Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements (2009)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

CHAPTER THREE APPLICATION OF CATHODIC PROTECTION BRIEF HISTORY OF USE IN NORTH AMERICA The very first application of cathodic protection to reinforced concrete elements was reported in 1959 by Caltrans (5). Dur- ing the late 1940s and the 1950s, Caltrans had spent more than $1 million in repairing damage caused by corrosion on the 7-mile San Mateo–Hayward Bridge located in San Francisco and were forced to look for ways to control or stop corrosion. An experimental system was installed on the reinforced con- crete beams of this structure. It used carbons rods and a con- ductive backfill, which were placed in wooden troughs and attached on to the concrete beams. Later, in 1972, based on this proof of concept, Caltrans installed a full-scale cathodic pro- tection system on the deck of the Sly Park Bridge near Placer- ville, California (6). This system used silicon iron anodes embedded in a layer of coke breeze (see Figure 14). The coke breeze was used as a conductor to distribute the current uni- formly over the bridge deck. As the coke breeze mix did not have the requisite material properties to serve as the riding surface, an overlay of asphalt was placed on top of the coke breeze. Based on the initial success at the Sly Park Bridge, Caltrans installed seven more asphalt–coke breeze overlay cathodic protection systems during 1974 and 1975. An eval- uation of these seven bridge deck cathodic protection sys- tems was performed and its report in 1981 established the feasibility of using such a system on bridge decks for miti- gating corrosion (14). With the application of the first system on Sly Park, the cathodic protection industry for reinforced concrete struc- tures was born. Several concurrent efforts for developing new technologies and implementing the one demonstrated at Sly Park were initiated in the 1970s. A majority of these efforts focused on the implementation of cathodic protection on bridge decks. FHWA led the way with Demonstration Project 34 (DP-34), Cathodic Protection for Reinforced Con- crete Bridge Decks, which began in 1975 and funded the installation of 14 asphalt–coke breeze systems by 1982 (15). Other reports indicated that by 1984 a total of 22 systems were operational in 11 states (16). In 1976, MTO reported installation of asphalt–coke breeze systems on two structures; one was a ramp at a major inter- change in Ontario and the other was the Duffins Creek Bridge. Ontario improved on the original design developed by Cal- trans by changing the mix design of the coke breeze layer and making it more stable. In addition, they installed the anodes and the wirings in cut outs on the reinforced concrete deck, thereby reducing their susceptibility to damage during replace- ment of the asphalt riding layer. By 1978, the asphalt–coke breeze overlay system had become one of the three standard procedures that MTO used for rehabilitation of reinforced con- crete bridge decks and as many as 30 systems were installed by 1984 (17,18). Although the basic concept of the asphalt–coke breeze system was sound and the systems (especially the designs employed by Ontario) were working well, the focus of the cathodic protection industry shifted to other materials and methods of installation, and these systems fell out of use in the United States. Recently, MTO also discontinued the use of this type of system. As slots cut on the deck surface provided a convenient mechanism to install anodes with- out adding any additional dead load, the focus of research and development shifted to anode and backfill materials that would be used in slots. In the late 1970s, two separate efforts evaluated the appli- cation of zinc anodes in the form of ribbons and sheets in Illinois. The first effort evaluated zinc ribbons placed in lon- gitudinal slots on the deck and backfilled with cementitious mortar and was conducted by the Illinois DOT. The anode spacings evaluated in this effort were 24 and 48 in., and this study concluded that the zinc ribbons were only capable of throwing the protective current to a distance of 3 in. on either side of the slot (19). The second effort was performed under NCHRP and it evaluated the zinc ribbons in the slot and zinc sheets on the surface of the deck. This effort was unable to come to any conclusions on the feasibility of using zinc on bridge decks as a cathodic protection anode material (20). The platinum niobium wire that was commercially avail- able became the next material of choice as the primary anode. It provided the necessary electrical properties, was durable, and could provide a reasonable service life. Research by FHWA and others indicated that spacing between slots not exceed 12 in. for effective current distribution by this anode material (21–23). The first evaluation of this system in 1977 used portland cement mortar as the backfill material and topped it off with a polymer modified mortar (21). The back- fill material failed owing to the generation of gasses and acid at the platinum wire, which resulted in acid attack. Several other materials, such as a proprietary conductive cementi- tious non-shrink grout (24) and a conductive grout mixture, 14

