This project studied the capability of microwave methods to detect thickness of induced corrosion byproduct on rebars embedded into concrete, and also similarly embedded delamination. Three microwave methods used or investigated included microwave synthetic aperture radar (SAR) imaging method, microwave resonance method, and microwave nonlinear measurement. Wideband, low-frequency antennas including a double-ridged horn and a Vivaldi antenna were designed for achieving reasonable spatial resolution while being able to penetrate lossy concrete. Simulations and experiments were conducted for all of these investigations. For the rebar samples use, the results showed that the corrosion thickness was very small (~50 µm) which seemed to be out of the resolution capabilities of the microwave imaging method. Microwave resonance method initially showed good indications based on the relationship between the resonant frequency and the corrosion thickness by simulation results, but it does not work when the corrosion thickness is below 1% for a rebar with a radius of 7.9 mm. Microwave nonlinear measurement method brings positive indications based on the results from the initial experiments, which showed that the metal-insulation-metal junction can produce relatively measurable harmonic power and the value of it is proportional to the insulation thickness. Microwave imaging method for concrete delamination detection were also examined by measurements. It was found that the antenna beam has significant effect on cross-range and range resolutions. This had not been previously investigated and was hence studied comprehensively with a significant journal paper (recently) submitted for possible publication

Research Center/Lab(s)

INSPIRE - University Transportation Center

Second Research Center/Lab

Re-Cast Tier1 University Transportation Center

Grant Number

USDOT #69A3551747126


Principal Investigator: Dr. Reza Zoughi

Grant Period: 30 Nov 2016 - 30 Jun 2022

Project Period: 01 Sep 2019 - 30 Jun 2020

Keywords and Phrases

Microwave NDE; SAR Imaging; Resolution

Document Type

Technical Report

Document Version

Final Version

File Type




Publication Date

01 Jul 2020