Galvashield LJ turns the tide on corrosion in Jersey

Citation

(2004), "Galvashield LJ turns the tide on corrosion in Jersey", Anti-Corrosion Methods and Materials, Vol. 51 No. 4. https://doi.org/10.1108/acmm.2004.12851dab.004

Galvashield LJ turns the tide on corrosion in Jersey

Galvashield LJ turns the tide on corrosion in Jersey

Keywords: Concrete, Corrosion, Fosroc, Galvanising, Steel

Corrosion is probably the single most serious cause of deterioration of reinforced concrete structures, and is particularly prevalent in buildings and structures subjected to salts from the sea and from de-icing activities.

Structures in coastal locations such as piers and jetties cause considerable problems for owners, since high concentrations of chloride borne in the air, rain, and sea spray, attack reinforced concrete with consequential spalling and deterioration of structural integrity.

One such structure is the jetty on the Albert Pier in St Helier, Jersey which is used by passengers of the roll-on-roll-off ferry which brings visitors to the island from Britain and France.

A survey in 2001 carried out by engineers Arup of the assets in the harbour on behalf of Jersey Harbours, revealed that the underside of this 1960s structure was suffering heavily from corrosion with large sections of cracked and spalled concrete compromising the integrity of the structure. Given that the jetty is a critical structure and in constant use it was vital that the concrete was not allowed to deteriorate any further and that repairs could be carried out swiftly.

Further structural analysis was carried out to establish the type of reinforcement, together with the consistency of the concrete allowing the most appropriate solution to be devised.

Arup opted to use Galvashield Lifejacket (LJ), an innovative solution from Fosroc which was installed by specialist contractors Hydrojet. This all-in-one repair system is based on the installation of a two piece fibreglass jacket lined with expanded zinc mesh. Before the Galvashield LF is installed, all areas of spalled and delaminated concrete are broken out. The Galvashield LJ is then fixed in position and a special grout is used to fill the annulus between the jacket and the pile and all the breakout voids. Concrete repair and galvanic cathodic protection is therefore carried out in one operation. The system is self-powered and regulates its current output according to the corrosion rate of the steel and its operating environment.

It is simple to install and requires minimal post-installation maintenance unlike other options such as impressed current systems, making Galvashield LJ a cost-effective solution. Nine units were installed around the concrete piles, including inclined columns on the structure.

The Galvashield LJ protection system was originally developed in the Florida Keys a decade back to protect the extensive road bridges linking the islands and is now used on coastal structures across the world. Studies carried out by the Florida Department of Transportation indicate that the anodes can have a life in excess of 40 years.

In addition to the simplicity of installation and maintenance, Arup were able to work closely with Fosroc during the specification and installation of the Galvashield LJ.

Steve Hold at Arup said: “We had initially considered using patch repairs on the jetty, but following further discussions cathodic protection was decided upon. This would provide us with a long term solution with maintenance kept to a minimum. We worked closely with Fosroc as this was a relatively new system in the UK and we had to be convinced that Galvashield LJ was the correct solution for us. They have been able to provide technical support throughout the project and we are pleased with the outcome”.