Comparison of Laboratory Testing Methods for Bridge Coatings

摘要

This study was performed to investigate the effect of combining a freeze cycle,an ultraviolet/condensation cycle (QUV), and a salt-fog plus pollutant/dry cycle (Prohension) in an accelerated laboratory weathering test on the performance of coating systems for steel bridges. The test results were compared with those obtained from the salt-fog test, the prohesion test, and natural marine exposure. The coating systems selected were water-based systems of acrylic, acrylic expoxy, inorganic zinc alkali silicate, vinyl, and zinc-rich epoxy, and solvent-based systems of calcium sulfonate/alkyd, high-solid epoxy, zinc-rich polyurethanes, epoxy mastic, epoxy urethane mastic, and low-VOC epoxy. Evaluation parameters for coating performance included coating film thickness, coating gloss, hardness, adhesion strength, blistering, rust, and creepages at scribe. The failure modes of these coatings are discussed and the coating performances are compared.