: The above description only provides you with the basic knowledge of surface resistivity testing. Experts recommend this test for the approval of any concrete mix design when it is used in an environment prone to steel corrosion. This is when embedded steel is used for reinforcement purposes.

Using the above tests, labor and time can be reduced as some other methods require time to approve the mixture design. The test takes only 10 minutes, is valid and effective. In contrast to other specimen testing methods, this test can be performed on cylindrical specimens prior to use in compression testing.