Performance comparison of structural steel coating systems : final report

"Prepared in cooperation with the Ohio Department of Transportation and the U.S. Department of Transportation, Federal Highway Administration."; "February 2016."; Includes bibliographical references (pages 106-107).; Final report.; Sponsoring Agency: Ohio Department of Transportation; State Job Number 135004Departments of Transportation currently use the conventional three-coat system as the predominant choice for the corrosion protection of steel bridge structures. Eliminating one step in the coating process could potentially save time and the cost associated with lane closures and traffic control costs. Available field performance data for the two-coat system, zinc-rich and a polysiloxane top coat, is somewhat limited. To set the stage for any potential field applications, a comprehensive testing approach is presented and conducted in this report. This experimental work evaluates several two-coat systems, based on the zinc-rich primer and polysiloxane top coat technology. All samples were conditioned and coated in a state-of-the-art, climate-controlled paint booth chamber, simulating common field environmental conditions (ENCON) (ENCON 1: 25 °C/50% RH, ENCON 2: 10 °C/40%RH, and ENCON 3 :32°C/80% RH). Severe accelerated weathering tests were performed on scribed and un-scribed panels. Test results include accelerated corrosion tests, dry film thickness, adhesion, chipping resistance, UV/Condensation, abrasion resistance, fresh and salt water immersion tests, and flexibility of the coating systems. Overall and regardless of the ENCON considered, the performance of the two-coat system is very comparable to the three-coat system. This coating technology offers much improved performance with quicker set time and better adhesion to steel structures. Considering the lower cost and ease of application, this two-coat system can be attractive to other Departments of Transportation and will enhance and extend the service life of the infrastructure assets