2020 Volume 76 Issue 3 Pages 158-170
In this paper, the experimental investigation for visualization of the area of internal crack and rebar corrosion in concrete structure by using electromagnetic wave radar was carried out. Firstly, the specimens with the rebar cover thickness (30, 60 mm) were made in which local corrosion area with different corrosion rate were introduced by electrolytic corrosion experiment, and the crack width and distribution characteristics and the corrosion distribution of the rebar were evaluated. Then, the visualization of internal cracks and corrosion areas by applying Self-Organizing Map (SOM) is tried by using indexes that the difference of electromagnetic wave reflection waveform data between damaged and sound parts are considered. As a result, by applying one-step SOM to corrosion specimens, it was confirmed that corrosion areas of rebar can be detected. Moreover, we propose a method to evaluate internal cracks and corrosion amount by two-step SOM and verified the applicable range. It was confirmed that the presence of internal cracks can be quantitatively and clearly evaluated, and it was confirmed that internal cracks of 0.1 to 0.4 mm and corrosion rates of about 4% can be detected.
