Research Paper: Evaluating pyrite-induced swelling

George Matheson (Matrock Consulting) and Paul Quigley (Irish Geotechnical Services Ltd) have published a paper on the petrological examination and assessment of aggregates that have undergone pyrite-induced swelling.

The paper, titled “Evaluating pyrite-induced swelling in Dublin mudrocks” follows previous presentations and publications by the Matheson:

Matheson, G.D, and Jones, G.L.I. (2015). The habit and form of gypsum crystals in Irish mudstone aggregate affected by pyrite-induced swelling. Quarterly Journal of Engineering Geology and Hydrogeology. 48, 167-174. Click here to read a summary of the paper.

Matheson, G. (2012). Pyrite-induced swelling. Annual Guest Lecture given to the Geotechnical Society of Ireland. 6.12.12, Engineers Ireland, Dublin. Click here to see original flyer.


“Expansion of structural backfill used as hardcore aggregate under floor slabs in the Dublin area of Ireland has resulted in significant structural damage and distress to buildings recorded since 2006. The hardcore or backfill aggregate typically comprises mudrocks of Carboniferous age that contain pyrite. The most recent estimates suggest that pyrite-induced reactions have resulted in structural damage affecting in excess of 10000 buildings in the Dublin area. This has a severe impact on the value of property and the remediation costs are set to run to hundreds of millions of euros.”
“A court case held in the High Court in Dublin in 2010 (upheld in 2014 on appeal to the Supreme Court) found that structural damage to Ballymun Youth Centre, Dublin had been caused by pyrite-induced reactions leading to swelling of the backfill as a result of forceful crystallization of gypsum. This paper describes the logic, chemical, X-ray diffraction and petrological techniques and procedures used to evaluate pyrite-induced swelling for this court case and in many hundreds of evaluations since. The paper also suggests procedures to reduce the costs of testing.”


Matheson, G.D, and Quigley, P. (2015). Evaluating pyrite-induced swelling in Dublin mudrocks. Quarterly Journal of Engineering Geology and Hydrogeology. Published Online First – 23rd December 2015.

The abstract and paper can be found on the Quarterly Journal of Engineering Geology and Hydrogeology website (click here).

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