More Derry homes will crumble

As a Derry home becomes one of the first confirmed cases of 'mica' in Northern Ireland, Derry Now reporter Catherine McGinty explains why 'mica' is a misleading term which barely scratches the surface of this unprecedented crisis.

A Derry home has been described as the first in Northern Ireland with a confirmed case of mica.

Danny and Kate Rafferty, from Beragh Hill Road in the Skeoge area of the city, carried out testing on their blocks when telltale 'spider cracks' appeared on the outer wall and chimney of their house.

As a journalist who covered the issue of defective concrete and defective concrete products extensively in Inishowen in recent years, I was struck by the framing of this news.

Reports of a house in the city built in 2006 ‘having mica’ exposed a worrying and substantial gap in experience, knowledge and understanding of the subject between Derry and Donegal.

An Inishowen home affected by defective concrete and defective concrete products.

For the latter, the word ‘mica’ has become shorthand for physically crumbling homes and foundations and utterly devastated families. 

However, international scientific research has proven beyond doubt that mica is not the problem. The term ‘mica crisis’ is a complete misnomer.

I will address how and why the idea of ‘mica being the problem' gained such traction, unfortunately, later in this piece.

Suffice to say, I have no doubt that, in the coming months and years, more and more homes and foundations in Derry, the rest of Northern Ireland and Britain will undoubtedly display the unmistakable signs of having been constructed using defective concrete and defective concrete products.

A good starting point for anyone seeking to understand what I would characterise as the humanitarian crisis currently unfolding in Inishowen - along Ireland’s western seaboard, in fact - would be the international conference ‘The Science and Societal Impacts of Defective Concrete’ taking place in the Clanree Hotel in Letterkenny this coming Tuesday (November 15).

Speaking to Derry News, conference co-organiser Professor Paul Dunlop said it drove him mad that people still referred to ‘mica’ rather than ‘defective concrete and defective concrete products’.

Professor Dunlop, a research director in geography and environmental sciences at Ulster University, Coleraine, will chair a roundtable discussion - ‘The Science of Defective Concrete’ - from 3.20pm to 4.00pm at the conference.

He co-authored a definitive paper on this subject titled: ‘Pyrrhotite and Internal Sulphate Attack in County Donegal’ with Dr Andreas Leemann [Swiss Federal Laboratories for Materials Science and Technology] and Thomas Campbell [Chartered Engineer], both of whom will also be speaking in Letterkenny.

In an interview with our sister paper Inish Times earlier this year, Dr Leemann said he knew of no mechanism directly involving mica in hardened blocks which caused the type of deterioration that had been observed in Inishowen and wider Donegal.

He also said he had seen no scientific evidence so far which showed mica was responsible for this deterioration.
Dr Leemann added: “As such, mica as the problem is pure hypothesis in my eyes.

“However, pyrrhotite oxidation with internal sulphate attack is no hypothesis. It is a process backed up by clear scientific evidence.”

Concrete damaged by Internal Sulphate Attack.

Paul Dunlop explained that internal sulphate attack was caused by iron sulphide minerals containing pyrrhotite, chalcopyrite, marcasite, rare pyrite and minor pyrite.

He said: “The testing of core samples revealed that these iron sulphide minerals were present in the blocks used to build homes in Inishowen.

“Dr Leemann stated recently that samples taken from four houses in Inishowen did not deteriorate due to the presence of mica.

“They deteriorated because pyrrhotite oxidation triggered internal sulphate attack, which led to the expansion of the concrete blocks and, in the second phase, to the disintegration of the cement hydrates.”

In 2016, in response to the concerning number of cases of concrete blocks used to build homes actually crumbling, the Irish government commissioned the Expert Panel on Concrete Blocks. Its report was published in June 2017.

In this report we can see the emergence of the idea that mica - and not defective concrete and defective concrete blocks - was responsible for the disintegration of Inishowen homes.

Inside the very cover of the report there was a disclaimer which read: “The Expert Panel did not commission or carry out any tests on buildings or building materials itself.”

In other words, the government did not include in the panel's remit the need or ability for it to commission any testing to verify the cause of the defects in the concrete and concrete products from which the homes and foundations in Inishowen and wider Donegal were constructed.

As a journalist working in Inishowen at the time, I found it extremely puzzling that the government appeared to have no interest in - and, in fact, seemed to be actively ruling out - any scientific research aimed at accurately ascertaining the cause of the defective concrete and defective concrete products destroying homes and foundations in Inishowen.

