Steps to Be Followed While Using a Concrete Resistivity Meter Surface resistivity measurements can be correlated to the chances of corrosion, the rate of corrosion, and chloride diffusion rates. Hence, measuring surface resistivity can provide useful information on the condition of a concrete structure and its long term durability. You can easily measure concrete resistivity using a specially designed meter, an advanced concrete resistivity meter is a fully integrated four-point Wenner probe that conducts the measurement in a nondestructive way. To date, it is the most accurate, stable, and fast concrete resistivity measuring device available. Here are the steps to follow when using it:
Understand how the device works – The concrete resistivity meter operates on the Wenner probe’s principle, so it will measure concrete’s electrical resistivity by applying current to two outer probes. The potential difference is determined between two inner probes and the resistivity calculated from these two values.
Taking measurements – The concrete resistivity meter automatically alters its measurement method to suit the material. It will typically attempt to drive a 200uA current through concrete, and if that is not possible because of a high resistance, the device will deliver a 50uA current. In cases of a very high resistance, the device will send voltage across outside probes and determine the induced current to get an estimate of the resistivity. This way, the device can measure extreme high resistivity values unlike what a conventional Wenner probe can do.
Ensure proper probe spacing – Wider spacing between probes will provide a highly consistent reading when measuring concrete or any other inhomogeneous material. Just make sure it is not too wide because the reinforcement steel may affect the measurement if it is within the current field. Remember the industry standard, which is 50mm, when spacing probes.
Use a contact extension cable kit – Some concrete resistivity meters come with a contact extension cable kit as an option. Use that to achieve variable spacing for every testing requirement. The kit should help you set up a 20mm to 85mm spacing.