15 FIGURE 14 Conductive coke breeze system with pancake anodes. FIGURE 15 Various stages of construction of a slotted FHWA conductive polymer cathodic protection system. were tested and they too could not withstand the acid attack. An industry supplier proposed a calcined petroleum coke back- fill topped with a flexible sealant. Although this combination was able to withstand the acid attack it was not durable enough for use on bridge decks (15,21). Continued FHWA research led to the development of the conductive polymer grout, which was able to meet all the requirements needed of the backfill material (21,25). From 1979 to 1984, slotted systems were installed on a total of 15 bridges distributed over 11 states. With the devel- opment of the FHWA conductive polymer grout, the number of bridges increased to more than 100 by 1989 (16). Missouri led with the maximum number of installations. In Missouri, the earlier slotted systems were overlaid with asphalt. Later, the asphalt overlays were replaced by cementitious overlays. In 1985, one of the largest slotted cathodic protection systems was installed on the elevated sections of I-64 in Charleston, West Virginia. The system is still operational and the last time it was evaluated in 2005 it was found to provide adequate pro- tection against corrosion (26). Figure 15 documents the instal- lation of one such system. The successes of the conductive polymer grout in the slots led to the development of the mounded system. The conduc- tive polymer grout was laid out in a grid on the surface of the

deck after deteriorated concrete was removed and patched and the deck was scarified (see Figure 16). The platinum wire was encapsulated in the grout in one direction of the grid and carbon fibers were used in the other direction of the grid. Car- bon fiber was used to reduce the cost of the system. Latex- modified concrete or a conventional concrete overlay was then placed over the grid to provide a riding surface. The first such system was installed in 1983 on the 42nd Street Bridge in South Minneapolis, Minnesota. This system was moni- tored for five years under an FHWA research program and was found to be operational until July 1996. The evaluation in May 1998 suggested that the system had fallen into dis- repair and was powered down (27). A few more of these sys- tems were installed on bridge decks and one was installed in a parking garage. For applications on concrete elements that are not subjected to traffic, conductive paint and mastics were developed in the late 1970s (28–31). The conductive coating type anode sys- tem completely covers the concrete surface and provides effi- cient current distribution. It is easy to install using a variety of common installation methods (spray, roll, or brush) and its low initial cost makes it a desirable system. The conductive coating is black, and a decorative overcoat latex paint is often required for safety and cosmetic purposes. NCHRP Project 12-19 identified several commercially available conductive paints that showed promise. The trial was conducted at a U.S. Army Corp of Engineers building at Ft. Lee, Virginia (31). The paint was used as a secondary anode and the platinum wire was used as the primary anode with the FHWA conduc- tive polymer providing the electrical contact between the plat- inum wire and the paint. Since 1975, the Florida DOT (FDOT) has been involved in conductive paint and mastic cathodic protection work on pilings, piers, caps, beams, and deck undersides and its work also indicated that conductive paints and mastics can be a viable anode material (32). A follow-up NCHRP effort, Project 12-19B, was charged with further eval- uation of conductive paint cathodic protection systems (28). This effort identified another conductive coating that was 16 judged as the best paint material tested and was used in a field application. In the early 1980s, MTO also conducted feasi- bility tests using different conductive coatings (33). At first, the conductive paints developed for other applications such as television tubes were used. Later, paints were specifically developed for use on reinforced concrete structures. The ser- vice life of the paint system is limited by the durability of the paint and its ability to weather. The durability of the paint in wet, freeze–thaw, and splash zones was a significant concern and was evidenced by the Ontario study in which the paint started to weather in 3 to 6 years. Conductive paint systems installed on two bridges in Virginia started to exhibit signif- icant deterioration of the paint within 10 years of operation (27–34); however, properly designed and well-installed sys- tems have provided adequate protection in humid environ- ments (28,30,33). Conductive paints have performed much better in parking garage structures (35). Arc sprayed zinc was developed as a conductive coating anode by Caltrans in 1983 and was used as an impressed current anode in the first field trial on Pier 4 of the Richmond– San Rafael Bridge located in San Francisco Bay, Califor- nia (36). Using the arc spray technique, the application rate was significantly increased over the older flame sprayed method. In the arc sprayed technique, an electrical arc between two zinc wires is used to melt the metal, which is applied to the concrete surface