Geotechnical Engineering Group

Department of Civil & Structural Engineering

Expansion of pyritic mudrock beneath domestic floor slabs

Gypsum crystals precipitated on a lamination surface within a mudrock particle


Towards the end of the economic boom in Ireland in the late 20th Century, the demand for building materials vastly outpaced the supply available and, because of this, unsuitable materials were used as fill beneath the ground-bearing floor slabs of many domestic properties. In many cases, these properties are now showing damage directly linked to the expansion of the pyrite-rich mudstone used as fill material.

Although the general process that leads to the expansion is understood, little is known about the impact that changing conditions has upon the rate and amount of heave seen in the material. This project will look at the influence certain factors such as temperature, moisture content and specific surface have upon the reaction process.

Laboratory testing is underway to study the effect of specific surface and grading upon the amount of heave seen over a specific amount of fill, and field testing is being prepared to look at the changing temperature and moisture profiles beneath a domestic property, which will in turn be used to support computer modelling of the conditions beneath the floor slab.


EPSRC CASE studentship with sponsorship from Liberty