This is the back up or change in building activity for when the housing market finally crashes.<p>RAAC is concrete sponge, its got air holes in, a fad or trendy building material for use after WW2, problem is no one knew how well it would last. So far Roman Concrete is still currently the longest lasting concrete on the planet and superior in so many ways.<p>Studies in the 1990's highlighted a problem, but its been largely ignored or kept quiet, and nobody kept records of what buildings are made of, like many properties in the UK.<p>So fast forward to a few years back, problems started to be noted with crumbling, still a game of pass the parcel and now the music has stopped and its become a problem, just in time for the housing market crash.<p>I guess one of the attractions for its use was low costs and pumping air into something probably helped reduce the need for so much concrete, when thinking of food rationing that was still in place after the end of WW2 and various countries who took part are getting back up off their knees.