Half-Cell Potential Survey

A half-cell potential survey is a non-destructive durability test that maps the probability of active reinforcement corrosion by measuring the electrochemical potential between the embedded steel and a standard reference electrode (commonly copper/copper-sulphate) placed on the concrete surface, over a grid. More negative potentials indicate a higher probability of active corrosion; the readings are contoured to identify corrosion-risk zones, following the ASTM C876 framework widely used to support IS 456 durability assessment of existing structures.

Interpretation is probabilistic, not a direct corrosion-rate measurement, and is sensitive to concrete moisture, resistivity, cover and carbonation/chloride condition — so it is used together with cover survey, carbonation-depth, chloride/sulphate testing, resistivity and visual mapping in a condition assessment before deciding on repair extent. It is a key tool in distress investigation of corrosion-damaged RCC (spalling, rust staining, cracking) and in prioritising repair/cathodic-protection strategies.