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As Britain is rocked this month by revelations of unsafe foam concrete in schools, construction experts who have gathered in Prague to celebrate the material are frantically gathering details of the scandal engulfing Britain.
“I’m under siege, and I’ve never been under siege,” says Professor Chris Goodier, who has made a name for himself as one of the few British experts with an in-depth understanding of concrete. “This is already a problem in the UK but not in other countries.”
Just days before the start of the academic year, the UK government has sparked a political firestorm by closing more than 100 school sites at risk of collapse and prompting departments across government to look for other public and private buildings containing reinforced autoclaved aerated concrete. effort, or RAAC.
The British government defended its record, saying awareness of the country’s problems stemmed from the country’s “world-leading” surveillance system.
But the move has sparked a debate over whether UK building standards lag behind other countries, with some experts telling the Financial Times that the UK’s Raac problems are caused by flaws in the design, construction and maintenance of UK public estates.
“This is very, very strange because AAC has been a very well-known and respected product for many years,” said Fouad H. Fouad, chair of the civil engineering department at the University of Alabama at Birmingham. In the 1980s, he helped introduce lightweight materials to the United States.
He added that he had studied some photos of British buildings that had failed and found “there is a specific problem in the UK”. . . Design, production and construction”.
In some cases, he said, concrete slabs appeared to have been cut in the wrong places, including at critical reinforcement points. In other cases, he noted that reinforcements were missing or not properly sealed against water.
Raac was a popular building material in postwar Europe and North America, especially in Germany. It is also used in construction in Australia, New Zealand and Mexico.
News of serious concerns over the integrity of buildings built using the material in the UK between the 1960s and 1990s, including reports of several collapses, alarmed overseas experts.
Four international experts who study the material told the Financial Times that they were not aware of any serious corrosion or collapse issues related to Raac outside the UK. The UK government was unable to point to known examples overseas or research showing this was an international problem.
The government said it had “taken decisive action to address this issue and adopted an appropriate approach guided by experts”.
“Expert professional advice on Raac has evolved over time, from advice in the 1990s that Raac did not pose a safety hazard to more recent advice on identifying and assessing structural adequacy,” the report said.
Raac was used extensively in post-war Britain to build large numbers of schools and hospitals at the lowest possible cost. More recently, during the past decade of Conservative government, the maintenance of public property has suffered.
The Institute for Government, a think tank, estimates that the overall capital budget for school repairs fell by more than a third between 2007-08 and 2020-21, from £7.9bn to £5.1bn in real terms.
Karl-Christian Thienel, chairman of the European standard-setting body for autoclaved aerated concrete, said the fragility of Raac’s public buildings stemmed in part from Britain’s cost-cutting approach.
“Poor maintenance leads to water intrusion . . . providing an opportunity for (steel) corrosion,” he said. “Also, old flagstones often have very little support.”
Others say it is only a matter of time before other countries discover similar problems. Patrick Hayes, technical director of the Institution of Structural Engineers, said he believed such cases had so far only been detected in the UK, where there are robust systems for confidential reporting of structural problems in buildings.
He and Goodill, professor of construction engineering and materials at Loughborough University, believe that at some point the failure will be discovered internationally.
But Goodill added that some Raac buildings in the UK had been found to have braces that were too small and reinforcements in the wrong places, “both of which can have structural consequences”.
In countries such as Germany, the construction industry tends to have “better training and construction practices,” he said. “They have higher quality (materials) than we do and they have good engineers.”
Jiří Kolísko, a professor at the Technical University in Prague, said Raac has been used in the Czech Republic for decades, mainly for walls and building facades. He said that in the UK it was mainly used to build long flat roofs, where it was more susceptible to rainfall and the concrete could erode if not properly sealed.
Professor Manfred Kuhlbach, director of the Institute of Concrete Structures at the University of Dresden, said he was not aware of Lack causing any problems in Germany. When asked why, he said: “Because when we use Raac, we use plastic-covered rebar (steel bars). (It’s) very expensive, but effective.”
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