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Reinforced Aerated Autoclaved Concrete

Reinforced Aerated Autoclaved Concrete:

More than 100 schools across England were recently ordered to close buildings because they were constructed using unsafe concrete known as Reinforced Aerated Autoclaved Concrete (RAAC).

  • Reinforced Aerated Autoclaved Concrete (RAAC) is a lightweight, bubbly form of concrete that was used in roofs, floors, and walls between the 1950s and 1990s.
  • It looks like standard concrete, but compared with the “traditional” reinforced material, which is typically denser, Raac is weak and less durable.
  • The material was favoured in construction projects because of its lightweight thermal properties.
  • It is made from a combination of cement, lime, water, and an aeration agent.
  • The mixture is poured into moulds and then subjected to high pressure and heat, known as autoclaving, to create a lightweight, strong, and porous material.
  • It is cheaper also quicker to produce and easier to install.
  • RAAC has excellent thermal insulation properties due to the air bubbles within the material.
  • It helps maintain a comfortable indoor temperature while reducing heating and cooling energy consumption.