More than 100 schools across the United Kingdom have been ordered to close over fears that potentially dangerous lightweight concrete used when they were built between the 1950s and the mid-90s could lead to the buildings falling down.
The crisis has left school administrators scrambling to find temporary accommodation and has forced many students to begin their school year with online classes from home.
This type of concrete, officially known as reinforced autoclaved aerated concrete (RAAC), is made from lime, water, and an aeration agent.
The mixture is poured into moulds that are exposed to high pressure and heat – known as autoclaving – to create a lightweight, strong, and porous material.
It is commonly referred to as “crumbling concrete” and described as “80 percent air”. It has also been nicknamed Aero Bar, a popular chocolate bar that contains pockets of air.
RAAC has been assessed to put buildings at risk of collapse after exceeding its 30-year lifespan.
In total, the UK government announced that 156 schools were built using RAAC. Out of those, 104 require urgent action, while 52 have already received repair works.
The UK schools minister, Nick Gibb, said these numbers would likely increase.
Many schools, listed by media outlets, are partially closed as the local councils are working on erecting temporary solutions.
UK’s Guardian newspaper claimed that teachers are scrambling to find temporary accommodation in libraries, marquees and Portakabins.
The government initially announced it would not pick up the bill for the temporary structures but withdrew the statement after a furious response from teachers.
On Sunday, UK Chancellor of the Exchequer Jeremy Hunt promised to “spend what it takes” to make classrooms safe again, and that an “exhaustive process has been carried out to identify schools at risk”.
While 35 schools in Scotland had been found to contain RAAC, the education secretary for Scotland, Jenny Gilruth, said they would not be shut.
Gilruth accused the UK government of deviating from advice given by the Institution of Structural Engineers.
More than 30 hospitals are also believed to be at risk, according to experts.
The Local Government Association has also said although municipal architects mainly used RAAC in schools and offices, it has also been found in other buildings, including shopping centres and homes.
Matthew Byatt, the head of the Institution of Structural Engineers, has claimed that high-rise buildings with flat roofs constructed between the late 1960s and the 90s could contain RAAC.
A criminal court in north London was reportedly shut down recently due to the use of RAAC.
There are fears that crumbling concrete could expose asbestos, a highly carcinogenic material that is now banned in the UK but was extensively used in construction between the 1950s and the 90s and remains in at least 300,000 non-domestic buildings across the country.
Asbestos is not considered harmful if undisturbed, but if exposed or broken into smaller parts, it can lead to cancers, in particular lung cancer, if inhaled.
If asbestos is found in schools that have been closed due to the presence of RAAC, it could hamper repair work and lead to months-long closures.
Sources: Al Jazeera, BBC.