Consultant: Infracorr Consulting
Contractor: Marine and Civil Maintenance Pty Ltd
Date – September 2013
The former HMAS Platypus submarine base precinct was rehabilitated and restored opening up a new public space for Sydney harbor and residents.
The 216 m long reinforced concrete wharf structure is suffering from chloride attack and corrosion to the reinforcing steel.
Elements of the structure upgrade had developed substantial spalling of concrete due to exposure from the marine environment.
Infracorr Consulting was contracted to perform a concrete condition assessment on elements of the structure as part of the upgrade process, the assessment detected reinforcement corrosion and the initiation of spalling concrete to a large proportion of the main beams.
The recommendation and remedial design selected the Duoguard Hybrid system to provide corrosion control. Duoguard features innovative duel technology utilising the same embedded anode in both an impressed current and galvanic current role.
Challenges included the access system required to install the system, shipping movements and wave action during busy periods and tidal influences.
Specialist Remediation contractors Marine and Civil Pty Ltd was the successful tender. The project went very smoothly because of their experience and highly trained technicians to install the system. The project was on time and on budget with over 8,000 anodes installed over a 6-month period.
Reinforced Concrete is a very durable and versatile construction material, however if poorly constructed or unprotected, can over time, deteriorate through reinforcement corrosion, leading to costly maintenance problems if left untreated.
Duoguard Hybrid anodes were installed into contaminated areas of reinforced concrete, identified as being at critical levels of corrosion. The system is discrete with no surface wiring or permanent control systems and is self-regulating with no permanent power source. The advantage with the Hybrid system was that localised area could be treated based on half-cell results, silane coating were applied to untreated areas to provide protection from chloride migration.