by a stream of air. As this coating is a metal, it is very conductive and a limited number of elec- trical contact points to the power supply are required if used as an impressed current anode. Unlike the conductive paints, the zinc coating is comparable in color to concrete and requires no decorative overcoat. The second largest application of arc sprayed zinc is the Yaquina Bay Bridge in Oregon (37), where it has been used as an impressed current anode. Oregon was instrumental in the development of good specifications for the application of arc sprayed zinc systems and quality control. The section of the structure that was receiving the arc sprayed zinc was enclosed to control the environment for the application of the zinc coating and to contain the dust gener- ated during concrete repair (see Figure 17). In the response to a survey question, the state of Oregon stated that “In Oregon, impressed current cathodic protection with arc sprayed zinc anodes appears to fill a niche market for the preservation of our historic bridges along the Pacific coastline. The effective life of the zinc anodes and the requirements for renewal or replacement of anodes is the subject of on-going research.” With the completion of ongoing construction, Oregon will have 1.17 million square feet of concrete under arc sprayed zinc cathodic protection making it the largest user of this type of system in North America. FDOT started to use it on sub- and superstructure elements as a galvanic anode. By 2002, it had been applied to 13 bridges with a combined protected concrete surface of approximately 350,000 square feet (38). In a typical application, the system is installed without any concrete restoration and the connec- tion to steel is achieved by applying the zinc directly on to FIGURE 16 Construction of mounded conductive polymer cathodic protection system.

17 the exposed reinforcement. The most common uses include structures where the deterioration is several feet above the tidal zone and on structures where only isolated areas need to be provided with corrosion control. The service life of this galvanic anode has been observed by FDOT to range from 5 to 10 years depending on the environmental conditions at the site, location above water level, and the type of reinforce- ment being protected. The ferex anode became available in 1984. This anode used a copper conductor covered by a flexible polymer anode material. Woven into a mesh, the anode was placed on the deck or the substructure element and encapsulated by a cementi- tious overlay material. Up to 50 systems were installed on bridge decks. However, by 1990 many of these systems were exhibiting anode deterioration and the anode is no longer used (16). There were several reasons for the failure of this anode material, ranging from deficient system design to inability to withstand the high alkaline environment in the concrete. FDOT developed the concept of conductive rubber and the rubber industry was able to manufacture it for use as an anode material. This rubber was produced as sheets with cor- rugation on one face and could be positioned on the pile sur- face and held in place by a compression jacket manufactured from fiber-reinforced polyester. The compression jacket used stainless steel bands to produce the requisite pressure to hold the system in place (see Figure 18). The first such system was installed in 1987 on the piles of a bridge carrying US-90 over the Intracoastal Waterway in Jacksonville, Florida. Results of 2 years of monitoring indicated uniform distribution of cur- rent on marine pilings (39). An update in 2002 reported that this system had been installed on three bridges and the sys- tems were providing adequate protection (38). This system is no longer used owing to the availability of better alternatives. The mixed metal oxide anode was developed in 1985 and has been used on both bridge decks and substructure elements. FIGURE 17 Yaquina Bay Bridge, Newport, Oregon, has the largest arc-sprayed zinc-impressed current cathodic protection system. FIGURE 18 Conductive rubber anodes. This anode is composed of a titanium base upon which propri- etary mixed metal oxides are sintered. The mixed metal–oxide catalyst is specific to the evolution of oxygen rather than chlo- rine, and the operating voltage is 0.5V below the theoretical voltage required to drive the oxidation of chloride ions to chlo- rine gas (40). This reduces acid attack on the concrete as a result of the generation of chlorine gas at the anode/concrete interface. The anode is supplied primarily in two forms: mesh and ribbon. In the mesh form, a titanium expanded mesh with diamond-shaped openings is used as a base and the mixed metal oxides are sintered on all exposed surfaces of the tita- nium. The mesh is supplied in 4-ft wide rolls, and can be installed on a horizontal or a vertical surface and is usually encapsulated in a cementitious overlay material. Power is supplied to the anode by means of titanium conductor bars welded to the anode at appropriate locations. The ribbon is available as either a solid ribbon or an expanded mesh ribbon and is usually installed in slots, which are then backfilled with a cementitious material. The first experimental bridge decks were constructed with this system between 1986 and 1987. Its first use on a substructure was in Ontario, Canada, where it was encapsulated with an acrylic polymer-modified

