Ozone as an oxidant for accelerated testing of pyrrhotite-induced concrete degradation

Published

July 27, 2026

Author(s)

Michael Mengason, Patrick Dixon, Ashley Carey, Osamah Dehwah, Stephanie Watson

Abstract

The iron-sulfide mineral pyrrhotite used in some home foundation construction is known to oxidize and form minerals deleterious to the concrete. The long timescale of the oxidation and deterioration requires a method of accelerated aging to study the process and to validate the suitability of the aggregate for use. We propose the use of ozone as an oxidant and present results of proof-of-concept experiments. Exposure of a thin mortar 'tile' to 500 ppb (ng/kg by wt.) ozone in air with 40% humidity for 14 days tarnished some grains but did not otherwise show evidence of reaction. Exposure of a tile in a UV/Ozone cleaner with 70 % humidity and a higher ozone concentration resulted in the growth of sulfate mineral encrustations on the surface and needle-like gypsum growth within the voids. Conceptually, the use of ozone avoids some complications associated with bleach submersion. Further study is needed to develop this potential method.

Conference Dates

May 12-14, 2026

Conference Location

Mystic, CT, US

Conference Title

2nd International Conference on Iron-Sulfide Reactions in Concrete

Pub Type

Conferences

Download Paper

https://doi.org/10.17605/OSF.IO/7Y4SG

Local Download

Keywords

pyrrhotite, oxidation, ozone, mortar-bar test, concrete degradation

Citation

Mengason, M. , Dixon, P. , Carey, A. , Dehwah, O. and Watson, S. (2026), Ozone as an oxidant for accelerated testing of pyrrhotite-induced concrete degradation, 2nd International Conference on Iron-Sulfide Reactions in Concrete, Mystic, CT, US, [online], https://doi.org/10.17605/OSF.IO/7Y4SG, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=961318 (Accessed October 1, 2026)

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