Comparison of the effect of mix proportion parameters on behaviour of geopolymer and Portland cement mortars

•Lithomarge-based geopolymer mortars behaved in a similar way as cement mixes.•w/s ratio had greater effect on workability of geopolymer mixes than paste content.•Setting times were increased while strength decreased with increase in w/s ratio.•Workable geopolymer mixes could be made with less free...

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Bibliographic Details
Published in:Construction & building materials 2018-10, Vol.187, p.635-651
Main Authors: Kwasny, Jacek, Soutsos, Marios N., McIntosh, John A., Cleland, David J.
Format: Article
Language:English
Subjects:
Cements (Building materials)
Centre composite design
Comparative analysis
Compressive strength
Geopolymer mortars
Kaolin
Lithomarge
Mechanical properties
Portland cement mortars
Setting time
Thermal properties
Workability
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Summary:•Lithomarge-based geopolymer mortars behaved in a similar way as cement mixes.•w/s ratio had greater effect on workability of geopolymer mixes than paste content.•Setting times were increased while strength decreased with increase in w/s ratio.•Workable geopolymer mixes could be made with less free water than cement mixes.•Geopolymer mortars had shorter setting times and a very rapid strength development. This work focuses on low-purity kaolin, widely accessible throughout the globe. Room temperature cured geopolymer mortars (GPMs) were formulated using an aluminosilicate precursor based on calcined lithomarge and potassium silicate activator. The effect of mix proportion parameters on the engineering properties of GPMs was investigated. The behaviour of GPMs was compared with that of Portland cement-based mortars (PCMs). Statistically designed experiments revealed that an increase in water-to-solid (w/s) ratio had a dominant effect on increasing the workability and setting time while decreasing the compressive strength of GPMs. In contrast to PCMs, GPMs proportioned with a constant water content showed a non-linear relationship between the w/s ratio and workability, which could be associated with changes to paste/sand proportions and/or water/alkali proportions. Like-for-like comparison of GPMs and PCMs showed that GPMs require lower free water content, and can offer shorter setting times and a rapid strength development.
ISSN:0950-0618
1879-0526
DOI:10.1016/j.conbuildmat.2018.07.165