Sulphate Attack in Concrete Floors - How Much?!?!
Posted 27 August 2003 - 07:38 PM
Does anyone have any experience of this problem? Is it common? Does it really need to be put right? Is digging up the whole floors the only option?
Posted 28 August 2003 - 08:25 AM
Posted 29 August 2003 - 12:06 PM
Posted 30 August 2003 - 03:23 PM
Posted 31 August 2003 - 10:57 AM
The force of the chemical reaction can displace external and sleeper walls on domestic and commercial buildings leading to the opening of skirting board joints, the bouncing of timber floors, cracking and displacement of the brickwork as well as disruption of concrete floors and sub floors. The physical defects described can take up to 10 to 20 years before they become evident. The correct remedial actions to sulphate attack is normally to remove all the defective concrete and contaminated hardcore and replace them which is a disruptive and costly process. Building insurance does not usually cover sulphate attack, as most policies tend to have a clause that exempts all forms of chemical attack.
Concrete footings and foundations can be subject to deterioration from chemical attack from acidic solutions or salts of sulphate. The risk is increased in areas of previous mining activity where the concentrations of minerals in the soils pose an increased risk. Rainwater absorbs carbon dioxide from the atmosphere forming carbonic acid that decomposes - in situ- the sulphides concentrated from mining waste to produce sulphates. The sulphates react with cement within the concrete before causing gradual degradation and eventual failure of the concrete.
Posted 24 March 2004 - 02:19 PM
SO3 & SO4 levels were found to be 0.01 & 0.13 respectively. I was advised that these levels are well within acceptable limits and therefore could not possibly cause a sulphate attack. I'm not convinced! Can anyone shed any light on exactly what levels are needed to cause a sulphate attack?
Posted 07 April 2004 - 06:25 PM
Guest_dave leese (Unregist_*
Posted 14 August 2004 - 08:07 AM
replaced because of ash grade B but the builder
who is doing the work has dug out 600m deep and
has left the ash under the divide walls and fireplace also he,s put the old concreate back in
this can,t be right or is it
any help a.s.a.p firstname.lastname@example.org
Posted 14 March 2005 - 08:47 AM
Thanks for any info that you can provide !
Posted 14 March 2005 - 12:38 PM
There must be moisture present for the reaction to take place so its unlikely itll affect upper floors but not impossible.
It would probably be best to ask your soliciter if the surveyor would be liable should it reoccur where he says it was remedied but then theres always the chance of it opping up elsewhere.
As for the ground floors,it happens when moisture and sulphates in the hardcore react with the concrete,one would have to suppose theres the same hardcore under the whole house therefore only one area being affected is unlikely in the long t5erm.
the problem is that if its the slab it can lead to your walls being unsupported and a bigger problem being that testing is destructive and expensive.
Id have at min a full survey done with particular note being made of the sulphate problem by your surveyor and see what he says.
Posted 14 March 2005 - 12:56 PM
Posted 14 March 2005 - 05:04 PM
Itll give you an idea and save me typing it out.
His suggestion though possible is vv unlikely.
Sad as it is I woouldnt buy,theres a good chance alls ok but theres plenty of houses on the market and Id have to think is it worth the risk?
My sympathys are with anyone who has the problem but at the end of the day thats not what your asking,youve got to weigh up the odds and in this case Id err on the side of caution unless its your dream home and no other will do then maybe its worth the risk
Posted 02 June 2005 - 04:17 PM
It was replaced with sd1 which states "the sulphate test is not to be used as a method of assesment in the risk of sulphate attack to a concrete floor"
The correct method to replace a concrete floor is to remove the concreter and lay a membrane.tHIS IS REFERENCED TO BRE 322 DATED 1997 Floor and flooring repairs Pye and Harrison.
The key elements are if the hardcore is dry and a membraine is present the concrete will not be attacked by the red ash or sulphates.
Reference Building Regs 1965 and the requirement to insert a membrane.
So if the property was built after 1965 it had a membrane and if it was laid properly the likely hood of sulphate attack would be extreemly remote.
For further reference go to the UK PARLIAMENT SITE TYPE IN RED ASH "joan Walley question to Mr Hope minister of building etc"
We wish to hear from any one who has had there property valued at £1 due to red ash or been forced to have there floor dug out on a valuation particularly if the house was built after 1965 and you are resident or live near to North Staffs.
We have found this out as the valuer insisted we provide a guarantee from a local expert.
Our floor sank by up to 11/2 inches after the work was completed and the floors relaid with laminate the work carried out was as per dave leese describes.
thats how we know all the bre stuff we did not need it doing and this comes from 2 structural engineers and trading stds.
WE NEED TO HEAR FROM ANY ONE ELSE WHO HAS SUFFERED THE SAME FATE TO COMPARE NOTES ON VALUERS AND CONTRACTORS.
Posted 21 April 2006 - 09:29 AM
Posted 21 April 2006 - 11:46 AM
Posted 21 April 2006 - 01:06 PM
If they wont let you test then Id walk away.
It doesnt matter what year it was built and your never going to get the mix sheet from concrete 50 yrs ago.
Posted 21 April 2006 - 05:43 PM
I think some of the fillers used included slag and ash from iron works and coal fired power stations. Some ash fillers are actually ok I believe.
Posted 24 April 2006 - 06:38 PM
Posted 14 September 2006 - 01:48 PM