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

Chapter: Chapter Four - Cathodic Protection Use: Policies and Practices

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Suggested Citation:"Chapter Four - Cathodic Protection Use: Policies and Practices." National Academies of Sciences, Engineering, and Medicine. 2009. Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements. Washington, DC: The National Academies Press. doi: 10.17226/14292.
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Suggested Citation:"Chapter Four - Cathodic Protection Use: Policies and Practices." National Academies of Sciences, Engineering, and Medicine. 2009. Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements. Washington, DC: The National Academies Press. doi: 10.17226/14292.
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Suggested Citation:"Chapter Four - Cathodic Protection Use: Policies and Practices." National Academies of Sciences, Engineering, and Medicine. 2009. Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements. Washington, DC: The National Academies Press. doi: 10.17226/14292.
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Suggested Citation:"Chapter Four - Cathodic Protection Use: Policies and Practices." National Academies of Sciences, Engineering, and Medicine. 2009. Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements. Washington, DC: The National Academies Press. doi: 10.17226/14292.
×
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Suggested Citation:"Chapter Four - Cathodic Protection Use: Policies and Practices." National Academies of Sciences, Engineering, and Medicine. 2009. Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements. Washington, DC: The National Academies Press. doi: 10.17226/14292.
×
Page 28
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Suggested Citation:"Chapter Four - Cathodic Protection Use: Policies and Practices." National Academies of Sciences, Engineering, and Medicine. 2009. Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements. Washington, DC: The National Academies Press. doi: 10.17226/14292.
×
Page 29
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Suggested Citation:"Chapter Four - Cathodic Protection Use: Policies and Practices." National Academies of Sciences, Engineering, and Medicine. 2009. Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements. Washington, DC: The National Academies Press. doi: 10.17226/14292.
×
Page 30
Page 31
Suggested Citation:"Chapter Four - Cathodic Protection Use: Policies and Practices." National Academies of Sciences, Engineering, and Medicine. 2009. Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements. Washington, DC: The National Academies Press. doi: 10.17226/14292.
×
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Suggested Citation:"Chapter Four - Cathodic Protection Use: Policies and Practices." National Academies of Sciences, Engineering, and Medicine. 2009. Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements. Washington, DC: The National Academies Press. doi: 10.17226/14292.
×
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Suggested Citation:"Chapter Four - Cathodic Protection Use: Policies and Practices." National Academies of Sciences, Engineering, and Medicine. 2009. Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements. Washington, DC: The National Academies Press. doi: 10.17226/14292.
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Page 33

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24 To obtain a more complete understanding of the use and the application of cathodic protection technology, the corrosiv- ity of the environment, the decision-making process, and the application and use of cathodic protection systems need to be analyzed. As cathodic protection technology is relatively more expensive than the other alternatives, with the excep- tion of electrochemical chloride extraction, the perception of corrosivity of the environment is very important in justifying its use. Similarly, if the decision-making processes for repair and rehabilitation either are not sophisticated enough or do not include cathodic protection as an alternative, then the use of the technology would be limited. The design, installation and quality control, and monitoring and maintenance prac- tices have a significant impact on the experience of use of this technology. The survey conducted in this effort focused sev- eral questions in these areas. A summary of the responses is presented here. MAGNITUDE OF THE PROBLEM A summary of responses to the question regarding the mag- nitude of the corrosion problem faced by the agency is pre- sented in Table 4. Mississippi is the only state among the respondents that does not have a corrosion problem on its reinforced concrete bridge structures. Four respondents (Ari- zona, Indiana, New Jersey, and Wyoming) indicated that it was a minor problem. A majority of respondents consider it to be a moderate problem. Eight respondents, Connecticut, New York, Oklahoma, Oregon, Pennsylvania, Utah, Vermont, and