gunite. Between 1985 and 1990, approximately 100 mixed metal oxide systems were installed on bridge decks and more than 3.9 million square feet of concrete surface area were pro- tected (16). Field evaluation of the various mixed metal oxide mesh anodes on twin structures in Virginia was reported after approximately 7 years of operation. The authors concluded that these anodes most likely could have a service life in the range of 60 to 90 years based on the normal current densities required for reinforced concrete bridge decks (41). In 1991, FDOT reported the use of perforated zinc sheets as galvanic anodes, which could be installed in the same fashion as the conductive rubber system (42). The zinc anodes were effective in providing the cathodic protection current; how- ever, the high consumption rate of the zinc at high tide was unacceptable. To overcome this drawback at the next installa- tion, on the B. B. McCormick Bridge in Jacksonville, Florida, a bulk zinc anode was added under the low water line to pro- vide the majority of the current during high tide. Based on the success of this system, a full-scale installation was designed and installed in 1993 on the Bryant Patton Bridge (43). In 1996, FDOT reported on another improvement to the system by embedding the zinc perforated sheet in a cementitious material and creating a jacket. The expanded zinc mesh in a fiberglass jacket has been commercially available since then and is a standard system of use in Florida. To date these jackets have been used in 51 projects in Florida and have been installed on 1,782 piles. According to the material supplier, this system has been installed on more than 4,000 piles in the state of Florida, most of which are installed on structures that do not belong to FDOT. A more recent effort evaluated the performance and the condition of jacketed cathodic protection systems in Florida and found some evidence to suggest that this system can be expected to provide cathodic protection for approximately 20 years (44). In 1996, a zinc foil with adhesive system was developed and was later marketed commercially (45). Arc sprayed tita- nium with a mixed metal oxide coating was first applied on the Depoe Bay Bridge located in Depoe Bay, Oregon, around 1996. This was an attempt to apply a successful anode material in a different form. The conductive ceramic anodes were devel- oped in the United Kingdom and are now available in North America. Under an FHWA research project, the aluminum– zinc–indium alloy for use in galvanic cathodic protection sys- tems was developed around 1998 (46). Around the same time, the activated zinc anodes became available commercially. These anodes use zinc as the core and encapsulate it with pro- prietary material. This ensures that the zinc remains active throughout its service life. They come in several different geometries for application in various different reinforced concrete components. The smaller anodes, designed for use in concrete repairs commonly known as hockey pucks, are increasingly being used in bridge repairs. Other geometries such as the cylindrical anodes for use in larger repair areas, as depicted in Figure 19, are now available. 18 FHWA provided funding for the installation of many of the experimental and trial cathodic protection systems through DP-34. It controlled the implementation of the technology from the early stages until the mid-1980s. After the joint com- mittee of AASHTO, Association of General Contractors of America (AGC), and American Road and Transportation Builders Association (ARTBA) started the Guide Specifi- cation for Cathodic Protection of Concrete Bridge Decks in 1989, DP-34 ended. The guide specification prepared by this committee was published in 1994. While the FHWA was involved in the implementation of the cathodic protection, it mandated a certain level of design quality, quality control and assurance during installation, and provided technical assistance, after which, state DOTs became responsible for the design, installation, monitoring and maintenance of the systems. Several states such as California, Florida, Missouri, and Oregon developed in-house expertise in this technology and have been effectively using it to control their maintenance costs. Similarly, the provinces of Alberta, New Brunswick, and Ontario are also using this technology to control corrosion- induced damage on their reinforced concrete bridge structures. In 1990, NACE developed a Standard Recommended Prac- tice for Cathodic Protection of Reinforcing Steel in Atmo- spherically Exposed Concrete Structures. The Strategic High- way Research Program (SHRP) published the SHRP-S-337 “Cathodic Protection of Reinforced Concrete Bridge Elements: A-State-of-the-Art-Report” in 1993 (16). PRESENT USE OF CATHODIC PROTECTION IN NORTH AMERICA A 1992 SHRP report documented the growth of the cathodic protection industry from 1973 until 1989, which is presented in Figure 20. Their survey results tallied a total of 287 cathodic protection systems applied to 200 bridges in North America (8). They estimated that the agencies that had not FIGURE 19 Activated cylindrical anodes used for a repair.

