Field Studies of Corrosion in Prestressed Concrete Bridges
D. Whiting and G. B. Stejskal
Appears on pages(s):
bridges (structures); chlorides; concretes; corrosion; deicing; field tests; harbor structures; nondestructive tests; prestressed concrete; sampling; Structural Research
A field survey was made of the condition of prestressed concrete bridge elements located in adverse, potentially corrosive environments. A total of 12 bridges were included in the detailed study. Bridges were located in various regions across the U.S., including the states of Connecticut, Florida, Illinois, Michigan, North Dakota, Oregon, and Rhode Island. Locations included marine sites where elements are exposed to corrosive saltwater and sites where elements are exposed to deicing agents. Surveys utilized a variety of nondestructive testing and concrete sampling techniques. These included visual and photographic documentation, potential surveys, delamination detection, cover measurements, linear polarization measurements, petrographic examination, and analyses of chloride contents. Results indicated that exposures to corrosive agents varied significantly between inland and marine environments. In marine areas, the entire support structure is exposed to corrosive conditions, the magnitude of which vary with respect to proximity of the given element to the waterline and attendant spray conditions. In deicing areas, exposure is much more localized, occurring mainly at beam ends immediately below leaking expansion joints, or between beams in the case of box girder bridges. Properly maintained joints and drainage systems can help to eliminate manly problems that occur on prestressed bridges subject to deicing applications. In warm marine environments where elements are directly exposed to seawater, more positive protection systems may be needed.