DEVELOPMENT OF AN EQUIVALENT-CIRCUIT MODEL FOR CEMENT PASTES FROM MICROSTRUCTURAL CONSIDERATIONS

The general approach to equivalent circuit modeling of cement pastes h as been to interpret spectra obtained from ac impedance measurements, assigning electrical responses to microstructural features such as hyd ration products and fluid-filled porosity. In this paper, we take an a lternative approach. Starting with a consideration of paste microstruc tures and the potential conduction pathways that such microstructures could support, we propose an equivalent circuit model, Ac impedance da ta from pore-reduced cements have been measured for the first time and are used to test the model, This approach has permitted estimation of conductivities of ill situ pore fluid, which we believe to be influen ced by hydrogen bonding to varying extents depending on pore size, and hydration product. Preliminary results are in broad agreement with da ta obtained by alternative methods.