The mechanism of cesium immobilization in densified silica-fume blended cement pastes

G. Bar-Nes, A. Katz, Y. Peled, Y. Zeiri

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

The role of silica-fume agglomerates, found in densified silica-fume (DSF) pastes, in the immobilization mechanism of Cs ions was studied. Samples of cementitious pastes containing two different forms of silica fume - DSF and raw silica fume (RSF) - were prepared. Leaching experiments showed that both additives reduced the leachability of the metal ion, but the effect of the DSF paste was much stronger. Scanning Electron Microscopy, together with Differential Thermal Analysis, proved that no agglomerated particles were present in the RSF pastes and that the extent of pozzolanic reactivity was higher. We therefore believe that unreacted silica within the DSF agglomerates adsorbs Cs ions and consequently increases their immobilization. Furthermore, this work suggests that during the pozzolanic reaction, a hydrated rim develops around the agglomerate that acts as an additional diffusion barrier for the Cs ions, resulting in an increased efficiency of Cs immobilization.

Original languageEnglish
Pages (from-to)667-674
Number of pages8
JournalCement and Concrete Research
Volume38
Issue number5
DOIs
StatePublished - 1 May 2008

Keywords

  • Agglomerate
  • Cement paste
  • Cesium
  • Densified silica fume
  • Immobilization

ASJC Scopus subject areas

  • Building and Construction
  • Materials Science (all)

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