How do heritage considerations impact engineering specifications?

In 2021, ACOR Consultants used a 'minimal intervention' strategy for high profile concrete repairs in Sydney Harbour National Park. The heritage-listed military fortifications at Middle Head - Gubbuh Gubbuh, Obelisk Bay and Georges Head required a solution to address extensive concrete spalling and enable safe visitation as part of a new walking track.

Testing identified carbonation as the dominant cause of corrosion, exacerbated by low cover. However, increasing concrete cover, protective coatings and galvanic anodes were ruled out, as they would alter the surface finish and geometry of the assets.

"The most sympathetic heritage solution was to repair the structures to their original geometry and surface finish, with the most resistant repair system that would stifle any possible future corrosion,” ACOR Consultants' Principal, Peter Johnsson, says.

With specification support from Fosroc ANZ's concrete repair expert Hamid Khan, Renderoc Plus repair mortars LA55 Plus and HB40 Plus were selected for their extra high build, high resistivity formula. Dapcor Building Services executed the repairs.

The heritage conservation work formed part of a $10 million new walking track project being undertaken to join this stretch of coastline with the iconic Sydney Harbour Scenic Walk.

A fantastic project by the NSW National Parks and Wildlife Service, ACOR Consultants and Dapcor Building Services.

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