Pore solution composition of alkali-activated slag/fly ash pastes
Yibing Zuo (TU Delft - Materials and Environment)
M. Nedeljkovic (TU Delft - Materials and Environment)
G. (Guang) Ye (TU Delft - Materials and Environment)
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Abstract
The pore solutions of a series of hardened alkali-activated slag/fly ash pastes were extracted by the steel-die method, and analyzed using ICP-OES analysis technique. According to the saturation index from thermodynamic calculations, the pore solutions of alkali-activated slag pastes kept oversaturated with respect to solid reaction products with time. In the pore solutions of alkali-activated fly ash pastes, an increase of temperature (from 40 °C to 60 °C) led to decreases of the concentrations of Si, Al, Ca, Na, OH−, K, Fe and Mg, while the soluble silicate in the alkaline activator resulted in increases of the concentrations of these elements. Compared to the alkali-activated slag paste with the same alkaline activator, 50% replacement of slag by fly ash did not result in a substantial change of the pore solution composition. Based on the experimental results, conceptual models were proposed to describe the elemental concentrations in the pore solutions.
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