Evaluation of Galvanized and Painted-Galvanized Steel Piling

Abstract

Corrosion is important in the design, maintenance, and preservation of bridge steel pile foundation systems. It is an inevitable phenomenon when steel is exposed to the environment, as metals tend to return to their lower energy state. While the corrosion rate of steel is predictable for atmospheric exposures, it is highly variable and difficult to predict for steel buried underground because of the high variability of soils. Applying a protective sacrificial layer is a common protection method to prevent corrosion. This study aims to evaluate the efficiency of a galvanized and painted galvanized steel bridge pile for achieving a 100-year service life and to economically compare them for using piles without a coating. To meet this objective, 21 steel coupon samples and nine 30 cm pile samples with galvanized coating, painted-galvanized coating, and no coating were tested in a cyclic corrosion test chamber to investigate the efficiency of each coating. The test was conducted for 600 days simulating a 100-year service life. Results from the experimental test revealed that galvanized and painted-galvanized coating methods show remarkable performance in protecting the piles against corrosion, and both methods can protect the piles from corrosion for 100 years. Further evaluation showed that, while the cost to increase the pile size was determined to be less than the premium for galvanizing or galvanizing and painting the piles for the bridge in this study, a cost–benefit evaluation for each protection measure is suggested, knowing that costs can vary widely depending on specific project requirements, location, market prices, etc.