SPR 22-613, Spot, Zone and Overcoat Painting of Steel Bridges

PROBLEM STATEMENT Steel bridges in Kentucky have gradually had lead-based coatings removed and replaced over the past 25 to 30 years. The typical replacement coating has been zinc-based systems. Many of these coating systems are reaching their end of service life and are in need of replacement. Many others are in various stages of degradation. When considering the aging steel bridge inventory and the cost of complete coating removal and replacement, it becomes necessary to consider less expensive options, such as spot, zone and overcoat painting. Removal and replacement (maintenance) painting is typically considered to last 20 years. In order to maintain the protective coatings of more than 1100 KYTC steel bridges it would be necessary to paint 50 bridges per year. Cost savings can be accomplished by performing coating condition assessments to identify steel bridges for spot, zone and/or overcoating, and by developing specific painting strategies that include single coat and two coat systems thereby reducing the total life cycle cost. New guidelines/criteria will be developed for spot, zone and/or overcoating steel bridges. Specification note for use in KYTC contracts will be developed. One coat and two coat systems can be employed in the field on selective bridges by KYTC and evaluated in the laboratory for their performance. OBJECTIVES 1. Identify other state DOTs current best practices employed for spot, zone and overcoat of steel bridges. It includes identifying guidelines being used by other state DOTs for employing spot, zone and overcoat as part of their bridge maintenance strategy. 2. Based on objective 1, develop criteria for KYTC to identify steel bridges for spot, zone and overcoat. 3. Develop special notes that includes surface preparation techniques for employing spot, zone and overcoat strategies in the field. 4. Monitor spot, zone and overcoating projects for KYTC to improve criteria and special notes.