Effect of Phase Geometry on the Dielectric Properties of Tricalcium Silicate Paste Based on Effective Medium Theory

Abstract

This paper presents a cross-scale prediction of the dielectric properties of long-term-cured tricalcium silicate (C3S) paste specimens and investigated the effect of different phase geometry models on the prediction results. Firstly, the dielectric properties of C3S paste specimens cured for 180 days were tested. Based on tests such as X-ray diffraction (XRD) and mercury intrusion porosity (MIP), the types of phases and the volume fractions of individual phases in the C3S paste specimens were determined. Subsequently, the dielectric performance of the phases was measured. The dielectric performance linkage between each phase and the C3S paste specimen was established based on the effective medium theory. The effects of three morphological models of the phase on the predicted results were dissected. The results showed that the volume fraction and dielectric constant of calcium silicate hydrates (C-S-H) gel were significantly higher than those of other phases in the C3S paste specimens. Among the three computational models of phase geometry, the standard spherical phase model produced the best prediction. The prediction results of the standard spherical model improved the accuracy by more than 45.8% compared with that of the oblate phase model and the prolate phase model. Among the phases, the trend of the dielectric constant of C-S-H gels with frequency was the most similar to the results obtained by the three prediction models.