They claim that hundreds of schools in the UK are at risk of collapsing just as children return to the classroom

Thousands of British boys started classes this Monday and but their schools will remain closed. They don’t know when they will be able to return. The person responsible is regular reinforced concrete (RAAC), a construction material that was used in the 60s and 70s, and has started to fall apart. The safety of schools is at risk today and they must be inspected, one by one, by structural engineers. Social houses and passers-by, who pass through the sidewalks of the buildings, are also at risk.

Hundreds of British schools still have no idea if they will teach in unsafe buildings, when students begin their new school year.

Ministers face demands to speed up school inspections after acknowledging on Sunday that It could be months to discover all the spread of dangerous concrete in classrooms.

The Department of Education has confirmed that there is autoclaved reinforced aerated concrete (RAAC) in 156 schools. Last week 104 were told that they would move or close.

Gillian Keegan, the Education Secretary, will face questions in the House of Commons on the RAAC issue.

But all eyes are on the current Prime Minister and former Chancellor of Finance, Rishi Sunak for not having adopted budgets on time to repair schools and social buildings.

It is believed that thousands of GP surgeries, courts and other facilities government contain RAAC. Experts wonder if ministers were discovering the extent of the problem.

Gillian Keegan, the Secretary of Education, was preparing to face more demands this Monday to publish a complete list of schools which were built using RAAC, during a questioning in the House of Commons.

He said he had “no choice” but to tell some schools to close, after discovering their buildings were in danger of collapsing.

Dame Rachel De Souza, England’s children’s commissioner, criticized the government’s handling of a topic that has been known for years. “I am extremely disappointed and frustrated that there was no plan for this to happen,” she told the BBC. “Maybe the government didn’t know this would happen this week. But we knew the stock was in this situation.”

Ministers insist they had to act after new collapses in structures previously considered safe led to a change in official advice. Jeremy Hunt, the current Chancellor of Finance promised “spend whatever it takes to solve this problem as quickly as possible.”

The cost to the taxpayer is likely amounts to hundreds of millions of pounds, which will be removed from existing budgets for educational infrastructure. This will raise fears that schools will be left behind in other repairs.

An education department source said ministers had cut back on school repairs because “politics is always in favor of a new school, rather than rebuilding existing ones.”

But Hunt denied that austerity measures had contributed to the problem. He said the government was carrying out a “comprehensive program” of investigations in schools. But he admitted: “Obviously, we could find new information in the next few weeks or months.”

Figures published in June revealed that more than 2,000 of 14,900 schools surveyed still they had not responded RAAC questionnaires. Government sources suggested hundreds of schools had yet to do so. This means they had no idea if their buildings contained concrete. Ministers are said to have telephoned schools directly to urge them to respond.

Nor have construction surveys been conducted at all schools suspected of having RAACs. Officials refused to deny suggestions that 450 schools had yet to be inspected by inspectors. But they insisted that the most delayed controls be done this week.

Hunt declined to give details about the figures, saying: “I think that might scare people unnecessarily.”

Angus Drummond, from RAAC Consulting and Solutions, explained that his company’s working hypothesis was that around 10 percent of UK schools, about 2,000, could be affected. The calculation was made after discussions with the construction sector and local government officials. But the government questions it.

Drummond, from Chelmsford, Essex, said the Department of Education survey sent to schools did not ask for an expert to determine the presence of concrete.

“There’s a good chance that the building administrator - or in old parlance, the janitor - has been taking a look at some schools,” he added.

“The defective construction material that is causing the closure of dozens of schools should never have been used in any permanent building,” said a former president of the Institution of Structural Engineers.

Dr. John Roberts, who was president of the professional body in the early 2000s, believes concrete was missold by manufacturers and that even then many engineers were suspicious.

In a letter to The Times, he wrote: “As a Chartered Structural Engineer in active practice since the early 1970s, I never considered using RAAC because it didn’t ‘seem’ right for permanent structures”.

Roberts, who worked on the construction of the London Eyeadded that “RAAC is particularly vulnerable when used on flat roof structures, as the porous nature of aerated concrete means thatthe slightest entry of water, will cause serious reinforcement corrosion of embedded steel”.

He explained that RAAC was sold as a commercially available product in the 1960s, 1970s, and 1980s. “You had to buy from a catalog and you completely trusted what the manufacturers told you. Was extremely cheap and said that it complied with all known codes and standards and that it would be fine,” he said.

“But some of us (in fact, many of us at the time) don’t use it for structures even though we all use it as blocks,” he clarified.

He explained that the aerated blocks, known as breeze blocksare widely used to this day because the air bubbles in the material provide a huge insulation benefit.

He added that the material It was safe to use on walls. The problem arises when it is reinforced with steel and used on roofs for large spaces.

“If it’s used on a roof and there’s some kind of moisture up there, steel bars will rusthe said. “Rust causes expansion because rust occupies about six times the volume of steel, which turns to rust. So there could be expansion and cracks and that’s what can cause concrete to fall” he detailed.

The RAAC can no longer be used in the UK. But Roberts said it was still being sold abroad. He believes the RAAC sold poorly when it became available in Britain because the manufacturers made “all sorts of claims about its performance.”

“The particular selling point was that it was an inexpensive way to cover large openings“, said.

“Companies that used it should be held accountable,” he added. But many have closed since then, which means it would be “extremely difficult”.

Roberts, now a visiting professor of structural engineering at the University of Manchester, cautions that the RAAC is likely is much more widespread than many suspect.

“Is pretty easy to identify, except it’s hidden behind false ceilings so you can’t really see it. You don’t necessarily know the material is there. You have to lift or remove the roof before you can look at the underside. I suspect there is much left to discover because the records kept about what was used in these buildings are variablesso to speak”.

Other experts claim that the material also can be found in social housing. Philip Morris, a registered architect, told Inside Housing magazine that the (RACC) “was widely used by council architects on council housing projects.”

And he added: “Without a doubt, It is a risk to life. Not only for residents but also for passers-by, if we talk about exterior cladding panels that They break loose and fall to the ground”.