Virginia, consider it to be a major problem. Table 4 indicates that corrosion is at least a moderate problem for 30 of 36 respondents. Considering that many states and several Canadian provinces that experience severe winters did not respond to this survey, the actual corrosion problem must be much more severe than that suggested by the responses received in this effort. Interestingly, the top five users of the cathodic protection technology, Missouri, New Brunswick, Florida, Ontario, and Alberta have classified their corrosion problem as moderate. Thus, it is reasonable to conclude that cathodic protection could be an applicable tool for a majority of the agencies, based on the magnitude of their corrosion problem. How- ever, many agencies now use epoxy-coated rebar and at least one state has questioned the applicability of cathodic protec- tion on the rebars. The perception of the magnitude of the corrosion prob- lem correlates reasonably well with their deicing salt use. From the four agencies that indicated that corrosion was a minor problem, two have salt use in the range of 0 to 5 tons and two in the range of 6 to 10 tons per lane-mile per year. Eight of the respondents that indicated that corrosion is a moderate problem use 0 to 5 tons per lane-mile per year. Of the remaining, 4 agencies use 6 to 10, 4 agencies use 11 to 15, and 2 agencies use 16 to 20 tons per lane-mile per year of deicing salts. Four respondents did not provide their deicing salt usage and one only has marine exposure. Three of the eight respondents that consider corrosion to be a major problem, Connecticut, Oklahoma, and Oregon, have salt use in the range of 0 to 5 tons per lane-mile per year. Oregon’s primary exposure condition is the marine envi- ronment along the Pacific Coast. Of the agencies that indi- cated it was a major problem, the state of Virginia uses 6 to 10, Utah and Vermont use 11 to 15, and New York and Pennsylvania use more than 20 tons per lane-mile per year of deicing salt. A summary of salt usage agencies is presented in Table 5. The majority of the respondents, 17 of the 32 agencies that provided salt usage information, have average salt usage in excess of 5 tons per lane-mile. The manner in which the SHRP Methods Application Manual (47) categorizes salt use implies that salt use of more than 5 tons per lane-mile is the highest category of use. Based on the SHRP Manual, a majority of the respondents are in the high usage category. The relationship between deicing salt use and the mag- nitude of the problem can be a simple one. However, the analysis is difficult to perform because (1) deicing salt data available from various sources are often incomplete; (2) data are often not compiled in a uniform manner; (3) deicing salt use varies from one part of the state to another; (4) the num- ber of bridges vary from one part of the state to another; (5) the exposure is a combination of deicing salts and marine environment; and (6) some of the states or portions of the states may be using non-chloride-bearing deicing salts. The climatic conditions can also have a significant impact on the rate of corrosion and the diffusion of chloride ions into the concrete and thereby influence the relationship between deicing salts and magnitude of the problem. For example, in every cold environment, although salt usage is much higher, the colder temperatures maintain corrosion at much lower levels. CHAPTER FOUR CATHODIC PROTECTION USE: POLICIES AND PRACTICES

25 EXPOSURE CONDITIONS For bridge decks the primary chloride exposure is deicing salts. Twenty-one respondents indicated that more than 70% of decks are exposed to deicing salts and 13 of those stated that all of their decks (100%) are exposed to deicing salts. A summary of exposure environments is presented in Table 6. The province of Prince Edward Island listed 100% of its bridges in the “Both” category; that is, exposed to both the deicing salts and the marine environment. Only Mississippi has more than 90% of its decks categorized as “Neither,” which correlates well with their perception of the corrosion problem. Understandably, the substructure exposure to deicing salts is lower than that of the bridge decks; only 6 of the 13 re- spondents (with 100% of bridge decks exposed to deicing salts) reported that all of their bridge substructures are exposed to it. The deicing salt exposure to substructure elements comes in two forms: (1) leakage of chloride-contaminated water through joints and (2) drains and splashing of the con- taminated solution onto the substructure elements by vehi- cles in the underpass. The substructure elements confront a more corrosive exposure when they are located in a marine environment. It may be noted that for the purpose of the sur- vey, marine exposure was defined to persist 2 miles around a saline body of water. In addition to Mississippi, Washington State has more than 90% of its substructures listed as “Neither.” PROCESS FOR SELECTION OF CORROSION MITIGATION ALTERNATIVES To ascertain the compatibility