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Structural safety of reinforced autoclaved aerated concrete (RAAC) planks
This Theme Page has been created to raise awareness of and encourage knowledge sharing on the structural safety of reinforced autoclaved aerated concrete (RAAC) planks.
It also acts as a knowledge hub for safety related information on RAAC planks.
What is RAAC?
Autoclaved aerated concrete (AAC) is different from normal dense concrete. It has no coarse aggregate, and is made in factories using fine aggregate, chemicals to create gas bubbles, and heat to cure the compound. It is relatively weak with a low capacity for developing bond with embedded reinforcement.
When reinforced (RAAC) to form structural units, the protection of the reinforcement against corrosion is provided by a bituminous or a cement latex coating. This is applied to the reinforcement prior to casting the planks. The reinforcement mesh is then introduced into the formwork and the liquid AAC mix added.
RAAC roof collapse
In late 2018, the Local Government Association (LGA) and the Department for Education (DfE) contacted all school building owners to draw attention to a recent failure involving a flat roof constructed using RAAC planks. There was little warning of the sudden collapse.
RAAC knowledge hub
This knowledge hub presents safety related information on RAAC planks from CROSS and third party organisations.
RAAC assessment undertaken by persons not suitably experienced
A reinforced aerated autoclaved concrete (RAAC) assessment was carried out by persons who did not appear to have appropriate experience, potentially putting building users at risk of harm.
RAAC planks in a 1970s shopping centre
An existing large shopping centre built circa 1975 had a number of external storerooms and loading bays with roofs constructed using reinforced autoclaved aerated concrete (RAAC) planks. The planks had deflected to the extent that they needed replacing.
Construction period of RAAC planks
A reporter says that there are structural issues with reinforced autoclaved aerated concrete (RAAC) panels installed in a building as late as 1998. This date is significantly later than previous reports suggest as the last significant use of RAAC elements in the UK.
Reinforced aerated autoclaved concrete planks found on pitched roof of 1990s hospital building
A building constructed in the early 1990s has been found to contain reinforced aerated autoclaved concrete (RAAC) planks. This date is important since it is much later than the previously thought last significant use of RAAC in buildings in the UK and potentially affects the scope of buildings that could require screening for RAAC problems.
IStructE publishes investigation and assessment of RAAC panels
The IStructE has published guidance that provides identification and remediation solutions for Reinforced Autoclaved Aerated Concrete (RAAC) planks.
IStructE RAAC Study Group & members with RAAC experience
The IStructE have formed a RAAC Study Group and created a list of professionally registered structural engineers who have experience of providing solutions for managing RAAC planks.
Reinforced autoclaved aerated concrete in roofing in schools
This document is for building owners to help them to identify the presence of reinforced autoclaved aerated concrete (RAAC) and to check whether any further investigation or action is needed.
Failure of RAAC planks in schools
A reporter was asked to investigate a reinforced autoclaved aerated concrete (RAAC) roof which had collapsed in a school.
Reinforced autoclaved aerated concrete roof planks - sharing experiences
A reporter has surveyed a number of buildings with reinforced autoclaved aerated concrete (RAAC) roof planks and wants to share their experiences to help others.
Failure of reinforced autoclaved aerated concrete (RAAC) planks
In late 2018, the Local Government Association (LGA) and the Department for Education (DfE) contacted all school building owners to draw attention to a recent failure involving a flat roof There was little warning of the sudden collapse.
Aerated concrete slabs
A reporter discusses the failure of precast reinforced autoclaved aerated concrete (RAAC) slabs during construction.
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