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

106 Citations (Scopus)


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
Issue number2
Publication statusPublished - Mar 2008


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


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