4.1 This test method is suitable for in-service evaluation and for use in research and development work.

4.2 This test method is applicable to members regardless of their size or the depth of concrete cover over the reinforcing steel. Concrete cover in excess of 3 in. (75 mm) can result in an averaging of adjacent reinforcement corrosion potentials that can result in a loss of the ability to discriminate variation in relative corrosion activity.

4.3 This test method is not applicable to reinforced concrete structures with epoxy-coated reinforcement.

4.4 This test method is not applicable to reinforced concrete structures in which waterproofing membranes are located between the reinforcement cage and the concrete surface as they can prevent the conduction of electricity and result in erroneous readings.

4.5 This test method may be used at any time during the life of a concrete member after the concrete has set, although it is generally most useful for evaluating mature reinforced concrete that is suspected to be susceptible to corrosion.

4.6 The results obtained by the use of this test method shall not be considered as a means for estimating the structural properties of the steel or of the reinforced concrete member.

4.7 Temperature and humidity can impact potential readings. This is particularly important for periodic testing of the same test location. An increase in the temperature leads to increasing ionic mobility, which in turn affects the reference electrode’s potential. The temperature influence can be neglected if the measurements are taken within the range of 22.2 °C ± 5.5 °C (72 °F ± 10 °F). Otherwise, the temperature-dependency of the measurements must be taken into account.

4.8 The potential measurements should be interpreted by engineers or technical specialists experienced in the fields of concrete materials and corrosion testing. It is often necessary to use other complementary data such as chloride contents, depth of carbonation, delamination survey, rate of corrosion, and environmental exposure conditions, in addition to corrosion potential measurements, to formulate conclusions concerning corrosion activity of embedded steel and its probable effect on the service life of a structure.

1.1 This test method covers the estimation of the electrical corrosion potential of uncoated reinforcing steel in field and laboratory concrete, for the purpose of determining the corrosion activity of the reinforcing steel.

1.2 This test method is limited by electrical circuitry. Concrete surface in building interiors and desert environments lose sufficient moisture so that the concrete resistivity becomes so high that special testing techniques not covered in this test method may be required (see 5.1.4.1). Concrete surfaces that are coated or treated with sealers may not provide an acceptable electrical circuit. The basic configuration of the electrical circuit is shown in Fig. 1.

FIG. 1 Reference Electrode Circuitry

1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.