Dielectric properties of the pore solution in cement-based materials

Abstract

Dielectric properties are intimately related to the content and composition of the liquid phase present in micro- and mesoporous materials. The presence of ions is recognized to affect the dielectric response of electrolytes in a complex way that depends on the ion-water and ion-ion interactions and respective concentrations. Pore solutions in cement-based materials are complex and age-dependent exhibiting different ion-pair states, which make them an interesting candidate for the study of the complex pore solution found in geomaterials in general. Here, we study the dielectric properties of bulk aqueous solutions representative of the pore solution found in cement-based materials using molecular dynamics simulations. Broadband dielectric spectra and frequency-dependent conductivities are provided. A mean-field upscaling strategy is deployed to compute the dielectric response at cement paste scale. In cement-based materials, the measurement of dielectric properties can be used for non-destructive monitoring of concrete structures conditions and to unravel details of the hierarchical pore structure of the material, notably at early-age when the microstructure of the material changes significantly. Our results can be used in the interpretation of high-frequency electromagnetic methods, such as ground-penetrating radar, enhancing the quality of interpretation and improving the confidence in the corresponding results.