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40 enough for severe bridge environments." This is in contrast distinguishing factor between cathodic protection systems with the experience of other states such as California, Florida, and barrier systems is that at the end of the service life Missouri, and Oregon and in Canadian provinces such as of the cathodic protection system there is no corrosion- Alberta, New Brunswick, and Ontario, who among them induced damage. Whereas barrier systems gradually fail have a total of 464 bridge structures with cathodic protec- and at the end of their service life, some chlorides have tion systems. A majority of all systems in Florida are in the migrated into the concrete and corrosion-induced damage marine environment. Many of the systems in the northeast- has occurred. ern provinces of Canada are in very aggressive marine and deicing salt environments. Missouri itself has mixed metal oxide and conductive polymer anode systems that have been CATHODIC PROTECTION MARKET operational for at least 19 years. The size of the present cathodic protection market is not suffi- Many of the problems and failures of cathodic protection cient to generate competition and drive innovation. There are systems discussed previously are symptomatic of the evolution only a few vendors and they do not necessarily focus on the same market segment and therefore competition is virtually of anode materials and the process of learning the material non-existent. The sale of the system is dependent on the own- interactions and limitations. With the exception of the con- ers already having faith in their products or their sales people ductive coke asphalt, ferex anode, and the zinc foil anode, all convincing them of the benefits of its use. Even the consulting other anodes are still successfully being used. Several differ- arena is quite limited as manufacturers and installers find it ent types of systems, both galvanic and impressed current, easier to sell design-build projects. The lack of demand for have been in operation for approximately 20 years. post-installation services also is not very helpful to the growth of the industry. The majority response from the industry indi- INITIAL AND LIFE-CYCLE COST cated that the industry is in decline. However, one vendor noted that they expect to install cathodic protection systems on A majority of the respondents indicated that the initial cost of 200 bridges in the next five years. They also indicated that they the cathodic protection systems is relatively high. Many are have been involved with the either the supply of materials, not convinced that the cost-benefit ratio is favorable. Some installation of the systems, or providing consulting and engi- agencies indicated that they would like to see documentation neering services for cathodic protection on 1,350 bridges since of performance for each type of cathodic protection system 1980. Because the number of structures reported by state and and a listing of both initial and operating costs. Some indicated provincial agencies is less than half that figure, it is assumed that the quality of the products available needs to be improved that many of those structures are located outside of North and the cost lowered for cathodic protection to be an attractive America or are not owned by state and provincial agencies. As alternative for them. Several also indicated that more innova- this vendor is a large international corporation, their sales fig- tion and competition in the marketplace is desired. ures and future projections are a clear indication of where the The second generation of bridge structures (bridges built after the 1970s) include improvements to design such as an TABLE 29 increase in cover, lower permeability concrete, use of epoxy- FACTORS THAT WILL ENCOURAGE APPLICATION OF CATHODIC PROTECTION SYSTEMS coated rebars, use of admixed corrosion inhibitors, etc. Cali- fornia uses a polyester concrete wear surface on bridge decks No. of Factors Responses that can be expected to provide a reasonably good level of Better understanding of the technology by agency 15 waterproofing and it can also be replaced overnight with min- staff imal traffic delays. These techniques do provide a reasonable Education of the consultants 4 extension in service life. Therefore, on this generation of struc- Trained applicators and contractors 4 tures, the need for cathodic protection will occur at a much Reduction in cost of the cathodic protection 22 later date. If we use the solution to Fick's Second Law of Dif- system fusion and estimate the impact of cover and diffusion coeffi- Availability of consultants to monitor and 9 cient on time-to-corrosion initiation, we find that the increase maintain cathodic protection systems in cover results in an exponential increase in time to corrosion. Improved technology to monitor and maintain 20 Similarly, the impact of improving the permeability, and to systems some extent diffusivity, also increased time-to-corrosion initi- Improved quality of the system components that 17 ation exponentially. When both are combined the impact is would reduce the frequency of repair and more dramatic. maintenance of cathodic protection components Improved design 11 Most agencies are very comfortable with barrier sys- Technical assistance in selection of appropriate 13 tems such sealers, concrete overlays, and waterproofing cathodic protection systems for each application membranes. The initial costs of cathodic protection will All of the above 8 generally be higher compared with these technologies. The Note: Table based on results of Question 53 of the survey.
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41 rest of the world is going with this technology. In North Amer- tion in cost is closely followed by improved technology to ica, the cathodic protection industry for bridge structures is monitor and maintain, improved quality of system components, somewhat weak. These numbers also provide insight into the improved understanding of the technology, and technical assis- marketplace in terms of monopoly and lack of competition. tance in selection of appropriate cathodic protection systems. Thus, for the growth of the market, more innovation and com- When agencies were questioned as to which factors will petition is required to reduce costs and improve the monitoring encourage the application of cathodic protection technology, systems and quality of the components. The industry and tech- reduction in cost was cited by the greatest number of agencies. nical associations will have to do more to provide better direc- In the summary of the responses presented in Table 29, reduc- tion in the selection process and design of the systems.