Concrete Corrosion Mapping

Concrete Corrosion Mapping allows rapid assessment of concrete surfaces for the presence of or tendency for chloride-induced corrosion in reinforcing steel. Operating on the half-cell potential method, this instrument is used on bridge decks, pavement, walls, and other structures.

Reinforcing steel in concrete is normally passive to corrosion until chlorides from the environment penetrate the concrete and start a flow of electrical currents. Half-cell measurements indicate corrosion activity using a probe electrically connected to the concrete through a water-saturated sponge. A separate cable is attached to rebar in the structure, completing the electrical circuit. The potential readings correlate to steel corrosion activity in the vicinity of the probe. Readings can be plotted on paper or on the concrete itself to provide a graphic assessment of the structure. A Rebar Locator is recommended to accurately reference bar position.

Features of Concrete Corrosion Mapping:

  • Quickly assesses the existence of or potential for chloride-induced corrosion in reinforcing steel
  • Easily examines bridge decks, pavement, walls, and other structures
  • Operates using the half-cell potential method
  • Fast concrete corrosion mapping before performing any destructive testing.

The Concrete Deterioration Process

There are many factors that lead to the corrosion of steel in concrete. Environmental factors are the greatest concern when dealing with concrete near marine environments, such as bridges and dams. Elements such as wind, water, river current, temperature change, and deicing salt are all corrosion causing agents affecting the strength of reinforced concrete. In addition, the lowering of the concrete’s PH level due to chlorides, carbonation, and acids within the slab are also factors contributing to the corrosion of reinforcing steel.

The deterioration of concrete begins out of sight, well within the slab. As rust starts to form, it occupies more space than the steel originally took up, resulting in the formation of small cracks and eventually delamination occurs.

Routine investigation is necessary to prevent the reinforced steel from getting to these later stages of deterioration. Although repairing deteriorating concrete may not be cheap, the price of repairs will only go up exponentially over time.