Chapter 2. Heave Rates and Mechanism of Pyritic Expansion in Unbound Aggregates
Michael L. J. Maher
WSP Golder, Whitby, Ontario, Canada
The occurrences of crushed rock aggregates prone to causing pyritic heave in buildings are random but all too frequent. This Chapter focuses on the devastating pyrite crisis in Ireland that was first detected in 2007 but is still having financial consequences and impacting peoples’ lives, some 15 years later. We describe various tests conducted to simulate the heave mechanism in calcareous mudstone aggregate in a laboratory setting. A sample diameter of 600 mm seemed to provide the best compromise between achieving representative results with aggregate sizes up to 80 mm and manageable size for a laboratory setting. To provide context, we also present some case studies where heave in buildings was monitored, in one case for up to eight years. In the case of the Tober Colleen mudstone aggregates, the typical rates of recorded heave are 3 to 4 mm per year for an equivalent 500 mm of compacted fill. The results show that laboratory swell tests can simulate actual building heave but probably need to be run for at least one year. To obtain more insights into the mechanism of the heave, we examined the patterns of gypsum formation in individual coarse aggregate particles. We attempted to undertake some measurements of the magnitude of heave in individual aggregate laminations. We noted that the gypsum crystal cluster formation typically only occupies less than a quarter of the lamination surface area. The magnitude of particle expansion is determined by the number of open laminations present and the height of the tallest crystal clusters.
Keywords: pyritic heave, laboratory simulation, in situ heave monitoring
Ballivy, G. and Bellaloui, A. (1999). New Swelling Test to Characterize the Expansion potential of Pyritic
Rockfill. Geotechnical News, 17(N4), 53-55.
Ballivy, G., Rivard, P., Pépin, C., Tanguay, M. G. and Dion, A. (2002). Damages to residential buildings related
to pyritic rockfills: field results of an investigation on the south shore of Montreal, Quebec, Canada. Can.J. Civ. Eng., 29, 246–255.
Ballivy, G., Bellaloui, A. and Rivard, P. (2004). Analyse Des Dommages Structuraux de Bâtiments Résidentiels
Associés aux Problèmes de Remblais Pyriteux [Analysis of Structural Damage to Residential Buildings
Associated with Pyritic Backfill Problems]. Report No. GR 04-12-01, La Société canadienne
d’hypothèques et de logement (SCHL), Québec.
Becherini, F., Del Favero, L., Fornasiero, M., Guastoni, A. and Bernardi, A. (2018). Pyrite Decay of Large
Fossils: The Case Study of the Hall of Palms in Padova, Italy. Minerals, 8, 40. DOI:10.3390/min8020040
Belgeri, J. J. and Siegel, T. C. (1998). Design and Performance of Foundations in Expansive Shale, Ohio. River
Valley Soils Seminar XXIX, Louisville, Kentucky.
Bellaloui, A., Nkurunziza, G. and Ballivy, G. (2000). Gonflement de Remblais de Fondation Simulation en
Laboratoire [Swelling of Foundation Fills Laboratory Simulation]. 53rd Annual Conference, CanadianGeotechnical Society, Montreal.
British Standards. (2002). Method of Test for Soils for Civil Engineering Purposes – Part 4: Compaction
related tests. BS 1377-4, 1990, Incorporating Amendments Nos. 1 and 2. BSI, London.
Bromley, Alan. (2008). Personal communication.
Czerewko, M. A. and Cripps, J. C. (2022). Investigation of destructive ground heave attributed to pyritic fill
affecting new-build properties in the Dublin area of Ireland. Engineering Geology, 299, 106534.
Daily Collegian. (2010). Forest Resources Building floor to be fixed. Archived News, September, 7,collegian.psu.edu.
Dougherty, M. T. and Barsotti, N. J. (1972). Structural Damage and Potentially Expansive Sulfide Minerals.
Bulletin of the Association of Engineering Geologists, IX (2).
HomeBond. (1993). House Building Manual. McCarthy, J. A., Farrell, E. and McFeely, A. National House
Building Guarantee Scheme Ltd. (HomeBond), Federation House, Canal Road, Dublin 6, Ireland.
Hoover, S. E., Wang, M. C. and Dempsey, B. (2004). Proceedings of the 5th International Conference on Case
Histories in Geotechnical Engineering, New York, United States.
Hoover, S. E., Greenawalt, W. and Tittmann, B. (2015). Experimental and Theoretical Modeling of Expansion
in Pyritic Shale. Geotechnical Testing Journal, 38(2).
Lacroix, P. and Côté, F. (1991). Concrete Floor Heave Due to Sulfating of Pyritic Shales (Eastern Canada Case
History). CANMET/ACI International Conference on Durability of Concrete: Second International Conference, Montreal, Canada.
Maher, M. L. J., Azzie, B., Gray, C. and Hunt, J. (2011). A large Scale Laboratory Swell Test to Establish the
Susceptibility to Expansion of Crushed Rock Containing Pyrite, Paper presented at the 14th Pan-American
Conference on Soil Mechanics and Geotechnical Engineering, Toronto, Canada.
Matheson, G. D. and Jones, G. Ll. (2015). The habit and form of gypsum crystals in Irish mudstone aggregate
affected by pyrite-induced swelling. QJEGH, 48, 167-174.
Morth, A. H. and Smith, E. E. (1966). Kinetics of the sulphide to sulphate reaction. American Chemical Society,
Division of Fuel Chemistry, Pre-prints 10(1), 83-92.
Pugh, C. E., Hossner, L. R. and Dixon, J. B. (1984). Oxidation rate of iron sulphides as affected by surface
area, morphology, oxygen concentration and automorphic bacteria. Soil Science, 137(5), 309-314.
Scheetz, B. E. and Ellsworth, C. J. (2007). Preliminary Assessment of Acid Producing Rock on Future
PennDOT Construction, Final Report, Pennsylvania Transportation Institute, Penn State University, PA, United States.
Smith, E. E. and Schumate, K. S. (1970). The sulphate to sulphide reaction mechanism. Water Pollution
Control, Research Series, Ohio State University Research Foundation, Columbus, Ohio, 129 pp.
Strogen, P. (2021). Lithological controls on the expansion of unbound aggregates in Dublin, eastern Ireland:
two contrasting cases. Quarterly Journal of Engineering Geology and Hydrogeology,
Sutton, D., McCabe, B., O’Connell, A. and Cripps, J. (2013). A laboratory study of the expansion of an Irish
pyritic mudstone/siltstone fill material. Engineering Geology, 152, 194-201.