Quantitative assessment of heavy-duty anticorrosion coating thickness via near-infrared measurements

The application of heavy-duty anticorrosion coatings is a typical method for preventing corrosion in steel bridges. However, thus far, no efficient and quantitative inspection technique has been established that can remotely and non-destructively evaluate the remaining thickness of the top coat in anticorrosion coatings. This study proposes a new inspection method called the "active self-reference lock-in near-infrared measurement method", which can accurately and quantitatively assess the remaining thickness of the top coat, irrespective of the lighting conditions. Experimental studies conducted on specimens and field studies carried out on on-site bridge measurements have confirmed the efficacy of the proposed method.