Half Cell Potential Measurement

• Principle
• Application
• Advantages
• Limitations
• Test Procedures

Principles

The principle involved in this method is appearance of an electrical potential between the reinforcing steel and a reference electrode named half-cell. The half-cell consists of a metal rod immersed in a solution of its own ions.

The role of the half-cell is to insure constant reference potential. The metal rod is connected with reinforcement steel by a voltmeter, and the ion solution is connected to the pore water via moist porous plug [1]. Measuring method is based on many measurements of potential and correlation of measured potentials with observed corrosion rate at reinforcement. Table 2 presents criteria according to ASTM C-876 standard for copper-copper sulphate electrode, and also for calomel and silver-silver chloride. The main application of this method is for cast in-situ concrete.

This test method covers the estimation of the electrical half-cell potential of uncoated steel reinforcement in field and laboratory concrete, for the purpose of determining the corrosion activity of the steel reinforcement.