Influence of solid solutions on chloride leaching from wasteforms

    Research output: Contribution to journalArticle

    Abstract

    NOTE: THE SYMBOLS IN THIS ABSTRACT CANNOT BE DISPLAYED CORRECTLY ON THIS PAGE. PLEASE REFER TO THE ABSTRACT AT THE PUBLISHER'S WEBSITE FOR AN ACCURATE DISPLAY. The hydration product Friedel's salt (Ca4Al2O6Cl2.10H2O) is frequently encountered in wasteforms solidified and stabilised using Portland cement. The ability of Friedel's salt to form solid solutions plays a role in chloride binding in such matrices. This paper addresses one practical example of this influence by examining the immobilisation of chloride ions from municipal solid waste incinerator fly ash in cementitious matrices also comprising Portland cement and fly ash from coal-fired power generation. Measurements of quantities and structural parameters of Friedel's salt in pastes containing incinerator fly ashes show that chloride ion release is lowest when large quantities of chloride-deficient Friedel's salt is generated. However, chloride is more tightly bound elsewhere in the material, probably in calcium silicate hydrate (CSH) gel. The dissolution of Friedel's salt is modelled using a geochemical modelling program capable of dealing with solid solutions. These observations reinforce the need to incorporate variable phase composition in models for predicting leaching from cementitious matrices containing waste materials.
    Original languageEnglish
    Pages (from-to)131-139
    Number of pages9
    JournalProceedings of the ICE : Waste and Resource Management
    Volume159
    Issue number3
    DOIs
    Publication statusPublished - 2006

    Keywords

    • Mathematical modelling
    • Landfill
    • Waste management and disposal

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