LONG-TERM FIELD TESTS OF REFERENCE ELECTRODES FOR CONCRETE - TEN YEAR RESULTS

AUTHORS

Frank J. Ansuini
Electrochemical Devices, Inc.
James R. Dimond
Dimondale Co., Inc.

 

 

ABSTRACT

NACE logo
Paper No. 01296 presented at Corrosion 2001, March 11 &45; 16, 2001, Houston, Texas
Published by NACE International, Houston, TX www.nace.org © NACE, 2005
This paper presents the results from ten years of stability testing of commercial silver/silver chloride, manganese oxide and graphite embedded reference electrodes used in reinforced concrete structures. Tests were performed in chloride-free and chloride-contaminated slabs exposed to the weather in the northeastern United States. Also included is the effect on potential readings of IR drops caused by corrosion of an embedded rebar.

CONCLUSIONS

Frank Ansuini is Technical Director of EDI which specializes in the development and marketing of corrosion control products. He has over 30 years experience in research and product development in corrosion. Frank may be contacted at PO Box 31, Albion, RI 02802 or franks address 1. Embedded silver/silver chloride reference electrodes which are designed to be compatible with a concrete environment show excellent long term stability in both chloride-free and chloride-contaminated slabs

2. The reference potential of the graphite cells remained stable for about three months after initial installation after which they began to deviate. Because of this behavior, these cells are only suitable for short term relative measurements. Graphite cells should not be used for long term or absolute measurements.

Jim Dimond is President of Dimondale Co., Inc which designs and manufactures cathodic protection products. He has over 30 years experience in cathodic protection including product design, manufacturing and field engineering. Jim may be contacted at PO Box 838, Middlefield, OH 44062 or jims address 3. Manganese oxide reference electrodes show good stability in chloride-free concrete but demonstrate long term deviations in chloride contaminated concrete.

4. Differential thermal expansion between the electrode body and the adjacent concrete can lead to an open circuit condition at cooler temperatures. To avoid this, it is necessary to use reference electrodes specifically designed for use in concrete.

Download selected diagrams and photos (580kb) 5. Corrosion currents resulting from corrosion of embedded rebars can set up a complex IR drop field within concrete which can affect potential readings. When calibrating embedded reference electrodes, this effect makes it appear that the reference potential has shifted when, in fact, the shift is simply a measurement error.

Click to download paper in PDF format (387kb) 6. There is no correlation between the resistance of an embedded reference electrode and whether or not it is providing reliable potential readings.

At Electrochemical Devices, Inc. (EDI) research is an ongoing part of our success. In this section are a number of topics covering our products and their use. Many of these can assist you in answering questions about why a particular product is the best choice for your corrosion control application. Others will help you to better understand what equipment should or should not be used with our products. If you need additional information about our products, please contact us.