Autoclaved Aerated Concrete Failure - Residential Buildings Affected?

[FiscoKing]

Morning All,

There's a big HooHaa in the press ATM about Autoclaved Aerated Concrete (AAC). The government are closing schools and public buildings that use it. After decades of use they've only just realised it can crumble. Story here:

https://www.bbc.co.uk/news/live/uk-66690889

My question; does AAC include breeze block and cinder block as used in residential housing since the 70's? My house is full of this stuff. It's easy to detect as you can just push a screwdriver into it, or saw it with a standard timber saw - picture below. All my cavity walls use it.

https://i.ibb.co/7pbBfWh/1500036.jpg

Thanks.

 

[Notch7]

AAC isnt used domestically for roofs generally which is where most of the concern is

if you have a house of breeze blocks -the bluish blocks, they are pretty strong

In any case your external wall is probably face brickwork

 

[Notch7]

I should add its the reinforced blocks (RAAC) that are the issue not AAC

 

[denso13]

does AAC include breeze block and cinder block as used in residential housing since the 70's?

No, different animal.

 

[Bod ...]

I should add its the reinforced blocks (RAAC) that are the issue not AAC

Is it what they called concrete cancer ️?

 

[transam]

There is a block of newish houses down this way ( timber framed)

We’re all the external walls are polystyrene with a thin coat of rendering on

A row of Decorative bricks (?) are under the windows and they are dummy’s just for show

If it was not for a sheet of ply behind the walls in the interior you could actually kick yer way into the house through the walls

Weird set up imho

 

[Notch7]

Is it what they called concrete cancer ️?

I don’t know TBH - I think that’s just reinforced concrete where the re-bar has started rusting causing the concrete to expand

 

[Bod ...]

I don’t know TBH - I think that’s just reinforced concrete where the re-bar has started rusting causing the concrete to expand

The problem is this has been ignored and ignored until it can't be ignored anymore.

Two schools have closed. The third school that is my daughter's have had the temporary marquees put up for until the more permanent temporary cabins will be installed (not my words). So they will be ok. The two primary schools are not so fortunate.

 

[Vinty]

Concrete has been used for thousands of years, it isn't as if we are a learning curve as if to what concrete can and cannot do.
The problem isn't concrete itself, its the greed and lack of accountability of those who sell lead as the new gold.
People need to be held accountable for their actions.

 

[Bod ...]

Concrete has been used for thousands of years, it isn't as if we are a learning curve as if to what concrete can and cannot do.
The problem isn't concrete itself, its the greed and lack of accountability of those who sell lead as the new gold.
People need to be held accountable for their actions.

You are Spot on those making the same greedy mistakes now and putting people's life's at risk still sit comfortably.

Has anyone been prosecuted for
Grenfell Tower yet?

No I don't think they have.

​

 

[transam]

Afaik This concrete is just not a UK issue

Apparently it’s widely used or been used in Europe

Are they having issues ???

 

[fillyboy]

Afaik This concrete is just not a UK issue

Apparently it’s widely used or been used in Europe

Are they having issues ???

I believe Sweden were one of the first to develope it. Been widely used in Germany, Belgium, France. Issues seem to be down to poor maintenance, once water gets into it it's *****d.

 

[mattylad]

I suspect that the problem in our schools is just the tip of the iceberg and that there are many many more building with it in that are past their use by date.

Now the media are onto it we can expect more to come to light.

 

[Tigercubrider]

From what I understand, part of the issue is that “normal” concrete is waterproof, but the RAAC is not. (Or at least more susceptible to damage)
If built to the intended standard and maintained, it should be covered in a high quality roofing material to prevent moisture.
However budget saving patching has resulted in the panels getting wet due to delays and cheap coverings.

The moisture affects the RAAC more than a solid concrete panel

At leat that’s what a guy on the radio said.

 

[Brigadier]

From what I understand, part of the issue is that “normal” concrete is waterproof, but the RAAC is not. (Or at least more susceptible to damage)
If built to the intended standard and maintained, it should be covered in a high quality roofing material to prevent moisture.
However budget saving patching has resulted in the panels getting wet due to delays and cheap coverings.

The moisture affects the RAAC more than a solid concrete panel

At leat that’s what a guy on the radio said.

That's about right.
Water gets in.
Crumbling, freeze-thaw, etc.
Rebar corrodes.
Add this is the fact that "soggy" concrete is a lot heavier than dry, aerated, and this is why it's a problem.