and the cost-effectiveness of a cathodic protection system on a reinforced concrete struc- ture, among other things, it is important that the severity of exposure, the presence of chloride ions in sound concrete, the presence of electrical continuity, the susceptibility of the concrete to alkali–silica reaction and freeze–thaw damage, and the presence of corrosion activity in sound areas be known. Analysis of test methods used by respondent agen- cies during Routine Bridge Inspection and corrosion condi- tion evaluation was performed and is summarized in Table 7. Magnitude of Corrosion No. of States Not a Problem 1 4roniM Moderate 23 8rojaM Total 36 Note: Table based on results of Question 4 of the survey. TABLE 4 MAGNITUDE OF THE CORROSION PROBLEM Tons Per Lane- Mile Per Year No. of Respondents None 1 0 to 5 14 6 to 10 7 11 to 15 6 16 to 20 2 >20 2 Note: Table based on results of Question 7 of the survey. TABLE 5 SALT USAGE erusopxEerutcurtsbuSerusopxEkceDegdirB % of Bridges Marine Exposure Deicing Salt Exposure Both Neither Marine Exposure Deicing Salt Exposure Both Neither 5–9 26 6 32 21 24 8 33 14 10–19 2 1 1 2 4 1 1 1 20–29 4 0 1 1 5 2 0 1 30–39 0 3 0 2 0 5 0 0 40–49 0 1 0 1 0 4 0 3 50–59 2 2 0 2 2 4 0 2 60–69 0 2 0 1 0 1 0 3 70–79 0 2 0 1 0 0 0 3 80–89 0 1 0 2 0 2 0 2 90–99 0 2 0 1 0 2 0 4 100 1 16 1 1 1 7 1 2 Note: Table based on results of Questions 5 and 6 of the survey. TABLE 6 DISTRIBUTION OF BRIDGES BASED ON EXPOSURE CONDITION

All agencies perform a visual survey during the Routine Bridge Inspection and a majority of them perform delamina- tion and crack surveys. Only a few perform chloride ion con- tent analysis, half-cell potential survey, electrical continuity testing, and concrete resistivity measurements. The testing protocol used by the majority of the agencies would provide a good measure of the symptoms of corrosion, rust staining, cracking, delamination, and spalling, and would reasonably indicate the overall condition of the structure and provide a basis for more in-depth evaluation. During an in-depth sur- vey or corrosion condition evaluation, the vast majority of the agencies perform a visual survey, delamination survey, chloride ion content analysis, and half-cell potential survey. Thus, information on the extent of chloride contamination and the presence of active corrosion is also being determined during these evaluations. Only a few agencies conduct elec- trical continuity; three perform carbonation testing, one con- siders petrographic analysis on select projects, and one uses corrosion rate measurements. North Dakota does not perform corrosion condition evaluation and only performs the visual survey during the Routine Bridge Inspection. Generally rein- forcing steel on a bridge deck is electrically continuous, and therefore, electing to test for continuity during the installa- tion of the cathodic protection system is acceptable. How- ever, ascertaining the susceptibility to alkali–silica reaction could be performed during the selection process, unless based on materials used in standard concrete mixes the susceptibil- ity is already known. Similarly, susceptibility to freeze–thaw could be ascertained during the selection of the alternative corrosion mitigation systems. A majority of the agencies have standard procedures, pro- tocols, or methodologies for conducting corrosion condition evaluations, analyzing the data collected during the evalua- tions, and selecting repair and corrosion control alternatives No. of Respondents Test Method Routine Bridge Inspection Corrosion Condition Evaluation 9263yevruSlausiV 6191yevruSkcarC 9212yevruSnoitanimaleD 824sisylanAtnetnoCnoIedirolhC 324yevruSlaitnetoPllec-flaH 30gnitseTnoitanobraC 62gnitseTytiunitnoClacirtcelE 20tnemerusaeMetaRnoisorroC 31gnitseTytivitsiseRetercnoC 10enoN 20rehtO Note: Table based on results of Questions 8 and 9 of the survey. TABLE 7 TEST METHODS USED oNseYsnoitseuQ 18 18 20 16 20 16 16 17 Note: Table based on results of Questions 10 to 12 and 14 of the survey. Are there agency-wide standard procedures, protocols, or methodologies for conducting corrosion condition evaluations of reinforced concrete structures? Does your agency have procedures, protocols, or methodologies to analyze the data collected during condition evaluation? Does your agency have procedures, protocols, or methodologies to select repair and corrosion control alternatives based on data collected from condition evaluations? If your agency has procedures, protocols, and/or methodologies to select repair and corrosion control alternatives, does it include cathodic protection? TABLE 8 USE OF PROCEDURES, PROTOCOLS, AND METHODOLOGIES 26 based on the data collected during the evaluations. Sixteen agencies include cathodic protection as an alternative in their selection process (see Table 8). Of the agencies that cited the corrosion problem as a major one, four, Connecticut, New York, Oregon, and Pennsylvania, include cathodic protection as one of the options, but Oklahoma, Utah, and Virginia do not. Eight respondents stated