Use of Impedance Spectroscopy for the Characterization of the Microstructure of Alkali Activated SiMn Slag: Influence of Activator and Time Evolution

Abstract

The impedance spectroscopy technique has been used to study the microstructure of the binder resulting from the alkaline activation of SiMn slag. Two alkaline activators were used: waterglass and NaOH. Three different concentrations were analysed for both activators: 3.0, 3.5 and 4.0% Na2O for NaOH; and 4.0, 4.5 and 5.0% Na2O for waterglass with a constant SiO2/Na2O ratio of 1.0. The time evolution of the microstructure has been followed up using the non-destructive technique of impedance spectroscopy. This technique has been proved to be effective describing the microstructural changes in alkali activated pastes, and also can help predicting the mechanical behavior of mortars. The use of the resistivity itself seems to be deficient, but the analysis of the electrical parameters calculated from the impedance spectra measured gives a complete idea of the evolution in the material.