The Science
Defective Concrete Science in Ireland: Timeline & Evidence
This timeline provides a detailed overview of defective concrete in Ireland, combining scientific research, government action, and homeowner experiences. All references are included for verification.
2025
Public Consultation on Draft I.S. 465
NSAI opened a public consultation for the draft revised I.S. 465, which for the first time incorporated pyrrhotite and other iron sulphides.
- Critiques: Proposed limits still exceed EU legally binding thresholds; consultation alone does not protect homes already damaged.
- References:
2024
Preliminary Scheme Adjustments
Following years of homeowner advocacy, scientific testimony and political support regarding the Science and the downgrading of homeowners, the Department of Housing announced that they intended to bring in legislation to allow for technical reviews of remediation applications based on new scientific findings. More than a year later, the legislation has still not been passed.
- Limitations: Being slow to implement changes despite evidence means homeowners have been stuck in limbo for years whilst others have carried out remediation that has not made their homes structurally safe and sound.
- Gov.ie Press Release, November 2024
2023-2024
Government-Funded Research Confirms ISA
Further research, funded by the Geological Survey of Ireland and carried out by Ulster University, Empa (Switzerland), Université Laval (Canada), University of Connecticut, and Concrete Research and Testing LLC (Ohio, USA), confirmed that:
- Pyrrhotite and iron sulphides, not mica, caused cracking and degradation.
- Foundations containing pyrrhotite are at risk of long-term failure.
- Authorities did not issue interim guidance or adjust testing protocols.
- Reference: Effect of exposure conditions and concrete quality on pyrrhotite oxidation – Ulster University, 2024
July 2023
Committee Hears Policy is Based on Obsolete Science
On 13 July 2023, hearings revealed that I.S. 465 relied on the outdated mica hypothesis, rather than the true damaging process: internal sulfate attack from pyrrhotite.
- Impact: Officials acknowledged that the grant scheme and testing regime had been based on incomplete science, but no interim guidance or corrective measures were issued.
- Oireachtas Committee Evidence, July 2023
March 2023
Independent Peer-Reviewed Research Overturns Mica Hypothesis
Research by Leemann, Dunlop, Lothenbach, Münch, Campbell, and colleagues demonstrated that pyrrhotite oxidation and internal sulfate attack, not mica, were the primary causes of block deterioration.
- Methods: Concrete samples from affected Donegal homes were analysed using microstructural and chemical techniques.
- Key Findings:
Pyrrhotite and other iron sulphides are the main causes of cracking and degradation.
I.S. 465 assumptions based on mica were scientifically invalid.
- References:
The “mica crisis” in Donegal – Cement and Concrete Research, 2023
High risk concrete blocks – Construction and Building Materials, 2023
2020-2022
Homeowners Discover Iron Sulphides
Homeowners began submitting core samples to laboratories, revealing high levels of pyrrhotite, which causes internal sulfate attack (ISA) — a chemical reaction that breaks down concrete and causes cracking and structural failure.
- Research Evidence:Ulster University research highlighted governance failures in how the crisis was managed.
An Examination of Governance Failure by the Irish State - Committee Submissions: Findings were submitted to the Oireachtas Joint Committee on Housing, Local Government and Heritage, but authorities continued using I.S. 465, which focused on mica and freeze-thaw damage.
Oireachtas Committee Evidence, June 2022
2017
Official Response Built on Limited Evidence
In June 2017, an expert panel set up by the Government published a report attributing cracking and block deterioration in Donegal and Mayo mainly to mica and pyrite in concrete blocks.
- Limitation: The panel did not conduct laboratory testing and relied entirely on desk studies and existing literature.
- Ignored Standards: EU regulations limiting harmful minerals such as pyrrhotite in concrete aggregates (EN 12620) were not considered.
- Impact: The grant scheme and the I.S. 465 standard that followed were based on assumptions, leaving homeowners to navigate a remediation process not grounded in evidence.
- Reference: Report of the Expert Panel on Concrete Blocks, gov.ie
State Negligence and Homeowner Fight
Testing and remediation standards were based on desk studies rather than laboratory analysis.
- EU standards for harmful mineral content were ignored.
- Homeowners repeatedly warned committees and provided laboratory evidence, yet no interim guidance was issued.
- Independent peer-reviewed research confirmed early assumptions were wrong, leaving families to bear structural, financial, and emotional burdens.
- Oireachtas Committee Evidence 2022
Learning from Canada
Debra McCoy, researcher and advocate from Connecticut, USA, has studied pyrite and pyrrhotite concrete failures since 2016.
- She has been hugely supportive of Irish homeowners, speaking at conferences in the USA, Canada, and Ireland.
- Her book, Ireland’s Timeline: On The Precipice, details similar problems in Canada and lessons Ireland can apply.
- Ireland’s Timeline: On The Precipice — Debra McCoy
Further Reading / Key Research
1. Effect of exposure conditions and concrete quality on pyrrhotite oxidation – Ulster University, 2024
2. The “mica crisis” in Donegal – Cement and Concrete Research, 2023
3. High risk concrete blocks – Construction and Building Materials, 2023
4. An Examination of Governance Failure by the Irish State – Ulster University, 2022
5. Pyrrhotite in concrete aggregate – Mechanism, damage, and research (Lindstad et al., 2022)
6. Concrete Damage Due to Oxidation of Pyrrhotite-Bearing Aggregate: A Review (Duchesne et al., 2021)