alt Hacker NewsThe UK crisis involved steel reinforced AAC beams that were used (of all places) to support roofs of schools. UK turned out to be a rainy place, the rain infused into the cellular structure and corroded the steel, with disastrous consequences.
It's a very particular use case of a very particular product, not relevant to the wide majority of AAC uses around the world, which is largely non-structural and not reinforced, or subjected to moderate compressive loads, such as lateral walls for 1-2 stories buildings in non-seismic areas.
Replies
rayiner • today at 2:45 AM
Using porous concrete reinforced with steel in a rainy place is a real WTF decision. It’s a miracle they didn’t collapse earlier.
The risks were understood (by engineers) and this usage was given a "shelf life". Unfortunately, those risks were put into the "Oh we'll forget about it" or "We'll wait until it looks a bit shifty" categories.
However as any fule (engineer) kno, reinforced and especially pre-stressed conc members will fail in quite a dramatic fashion. Unless you notice rust dribbling out then you can end up with anything from the roof failing to the roof exploding. I don't think anyone was daft enough to pre-stress these things.
I don't know how much money was saved but it was a really stupid application and basically ended up punting far greater costs due to remediation down the road.