Damage Detection of GFRP-Concrete Systems Using Electromagnetic Waves

The objective of this book is to develop an integrated nondestructive testing (NDT) capability for the detection of defects, damages, and rebars in the near-surface region of glass fiber reinforced polymer (GFRP)-retrofitted concrete cylinders through the use of far-field electromagnetic (EM) measurements (or EM waves or radar signals). In this development, two far-field monostatic ISAR (inverse synthetic aperture radar) measurement schemes are identified for collecting radar measurements, and the backprojection algorithm is applied for processing radar measurements into spatial images for visualization and condition assessment. Reconstructed images are further analyzed by mathematical morphology to extract a numerical index representing the feature of the image as a basis for quantitative evaluation. EM waves in the frequency range of 8 GHz to 18 GHz are found effective for damage detection in the near-surface region of the specimens. Dielectric properties of materials are investigated for their use in numerical simulation and for improving the precision of reconstructed images.