Ageing Port Infrastructure Gains New Life
The corrosion of reinforced steel in concrete structures is a global problem. A number of highly technical repair materials are now available to repair concrete structures suffering steel corrosion damage of reinforcing steel. The June 2009 issue of World Port Development provided an overview of protection systems for reinforced concrete piers and wharves. For additional information click here.
Long-term Performance and Versatility of Zinc Sacrificial Anodes for Control of Reinforcement Corrosion, Sergi, Simpson & Potter
Since its development in the mid-nineties, numerous installations of the Fosroc zinc sacrificial anode have been carried out in repairs to steel reinforced concrete structural elements suffering from corrosion. From these, more than a dozen sites have been thoroughly monitored in the UK and worldwide. Results so far have been very encouraging with current densities ranging between 0.8 mA/m2 and 10 mA/m2 of steel surface depending on the type of application which includes cathodic prevention, corrosion control and cathodic protection. These levels of currents were shown to be sufficient to overcome any further visible corrosion of the steel reinforcement extending the service life of the repairs significantly. Some of the early trials have been monitored for nearly ten years now. This presents an opportunity for the results to be analysed and the performance of the sacrificial anodes to be critically assessed medium to long term. This paper reviews the performance of the anodes in terms of current output and steel polarisation levels over the years. The prospects of a further recently developed improved sacrificial anode system achieving substantially improved performance are reviewed and discussed. (read more)
Corrosion of Steel in Concrete & Assessment Techniques, Sergi
Concrete is a porous material whose pores contain an electrolyte made up primarily of sodium and potassium hydroxides. Steel reinforcement is normally protected in such an electrolyte owing to the formation of a dense and uniform passive oxide film. Carbonation of the concrete (neutralisation of the alkali constituents by CO2 gas from the atmosphere), or infestation of the concrete with salt from seawater or from deicing agents leads to the breakdown of the protective oxide film and to corrosion of the steel. Corrosion of steel in concrete is an electrochemical process whereby anodic and cathodic reactions occur simultaneously on the surface of the steel resulting in the dissolution of the metal at the anodic sites. (read more)
