Reinforced Autoclaved Aerated Concrete (RAAC) is a type of lightweight precast concrete that was commonly used in building construction during the second half of the 20th century. It is a reinforced version of Autoclaved Aerated Concrete (AAC), which is made in factories using fine aggregate, chemicals, and water, without the inclusion of coarse aggregate. RAAC is known for its unique material properties and structural behavior, which differ significantly from traditional reinforced concrete.
Some key points about RAAC include:
- Lightweight: RAAC is a lightweight construction material, making it suitable for various applications, including roofing and wall construction.
- Widespread use: RAAC was frequently used in public sector buildings in the UK from the mid-1960s to the 1990s.
- Concerns about safety: In recent years, concerns have been raised about the structural safety of RAAC, particularly in the form of RAAC planks used in buildings. As a result, some buildings, including schools, have been closed or undergone inspections and remedial work.
- Research and action: NHS England/Improvement and the Department for Education (DfE) have been leading efforts to understand and address the issue of RAAC in buildings. Loughborough University has been commissioned to conduct research on the unique nature of the material and the problem it poses.
