Electrochemical cell design and impedance spectroscopy of cement hydration
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Electrochemical cell design and impedance spectroscopy of cement hydration Aldo F. Sosa Gallardo1 and John L. Provis1,* 1
Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin St, Sheffield S1 3JD, UK
Received: 20 August 2020
ABSTRACT
Accepted: 25 September 2020
Understanding the complexity of the chemical and microstructural evolution of cement during hydration remains a controversial subject, and although numerous techniques have been used to assess this process, further insight is still needed. Alternating current impedance spectroscopy has been demonstrated to be a sensitive and powerful technique for cement characterisation in both fresh and hardened states; however, it has also shown certain experimental limitations (e.g. data interpretation, electrode, and parasitic effects) that prevent its wider acceptance. This study assesses electrochemical cell design and the impedance response during cement hydration. The results show that a significant decrease in the parasitic effects at high frequencies (caused mainly by leads and electrode effects) can be achieved through an optimal cell design and impedance measurements correction, enabling correlation of impedance measurements to particular aspects of the cement hydration process. However, due the limited solid phase microstructural development and the high conductivity of cement paste at low degrees of hydration, the parasitic effects could not be fully eliminated for fresh or early-age cement pastes.
Published online: 12 October 2020
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The Author(s) 2020
Introduction Portland cement is one of the most-used materials in the world ([ 4 Gt p.a.), but hardens and gains strength via what is arguably one of the most chemically complex non-biological reaction processes that is studied by scientists and engineers. Therefore, there are still important aspects that are not fully
Handling Editor: M. Grant Norton.
Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10853-020-05397-6
understood about this material. Cement hydration is critically important, since it determines the final microstructure, physical, and mechanical properties of the hydrated cement paste. The hydration process consists of a series of simultaneous and sequential chemical reactions, involving dissolution of multi-mineral clinkers and ancillary sulphate phases, water consumption, hydrate product formation, heat release, and the
1204 development of a solid microstructure containing a high ionic-strength pore solution [1–4]. The full understanding of cement hydration is of great importance to enhance its early and final properties and to achieve better performance (technical and environmental) in its applications. Many different techniques, tools, and interpretation methods have been used to assess cement hydration. One of these techniques is alternating current impedance spectroscopy (ACIS). Although ACIS has been demonstrated to be an effective and powerful technique and used in many studies in the
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