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The UK’s two busiest international airports, Heathrow and Gatwick, have detected the type of concrete that recently forced hundreds of UK schools to close and sparked a political crisis.
The airports, which together handle nearly 100mn passengers a year, said they were aware of the presence of reinforced autoclaved aerated concrete, or Raac, before its use attracted national attention last week.
The identification of the substance at two of the UK’s largest airports points to the far-ranging prevalence of the material, which is prone to corrosion and cracking as it ages.
The porous concrete was used most commonly in public buildings from the mid-1950s to mid-1990, but it was also used in the construction of commercial private sector buildings such as offices, supermarkets and warehouses.
Heathrow and Gatwick were both privatised in the 1980s when the UK government publicly listed the British Airports Authority.
Raac was first found in Heathrow’s Terminal 3 last year, prompting temporary remedies to be introduced while the airport prepared a permanent solution.
The furore over schools led Heathrow to assess its management of the material. It has since concluded that its original plan remains suitable.
“Industry has been aware and acting on the remedial steps that should be taken in buildings that contain this material,” the airport said, adding that many other organisations are also assessing their estates for the material.
“Passenger and colleague safety will always be our first priority. We will continue to update stakeholders across the sector as our plans for permanent solutions progress.”
Structural engineers say that the presence of Raac is of most concern in buildings that have been poorly maintained. This is more common in the public estate where government cuts have meant investment in upgrades and repairs has been inconsistent.
Chris Goodier, professor of construction engineering and materials at Loughborough University, and one of the UK’s few experts on Raac, said that the presence of the material poses much less of a threat at airports than at schools and hospitals.
“There are people there running the place seven days a week with a big full-time maintenance team whose only job is to keep it running 24/7,” he said, adding that most airport maintenance staff will have been aware of the presence of the material for some time.
“They’ve got money and they spend money because if they had to close a building it would cost them a lot,” he added.
Goodier also noted that Raac could well be present in office or storage buildings attached to airports, and is not necessarily located in passenger terminals.
Gatwick airport said: “We have a register of locations containing Raac on the airport campus, which are closely monitored through a regular comprehensive structural inspection regime.
“Our most recent inspection in June 2023 did not present any concerns and we will continue to monitor on a regular basis,” it added.
Manchester airport is also carrying out checks to determine whether any of its buildings contain Raac, although it currently assesses the likelihood of its presence to be “very low”, according to a person briefed on the matter.