Critical evaluation of rheological behaviour of low-calcium fly ash geopolymer pastes

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

Abstract

The rheological behaviour of alkali-activated low-calcium fly ash (AAF) pastes is evaluated. The sodium-based, alkali-silicate activating solutions are proportioned for specific reactive oxide ratios in the paste considering the reactive content of the fly ash. Alkali-silicate activating solutions with different silica contents, with an MS value (the mass ratio silica to sodium oxide (SiO2 : Na2O)) of less than 1.80 are used. The activating solutions exhibit a Newtonian behaviour with higher viscosities at larger silica contents or lower MS. The yield stress and the viscosity of the AAF pastes increase with the viscosity of the activating solution. The zeta potential of the fly ash particles in the alkaline solution with dissolved silica is lowered on decreasing its MS. The yield stress of the AAF paste increases sensitively on decreasing the MS of the activating solution due to the combined influences of reducing the zeta potential of fly ash particles and increasing the viscosity of the activating solution. There are counteracting effects of increasing the viscosity of the activating solution and raising the zeta potential of fly ash, produced by increasing the silica content in the activating solution. The yield stress of AAF paste is less sensitive to the silica content in the activating solution.

Details

Original languageEnglish
Pages (from-to)109-119
Number of pages11
JournalAdvances in Cement Research
Volume34
Issue number3
Publication statusPublished - 1 Mar 2022
Peer-reviewedYes

External IDs

Scopus 85119177755
unpaywall 10.1680/jadcr.20.00043
Mendeley fbf99e26-e2d8-3de5-95df-7dd991a45124

Keywords

Research priority areas of TU Dresden

DFG Classification of Subject Areas according to Review Boards

Subject groups, research areas, subject areas according to Destatis

Keywords

  • 3D concrete printing, Low calcium flyash