UK concrete crisis: What is RAAC and why is it ‘falling apart’?

This September has not been a normal ‘back to school’ for many UK students.

More than 150 schools in the country have been forced to close – in whole or in part – thanks to being equipped with a type of concrete that could suddenly collapse.

Autoclaved reinforced cellular concrete, also known as RAAC, is a lightweight construction material that was used from the 1950s to the mid-1990s in the UK and around the world.

It has recently been considered to be in danger of collapsing and is not only present in schools, but also in hospitals, airports, apartment blocks, theaters and other public buildings.

The British government has come under huge criticism for its handling of the situation and ministers in England and Scotland have been accused of covering up evidence about the seriousness of the problem for months.

Earlier this week, UK Education Secretary Gillian Keegan was forced to apologize after making “off-the-cuff” comments on camera while expressing frustration over the crisis of crumbling concrete in schools.

“Has anyone ever said ‘do you know what you’ve done, damn good job because everyone else has sat on their butts and done nothing?'” Keegan said at the end of an interview with broadcaster ITV. .

Before the controversy over RAAC – and the much-maligned government reaction – came to light, a report by the UK’s spending watchdog, the National Audit Office (NAO), had highlighted the cost and complexity which involved addressing the problem.

The government has since pledged to completely rebuild seven “structurally unsound” RAAC-built hospitals, but parents and political opponents alike are outraged following parliament’s response, with some saying it was “too slow” and “not going far enough.”

If you find it difficult to understand the controversy surrounding RAAC, as well as the magnitude of the problem, Euronews is here to help, with the assistance of some construction experts.

What is the RAAC?

RAAC is known as a less durable form of concrete, with a lifespan of around 30 years. It is prone to collapsing when wet. Surprisingly, concerns about its structural integrity were first raised by researchers almost 30 years ago, back in 1994.

Manufacturing in the UK stopped in the 1980s and, although it is not entirely clear why it was ended, researchers believed the material could be prone to problems.

“Due to their light weight, RAAC planks were commonly used for flat roofs, which is one of the main reasons why the current circumstances are dangerous. In the 1990s, even when RAAC was still in use, structural engineers discovered that its durability did not last over the years,” Stuart Bosley, managing director of Quantum and Project Consulting at DeSimone Consulting Engineers, told Euronews.

“As RAAC ages, it can weaken, increasing the risk of structural collapses. Its initial popularity was due to its light weight, ease of installation and affordability. At its peak of use, it was considered an efficient, cutting-edge building material,” Bosley added.

Where was RAAC used?

Contrary to some current reports, RAAC was not used only in the United Kingdom.

It was also very popular in countries such as Ireland, Australia, New Zealand and South Africa from the 1950s to the 1980s.

Experts said it was highly unlikely that RAACs made in countries other than the UK would be able to avoid similar problems.

“RAAC was used in various parts of Europe, but the extent to which each country or region adopted it would vary,” explained Stuart Bosley.

“(Other collapses in Europe) could raise questions about the use of RAAC or similar materials in other European structures. However, it is essential to investigate each incident individually to determine the exact causes,” he adds.

How dangerous is RAAC?

“RAAC has a shorter shelf life due to its inherent properties. Its large volume of pores makes it less reliable for structural purposes,” Andrew Coombe, CEO of My Build My Way, told Euronews.

“Larger RAAC units are particularly prone to sudden cracking, which can be catastrophic on load-bearing members, and a collapse can occur without warning,” Coome added, “As a porous structure, RAAC is vulnerable to moisture, chloride and carbon dioxide. , which can cause corrosion of the steel bars or welded metal fabric that act as reinforcing agents within the concrete.”

While it is not entirely clear exactly how many buildings contain RAAC, Stuart Bosley explained that it was absolutely crucial that they were all checked to ensure the safety of the people inside and nearby.

“Any structure built with RAAC during its period of popular use should be evaluated for potential risks,” he said.

The present problem dates back to at least 2018 in the United Kingdom, when part of the roof collapsed at Singlewell Primary School in Gravesend, Kent. RAAC was linked to the roof collapse and although no one was injured, government opponents say the Conservatives should have acted much quicker after that incident.

Where do the concerns around RAAC come from?

While you may not have heard of RAAC until 2023, the root of the problem actually goes back decades.

In fact, some problems with the material have been known for about forty years.

As early as the 1980s, roof collapses were reported on several buildings, due to decades of corrosion. Some required demolition and many were found to not contain adequate steel reinforcements.

In the late 1990s and early 2000s, the Building Research Establishment (BRE) published research papers which found that excessive deflections and cracks had been identified in a number of RAAC roof planks and highlighted “excessive” problems in a significant number of older buildings that used the material.

In 2019, the Standing Committee on Structural Safety issued an alert about the collapse to government departments, as well as hospitals, churches, construction professionals and local authorities in charge of schools. They wanted “pre-1980 RAAC planks to have already exceeded their expected useful life and it is recommended that they be considered for replacement.”

This event, and others, led to the Department for Education (DfE) publishing safety guidance on RAAC. There were delays, apparently due to insufficient funding and COVID-19-related delays, until February this year, when seven education unions demanded urgent action over the “shocking state” of school buildings at risk of collapse.

At the time, union bosses said the situation had “hit rock bottom.” In June, four schools in Essex and the North East of England were forced to close due to the presence of RAAC on their roofs. Affected students were taught remotely or in alternative, safe locations.

What’s next to prevent any RAAC-based catastrophe?

It has certainly been a difficult time for those who have been informed that their buildings contain RAAC.

Some pupils are being told they will have to take pandemic-style remote lessons, while other school leaders have been desperately searching for temporary facilities.

Around 14 hospitals, built “wholly or largely with RAAC”, have been declared dangerous, with seven of them considered “critical” and unfit for use beyond 2030.

As we head into the colder months, the National Risk Registry warned of the threat posed to schools by “low temperatures” and “heavy snowfall,” which could pose a “significant threat to human well-being.”

Opposition leader Sir Keir Starmer has blamed the unraveling concrete crisis on government “cutting corners” and “plaster policy”, joining industry experts in that sentiment.

“You could argue that the government could have taken more rigorous measures to determine the true extent of the risk,” Stuart Bosley told Euronews. He added: “Given that these concerns have persisted for more than a decade, a well-orchestrated risk management approach could have avoided this widespread dilemma.”

A government spokesman refuted allegations of wrongdoing and said ministers had acted “decisively” to address the RAAC scandal. The DfE has asked schools to proactively check for RAAC in their buildings and say they will offer funding so expert guidance can be sought.

Some have questioned whether this is enough or whether it is simply too little, too late.

“Upon identifying any wear and tear, schools should quickly establish safety measures, including separating compromised areas,” Bosley explained. “It is essential to update evacuation procedures, emphasizing safeguards against possible structural emergencies.”