Rheology and setting of alkali-activated slag pastes and mortars: Effect of organic admixture

Marta Palacios, P. F G Banfill, Francisca Puertas

    Research output: Contribution to journalArticlepeer-review

    132 Citations (SciVal)

    Abstract

    The rheology of waterglass-(Na2O·nSiO2· mH2O) and NaOH-activated slag pastes and mortars depends on the nature of the alkaline activator used: in waterglass-activated slag pastes and mortars, the extensive structural breakdown under shear makes the Herschel-Bulkley model a better fit to the down ramp of the flow curve, whereas NaOH-activated pastes and mortars, such as portland-cement pastes and mortars, behaved like Bingham fluids. Admixtures were unable to reduce the yield stress of waterglass-activated slag pastes, but the inclusion of a naphthalene derivative admixture in NaOH-activated slag pastes reduced the yield stress by 80%. The problem of undesirably short setting times for waterglass-activated slag mortars and concretes could be overcome by an extended mixing time, giving an initial set of nearly 3 hours. Copyright © 2008, American Concrete institute. All rights reserved.

    Original languageEnglish
    Pages (from-to)140-148
    Number of pages9
    JournalACI Materials Journal
    Volume105
    Issue number2
    Publication statusPublished - Mar 2008

    Keywords

    • Alkali-activated cement
    • Cement paste
    • Mortar
    • Rheology
    • Setting
    • Shrinkage

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