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Stabilization/solidification of hazardous and radioactive wastes with alkali-activated cements

Authors
Journal
Journal of Hazardous Materials
0304-3894
Publisher
Elsevier
Publication Date
Volume
137
Issue
3
Identifiers
DOI: 10.1016/j.jhazmat.2006.05.008
Keywords
  • Stabilization/Solidification
  • Alkali-Activated Cements
  • Hazardous Wastes
  • Radioactive Wastes
  • Leachability
Disciplines
  • Design
  • Earth Science
  • Geography

Abstract

Abstract This paper reviews progresses on the use of alkali-activated cements for stabilization/solidification of hazardous and radioactive wastes. Alkali-activated cements consist of an alkaline activator and cementing components, such as blast furnace slag, coal fly ash, phosphorus slag, steel slag, metakaolin, etc., or a combination of two or more of them. Properly designed alkali-activated cements can exhibit both higher early and later strengths than conventional portland cement. The main hydration product of alkali-activated cements is calcium silicate hydrate (C S H) with low Ca/Si ratios or aluminosilicate gel at room temperature; C S H, tobmorite, xonotlite and/or zeolites under hydrothermal condition, no metastable crystalline compounds such as Ca(OH) 2 and calcium sulphoaluminates exist. Alkali-activated cements also exhibit excellent resistance to corrosive environments. The leachability of contaminants from alkali-activated cement stabilized hazardous and radioactive wastes is lower than that from hardened portland cement stabilized wastes. From all these aspects, it is concluded that alkali-activated cements are better matrix for solidification/stabilization of hazardous and radioactive wastes than Portland cement.

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