that their agencies included cathodic protection as an alternative because it provides service-life extension desired for many of the high use structures and/or its agency staff has significant success in the use of the tech- nology. The province of New Brunswick includes it, as it does not have any alternatives for the severe exposure condi- tions its structures have to withstand. The quantity of damage was reported by 16 agencies to be the determining factor for the selection of a corrosion control system and the cost of application and repair was identified by 6 agencies (see Table 9). Only four agencies reported that the presence of chloride ions would be the determining factor and, for three respondents, the extension in service life was the determining factor. All other choices in the list were picked by two or fewer respondents. These responses suggest that the procedures, protocols, and methodologies used by these agencies may not be effec- tively using the data obtained during surveys to properly select a corrosion mitigation system. The quantity of dam- age signifies the magnitude of the problem and not its cause. It is more appropriate for the selection of the repair; however, it would have to be the presence and distribution of chloride ions in the remaining sound concrete that would control which corrosion control system would be the most effective and viable in that application. Twenty-three agencies have or would consider cathodic protection for its ability to prevent future damage and to sub- stantially extend the service life (Table 10). Recommenda- tions of their own agency research and development efforts have encouraged the use of cathodic protection for many agencies. The cost of other alternatives, the level of chloride

27 Funding from other sources has encouraged the use of the technology for some agencies and their experience with the technology only encouraged its use in seven agencies. This last response raises a question; what has been the experience of user agencies with cathodic protection systems? The sum- mary of responses in Table 12 provides some answers to this question; nine agencies do not include cathodic protection as an alternative corrosion mitigation system in their proce- dures, protocols, and methodologies for selecting repair and corrosion control alternatives owing to disappointing past experience and eight agencies do not use it because it is more Factors No. of Respondents 61egamaDfoytitnauQ 4snoIedirolhCfoecneserP 3efiLecivreSfonoisnetxE 2stsoCelcyC-efiL 6noitatilibaheRdnariapeRfotsoC 0noitarepOegdirBninoitpursiD 0epyTerutcurtS 1elbaliavAsdnuF Consultant Familiarity with Corrosion Control System 0 Past Experience with Corrosion Control System 2ecitcarPycnegA 0sgnidniFhcraeseRycnegA Note: Table based on results of Question 13 of the survey. 2 TABLE 9 FACTORS MOST LIKELY TO DETERMINE WHICH CORROSION CONTROL SYSTEM WILL BE SELECTED ion contamination, and the location of the structure were also considered by several agencies as reasons for its use. The summary in Table 11 indicates cathodic protection has been used when service life in excess of 20 years was desired if the structure was located in a very aggressive environment, if no other alternatives are available, or if it is located in a marine environment. Reason No. of Respondents 9egamaDetercnoCfoytitnauQ 21noitanimatnoCnoIedirolhCfoleveL 31sevitanretlArehtOfotsoC 22egamaDerutuFfonoitneverP Agency Research and Development Recommendation Funding Available from Other Sources such as FHWA or Congressional Mandate to Use 10 11erutcurtSfonoitacoL 8epyTerutcurtS 11erusopxEfoytireveS Extension of Service Life Provided by Cathodic Protection 23 6sisylanAtsoCelcyC-efiL 1noitadnemmoceRtnatlusnoC 3noitadnemmoceRAWHF 7noitcetorPcidohtaChtiwecneirepxE 4rehtO Note: Table based on results of Question 18 of the Survey Cathodic Protection 13 TABLE 10 REASONS FOR WHICH CATHODIC PROTECTION WAS CONSIDERED Reason No. of Respondents 8 9 3 13 10 7erutcurtsfoepyT 6rehtO Note: Table based on results of Question 29 of the survey. Marine environment where exposure is very corrosive and no other corrosion control system provides service life extension of more than 5 years Deicing salt exposure that has resulted in high and uniform chloride ion contamination and no other corrosion control system is expected to provide service life extension of more than 5 years Location of the structure required use of an aggressive corrosion protection system Cathodic protection system was expected to provide service life extension in excess of 20 years Life-cycle cost of cathodic protection system was lower than any other corrosion control system TABLE 11 CATHODIC PROTECTION USED FOR THE FOLLOWING REASONS Reason No. of Respondents 4 8 5 3 9 Note: Table based on results of Question 15 of the survey. Exposure environment is not sufficiently corrosive to warrant the use of cathodic protection Cathodic protection technology is relatively more expensive than other options available Engineers and contractors that serve the agency do not have any experience with the technology Cathodic protection is too complicated and the agency does not have sufficient understanding to use it Past experience with cathodic protection has been disappointing TABLE 12 REASONS FOR NOT INCLUDING CATHODIC PROTECTION AS AN ALTERNATIVE CORROSION CONTROL SYSTEM

