There has been a call for urgent action after the first identification of Raac at a school in Northern Ireland.
It was confirmed on Wednesday afternoon that the crumbling concrete had been found in an eight-classroom block at Cairnshill Primary School in south Belfast.
The Department of Education said engineers have confirmed that the block is unsafe for continued use.
It said steps have been taken to close the classrooms affected and the rest of the building remains safe to use for staff and pupils.
The department’s permanent secretary, Dr Mark Browne, said remedial work is taking place.
“The safety of our teachers, staff and pupils in our schools is our highest priority.
“We fully understand that this news will be concerning for staff, parents/carers and the wider school community,” he said.
“The department and the Education Authority are working closely with the school to ensure those classes affected can return as early as possible next week.
“The department will provide funding for all remedial works required and we are committed to ensuring that there will be as little as disruption as possible for the school and parents.”
Raac, a lightweight, “bubbly” form of concrete commonly used in construction between the 1950s and mid-1990s, has been identified in a number of buildings in England and Scotland.
In September, Northern Ireland’s Department of Education commissioned the Education Authority to carry out structural surveys to ascertain whether RAAC was present within schools in the region.
The EA’s maintenance service has been carrying this work out.
Dr Patrick Roach, general secretary of the teachers’ union the NASUWT described the news as “inevitable” with RAAC having been confirmed in schools in Great Britain.
“The most important thing now is to get to the bottom of how many schools may be affected and complete the survey of school buildings as quickly as possible,” he said.
“Parents, pupils and school staff need reassurance to ensure safety remains the highest priority.”
“Children and young people should not be facing the prospect of having their education disrupted as a result of lack of investment by the Executive in Northern Ireland’s schools.
“Officials must, as a matter of urgency, take all steps to ensure we have a detailed picture of the situation as soon as possible.”
South Belfast MP Claire Hanna said the discovery of Raac at Cairnshill Primary School will cause concern, but said that “every precaution is now being taken to prioritise the safety of children, teachers, staff and parents”.
“I have been in touch with the school leadership and the Education Authority and I am confident that their initial response has been guided by the singular priority of keeping children and school users safe,” she said.
“This is an evolving situation and in order to protect the wellbeing of children, teachers and other staff, eight classrooms have been closed and evacuated as a precaution.
“This is exactly the right approach as we learn more about the risks to these sites.
“I will continue to liaise with the school and the Education Authority as more information becomes available and a plan is put in place to manage this situation.
“We need to deal with this at pace to ensure that there is minimal interruption to the education of these kids.
“There will undoubtedly be disruption to the lives and schedules of everyone involved, I would appeal to all those affected to work with the school and with the rest of us, we all want this to be dealt with safely and swiftly in the interests of children, parents and staff.”