Steel highway bridge coatings fail unevenly. Failures initiate on sharp edges and in highly stressed locations, particularly under leaking expansion joints. Typical spot painting specifications aimed at addressing coating failures require a Society for Protective Coatings Standard (SSPC) SP-10 surface preparation, or better. The costly surface preparation and containment systems needed to facilitate the SP-10 standard negatively impact the ability of owners to address the localized distress. Consequently, significant section loss in the bearing area of steel girders is not an uncommon consequence, requiring unanticipated (demand) repairs. Identifying maintenance friendly coatings that can be applied with minimal surface preparation (at least SSPC SP-3), yet are capable of extending the service life of the existing coating until more substantial treatments can be applied, will mitigate demand maintenance needs and allow for more steel bridges to be recoated according to schedule.
Maintaining the coating system so that the anticipated service life of the coating is realized will reduce the program costs for steel coatings. In addition, a coatings maintenance program will retard section loss of the steel elements and reduce the burden of demand repairs.
The objective of this research was to develop guidelines for the selection and use of a broad spectrum of protective materials for spot treatment of failed coatings on steel highway bridges. Materials and application guidelines should be suitable for implementation as an effective maintenance program by state DOTs.
