GRAIN BERTH & MULTIPURPOSE BERTH, PORT KEMBLA, NSW
In 2000, Port Kembla Port Corporation embarked on a four-stage programme to carry out concrete repairs and install cathodic protection ("CP") to the undersides of two busy wharves at the Inner Harbour. Marine & Civil Maintenance tendered for and won the second, third and last stages, each of two separable contracts, in subsequent years 2003-2006.
The wharves are relatively low in the water, making the access platforms permanently underwater and requiring all equipment to be powered by compressed air rather than electricity. In addition, ship movements and loading at the berths required stringent safety precautions to protect the site team from the port operations, while ensuring those operations could continue without interruption.
Concrete repairs were carried out wherever the wharf soffits were delaminated or spalling. This was done by hydrodemolition, which uses a very-high-pressure water jet to break out the concrete; and gunite, which involves spraying a high-performance repair mortar to reinstate the original surface.
In all, over 200m² of concrete was repaired. The repairs were regularly cored and tested for compressive strength, adhesion and electrical resistivity.
The cathodic protection system consisted of a titanium ribbon mesh anode, cast into chases which were cut into the surface of the affected beams and slabs under each wharf. Silane was applied to protect some areas of concrete that were less exposed to deterioration.
In total, nearly 12km of anode ribbon was installed, with 119 reference electrodes cast into the concrete to monitor the system performance. The two CP systems are controlled by transformer-rectifier units mounted on each wharf.
Each stage was commissioned and monitored before handover to the client. The complete structures have been successfully protected since late 2006.
Other contracts carried out by Marine & Civil Maintenance at the Port during this time included the concrete repair and galvanic cathodic protection of three mooring dolphins at the Oil Berth.