Dielectric characterisation of rock aggregates with different grain size distributions

Abstract

Aggregates largely influence a road's dielectric properties, which is an important physical parameter when using non-destructive methods such as ground penetrating radar to evaluate a road's geometry. Due to the irregular shapes, the direct measurement of an aggregate piece by piece in the microwave domain is not easy. To address this problem, an epoxy-based composite is used to estimate the dielectric constant of the aggregates by resonant test and mixing law calculation. As a water-free binder, the epoxy composite eliminates the water effect on the dielectric properties. Meanwhile, the distribution of each component can be studied by X-ray computed tomography, which allows knowing the composite's morphology. Moreover, the composite has a smooth surface that avoids the texture effects on the dielectric measurement. In addition, the impedance analysis of individual aggregates at low frequencies was used to evaluate the results obtained with composites and mixing laws.

KEYWORDS:

• Aggregates
• dielectric permittivity
• analytical approaches for dielectric mixtures
• X-ray computed tomography

Acknowledgements

The authors are grateful to AGIR-CTCV for providing the aggregates with different size distributions. The authors are also grateful to Mr. Bruno Beaucamp and Mr. Cyril Ledun for the dielectric cavity measurement.

Disclosure statement

No potential conflict of interest was reported by the author(s).