A Scientific study has claimed that mica is not the primary issue in the defective blocks crisis.
The report titled ‘The “mica crisis” in Donegal, Ireland – A case of internal sulfate attack?’ investigated the cause of the defective block scandal that is affecting thousands of homes in Donegal.
The four investigated homes are located in the Inishowen Peninsula in North Donegal. All homes were built between 2001 and 2004 and for all the decision to demolish them was taken by a Chartered Engineer who followed the I.S. 465 protocols.
The homes showed the typical signs of distress associated with defective concrete blocks and displayed patterned cracking on the external leaf, with cracks typically ranging in width from 1 mm up to 16 mm.
In this project the concrete blocks of four affected homes were investigated by microstructural and chemical analysis combined with thermodynamic modelling.
The investigation has revealed that, apart from mica, the aggregates contain iron sulphides mainly in the form of pyrrhotite.
The report details, “The sulfur content of the aggregates considerably exceeds the limit value defined by the European standard for concrete aggregates (EN 12620).
“The results of the microstructural analysis coupled with thermodynamic modelling demonstrate that the concrete suffers from internal sulfate attack triggered by pyrrhotite oxidation.
“The comparison of the results of this investigation with the data collected by chartered engineers on almost hundred damaged homes shows that the four investigated cases are representative of the situation in Donegal.”
The full report is available online at: https://www.sciencedirect.com/science/article/pii/S0008884623000613?via%3Dihub
MORE ON THIS STORY IN MONDAY’S DONEGAL NEWS. GET IT IN STORES OR ONLINE AT https://my.donegalnews.com/.
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