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A platform for research: civil engineering, architecture and urbanism
Effect of Pyrrhotite Content on the Deterioration Potential of Concrete in Sulfide-Bearing Aggregates as Assessed by the Oxygen Consumption Test
Oxidation of sulfide-bearing aggregates is a major cause of concrete damage in numerous buildings in Trois-Rivières, Canada; Connecticut, USA; and Donegal County, Ireland. In the presence of moisture and oxygen, pyrrhotite oxidizes to form iron- and sulfate-rich secondary minerals that cause internal sulfate attack. This study evaluates the deleterious potential of a pyrrhotite-bearing aggregate for use in concrete using the oxygen consumption test. This test quantitatively assesses sulfide oxidation potential by measuring the oxygen consumed by oxidation in a sealed cell containing a layer of the ground aggregate material in the presence of a specified moisture content. A series of aggregate samples, carefully controlled for total sulfur content ranging from 0.03 to 0.82 wt%, are used to evaluate the response to the oxygen consumption test. Polished concrete slabs were prepared from the base aggregates for semi-quantitative chemical in-situ analysis by µXRF to determine the proportions of the various sulfide minerals. The oxygen consumption ranged from 4 (control) to 24% for the richest sample containing 0.82% total sulfur. A strong correlation factor (R2) of 0.95 was obtained between the amount of oxygen consumed as a function of the volume content of iron sulfides, thus potentially reflecting the effect of reactive iron sulfide content on concrete deterioration. Analysis of a larger number of samples is needed to establish a limit on the amount of oxygen consumed for the quality control of sulfide-bearing aggregates.
Effect of Pyrrhotite Content on the Deterioration Potential of Concrete in Sulfide-Bearing Aggregates as Assessed by the Oxygen Consumption Test
Oxidation of sulfide-bearing aggregates is a major cause of concrete damage in numerous buildings in Trois-Rivières, Canada; Connecticut, USA; and Donegal County, Ireland. In the presence of moisture and oxygen, pyrrhotite oxidizes to form iron- and sulfate-rich secondary minerals that cause internal sulfate attack. This study evaluates the deleterious potential of a pyrrhotite-bearing aggregate for use in concrete using the oxygen consumption test. This test quantitatively assesses sulfide oxidation potential by measuring the oxygen consumed by oxidation in a sealed cell containing a layer of the ground aggregate material in the presence of a specified moisture content. A series of aggregate samples, carefully controlled for total sulfur content ranging from 0.03 to 0.82 wt%, are used to evaluate the response to the oxygen consumption test. Polished concrete slabs were prepared from the base aggregates for semi-quantitative chemical in-situ analysis by µXRF to determine the proportions of the various sulfide minerals. The oxygen consumption ranged from 4 (control) to 24% for the richest sample containing 0.82% total sulfur. A strong correlation factor (R2) of 0.95 was obtained between the amount of oxygen consumed as a function of the volume content of iron sulfides, thus potentially reflecting the effect of reactive iron sulfide content on concrete deterioration. Analysis of a larger number of samples is needed to establish a limit on the amount of oxygen consumed for the quality control of sulfide-bearing aggregates.
Effect of Pyrrhotite Content on the Deterioration Potential of Concrete in Sulfide-Bearing Aggregates as Assessed by the Oxygen Consumption Test
RILEM Bookseries
Beushausen, Hans (editor) / Ndawula, Joanitta (editor) / Alexander, Mark (editor) / Dehn, Frank (editor) / Moyo, Pilate (editor) / Duchesne, Josée (author) / Fournier, Benoit (author) / Amor, Malek Ben (author) / Rodrigues, Andrea (author)
International Conference on Concrete Repair, Rehabilitation and Retrofitting ; 2024 ; Cape Town, South Africa
2024-11-01
9 pages
Article/Chapter (Book)
Electronic Resource
English
| Elsevier | 2024