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Chloride effect on sulfate attack in hydrated Portland-limestone cement assessed by 29Si NMR spectroscopy and thermal analysis
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SYSNO ASEP 0575568 Document Type C - Proceedings Paper (int. conf.) R&D Document Type Conference Paper Title Chloride effect on sulfate attack in hydrated Portland-limestone cement assessed by 29Si NMR spectroscopy and thermal analysis Author(s) Sotiriadis, Konstantinos (UTAM-F) RID, ORCID, SAI
Mazur, A. (RU)
Tolstoy, P. M. (RU)
Frankeová, Dita (UTAM-F) RID, SAI, ORCIDNumber of authors 4 Source Title Materials Today: Proceedings, 4th International Congress on Materials and Structural Stability. - Amsterdam : Elsevier, 2023 Number of pages 6 s. Publication form Online - E Action International congress on materials and structural stability /4./ Event date 08.03.2023 - 10.03.2023 VEvent location Rabat Country MA - Morocco Event type WRD Language eng - English Country NL - Netherlands Keywords limestone cements ; sulfates ; chlorides ; thaumasite ; NMR spectroscopy ; thermal analysis OECD category Materials engineering R&D Projects GC21-35772J GA ČR - Czech Science Foundation (CSF) Institutional support UTAM-F - RVO:68378297 DOI 10.1016/j.matpr.2023.06.185 Annotation Structural alterations in the C-S-H phase of hydrated Portland-limestone cements, caused by magnesium sulfate attack, were quantitatively assessed using 29Si MAS NMR spectroscopy, considering the presence of sodium chloride in the corrosive medium and the limestone content in cement. Quantitative information about crystalline deterioration products (ettringite, thaumasite, gypsum, brucite) was retrieved from thermogravimetric analysis. Scanning electron microscopy combined with elemental analysis indicated their accumulation areas. Formation of cross-linked silicate chains and reduction of bridging/pairing SiO4 tetrahedra in C-S-H was noted. The presence of chlorides decreased cross-linking of SiO4 tetrahedra and reduced gypsum formation and Ca depletion from the matrix. Precipitation of brucite at the edge of the specimens possibly inhibited the promotion of the attack process. Chlorides penetrated deeper into the matrix compared to sulfates. Increasing limestone content in cement led to a higher mean chain length of cross-linked chains and AlO4/SiO4 ratio in the sulfate-bearing environment. The extent of C-S-H degradation in the cement pastes with the highest limestone content was independent of the exposure conditions. Cement with approx. 12% limestone content can be considered of equal performance to ordinary Portland cement in severe sulfate–chloride solutions. Workplace Institute of Theoretical and Applied Mechanics Contact Kulawiecová Kateřina, kulawiecova@itam.cas.cz, Tel.: 225 443 285 Year of Publishing 2025 Electronic address https://doi.org/10.1016/j.matpr.2023.06.185
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