Influence of slag incorporation on electrochemical behavior of carbonated cement

- Slag effect on electrochemical behavior of carbonated cement is studied.
- Slag cement exhibits larger semi-circles of Nyquist curve than plain cement paste.
- An increase of slag content can hinder the ion transport process in cement system.
- Slag cement has less resistance of ion transport than fly ash cement.

A research work is carried out to understand the influence of slag incorporation on the electrochemical behavior of carbonated cement systems. Measurement of carbonation depth and electrochemical impedance spectroscopy is conducted. A suitable equivalent circuit model is applied to fit the measured electrochemical impedance data (Nyquist curve) and quantitatively obtain the electrochemical property for carbonated slag blended cement. Test results demonstrate that increasing the slag replacement ratio in cement can increase the carbonation depth, enlarge the semi-circle of the Nyquist curve, and improve the resistance of ion transfer at the “solid-liquid phase” interface. We also compare the slag incorporation effect on the electrochemical system of carbonated cement with another common mineral admixture (i.e. fly ash). It is found that slag blended cement exhibits smaller semi-circle of Nyquist curve and larger carbonation depth than fly ash blended cement. Based on the electrochemical modification, we also predict the carbonation depth of blended cements with different slag contents.

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