United Kingdom

Brutalism was also a thing in that period, and that had a lot of externally-visible concrete. But I don't know if that specifically was linked to this particular RAAC stuff.

https://en.wikipedia.org/wiki/Brutalist_architecture

Brutalist architecture is an architectural style that emerged during the 1950s in the United Kingdom, among the reconstruction projects of the post-war era.[1][2][3] Brutalist buildings are characterised by minimalist constructions that showcase the bare building materials and structural elements over decorative design.[4][5] The style commonly makes use of exposed, unpainted concrete or brick, angular geometric shapes and a predominantly monochrome colour palette;[6][5] other materials, such as steel, timber, and glass, are also featured.[7]

In the United Kingdom, brutalism was featured in the design of utilitarian, low-cost social housing influenced by socialist principles and soon spread to other regions around the world.[4][5][14] Brutalist designs became most commonly used in the design of institutional buildings, such as universities, libraries, courts, and city halls. The popularity of the movement began to decline in the late 1970s, with some associating the style with urban decay and totalitarianism.[5]

Looking at the one identified school which has had a collapse so far, Singlewell Primary in Kent, it looks like single-story brick buildings to my quick glance. Not Brutalist.

https://www.ablecanopies.co.uk/installations/singlewell-primary-school-second-installation/