The current work focuses on the application of a.c. impedance spectroscopy techniques to cementitious systems while still in the liquid state (i.e. during the dormant period). A variety of formats of data presentation are presented and exploited to understand the origins of polarization processes within these systems. The theoretical treatment also allows simulation of the experimental data to provide an interpretation of the bulk impedance response. Data are obtained over the frequency range 1 Hz to 20 MHz, but interpretation and analysis is focused, in the main, on the range 1 kHz to 1 MHz.