Study the impedance spectroscopy of early-age cement paste hydration process using Electrodeless impedance analyzer (EIA)

•Without the side effects caused by electrodes, the impedance spectrum of cement specimen drawn in Nyquist plot forms as a perfect semicircle.•The impedance spectroscopy behavior of cement-based materials was induced by the frequency dependent conductance of ions inside pore solution, and this behavior was not impacted by pore structures.•Impedance spectrum may be not an effective tool to reveal a credible relationship with the pore size distribution of cement-based materials. Electrodeless Impedance Analyzer (EIA) --- a new non-contacting electrodeless impedance spectroscopy (IS) measurement device was recently invented to monitor and interpret the hydration process of cement pastes with different water to binder ratios and composites. A perfect arc was observed in the Nyquist plot, and cement pastes seem to have an inductive behavior which has never been recorded before. In order to trace back to the sources of the complex resistivity behavior of cement-based materials, electrolyte, the major conductive phase inside the composite matrix, was detected together with cement pastes. An equivalent circuit model for impedance spectroscopy (IS) of cement paste has been proposed which seems quite different with previous models.