Determination of physical properties of concrete by using microwave nondestructive techniques

Determination of the electrical properties of concretes with different water/cement ratios and investigation of the relationship between their electrical and mechanical properties is a promising technique towards improving novel nondestructive microwave based methods. In this study, this relationship between water-cement ratios/mechanical properties and electrical characteristics of various concretes is investigated in the frequency range of 3-18 GHz. The obtained data provides an accurate measurement results for the researchers to design microwave sensors operating at a constant frequency. Besides, the relationship between the electrical properties and the pressure applied to the concrete is also investigated experimentally for various cement types. The experimental study demonstrates the presumable mechanical characteristic of the concrete by using its dielectric constant values. The dielectric constant is retrieved from the reflection and transmission coefficients (which are more commonly known as scattering parameters) by using Nicolson Ross Weir (NRW) Technique. It is revealed that the most significant frequency point is 18 GHz to determine water/cement ratio and 17 GHz to differentiate applied pressure level by using dielectric constant values of the concrete.