STOP THE DAM
Kings Beach – Let the salt be 🌊
News - 26/10/2026
Does salt damage concrete? A question about the wall
This one was written by the member of our group who used to work in engineering, who would like it known that their background is in water supply and not marine structures, and that they have been retired for nine years.
Reinforced concrete near the sea deteriorates mainly because of chlorides. They diffuse slowly through the concrete until they reach the reinforcing steel, at which point the steel begins to corrode, and because the corrosion product occupies a larger volume than the steel it replaces, the concrete cracks and spalls from the inside. Anyone who has lived in a coastal unit block will know this as concrete cancer, and will be familiar with what it does to the strata levy. The subject has been studied at length, including in long-term field trials on the Swedish coast, and it can be managed with adequate cover, low water-cement ratios and regular inspection, provided somebody budgets for those things.
What I asked at the Dam Kings Beach stall, and would still like answered, is what exposure classification they have assumed, given the wall would have seawater against one face and, on their own figures, up to 42,350 tonnes of salt against the other. I was given a fact sheet. A design life of more than 50 years may well be achievable, but their $47.2 million only includes the first ten years of monitoring and maintenance, and it is not clear to me who is responsible for the wall after that.