Quick Dips

Concrete is Not Forever

Researchers have been investigating ways in which concrete can be made more resistant to common types of deterioration.

"To many people, concrete symbolises strength, function and reliability. Yet despite concrete's image as a permanent material, the last 20 years or so have seen many concrete structures world-wide being repaired to restore their original performance," says research leader, Sue Freitag, of Central Laboratories of Opus International Consultants Ltd.

Much of our infrastructure is close to the sea, so salt-induced corrosion of steel reinforcement is common. It is also the most severe form of concrete deterioration in New Zealand.

As well as finding ways to reduce the risk of corrosion, the research is examining the effects of the stone which is used to make concrete and how this effects long-term performance.

"Current information about the behaviour of the raw materials used to make concrete in New Zealand isn't good enough to confidently predict the likely life of concrete structures at the time they are designed and built.

"Although concrete technology developed overseas can be applied here, we need to find out more about our own local materials," says Freitag.

"Ultimately this information will tell us if and when repairs are likely to be needed, so the lifetime cost of the structure can be estimated at the design stage."