The “mica crisis” in Donegal, Ireland – A case of internal sulfate attack?

In County Donegal, northwest Ireland, thousands of homes built with concrete blocks show an increasing degree severe structural defects attributed to high mica content in the aggregates. Consequently, problem is popularly known as “Mica Crisis”. this project four affected are investigated by microstructural and chemical analysis combined thermodynamic modelling. Apart from mica, aggregates contain iron sulphides mainly form pyrrhotite. The sulfur considerably exceeds limit value defined European standard for (EN 12620). results coupled modelling demonstrate that suffers internal sulfate attack triggered pyrrhotite oxidation. comparison investigation data collected chartered engineers on almost hundred damaged shows cases representative situation Donegal.