We have discussed so far general corrosion phenomenon, principle of corrosion, various kinds of corrosion, electrochemical reaction, cells, electrodes, types of cells, thermodynamic principles, electrode potential, measurement of EMF of a cell, Half-cell potential
, standard hydrogen cell, reference electrodes, free, energy, pH (Power or fugacity of hydrogen) etc.
 DGfZP: Specification B 03, Electrochemical Half-Cell Potential
Measurements for the Detection of Reinforcement Corrosion, DGZfP, Berlin, Germany, 2014.
measurements are one of the most widely used nondestructive methods to monitor and assess steel bar corrosion in concrete structures [21, 22].
The ASTM standard C879-09 was used as a starting point to obtain the half-cell potential
. The technique allows one to obtain, through the utilization of a voltage gauge, the difference in potential between a reference electrode and the rebar.
However, half-cell potential
has been recognized by many researchers as the main method to detect the corrosion activity in RC structures .
Both of the electrical current readings and half-cell potential
measurements were used to detect the corrosion initiation in the tested prism samples.
Methods used in these experiments are by measureing half-cell potential
[14,15], corrosion potential and polarization resistance  in accelerated corrosion condition in laboratory.
A voltage known as the half-cell potential
develops across the interface due to an uneven distribution of anions and cations.
It uses the half-cell potential
method to locate the areas without the expense and time consumed by demolition.
For this study, the half-cell potential
technique is used by obtaining electrical potential on the surface of the concrete.
The most popular method of in situ corrosion testing is the half-cell potential
measurement, the idea of which is illustrated in Figure 1(a).