No. of Respondents Corrosion Control Technologies Used on New Structures Used on Existing Structures 8161senarbmeMgnifoorpretaW 71yalrevOtlahpsAhtiwgnifoorpretaW 8272srelaeS 9232syalrevOetercnoC 9etercnoCytlaicepS 21saerAriapeRnisrabeRnosgnitaoC 3121srotibihnInoisorroCdeximdA 016srotibihnInoisorroCdeilppAecafruS 91)skcupyekcoh(sedonAcniZdezilacoL 311noitcetorPcidohtaCtnerruCdesserpmI 517noitcetorPcidohtaCcinavlaG 5noitcartxEedirolhClacimehcortcelE 24rehtO Note: Table based on results of Questions 16 and 17 of the survey. TABLE 13 CORROSION CONTROL SYSTEMS USED BY RESPONDENTS oNseY 6 18 Design of cathodic protection systems are normally performed by: 31ffatSycnegA 6 8 1 1rellatsnIrorotcartnoC 8tnatlusnoChtiwnoitcnujnoCniffatSycnegA Note: Table based on results of Questions 23 and 24 of the survey. Does your agency have any standards for design and/or construction specifications governing the use of cathodic protection on reinforced concrete structures? Consultant—Engineering Firm with Access to NACE-Certified Cathodic Protection Specialist Consultant—Engineering Firm with Assistance from Manufacturer and/or Installer Consultant—Engineering Firm Based on Agency Standards and Construction Specifications TABLE 14 DESIGN PROTOCOLS AND DESIGN RESPONSIBILITY 28 expensive than the other options available. Some agencies do not have the requisite expertise and a few others find the tech- nology too complicated. Of the agencies that have never used or have not used cathodic protection in the last 5 years, 18 responded in the affirmative that they would consider it in the future, whereas 7 responded in the negative. CORROSION MITIGATION TECHNOLOGIES IN USE The survey also tried to identify what other corrosion miti- gation technologies the respondents are using. Table 13 sum- marizes the various kinds of corrosion control systems that agencies use on new and existing structures. Sealers and concrete overlays are used by a majority of the agencies on both new and existing structures. Waterproofing with asphalt overlay is primarily used on new structures and waterproof- ing membranes are used on both. Admixed corrosion inhi- bitors, galvanic cathodic protection, and surface-applied inhibitors are used by a decreasing number of agencies, espe- cially for new structures. Impressed current cathodic protec- tion is used by a single agency as a prevention technology. On existing structures, localized zinc point anodes, galvanic cathodic protection, impressed current cathodic protection, admixed corrosion inhibitors, and surface-applied corrosion inhibitors are used by a decreasing number of agencies. The trend indicates that agencies are choosing the simplest options with minimal or no monitoring and maintenance require- ment. Electrochemical chloride extraction is used by five agencies. Four technologies were listed in the “Other” category for new structures: polyester concrete overlay, thin-bonded overlay, epoxy-coated rebars, and fiberglass-reinforced poly- mer reinforcing bars. Although not included as an option, epoxy-coated reinforcing bars are also a corrosion control system and are primarily used in new structures; however, a few agencies indicated it is the other option for both new and existing structures. Wyoming also uses crack healers and sealers on existing structures. IMPLEMENTATION OF CATHODIC PROTECTION SYSTEMS As indicated in Table 14, only six agencies have standards for design and/or construction specifications governing the use of cathodic protection on reinforced concrete structures. Designs of cathodic protection systems are generally per- formed by agency staff and some of the respondents obtain assistance from a consultant. Some of the agencies that indi- cated that they use in-house staff to design cathodic protec- tion systems may not have staff with sufficient qualifications, and at least one has indicated that all systems they have installed have failed. A NACE-certified Cathodic Protection Specialist is involved in the design of the cathodic protection system through a consultant only for a few agencies and some agencies use consultants who work in conjunction with the material manufacturer or supplier. Rarely is a consultant asked to design a system based on Agency Standards and Construction Specifications or a contractor/installer charged with design responsibilities. For cathodic protection systems to perform as desired it is imperative that the design be per- formed by qualified and experienced personnel using current recommended or standard practice. NACE has a Standard Practice, NACE SP0290-2007, available and it recommends that such activities be performed under the direction of a reg- istered professional engineer or a certified NACE corrosion specialist or cathodic protection specialist. It is important that

