Microwave reflection properties of concrete exposed periodically to chloride solution of 3% salinity and compression force

Microwave nondestructive evaluation (NDE) techniques applied to mortar have proven successful in the past for detecting mixture constitutes, salt ingress, loading and cure state monitoring. In this paper, a similar microwave NDE technique is used to evaluate reflection properties of concrete for cyclical exposure to salt ingress and loading at S-(2.6-3.95 GHz) and X-(8.2-12.4 GHz) microwave frequency bands. Four identical cubic specimens were prepared: one soaked in distilled water, one soaked in a 3%-salt solution, one soaked in a 3%-salt solution and loaded and finally one that was neither soaked nor loaded. Using both magnitude and phase of microwave reflection coefficient, it is shown that the cubes can be distinguished from one another using this technique.