Reinforced concrete structures such as bridges, buildings, industrial facilities, and marine infrastructure are designed to provide long service lives. However, over time, environmental exposure, moisture penetration, chloride contamination, and carbonation can gradually reduce their durability. One of the most common causes of deterioration in aging concrete structures is the corrosion of embedded steel reinforcement. As corrosion progresses, the steel expands, leading to cracking, delamination, spalling of concrete cover, reduction in steel cross-section, and eventually a loss of structural capacity.
Half Cell Potential (HCP) testing is one of the most widely used non-destructive techniques for assessing the likelihood of reinforcement corrosion in concrete structures. The method works by measuring the electrical potential difference between the embedded reinforcing steel and a reference electrode placed on the concrete surface. The measured potential values provide an indication of the probability that corrosion is actively occurring within the reinforcement network.
Unlike visual inspections, which can only identify damage after it becomes visible, Half Cell Potential testing helps detect corrosion activity at an early stage. This makes it an important tool for preventive maintenance and durability assessment programs. By taking measurements across a predefined grid and plotting the results on contour maps, engineers can identify areas where corrosion activity is more likely to occur and prioritize further investigations or repairs.
The technique is particularly valuable for evaluating aging infrastructure because it allows large areas to be assessed quickly without damaging the structure. It is commonly used during condition assessments, rehabilitation studies, structural audits, and asset management programs. The interpretation of results is generally based on the guidance provided in ASTM C876 – Standard Test Method for Corrosion Potentials of Uncoated Reinforcing Steel in Concrete, which remains the most widely accepted standard for Half Cell Potential Test worldwide.