29 the designer’s professional experience include suitable expe- rience in cathodic protection of reinforced concrete struc- tures. Although manufacturers and installers of the systems have an intimate knowledge of their products, design by third parties is preferred to allow for a more robust analysis of the suitability of the various systems available for the subject project and the avoidance of any conflict of interest issues. As is the practice in the design of civil structures, it is impor- tant that the manufacturer’s and installers be consulted and their assistance used by the third-party designers to ensure that the full knowledge of the system is brought to bear on the design. All cathodic protection systems on bridge structures in Washington State (a total of 3) have been installed using design-build contracts. Colorado, with six reported systems, has used design-build contracts on 50% (3) of them. One of the major users of this technology, New Brunswick, uses such contracts on 20% of its projects and another large user, Florida, uses it on 2% of its projects. This survey result appears to be in contrast to the responses received from the industry, which indicated that 50% of the cathodic protection projects are design-build. In general, the design-build con- tracts are awarded to general contractors with cathodic pro- tection materials supplier and/or installer as a subcontractor (Table 15). To obtain the desired performance it is impera- tive that the design-build contractor be required to possess or have access to the skill sets and experience described by the NACE SP0290-2007 Standard Practice. Table 16 shows that the responsibility for quality control during installation is often carried out by the agency staff and less frequently by the contractor, manufacturer, or installer. An independent NACE-certified or a qualified inspector or a NACE-certified inspector hired through a consultant is used infrequently. Agency staff performing the quality control is most desired; however, agency staff must have the requisite qualification and experience to do the job. Quality control by a contractor, manufacturer, or installer is not desirable unless they are required to provide an independent qualified and experienced inspector who can certify that the project was installed in accordance with the project specifications. Connecticut, Florida, Indiana, Vermont, and Prince Edward Island monitor all cathodic protection systems under their jurisdiction as depicted in Table 17. The California, Missouri, Ontario, and Oregon DOTs monitor a majority of the sys- tems. New Brunswick indicated that it does monitor its cathodic protection systems, but did not indicate how many of its systems it does monitor. All other responding agencies do not monitor the cathodic protection systems they have. Monitoring of the systems is absolutely imperative to its con- tinued performance, as unmonitored systems essentially mean non-performing systems. Table 18 suggests that the majority of the agencies that mon- itor their cathodic protection systems use agency staff for that purpose. In some agencies, agency staff and a contractor mon- itor the systems. Nine agencies have at least one trained per- son to monitor and maintain their systems and seven agencies believe that they have sufficient personnel to perform the job (Table 19). Seven agencies have a program in place to moni- tor and maintain their cathodic protection systems and five use consultants on a regular basis. Remote monitoring units are used by eight agencies. The frequency of remote monitor- ing; that is, remotely connecting to the system and obtaining a status report, might be performed at least once a month for impressed current cathodic protection systems. The remote monitoring system is to be set to obtain system parameters at oNseY Cathodic Protection Projects Bid Out as Design-Build Projects Generally Awarded to: Cathodic Protection Materials Provider and/or Installer General Contractors with Cathodic Protection Materials Supplier and/or Installer as Subcontractor 6 General Contractor with an Independent Cathodic Protection Consultant 1 2rehtO Note: Table based on results of Questions 25 and 26 of the survey. 195 0 TABLE 15 FREQUENCY OF DESIGN-BUILD CONTRACTS seYyBdemrofreP 81ffatSycnegA Consultant—Engineering Firm with NACE-Certified Personnel 4 1mriFgnireenignE—tnatlusnoC 8rellatsnI,rerutcafunaM,rotcartnoC Independent NACE-Certified or Qualified Cathodic Protection Inspector 3 0enOoN Note: Table based on results of Question 27 of the survey. TABLE 16 QUALITY CONTROL DURING INSTALLATION No. Monitored Agencies No. of Systems Prince Edward Island, Canada 2 2 New Brunswick, Canada N/A 85 0201ainrofilaC 3131tucitcennoC 1717adirolF 5151anaidnI 76169iruossiM 0604adanaC,oiratnO 119nogerO 11tnomreV N/A = not available. Note: Table based on results of Question 32 of the survey. TABLE 17 NUMBER OF BRIDGES BEING MONITORED

