A five-year study to evaluate the long-term performance of various cathodic protection systems installed on bridge deck and substructure elements and on the underside of a roadway slab inside a tunnel was initiated in 1994. This work was a continuation of a portion of the research completed under the structures segment of the Strategic Highway Research Program. The performance of 10of the cathodic protection systems included in this study is discussed. These systems have been in service form 5to 15years.
In 1988, the Strategic Highway Research Program (SHRP), mandated by the United States Congress, launched multiple research efforts to study all aspects of reinforced concrete deterioration. Three of these SHRP programs (C-102D, C102F, and C-102G) established numerous field sites to study the effectiveness and of cathodic protection (CP), electrochemical chloride extraction (ECE), and corrosion inhibitors (CI) in mitigating corrosion of reinforced concrete bridge structures. These programs were completed in June, 1993. In order to obtain long-term performance data on the aforementioned corrosion protection systems at the sites established or identified by the SHRP programs, the Federal Highway Administration (FHWA) initiated the subject research study in July, 1994. Also included were laboratory concrete slabs that had been prepared by the SHRP efforts and subsequently treated with ECE and CI. The primary objective of the overall effort was to determine the effectiveness of CP, CI and ECE through a 5-year evaluation of 30 to 42 sites located in the United States and Canada. Upon initiation of the project, it was realized that some of the originally selected field test sites were not good candidates for long-term evaluation or were no longer available. These structures were eliminated from the study and several other bridge structures were identified as suitable replacements. The final group of sites to be evaluated includes 31 bridge structures and one tunnel.
This paper discusses the findings on 10of the impressed current CP systems included in the study. These systems were installed on conventionally reinforced bridge decks and substructure components and on the underside of a roadway slab inside a tunnel. The CP systems have been in service for 5to 15years and are dispersed throughout the continental United States and one Canadian Province.