Disclaimer

These demonstration videos are for educational purposes only. For brevity, a number of steps might have been omitted. Users are responsible for safety and reading/following standards that govern the tests described in the videos. Oregon State University does not endorse any particular device that is used in these videos.

Measuring bulk resistivity of concrete cylinders

Bulk resistivity of concrete can be measured standard concrete cylinders or cores extracted from structures in the field. ASTM C1760 (Standard Test Method for Bulk Electrical Conductivity of Hardened Concrete) provides the details of the method for determining the bulk electrical conductivity (inverse of resistivity) of saturated specimens of hardened concrete.

Measuring surface resistivity of concrete

Surface resistivity of concrete is typically performed using a four-electrode Wenner probe. AASHTO T 358 provides the details of the method, which can be used for structural surfaces in the field or on concrete cylinders in the lab. Surface resistivity measurements can be correlated to bulk resistivity measurements using geometry correction factors. Several factors (e.g. rebars, probe orientation with respect to rebars and cracks, moisture, etc.) can affect surface resistivity measurements; therefore, these factors should be considered in field measurements.

Measuring pore solution resistivity

The electrical resistivity of pore solution can be determined using several methods. One method is to express the pore solution and measure its resistivity directly using a small cell. This video describes this procedure. If the chemical composition of pore solution is known, its resistivity can also be calculated. Such a calculator is provided in the calculators section.

XRF analysis of pore solution and calculation of its resistivity

The chemical composition of concrete pore solutions can be determined using XRF analysis. This video describes this procedure. If the chemical composition of pore solution is known, its resistivity can also be calculated. Such a calculator is provided in the calculators section.

Temperature corrections for resistivity

Electrical resistivity of concrete or its pore solution is affected by temperature. this video shos how to correct for these resistivity measurements for temperature.