Rubbish aerated concrete

[Mr Pointy]

So 104 schools are to be shut along with some hospitals. How has this come about? presumably it's not the same company building them all or supplying the concrete (although maybe it is) so how come we are suddenly having problems with a material even the Romans mastered?

Engineers & architects know how to use the stuff so how come the foamy type got past al the testing that was presumably undertaken?

[dundarach]

It's the age and maintenance of it that's the issue.

[Vasco]

Reports this morning said it was cheaper but had only a 30year lifespan.
Do schools only last 30 years?

[Essarell]

dundarach said:

It's the age and maintenance of it that's the issue.

This is going to be a massive problem right across the country as our infrastructure ages………Britain is crumbling……..

[deckster]

Vasco said:

Reports this morning said it was cheaper but had only a 30year lifespan.
Do schools only last 30 years?

Budgets and foresight typically last much less time than that.

30 years? The decision makers will be well retired by the time it becomes the next guy's problem.

[Mabbs9]

Vasco said:

Reports this morning said it was cheaper but had only a 30year lifespan.
Do schools only last 30 years?

A construction professor was on the Beeb just now. Nearly all buildings have a nominal life span of 30-40yrs where a bridge/tunnel uses a design life span of 100yrs.

The material can last very much longer if maintained. Which means protected from the elements with this type of concrete. So in some cases it may have been wet and this means it has deteriorated.

He also stressed it was a suitable material to use.

[Chris Type R]

deckster said:

Vasco said:

Reports this morning said it was cheaper but had only a 30year lifespan.
Do schools only last 30 years?

Budgets and foresight typically last much less time than that.

30 years? The decision makers will be well retired by the time it becomes the next guy's problem.

That to me is the surprising part - especially in a country where buildings over 200 years of age are not a rarity. Was the assumption that the buildings would be knocked down and rebuilt every 30 years - it seems a terrible decision. I wonder if the same pattern will emerge when the PFI funded developments reach 'age'.

[boyse7en]

Is this the same issue that was called "concrete cancer" a few decades ago? My old school had that and was pulled down a while back despite being only about 40 years ago.

[ARHarh]

The "expert" on the telly this morning said "they did not anticipate the 30 years life span when they built them", it is only as time has passed and problems been found that the estimated lifespan has come about. No one could test for 40 years exposure without having 40 years to wait and see what happens. Yes you could simulate it to the best of your knowledge but that might not cover a real life scenario.

Bound to be plenty more buildings made with this stuff, probably the rest of flats that got away with the cladding issue

[epom]

Massive issues in the likes of Donegal with this. Google Mica concrete.

[Silvanus]

I spent a good number of years working in school construction/maintenance. This issue has been known about for quite some time and there has been a lot of burying of heads in the sand. This could have been dealt with so much better.

[Zarco]

Mr Pointy said:

So 104 schools are to be shut along with some hospitals. How has this come about? presumably it's not the same company building them all or supplying the concrete (although maybe it is) so how come we are suddenly having problems with a material even the Romans mastered?

Engineers & architects know how to use the stuff so how come the foamy type got past al the testing that was presumably undertaken?

I'd never heard of it until yesterday. From the few news stories I read:

- It was used between 1960s and 1990s before anyone realised it deteriorated over time.
- The system was favoured as it made the concrete lighter, presumably reducing load and cost on other elements of the structure. Engineers and architects thought it was OK at the time.

I'm guessing that the last batch of buildings that used aerated concrete have reached 30yrs old and we have seen another failure. This has prompted another round of inspections to check for the material. Why they are only checking properly now is the bigger question (with an obvious answer - money!).

[epom]

Seemingly this was highlighted a number of months ago, but heads were buried in the sand.

[ChocolateFrog]

Buildings built from the 50's.

So some are potentially over 70 years old and all of a sudden they're unsafe. I get that it stems from 1 roof collapse.

Why can't the buildings just be inspected. 104 buildings isn't exactly an unmanageable number for a country of 65 million people.

[Drumroll]

Mr Pointy said:

So 104 schools are to be shut along with some hospitals. How has this come about? presumably it's not the same company building them all or supplying the concrete (although maybe it is) so how come we are suddenly having problems with a material even the Romans mastered?

Engineers & architects know how to use the stuff so how come the foamy type got past al the testing that was presumably undertaken?

Like so many things, it was/is a lot more complex than it first appears. As they were precast units, then there are likely to be fewer manufactures than if they had been made using batched concrete (truck mixed) RAAC was also used extensively in Europe.

Cost was undoubtedly a factor, but by designing a building using lighter material you don't need as much "support" for it, so the whole design is cheaper. Which unfortunately also means that you can't just replace the roof or side panels.

Where as the famous "concrete cancer" at spaghetti junction (and other locations) could be done as on going repairs. The RAAC can fail suddenly and that is the concern. Interestingly whilst they have closed the schools affected they have said nothing about the hospitals with RAAC.

[Vasco]

Seems that it starts to sag but can, sometimes, survive merely just by receiving additional supports in the right places.
Presumably, for many places it will mean eventual demolition rather than repairs.
Will this be affecting tower blocks, offices, factories etc in addition to schools ?

[Mr Pointy]

Right, so it's a historic problem (although not that far back in history) rather than a recent material that's gone wrong. I knew we would have some knowledgeable posters with the answer.

[Vasco]

When did we stop using it - or do we still ??

[Zarco]

Vasco said:

When did we stop using it - or do we still ??

Used up until 1990s (presumably when the earliest buildings started to fail!).

[Zarco]

Silvanus said:

I spent a good number of years working in school construction/maintenance. This issue has been known about for quite some time and there has been a lot of burying of heads in the sand. This could have been dealt with so much better.

Can quite believe this.