Use of Raman spectroscopy to characterize the effect of nanomagnetite as an addition to Portland cement paste on mitigating internal sulfate attack

•Cement paste mixtures containing pyrite and nanomagnetite were tested.•Pastes were analysed by FEG SEM/EDS, XRD and Raman spectroscopy.•Nanomagnetite (1%) assisted in mitigating the effects of internal sulphate attack.•The oxidation product, goethite, was identified by Raman spectroscopy. Cement pa...

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Bibliographic Details
Published in:Construction & building materials 2020-11, Vol.262, p.120803, Article 120803
Main Authors: Oliveira, Tassiane A., Pinkoski, Igor M., Bragança, Mariana O.G.P., Assmann, André, Oliveira, Isabela C., Pereira, Eduardo
Format: Article
Language:English
Subjects:
Building pathology
Characterization technique
Microstructure
Nano-Fe3O4
Pyrite
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Summary:•Cement paste mixtures containing pyrite and nanomagnetite were tested.•Pastes were analysed by FEG SEM/EDS, XRD and Raman spectroscopy.•Nanomagnetite (1%) assisted in mitigating the effects of internal sulphate attack.•The oxidation product, goethite, was identified by Raman spectroscopy. Cement pastes containing nanomagnetite and pyrite were exposed to oxygen and moisture for 90 days. The paste containing pyrite showed evidence of internal sulfate attack, through a reduction in mechanical strength and presence of microcracks with ettringite verified by FEG SEM/EDS. Nanomagnetite increased the mechanical strengths, verified by the pore filling and formation of more chemically stable compounds in the matrix, such as hydrated C4AF. One percent nanomagnetite was the most effective concentration to mitigate the effects of internal sulfate attack. Raman spectroscopy is a differentiated technique for identifying nanomagnetite, pyrite oxidation product and low crystallinity compounds, such as C-S-H.
ISSN:0950-0618
DOI:10.1016/j.conbuildmat.2020.120803