Accelerated exposure tests as evaluation tool for estimating life of organic coatings on steel bridges

Abstract

The present study performed accelerated exposure tests on 5 types of painting systems, which are commonly used for steel bridges in Japan, and discussed corrosion degradation from initial defects on the paintings. The structural steel plates were surface treated and painted conforming to the 'Japanese painting manual', and circular defects with 0?2, 1?0 and 2?0 mm in diameters reaching the steel substrate were created on each of the painted plate. The painted steels were exposed into an environmental testing chamber controlled by the S6 cycle test condition, which is a laboratory cyclic accelerated exposure test condition of spraying/wetting/drying, for up to 600 days. The corrosion degradation curve of the each painting system was evaluated based on rusting area from the circular defects, which was measured by using laser focus measuring instrument at 250 mm intervals. The proposed degradation curves were applied to evaluating remaining lifetime of the painted steels with initial defects to the future conditions. The evaluation procedure for field environments was also presented based on the acceleration coefficient of the S6 cycle tests and the amount of flying salt.

Performance profiles of metallic bridges subject to coating degradation and atmospheric corrosion

“…Experimental results (Itoh & Kim, 2006, Kim & Itoh, 2007 suggest that the coating itself will gradually deteriorate with time and will eventually become completely ineffective. This assumes that the application of the coating is carried out by competent coating contractors, and, hence, the possibility of rapid deterioration and/or premature peeling are minimised.…”

Prediction of long-term service life of an organic coating based on short-term exposure results

“…Nowadays, coating protection performance is usually evaluated according to the following coating characteristics: The physical and chemical changes, such as the gloss loss (Guseva et al , 2003; Evans, 2012), the color change (Lee and Chang, 2016), the emergence of rust (Kim and Itoh, 2007), the adhesion failure (Zhang et al , 2020a; Zhang et al , 2020b; Meng et al , 2017) and the occurrence of blistering (Latif et al , 2017; Chuang and Nguyen, 1997; Bethencourt et al , 2004; Xu et al , 2021; Zheng et al , 2021). The electrochemical resistance reduction, such as the decreased coating resistance (Cmaitland and Mayne, 1962; Deflotian et al , 2008; Yong et al , 2021) and the reduced low frequency modulus (Bierwagen et al , 2001; Shreeoathi et al , 2011; Su et al , 2015).…”

“…The physical and chemical changes, such as the gloss loss (Guseva et al , 2003; Evans, 2012), the color change (Lee and Chang, 2016), the emergence of rust (Kim and Itoh, 2007), the adhesion failure (Zhang et al , 2020a; Zhang et al , 2020b; Meng et al , 2017) and the occurrence of blistering (Latif et al , 2017; Chuang and Nguyen, 1997; Bethencourt et al , 2004; Xu et al , 2021; Zheng et al , 2021).…”

An approach for evaluating tensile strength of painted steel plates from the surface rusting grade

“…To avoid deterioration by corrosion, one or more coating systems are applied to steel structures to maintain the aesthetic appearance and structural performance. The coatings in corrosive environments deteriorate with increased exposure time, and periodic recoating is necessary for steel structures to extend their service life [1].…”