In addition, in terms of homes and foundations in Derry being ruined by defective concrete and defective concrete products originating from the Republic of Ireland, ‘2.9 Conclusions’ of the Expert Panel report made for interesting reading.

It said: “Finally, it is not normal for concrete blocks to fail in the manner observed. It is the panel’s opinion, which was supported by the laboratory reports provided, that the concrete blocks which deteriorated in the manner observed were not fit for purpose.”

In a nutshell, the Expert Panel on Concrete Blocks said the concrete blocks were “not fit for purpose”. This begs the question, ‘Why then were they sold on into Derry and the rest of Northern Ireland, which was then in the European Union?’

Were any of these “not fit for purpose” concrete blocks sold into Britain? Were they sold into any other European Union countries? Have those who subsequently purchased them got any legal or other means of redress?

Derry people with holiday homes in Donegal affected by defective concrete and defective concrete products were excluded from the now stalled ‘90/10 Defective Concrete Blocks Grants Scheme’ administered by Donegal County Council.

They were also excluded from the controversial ‘Enhanced Defective Concrete Blocks Scheme Grant Scheme’, which came into law in July 2022.

It would appear, to a seasoned observer, that the Irish government had absolutely no interest in helping those whose primary residence is not in its jurisdiction remediate their holiday homes.

I would have to wonder, therefore, about the efficacy of recent appeals to it to offer help to homeowners in Derry - and possibly throughout the six counties - whose houses are crumbling due to defective concrete and defective concrete products which originated in the Republic of Ireland.

According to Professor Paul Dunlop, there was a “severe lack of detailed science” in the so-called 'Expert Panel's' report.

Professor Paul Dunlop.

He added: “It was not until Inishowen people started getting their homes tested, under the IS465 protocol, that Petrolab Ltd [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 because what it did was to guess at the cause of the deterioration in the blocks. It was just guesswork.

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

This, I would argue, is where the belief that mica was the cause of crumbling homes in Inishowen - and now Derry - was incorrectly, yet deliberately promoted.

Following the publication of the report, Donegal County Council’s senior executive engineer and a chartered engineer closely associated with the Mica Action Group, which comprised affected homeowners, were among those appointed to the National Standards Authority of Ireland Technical Committee 063.

This committee was tasked by the Irish government to design and create a Defective Concrete Blocks standard for mica in County Donegal and Pyrite for County Mayo. The standard is known as I.S. 465:2018+A1:2020 (IS465).

The scientific research carried out by Dr Andreas Leemann, which will be presented at the Letterkenny conference next week, demonstrates how pyrrhotite oxidation with internal sulphate attack takes place in defective concrete and defective concrete products, causing the crumbling of blocks as witnessed in Inishowen and Derry.

Critics would argue pyrrhotite oxidation with internal sulphate attack renders IS 465 not fit for purpose.

It is a standard for mica only (for Donegal) and pyrite only (for Mayo).

However, IS465 is itself just a guidance protocol standard for entry to the ‘90/10 Defective Concrete Blocks Grant Scheme’ and the ‘Enhanced Defective Concrete Blocks Grant Scheme’.

As we saw in Donegal, chartered engineers refused to ignore the Petrolab test results which showed visual estimates of reactive iron sulphide minerals above the permitted level of 0.1%.

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Engineers were legally obliged to advise their clients on a full set of forensic test results completed on the structure, before advising them on what the correct engineering solution was for that property.

This superseded any advice that applied to the IS 465 guidance protocol standard, which ignored any other deleterious materials and reactive iron sulphide minerals present.

Professor Dunlop - himself an affected homeowner - said the authors of the ‘Report of the Expert Panel on Concrete Blocks’ had 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'.

“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 flagged by chartered engineer, Dr Ambrose McCloskey, from Dungiven, who identified a problem: engineers were being told to fix homes, but no-one was looking at the issue of internal sulphate attack,” said Professor Dunlop.

Professor Dunlop subsequently reached out to Dr Andreas Leemann and they collaborated on an 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 that 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 being given out 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 Professor Dunlop.

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

Dr Andreas Leemann.

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

Far be it for the cynic in me to suggest the Irish government realised, as far back as 2016, the enormous cost to the exchequer of demolishing and rebuilding homes and foundations affected by pyrrhotite and internal sulphate attack, and subsequently skewed a report and created an Irish standard, based on no scientific evidence, just to save money.

The proof of the pudding will indeed be in the eating. Let us see how effective the ‘Enhanced Defective Concrete Blocks Scheme Grant Scheme’ is in Inishowen.

Indeed, let us see what redress is forthcoming for Derry homeowners who bought defective concrete and defective concrete products in Donegal.