19 responded to the survey had an additional 20 systems installed on their bridges. In 1989, five states, California, Florida, New Jersey, Ohio, and Pennsylvania had between 6 and 20 cathodic protection systems installed and two agencies, Missouri and Ontario had more than 20 cathodic protection systems. Missouri had the most with 121 systems, and was followed by Ontario (44), New Jersey (18), California (17), and Ohio (14). To determine the extent of use of cathodic protection sys- tems at the time of this synthesis, two approaches were used; in the first approach, the NBI database was queried, and the second approach was to request the inventory of cathodic pro- tection systems from the public agencies in the survey. It may be noted that the NBI only contains information on structures located in the United States. Item 108C of the NBI database requires the deck protection type to be listed. One of the several deck protection types that can be coded for is cathodic protection. The code for cathodic protection in this database for Item 108C is 4. Only cathodic protection systems installed on bridge decks can be input into the NBI database; systems installed on any other elements are not accounted for. The results of the NBI query and the response of the survey are combined in Table 1. Of the 36 states in the Unites States which are known to have a cathodic protection system in the NBI database, 24 responded to the survey. Eight states that did not have any cathodic protection systems listed in the NBI database also responded. The state of Ohio responded; how- ever, it did not have any information on inventory to provide. A total of 375 deck cathodic protection systems are listed in the NBI database for structures located in the United States. The number of deck cathodic protection systems listed in the NBI database for states that responded to the survey is 309. However, the states in the survey reported a total of 279 deck cathodic protection systems. The difference in the numbers may be accounted for by cathodic protection systems that have been decommissioned, have failed, or the bridge decks have been replaced. For the state of New Jersey, the NBI database has 22 bridges with a deck cathodic protection system; how- ever, the survey response lists no bridges with cathodic pro- tection systems. Similarly, for Illinois, the NBI lists 25 bridges with a deck cathodic protection system and the state reports 8 for the bridge decks. Missouri has 32 more deck systems than the listing in the NBI database. Ohio has coded a total of 29 bridges in the database. However, the state DOT at present does not have any information on the status of any impressed current cathodic protection system installed. At present they only use localized anodes in repairs. It is possible that some of the localized anodes installed in repairs have been coded as cathodic protection systems. There is no simple way to judge which of the two sets of numbers is more accurate, the NBI listing or the numbers reported by the states in the survey. It is assumed that the state responses are more accurate and that the coding in the NBI database may not reflect the actual con- ditions on the ground. A total of 586 structures have cathodic protection sys- tems installed in North America with 389 located in the United States and 197 in Canada. Of the 586 structures, 375 have cathodic protection systems installed on decks, 47 on superstructure elements such as beams and girders, 49 on caps, 83 on columns, 107 on piles, and 15 on footers. Twenty- five of the 36 respondents have cathodic protection systems installed on bridge structures. One respondent has no infor- mation available