The Mechanism of Cesium Immobilization in Densified Silica-fume Blended Cement Pastes

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 2 different forms of silica fume--SF 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. The authors believe that unreacted silica within the DSF agglomerates adsorbs Cs ions and consequently increases their immobilization. Additionally, this work suggests that during pozzolanic reactions, a hydrated rim develops around the agglomerate that acts as an additional diffusion barrier for Cs ions, resulting in an increased efficiency of Cs immobilization.

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  • English

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  • Accession Number: 01099446
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 5 2008 12:20PM