Half Cell Potential

A half-cell potential measurement is a non-destructive method to assess the corrosion risk of steels in concrete. The half-cell potential measurement can only indicate the corrosion probability at a given location and time, but long-term monitoring of the half-cell potential reading is necessary to correctly assess and predict the corrosion severity. The method is generally used  in conjunction with other tests.It  eliminates the requirement of hacking concrete to physically view rebar condition. The readings are at times weather sensitive and require that concrete is moist before conducting the test.

In reinforcing concrete, an electrode forms one half of the cell and the reinforcing steels in the concrete form the other half cell. The behavior of steel in concrete can be characterized by measuring its half-cell potential. The chances of corrosion occurring on the steel in concrete and half-cell potential are directly proportional; the higher the potential, the higher the risk of corrosion occurrence

Precautions

The test is best conducted at the onset of corrosion and in combination with carbonation test.

Code Compliance

Geo Dynamics conforms to ASTM- C 876 and BS 1881 (Part 201): 1986

Carbonation Test

It is a simple yet effective test to assess carbonation in concrete and possible risk of reinforcement corrosion for fire damaged or old concrete structures. The test is conducted by spraying phenolphthalein solution inside concrete or onto concrete cores.

Concrete begins reacting with carbon dioxide the instant it is exposed to the air. Concrete itself is highly alkaline (high pH). This high alkalinity reacts with the exposed  steel on reinforcing steel and creates an oxide film around the steel called a passivation layer. This layer protects the steel from corrosion. The reaction of concrete with carbon dioxide reduces the pH in the concrete. This process starts at the surface and works its way into the concrete. The reaction can be expedited by cracking in the concrete surface. The carbonation test assesses the extent of carbonation in concrete and possible risk of damage to concrete due to fire or due to carbonation reaction in case of old structures.

Precautions:

The test is best conducted at the onset of corrosion and in combination with half cell potential test.

Code Compliance:

Geo Dynamics conforms to IS-516 (Part 5/Sec 3):2021