on the installed systems and, therefore, is not included in the count. According to survey responses, Missouri has the highest number of bridges with deck cathodic protection systems, 161 of 375 (43%) and Ontario, New Brunswick, and Alberta have 40, 35, and 20 bridges, respectively. For superstructure elements, Oregon has 11 bridges and Alberta and Ontario have 10 bridges each out of a total of 47. Cathodic protection has been installed on caps of 49 structures, 10 of which are located in Alberta and 9 in Oregon. On piles, Florida has the most with 50 bridges (46%), followed by New Brunswick with 40 bridges (37%) out of a total of 107 bridges reported. Also, on footers, Florida has the most with 10 bridges out of the total 15 (67%). Over the next 5 years, 159 new cathodic protection systems are being planned for installation by the responding agencies. Table 2 provides the number of agencies that have a catho- dic protection system on each type of bridge component. Bridge decks and columns appear to be the elements on which the vast majority of agencies have installed cathodic protection systems. These are followed by caps, superstructure elements, piles, and footers in descending order. The distribution of the use of the various types of cathodic protection systems on various bridge components is listed in Table 3. This table documents the number of respondents using the particular system on each type of bridge element. In the impressed current category, the titanium mesh was found FIGURE 20 Number of cathodic protection system installations per year (1973–1989). 1 5 8 1 7 6 3 4 2 10 20 56 39 47 42 22 0 10 20 30 40 50 60 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 Year N um be r o f B rid ge s 10

State/Province State Code Responded to Survey NBI Reported Total Deck Superstructure Caps Columns Piles Footers Alabama AL No 0 Alaska AK No 2 Arizona AZ Yes 0 1 0 0 0 0 0 0 Arkansas AR Yes 0 0 0 0 0 0 0 0 California CA Yes 6 20 12 1 0 6 1 1 Colorado CO Yes 13 6 6 0 0 1 0 0 Connecticut CT Yes 12 13 12 1 Delaware DE No 1 District of Columbia DC No 0 Florida FL Yes 1 71 3 5 6 10 50 10 Georgia GA No 0 Hawaii HI Yes 0 0 0 0 0 0 0 0 Idaho ID No 2 Illinois IL Yes 25 15 8 3 2 1 1 0 Indiana IN Yes 20 15 15 0 0 0 0 0 Iowa IA Yes 13 6 3 2 0 1 0 0 Kansas KS No 5 Kentucky KY No 0 Louisiana LA No 0 Maine ME No 1 Maryland MD Yes 13 15 14 0 0 1 0 0 Massachusetts MA No 3 Michigan MI No 5 Minnesota MN No 1 Mississippi MS Yes 1 0 0 0 0 0 0 0 Missouri MO Yes 129 167 161 0 0 2 0 0 Montana MT Yes 1 0 0 0 0 0 0 0 Nebraska NE No 8 Nevada NV No 0 New Hampshire NH No 2 TABLE 1 NUMBER OF CATHODIC PROTECTION SYSTEMS IN EACH STATE OR PROVINCE (continued )

TABLE 1 (continued ) New Jersey NJ Yes 22 0 0 0 0 0 0 0 New Mexico NM Yes 1 0 0 0 0 0 0 0 New York NY Yes 2 4 3 0 0 1 0 0 North Carolina NC Yes 0 3 0 0 2 2 1 2 North Dakota ND Yes 0 0 0 0 0 0 0 0 Ohio OH Yes 29 Oklahoma OK Yes 2 0 2 0 5 15 0 0 Oregon OR Yes 8 11 9 11 9 7 0 0 Pennsylvania PA Yes 12 11 11 0 0 1 0 0 Puerto Rico PR No 0 Rhode Island RI No 0 South Carolina SC Yes 0 0 0 0 0 0 0 0 South Dakota SD Yes 3 12 8 0 3 1 0 0 Tennessee TN Yes 7 0 0 0 0 0 0 0 Texas TX Yes 8 1 1 4 5 5 3 2 Utah UT Yes 0 2 2 0 0 0 0 0 Vermont VT Yes 0 1 0 0 1 1 0 0 Virginia VA Yes 6 12 7 0 4 7 1 0 Washington WA Yes 3 3 2 1 0 0 0 0 West Virginia WV No 4 Wisconsin WI No 3 Wyoming WY Yes 1 0 0 0 0 0 0 0 Prince Edward Island, Canada PEI-CA 2 1 1 1 New Brunswick, Canada NB-CA 85 35 10 40 Nova Scotia, Canada NS-CA Ontario, Canada ONT-CA 60 40 10 10 Alberta, Canada AL-CA 50 20 10 10 0 10 0 Totals 375 586 375 47 49 83 107 15 Note: Table based on results of Questions 20 and 21 of the survey and data mined from the NBI Database.

