Pioneer move electrifies apartments for long life - Pyrotek


Belying its age, this renovated residential block is one of the first in Australia to install impressed-current CP, which will preserve it for three or four decades more.

Truly "electrifying" news comes from Preservation Technologies who has just completed the first installation on the NSW Central Coast of impressed-current cathodic protection to residential apartments and among the first half dozen done in Australia.

The move sets an example to residential block owners, especially those near the sea, to take up a technology increasingly used in bridges, wharves and other infrastructure assets for long term protection against "concrete cancer".

With admirable foresight, the owners' corporation at Avoca's "Marese" apartments on Avoca Drive opted for the CP solution by Preservation Technologies over more conventional options offering less certain longevity.

"Built in the '70s, the three-storey walk-up was clearly facing corrosion-related problems due to chloride ion attack from the salt air environment on its reinforcing steel," Preservation Technologies' John O'Connell explains. "Now renovated and protected by the latest in CP technology, the building can look forward to 30-40 years trouble-free life extension.

"This is a far cry from other more conventional measures, which cannot offer certainty even of their often quoted ten year life."

The general make-over of the building by Preservation Technologies involved demolition including removal of the old balconies, concrete repair, structural steel repair, new balcony screeds and tiling, construction of reinforced hobs, brick work replacement, protective coatings and installation of new frameless stainless steel balustrades.

"We installed a junction box at each new balcony and ran wiring up through cavities to the roof, across the roof and down to the switch room for connection to the transformer/rectifier which will pass a low current through the building for the rest of its days," John explains, adding that all the wiring is hidden and protected for the safety of tenants.

The current needed differs for each building. It is precisely calculated per unit area of steel surface to be protected and the CP equipment continues to monitor it throughout the life of the structure.

"The impressed current shifts the corrosion potential of the steel within the building away from a high oxidation anodic state, effectively making the steel a cathode, and keeps it there," John says.

"The cost of running it is minimal and, of course, it is infinitely less than most seaside owners' corporations will pay out for chasing corrosion through their buildings, cutting it out and repairing it when the sea air, unchecked by the protection of impressed-current CP, wreaks its inevitable havoc and possibly even makes their structures unsafe."

Illustrating the safety aspect, John points to the case in Manly where it was a miracle that no one was killed when two cantilever balconies sheared off cleanly under their own weight because their reinforcing steel had corroded so badly.

In addition to CP installation on residential apartments, Preservation Technologies undertake structural strengthening, building fa├žade repair, heritage restoration, roof waterproofing and infrastructure repair. One of the most prominent among their recent projects is the heritage restoration of the façade of the NSW Teachers Federation building in Surry Hills.