@HowMuchMore2 - I believe this is an important story for several reasons.
Firstly, this issue has been known about for 5 years - maybe longer! Yes, the ceiling that collapsed did not hurt anyone - but that was sheer luck - and it wasn't the only collapse then - there was also a ceiling collapse in a university building. The authorities have 5 years to do inspections, and to remediate any issues on a planned basis, rather than it becoming an urgent situation.
In fact, according to the Times today, back in 2002 there was a similar issue with a similar type of concrete, and experts warned back then that there were risks with this and similar types of it.
Secondly, this RAAC concrete is not just in schools - it is also in Crown Courts, Universities, hospitals and other public buildings - some of which are occupied 24 hours a day, so a collapse has a higher risk of hurting someone.
Basically, the Government and the local authorities have known buildings containing this RAAC could collapse, and if people were in the building at the time, it could cause injuries or even deaths, and they have done absolutely NOTHING about it - and have merrily allowed children to carry on learning in classrooms which could fall on their heads. How is that not an issue?
The issue with RAAC is that it has a very open, bubbly texture - like an Aero bar - and its strength comes from reinforcing bars within it, but the texture means that if any water gets in, it can get to the bars and cause them to rust - and as they are what provides the strength in the concrete, it becomes susceptible to collapse. Add to that the fact that, when this was being used, flat roofed buildings were in vogue, and flat roof buildings are notorious for water ingress, and you have a perfect recipe for rusted supports and crumbling concrete, over people's heads.