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Crack Formation Modeling in Concrete Affected by Iron-Sulfide Reactions

Published

Author(s)

Osamah Dehwah, Nicos Martys, Edward Garboczi, Michael Mengason, Patrick Dixon, Stephanie Watson

Abstract

Damage in concrete containing sulfide-bearing aggregates has become a critical issue in several countries such as the USA, Canada, and Ireland. This deterioration unfolds over decades and is driven by oxidation reactions in sulfide-bearing aggregates, followed by internal sulfate attack within the cementitious matrix. About 60 % to 75% of concrete is composed of aggregates, and the oxidation of sulfide-bearing particles causes aggregate expansion, enabling sulfate release and leading to progressive cracking. This process severely impacts the mechanical and durability properties of concrete by altering its microstructure. Pyrrhotite-related deterioration has prompted extensive research aimed at understanding the underlying chemical and mechanical mechanisms. To investigate crack formation and propagation, a quasi-static two-dimensional finite element model (FEM) was developed to simulate crack network evolution with a pixelated approach used to identify the different phases in concrete. The model provides valuable insights into the influence of microstructural characteristics on crack network formation and the role of internal phase expansion in degrading the elastic properties of concrete. A scanning electron microscopy (SEM) image of undamaged concrete from a Connecticut (CT) house that had a damaged foundation was examined, and the crack network was simulated using the developed FEM. A sensitivity analysis was performed to assess the impact of convergence criteria on model precision and computational efficiency. The model can be used to clarifiy damage mechanisms caused by internal chemical reactions and localized expansion.
Proceedings Title
Crack Formation Modeling in Concrete Affected by Iron-Sulfide Reactions
Conference Dates
May 12-14, 2026
Conference Location
Mystic, CT, US
Conference Title
2nd International Conference on Iron-Sulfide Reactions in Concrete

Keywords

concrete degradation, crack nucleation and initiation, crack propagation, pyrrhotite

Citation

Dehwah, O. , Martys, N. , Garboczi, E. , Mengason, M. , Dixon, P. and Watson, S. (2026), Crack Formation Modeling in Concrete Affected by Iron-Sulfide Reactions, Crack Formation Modeling in Concrete Affected by Iron-Sulfide Reactions, Mystic, CT, US, [online], https://doi.org/10.17605/OSF.IO/7Y4SG, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=961288 (Accessed August 4, 2026)
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Created June 24, 2026, Updated August 3, 2026
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