RAAC: pressure test shows risk posed by crumble-risk concrete

Ministers have ordered schools to immediately shut structures built using reinforced autoclaved aerated concrete (RAAC) until safety work is undertaken. The decision could result in thousands of pupils at more than 100 schools in England beginning the autumn term via remote lessons. RAAC, a lightweight building material used between the 1950s and the mid-1990s, is now assessed to be at risk of collapse. Demonstrations show the lightweight nature of RAAC and how it lacks the strength of modern concrete What is RAAC and why is it forcing schools to shut buildings?