22 and decks. Arc sprayed zinc comes in a distant second and also has been used on all bridge components, most often on columns. The third contender is the arc sprayed aluminum– zinc–indium alloy and it also has been used on all bridge components. The zinc foil has been used on all components other than the struts and the footers. INTERNATIONAL USE OF CATHODIC PROTECTION Around 1984, European countries started to recognize the magnitude of the corrosion problem and, in 1985, the United Kingdom began an evaluation of the technology. Since then, 2.15 million square feet of concrete surface has been pro- tected using various different types of cathodic protection systems. In Northern Europe, Denmark leads with more than 60 installations, with 8 to 10 installations added each year. At present, the majority of the cathodic protection systems are being installed on swimming pools. Two manufacturers of remote monitoring and control systems for cathodic pro- tection are located in Denmark, and one of them is also an anode supplier. Conductive coating systems are a norm in Norway and four bridge structures have been protected in the last 8 years. In Norway, the installation activity is more focused on parking structures. Several tunnels and bridges have received cathodic protection in Switzerland and the area protected in 1997 was estimated to be more Cathodic Protection Installed on Bridge Components No. of Respondents 22kceD Superstructure 9 21spaC 91snmuloC 8seliP 4sretooF Note: Table based on results of Question 21 of the survey. Impressed Current Cathodic Protection Galvanic Cathodic Protection Bridge Elements A rc Sp ra ye d Zi n c A rc S pr ay ed T ita ni u m A rc S pr ay ed A llo ys Co n du ct iv e Pa in t Fe re x A n o de Ce ra m ic A no de Co n du ct iv e Po ly m er Ti ta n iu m M es h Ti ta n iu m R ib bo n O th er A rc Sp ra ye d Zi n c A rc S pr ay ed A llo ys H oc ke y Pu ck Zi nc A no de s Zi n c Fo il A no de s Ja ck et s w ith Ex pa nd ed Z in c M es h Zi n c B u lk A n o de O th er 310171125215300012skceDegdirB Beams, Girders, and Diaphragms 1 1 0 1 0 0 1 2 0 0 4 3 4 3 1 1 0 00039440031003105spaC 022421580041103105snmuloC 17322221110001000seliP 00003130111002001sturtS 12001120111102001sretooF Note: Table based on results of Question 22 of the survey. TABLE 2 USE OF CATHODIC PROTECTION ON VARIOUS BRIDGE COMPONENTS TABLE 3 TYPES OF CATHODIC PROTECTION SYSTEMS USED BY RESPONDENTS to have been used on all bridge components by the greatest number of agencies. Arc sprayed zinc was reported as the sec- ond most used system. However, more applications of it are found to be on caps and columns. The conductive paint has been used on all bridge components, with the exception of the bridge deck and is the third most used system. The point zinc anodes (hockey pucks) lead the galvanic cathodic protection category by a wide margin and have been used on all bridge components, most often on columns, caps,

23 than 107,000 square feet. Italy has installed cathodic protec- tion on 1.6 million square feet of deck surface of new bridges containing prestressing elements. The British Standard Insti- tute has developed a standard for the use of cathodic protec- tion technology in Europe. As early as 1996, Australia and Hong Kong started to use cathodic protection. In Australia, a number of bridges, wharves, and other structures, including the supports of the Sydney Opera House, have received cathodic protection. With Hong Kong’s large coastal exposure, several bridges and wharves have received cathodic protection. South Korea, Singapore, and Japan also have a few installations. China began using cathodic protection on structures built for the 2008 Olympics. Some activity is also underway in India. One of the largest reinforced concrete cathodic protec- tion systems to be installed in the Middle East is the titanium mesh anode system installed in Yanubu, Saudi Arabia, in 1987. Since then, many new and old structures in the Middle East have received cathodic protection. The total protected area is estimated to be in excess of 5.4 million square feet.