I'm certainly no expert but is it not blindingly obvious that using concrete with so many aerated holes in comes with certain risks? Concrete is porous and so using RAAC will only increase the risk of water infiltration leading to both a weakening and crumbling of the concrete itself as well as erosion of any steel rebars. This surely must have been known?

Used properly, in situations where it can be protected from water ingress, I'm sure it's own benefits in being far lighter and cheaper to manufacture were valid but water is very adept at seeping into anywhere and very clearly it looks like the old "cutting costs" factor has come home to roost. Well before all this current squit about schools hit the news, there were already stories about numerous local hospitals looking like building sites with props in corridors etc to support sagging ceilings. This is bound indeed to cost an eye watering amount of money to resolve and sincerely doubt that anyone will be held accountable. Guess it won't be just a problem in the UK either though.