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Time evolution of rheological parameters of slag activated with various activators
Pazour, Miroslav ; Smilek, Jiří (oponent) ; Bílek, Vlastimil (vedoucí práce)
This master thesis focuses on the state-of-art review, alongside with optimization of the oscillatory measurements using hybrid rheometer, but mainly on observation of changes in rheological parameters in time of ground granulated blast furnace slag activated with various activating solutions at two concentrations of M: 4 and 7.5 moldm. Vicat method and isothermal calorimetry outputs supported the results. In all samples, linear viscoelastic region limits decreased over time. In time sweep tests, it was observed that silicates-activated pastes had the lowest complex modulus values, slag activated with hydroxides had the highest at 4 moldm, and somewhere in the middle were other pastes that were comparable to each other. The same pattern was observed for time evolution of yield oscillation stress obtained from amplitude sweep tests (continuous and discontinuous). Due to the more interconnected structure at later stages, both mentioned parameters, complex modulus and yield stress, evolved in time. All tests showed that surface chemistry is very important for rheology behavior. Hence, the activator nature and concentration affected the rheological properties through the Na and K ions effects, as well as the concentration have impact on the electric double layer. The rheological behavior may also be affected by other factors, e.g., the viscosity of the activating solution and the overall hydration kinetics.
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Time evolution of rheological parameters of slag activated with various activators
Pazour, Miroslav ; Smilek, Jiří (oponent) ; Bílek, Vlastimil (vedoucí práce)
This master thesis focuses on the state-of-art review, alongside with optimization of the oscillatory measurements using hybrid rheometer, but mainly on observation of changes in rheological parameters in time of ground granulated blast furnace slag activated with various activating solutions at two concentrations of M: 4 and 7.5 moldm. Vicat method and isothermal calorimetry outputs supported the results. In all samples, linear viscoelastic region limits decreased over time. In time sweep tests, it was observed that silicates-activated pastes had the lowest complex modulus values, slag activated with hydroxides had the highest at 4 moldm, and somewhere in the middle were other pastes that were comparable to each other. The same pattern was observed for time evolution of yield oscillation stress obtained from amplitude sweep tests (continuous and discontinuous). Due to the more interconnected structure at later stages, both mentioned parameters, complex modulus and yield stress, evolved in time. All tests showed that surface chemistry is very important for rheology behavior. Hence, the activator nature and concentration affected the rheological properties through the Na and K ions effects, as well as the concentration have impact on the electric double layer. The rheological behavior may also be affected by other factors, e.g., the viscosity of the activating solution and the overall hydration kinetics.
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