[gerdesj]

It seems that the term "Concrete Cancer" has been somewhat watered down since I studied Civ Eng at Plymouth Polytechnic (Devon, UK) in '89-91. I think you are referring to spalling.

It was a while back but I recall that the characteristic map cracking and eventual failure need salty water as well as the correct chemical composition of the cement used. I think there are something like three conditions needed. Stop one and you fix the problem. I seem to also recall that PP's Civ Eng dept did a lot of work on this in the '80s. Plymouth is a sea side city and has a lot of concrete structures that suffered eg Charles Cross multistory car park.

To be honest I would find it hard to believe that a structure that size would be designed to that short time scale. I'm not familiar with Aussie building regs (I'm not familiar with anyone's outside the UK and saw a.com.au link!) but it would be very hard to design for so short a lifespan. There will be a minimum conc. depth to the reinforcing bars, just for fire regs, let alone spalling. If the weather is a bit fierce then the other design criteria like being able to withstand a 1 in 100 or 200 or whatever year event will also play a part in the lifespan. Obviously there will also be a factor of safety applied which could be as high as 1.4. Take a close look at the final finish, it may have been sealed in some way. Keep the water and freeze/thaw and the like away and conc. can last a bloody long time.