07 Jul 2022

Redress schemes based on 'guesswork'

Scientific evidence shows Internal Sulphate Attack is the problem - expert

Scientific evidence shows Internal Sulphate Attack is the problem - expert

Internal Sulphate Attack results

The 90/10 mica redress scheme and its proposed replacement, which is coming before Cabinet on May 31, apparently without pre legislative scrutiny, are based on “guesswork”.

They cannot and will not address the issue of crumbling homes in Inishowen and beyond because they are not based on any empirical scientific studies.

This is according to an Inishowen scientist currently involved in an international study aimed at finding the correct cause of the ongoing deterioration in properties all along Ireland's western seaboard.

Professor Paul Dunlop.

Buncrana's Paul Dunlop, Professor of Glaciology and Research Doctor for Geography and Environmental Sciences at Ulster University, is collaborating with Dr Andreas Leemann, Head of the Concrete Technology Group at Empa [Federal Research Institute on Materials] in Switzerland.

Speaking to Inish Times, Dr Leemann said he knew of no mechanism directly involving Mica in hardened blocks, which caused the type of deterioration that has been observed.

He said: “And I have seen no scientific evidence so far, that does show this. As such, Mica as the problem is pure hypothesis in my eyes.

“Pyrrhotite oxidation with Internal Sulphate Attack is no hypothesis but a process backed up by clear scientific evidence.”

Explaining Internal Sulphate Attack, Professor Dunlop said it was caused by Iron Sulphide Minerals including, Pyrrhotite, Chalcopyrite, Marcasite, Rare Pyrite and Minor Pyrite, which core testing revealed were present in people's blocks.

He elaborated: “When Government commissioned the Report of the Expert Panel on Concrete Blocks, there was no mention of Iron Sulphide minerals being an issue in Donegal. There was a severe lack of detailed science in that report.

“It was not until people started to get their homes tested under the IS465 protocol, that Petrolab Limited [mineralogy and petrography specialists] in Cornwall in England, started to report high levels of free Muscovite Mica in people's blocks, as well these other Iron Sulphide minerals including, Pyrrhotite, Chalcopyrite, Marcasite, Rare Pyrite and Minor Pyrite.

“The reason they were being flagged was because Petrolab was doing detailed petrographic analysis.

“That type of work should have been done before the Report of the Expert Panel on Concrete Blocks was published in June 2017 because what they did was guess at the cause of the deterioration in the blocks. It was just guess work.

“The IS465 protocol, which came out of that report, is based on the notion that mica was the problem in Donegal, simply because mica is a known issue in concrete.”

Professor Dunlop, himself an affected homeowner, said the authors of the 2017 report, hung their hats on the idea there was a freeze/thaw in 2010/2011, which coincided with the cracking.

He added: “They just said, 'Okay, mica attracts water. It must have attracted water around that time and the cold weather must have fractured the blocks'.

“And a whole remediation scheme came out based on that notion, which had very little scientific evidence supporting it.

“Essentially, they came up with a scheme without actually finding out what the problem was first.

“When pyrrhotite and these iron sulphide minerals were being flagged from people's homes, as a result of core testing, the issue should have been re-examined but no-one was looking at it.

“It was being flagged by chartered engineer, Dr Ambrose McCloskey, who identified a problem. Engineers were being told to fix homes but no-one was looking at the issue of Internal Sulphate Attack.”

Mr Dunlop said he found geologists were not interested in carrying out research. He subsequently reached out to Dr Leemann and they are now collaborating on a Ulster University pilot study.

He said: “I sampled four homes with different states of degradation from minor cracking to complete disintegration.

“I sent the concrete to Dr Leemann and within a few weeks, he identified the problem as Thaumasite, a Calcium Silicate mineral, growing inside the walls, a Sulphate salt.

“Dr McCloskey was right. He was flagging the issue there was more than mica going on with blocks and engineers were being asked to make recommendations to remediate homes but he had not seen any independent science to show what was going on inside people's walls.

“Andreas and I have been able to sample homes independently and he has been able to demonstrate clearly the mechanism of cracking relating to Pyrrhotite changing. That is the key piece missing from all of the narratives people were giving since homes began cracking.

“Dr McCloskey flagged the fact there were issues other than Mica. He said outer leaf remediation was leaving concrete in the blockwork that had Pyrrhotite, which might react and cause problems further down the line,” said Paul Dunlop.

Professor Dunlop said, Dr Andreas Leemann stated in a recent presentation, the sample from four houses in Donegal did not deteriorate due to the presence of Mica.

“They deteriorated because Pyrrhotite oxidation triggers Internal Sulphate Attack, which leads to the expansion of the concrete blocks and in a second phase to the disintegration of the cement hydrates.

“The Government has put the cart before the horse in introducing two redress schemes without having done and empirical scientific research into what is actually causing blocks and possibly foundations to disintegrate so catastrophically.”

Watch: Dr Andreas Leemann explaining Internal Sulphate Attack

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