Paris CDG Airport - Al-Zn-In Coated Panels
An example of corrosion protection using the aluminium, zinc and indium alloy has been trialled by Aero ports de Paris at Charles de Gaulle (Roissy) airport. Aero ports de Paris, responsible for the maintenance of most of the Roissy airport infrastructure, recognised deterioration in some of the concrete panels at the airport and sought a long-term corrosion protection solution. The precast concrete panels, which are 2.6 x 2.8m of lightly reinforced 8cm thick units, form the underside of the concrete viaducts carrying road traffic to and from a busy terminal complex. Run-off from de-icing salt has led to an important level of chloride in the panel concrete. Although the panels are not structurally significant, spalling could present a hazard to passing traffic.
Following a stringent review and testing of the panels to establish the deteriorating condition, an anode was applied to the panels in a test area. After grit blasting the panel surface, the anode of aluminium/zinc/indium alloy was applied by a Metallisation arc spray system to an application thickness of 300 microns. The anode connection plate in the centre of each panel is clearly visible by its red anode cable, which would not normally be on show in a typical commercial application. The other cables run to connections to the re-bars and to embedded reference electrodes. As this is a test site it was necessary to install monitoring equipment. This was to allow the connection between the anode and cathode to be interrupted for measurement of electrochemical performance. After two years the system appears to be well adapted to treat corrosion of the viaduct panels and is deemed to be a successful test.
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