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Rheology of Alkali-Activated Blended Binder Mixtures
Biruk Hailu Tekle1, Ludwig Hertwig1, Klaus Holschemacher1
1Structural Concrete Institute (IfB), Leipzig University of Applied Sciences (HTWK Leipzig), 04277 Leipzig, Germany.
Materials (Basel, Switzerland)
|September 28, 2021
Summary
This study examines ambient-cured alkali-activated cement (AAC) rheology. Key findings show binder content and water ratio significantly impact flow properties, with borax reducing yield stress.
Area of Science:
- Materials Science
- Civil Engineering
Background:
- Alkali-activated cement (AAC) offers environmental benefits over traditional Portland cement.
- Research predominantly focuses on mechanical properties of heat-cured AAC, neglecting fresh properties of ambient-cured systems.
Purpose of the Study:
- Investigate the rheological properties of ambient-temperature-cured alkali-activated blended binder mixtures.
- Determine the influence of key mix design parameters on fresh properties.
Main Methods:
- Systematic variation of binder amount, alkaline solid to binder ratio (AS/B), sodium silicate to sodium hydroxide solids ratio (SS/SH), and total water to total solid (TW/TS) ratio.
- Evaluation of borax as an admixture and silica fume as a fly ash replacement.
Main Results:
- Yield stress and plastic viscosity are primarily influenced by binder content and TW/TS ratio, decreasing with increased values.
- Yield stress increases with a higher SS/SH ratio.
- Borax significantly reduces yield stress; silica fume's effect varies with dosage.
Conclusions:
- Binder content and TW/TS ratio are critical for controlling the workability of ambient-cured AAC.
- The SS/SH ratio influences yield stress, while admixtures like borax and silica fume offer tunable rheological control.
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