Electromagnetic Characterization of Concrete Using a Calibrated Density- and Moisture-Dependent CRIM Framework

Accurate prediction of the electromagnetic properties of concrete is important for microwave non-destructive testing, ground-penetrating radar, structural health monitoring, and radio wave propagation analysis in buildings. Because concrete is a heterogeneous material, its dielectric response depends on frequency, density, porosity, and moisture content. This study presents a calibrated Complex Refractive Index Model (CRIM) framework for estimating the effective complex permittivity of ordinary structural concrete as a function of density and volumetric moisture content. The proposed formulation combines the physical interpretation of mixture theory with calibration based on representative dielectric data reported in the literature. The model is compared with the empirical ITU-R approach and the Jonscher frequency dispersion model over the frequency range 0.1–10 GHz. The proposed formulation is an engineering model calibrated using data from available literature. Within the investigated calibration range, the model provides a physically interpretable framework for estimating frequency-dependent dielectric properties and may support numerical electromagnetic simulations and future non-destructive evaluation applications.