A thermomagnetic technique to quantify the risk of internal sulfur attack due to pyrrhotite. (January 2019)

• Record Type: Journal Article
• Authors: Geiss, Christoph E.; Gourley, Jonathan R.
• Is Part Of: Cement and concrete research. Volume 115(2019)
• Page Start: 1
• Page End: 7
• Publication Date: 2019-01
• Subjects: Sulfate attack -- Magnetic properties -- Pyrrhotite; Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2018.09.010
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: The use of pyrrhotite-containing aggregate in concrete has led to the premature deterioration of building foundations in Connecticut (U.S.A.). Pyrrhotite is a highly reactive iron-sulfide mineral that can initiate internal sulfate attack in concrete structures, because it serves as a source of sulfate ions for secondary minerals. Associated increases in mineral volume can lead to spalling, cracking and a loss of structural integrity. Since pyrrhotite is a strongly ferrimagnetic mineral with a Curie-temperature of 325 °C and several diagnostic phase transitions, we measured the variation of magnetic susceptibility between room-temperature and 700 °C. Such a thermomagnetic measurement serves as a rapid and sensitive semi-quantitative indicator of pyrrhotite in aggregate or concrete samples. In combination with measurements of total sulfur concentrations, pyrrhotite concentrations as low as 0.1% can be detected. The analysis can aid in the quantification of risk of internal sulfur attack due to the presence of pyrrhotite. Graphical abstract: Unlabelled Image