Effect of milling and acid washing on the pozzolanic activity of incinerator sewage sludge ash

S Donatello, A Freeman-Pask, M Tyrer, CR Cheeseman

    Research output: Contribution to journalArticle

    60 Citations (Scopus)

    Abstract

    Incinerator sewage sludge ash (ISSA) is a problematic waste that contains significant levels of phosphates, primarily in the form of whitlockite (Ca3(PO4)2). Phosphate is a valuable finite resource, and a number of studies have shown that it can be extracted from ISSA by acid washing. This produces an acid washed residue that has potential to be used in construction products. The effects of milling and acid washing on the pozzolanic activity of ISSA have been evaluated using the strength activity index (SAI) test and the Frattini test. Coal fly ash (FA), metakaolin (MK) and quartz sand were also tested for comparison. Milling improved the pozzolanic activity of FA and ISSA according to both the SAI and Frattini tests. If ISSA is acid washed to recover phosphate, the process is likely to produce an acid insoluble material with little or no pozzolanic activity. The Frattini test is considered a more suitable method for directly assessing pozzolanic activity as a range of factors can affect SAI test results.
    Original languageEnglish
    Pages (from-to)54-61
    Number of pages8
    JournalCement and Concrete Composites
    Volume32
    Issue number1
    Early online date19 Sep 2009
    DOIs
    Publication statusPublished - Jan 2010

    Keywords

    • Pozzolan
    • Pozzolanic activity
    • Strength activity index
    • Frattini test
    • Incinerator sewage sludge ash
    • Coal fly ash
    • Metakaolin

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