least once a day. The results in Table 20 show that only three agencies meet this criterion. The frequency for galvanic sys- tems can be as little as once a year. The recommended fre- quency for site visits to ascertain the condition of impressed current systems is once a year and galvanic cathodic protection systems about once every 5 years. Ten agencies meet the impressed current criteria. CASE HISTORIES Several agencies have adopted cathodic protection technol- ogy as one of several bridge preservation tools. Five case studies are presented in this section. These case studies high- light various mechanisms that agencies have used to success- fully implement corrosion mitigation technologies, not just cathodic protection, thereby reducing their maintenance costs and increasing the average service lives of their bridge structures. Missouri In Missouri all bridge decks and 35% of substructure ele- ments are exposed to deicing salt. The state’s corrosion prob- lem is characterized as moderate and its average salt usage rate is the range of 0 to 5 tons per lane-mile per year. Their initial experience with cathodic protection technology was gained in the 1970s during the installation of three conduc- tive coke breeze cast iron anode cathodic protection systems. These cathodic protection systems were installed during ongoing regular construction projects and were funded by 30 DP-34. These systems were based on the Caltrans design of the same era. Two engineers in the Missouri DOT (MDOT) became familiar with the technology. One of them special- ized in the construction/electrical area and the other in the materials engineering field. The success of these first instal- lations sufficiently impressed the DOT’s Bridge Engineer to champion the use of this technology. The department’s pol- icy was modified to include the use of cathodic protection technology. At present, there are 167 bridge structures in the state with operational cathodic protection systems. The oldest operating system in the state, slotted with platinum–niobium wire anode, is 23 years old. MDOT created a formal team to handle cathodic protec- tion technology under their Materials Group. This team was charged with the selection, design, installation, and operation of all cathodic protection systems in the state. For training purposes, the DOT sent personnel to a cathodic protection training course conducted by a private organization. The DOT staff also received in-house training and additional training from workshops conducted under the SHRP Showcase Pro- gram and Demonstration Project 84. In 2000, as the districts acquired many of the required skill sets in the use of this technology, the formal team was dissolved. The Research Group and the Central Bridge Design Office now have one expert each in this technology area. In the districts, there are approximately 12 full-time dedicated personnel for moni- toring the installed systems. Personnel from diverse techni- cal backgrounds such as Traffic Signal Electricians, Traffic Engineers, Bridge Maintenance Engineers, and Construction Inspectors have acquired cathodic protection expertise. The Traffic Engineers and Signal Electricians use electrical and electronic systems quite similar to those used in impressed current cathodic protection systems and, therefore, are easily trained to perform monitoring and maintenance tasks. The Bridge Maintenance Engineers handle the regular mainte- nance required on the systems and the Construction Inspec- tors provide quality control and assurance during installation. This philosophy has allowed MDOT to use their available in- house resources to implement the cathodic protection tech- nology. Funding for all cathodic protection work comes from the general maintenance fund and all research on cathodic protection is performed in-house. Design of all cathodic protection systems is also done in- house. The state has developed Standard Specifications based on the AASHTO Guidelines. Design and installation specifica- Performed By Yes No Agency Personnel 14 22 Contractor 1 35 Both 6 30 Note: Table based on results of Question 33 of the survey. TABLE 18 CATHODIC PROTECTION MONITORING oNseY Does your agency have any personnel trained to monitor and maintain cathodic protection systems? 9 15 Does your agency have sufficient trained personnel to monitor and maintain all cathodic protection systems under your jurisdiction? 7 17 Does your agency use consultants on regular basis to monitor and maintain cathodic protection systems? 5 19 Does your agency have a program in place to monitor and maintain the cathodic protection systems? 7 17 Are remote monitoring units used to monitor some or all of the cathodic protection systems? 8 16 Note: Table based on results of Questions 34 to 38 of the survey. TABLE 19 RESOURCES FOR MONITORING AND MAINTENANCE OF CATHODIC PROTECTION SYSTEMS Remote Monitoring Site Visits Once a week 2 Once every three months 0 Once a month 1 Once every six months 5 Twice a year 1 Once every year 5 Once a year 4 Once every two years 8 Once every five years 1 Note: Table based on results of Questions 39 and 40 of the survey. TABLE 20 FREQUENCY OF MONITORING

