Permittivity measurement of cementitious materials and constituents with an open-ended coaxial probe: combination of experimental data, numerical modelling and a capacitive model

The study presents the development of a new two-dimensional FEM numerical model describing the operation of two large open-ended coaxial probes designed to investigate the permittivity of concrete, and its constituents. This numerical simulation, combined with a capacitive approach describing the behaviour of the probes, enabled to prove the suitability of such device to determine the permittivity of dispersive dielectrics. Finding back the permittivity of a specified material by calculation of the S parameters, change of the reference plane and use of the capacitive model is the key to the proof. Measurements performed onto different materials show good similarities with the numerical simulations. Special considerations are mentioned concerning the size of the probe and its ability to measure the permittivity of heterogeneous materials made of large inclusions. Combination of such numerical tool and measuring device can be used as a non-destructive testing technique to assess the near surface permittivity of concrete structures or as a calibration technique for GPR measurements.

This creative work has been published under the Creative Commons Attribution 4.0 International (CC-BY 4.0) license which allows copying, and redistribution as well as adaptation of the original work provided appropriate credit is given to the original author and the conditions of the license are met.