Quantitative deterioration evaluation of corrosion protection coating by near-infrared measurement

Abstract

Heavy anticorrosion paint is applied on the surface of steel bridges for protecting corrosion. The heavy anticorrosion coating is composed of multiple paint layers such as zinc rich paint undercoating for electric corrosion protection, epoxy resin middle coat paint for protecting the zinc rich paint, and weather proof fluorine resin top coat. In the maintenance program of steel bridge anticorrosion coating, it is important to decide the timing of repainting repair, and in general the timing is set when the weather proof fluorine resin top coat is lost. However it is difficult to detect the loss of top coat by visual testing. Therefore it is beneficial for the preventive maintenance to determine the wear of top coat quantitatively before the top coat is completely lost. In this study, experiments were conducted with the aim of quantitative estimation of the degree of abrasion of the top coat thickness. It was found that it is possible to estimate the topcoat thickness based on the infrared luminance value.