Concrete damage due to oxidation of pyrrhotite-bearing aggregate: a review

Abstract

Oxidation of pyrrhotite-bearing aggregates is one of the major causes of concrete damage in numerous buildings in Trois-Rivières in Canada and Connecticut in the USA. In the presence of moisture and oxygen, pyrrhotite oxidizes to generate iron-and sulfate-rich secondary minerals that cause internal sulfate attack. Iron sulfides are accessory minerals of different rock types. The distribution of sulfides is often very heterogeneous in terms of aggregate particles, even at the level of the quarries in which some areas may contain copious amounts than others, which complicates the sampling method. Pyrrhotite is a complex mineral with varying chemical composition, crystallographic structure, and specific surface area. These factors influence the reactivity of pyrrhotite. Therefore, it is challenging to control the quality of the aggregate sources.
 In this study, recent advances in the identification and quantification of pyrrhotite to diagnose complicated cases are presented, and a performance-based approach for the quality control of new sources of aggregates is introduced. The performance-based approach is preferred because it eliminates the influence of the oxidation of pyrrhotite.

The "Mica Crisis" in Donegal, Ireland – a Case of Internal Sulfate Attack?

“…As the amount of FeS 2 is too small to be detected in the XRD of the bulk sample, it is not clear, if FeS 2 is present as pyrite or marcasite. The majority of the analyzed pyrrhotite shows an atomic Fe/S-ratio > 0.92, indicating that monoclinic Fe 11 S 12 is the dominant type of pyrrhotite [41]. The pyrrhotite is present in strongly varying degrees of oxidation.…”

Defective Homes in Donegal, Ireland: Effect of Exposure Conditions and Concrete Quality on Pyrrhotite Oxidation and Internal Sulfate Attack

“…8A and 8B). The pyrrhotite usually shows an atomic Fe/S-ratio > 0.92, pointing towards monoclinic Fe 11 S 12 as the dominant type [24]. This preprint research paper has not been peer reviewed.…”

“…Pyrrhotite oxidation and ISA are not limited to Ireland. Widespread damages in foundations of thousands of homes have been reported from Canada and the United States in recent years [19][20][21][22][23][24][25]. In regard to the damaged homes in Donegal, no systematic investigation of all four structural concrete components has been conducted so far.…”

Assessing and Forecasting ISR-Affected Critical Infrastructure: State-of-the-Art and Challenges

“…A range of mineral sulfides, including pyrite (Fe 2 S) and pyrrhotite (Fe 1−x S), are commonly present in aggregates. When these sulfides are exposed to water and oxygen, they oxidize, resulting in the generation of sulfuric acid [ 25 ]. As a result, the sulfuric acid reacts with the components of cement paste, leading to an internal sulfate attack characterized by the formation of gypsum, ettringite, thaumasite, and iron oxides, commonly referred to as “rust” [ 26 ].…”