Chloride binding in Portland composite cements containing metakaolin and silica fume

Arezou Baba Ahmadi*, Alisa Machner, Wolfgang Kunther, João Figueira, Petter Hemstad, Klaartje De Weerdt

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

This paper investigates how the composition of Portland composite cements affects their chloride-binding properties. Hydrated cement pastes prepared with a reference Portland cement and composite Portland cements containing metakaolin and/or silica fume were exposed to NaCl or CaCl2 solutions. Chloride-binding isotherms were determined and the hydrate assemblage was investigated using TGA, XRD, 27Al NMR, 29Si NMR and thermodynamic modelling. Compared to the reference Portland cement paste, silica fume replacement did not alter the chloride-binding capacity. The metakaolin replacement resulted in the highest chloride-binding capacity. When combining silica fume with metakaolin, the chloride binding is similar to the reference Portland cement. In this study the differences in chloride binding were linked not only to changes in the AFm content, but also to alterations in the Al-uptake and chain length of the C(-A)-S-H.
Original languageEnglish
Article number106924
JournalCement and Concrete Research
Volume161
Number of pages17
ISSN0008-8846
DOIs
Publication statusPublished - 2022

Keywords

  • Supplementary cementitious materials (SCM)
  • Durability
  • Sustainability
  • Chemical and physical chloride binding
  • Friedel's salt

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