Corrosion Protection of Reinforced Concrete Structures in Remote Locations: Cape Don Lighthouse, NT.

Cape Don Lighthouse is located at the tip of the Cobourg Peninsula in the Garig Gunak Barlu National Park, Northern Territory. It is 170km north-east of Darwin and accessible only by sea or by air. The 28m high, reinforced concrete tower was built in 1916 and has suffered from corrosion of the reinforcing steel for many years. Restoration works were called for in 2012 to extend the working life of the lighthouse for a further 50 years under a design-and-construct contract that included extensive concrete repairs, corrosion protection of the reinforcing steel and protective coatings. 

The remote location required the amount of future maintenance to be minimised. A Hybrid corrosion protection system was therefore selected for the reinforced concrete elements. This technology offers many of the advantages of traditional impressed-current cathodic protection (ICCP), including corrosion control and reduced concrete removal, without the high cost and maintenance of power supplies, cables and electronic control systems. It utilizes zinc alloy anodes grouted into drilled holes, with the anodes initially powered with direct current and subsequently operating in galvanic mode. 

This paper is a case study of the design philosophy, installation and operation of a hybrid corrosion protection system, including concrete repairs and coatings, to protect the reinforced concrete elements of a heritage structure in a remote location. The site works, including a novel access system, are described, with reference to the technical and practical aspects of working in a remote and exposed tropical location.