31 tions have also been developed. The condition of the concrete superstructure, availability of power, chloride ion content, and half-cell potential survey results are used for ascertaining the need for a cathodic protection system on a bridge deck. A Spe- cial Provision is added to every contract that requires installa- tion of a cathodic protection system. Construction inspectors trained by personnel from Research perform inspections during installations and Traffic Signal Electricians conduct acceptance testing on rectifiers. All maintenance work on the cathodic pro- tection systems is done in-house. Almost all of the cathodic protection systems, 161 of 167, are installed on bridge decks, with the remaining systems installed on substructure elements. A majority of the deck systems are slotted and use the platinum–niobium anode wire. The oldest titanium-mixed metal oxide anode-based system in the state is 19 years old. In the last 8 years, all deck systems installed have been mixed metal oxide anode sys- tems. The current Contract Specifications provide a choice between slotted and mixed metal oxide; however, the mixed metal oxides have been preferred. With more than three decades of use, the state has experi- enced much success, but some failures as well. The ferex anode-based systems installed on two dozen bridges failed in fewer than 5 years and had to be replaced. MDOT believes that the choices available in the marketplace are limited and that monopoly is stifling innovation. There are only two experienced contractors in the state. They would prefer to see more cathodic protection systems on substructure elements; however, they believe innovation is necessary for large-scale adoption. Florida Florida has 6,000 bridges located in the marine environment and corrosion of the substructures is observable within 12 years of construction. The collapse of the Anclote River Bridge in Pinellas County on December 17, 1968, and the accom- panying loss of life led to an investigation that concluded that the failure had resulted from corrosion of the reinforced con- crete bridge components. To ensure that the corrosion prob- lem was properly managed, the state hired a corrosion expert who started the FDOT corrosion program. Now the state has a Corrosion Laboratory housed in the Central Office of FDOT, which is a part of the Materials Office. The Corrosion Laboratory has nine full-time personnel, various contract workers, and two consultants to assist it in carrying out its mission. Initially, the corrosion program trained personnel in-house. Later, they hired people with formal training in corrosion. Its personnel receive training from NACE programs and keep current with the corrosion technology through attendance at various conferences. The Corrosion Laboratory, funded by the State Material Office Budget, is fully equipped to perform much of the material testing and conduct research efforts in corrosion-related areas. The labo- ratory is also capable of executing condition evaluation, research installation, and monitoring and maintenance of cathodic protection systems or other corrosion mitigation technologies. FDOT has a very robust research and development pro- gram in the area of corrosion mitigation. It has developed many of the technologies currently in use on substructure ele- ments. The corrosion group has been involved in the devel- opment of various cathodic protection systems since the early 1970s. Initially, all research was performed by the corrosion group. Later, the program was expanded, and several Florida universities were contracted to perform both theoretical and field research. Consultants are also used in some of the research efforts. The use of zinc penny sheets, conductive rubber, zinc mesh in jackets, arc sprayed zinc above the tidal zones, and bulk anodes on marine pilings have all been outcomes of these research efforts. As would be expected in any such undertaking, the Cor- rosion Laboratory initially experienced failures in some of the earlier systems. Owing to a lack of confidence, many of the districts were initially reluctant to implement the tech- nology developed or adopted by the Corrosion Laboratory. As they started to experience success and bridge inspection teams recognized the reduction in inspection and maintenance needs, districts adopted the technologies and procedures developed and started to implement cathodic protection tech- nology on all of its structures. The Corrosion Laboratory provides a complete corrosion package. It can evaluate the structure and ascertain the need for corrosion mitigation, provide options for corrosion con- trol, provide quality control and quality assurance services and assistance during construction, and monitor and maintain the cathodic protection systems. The Corrosion Laboratory does not limit itself to cathodic protection technology; it uses all corrosion mitigation technologies depending on their applicability and the need for extension in service life. Con- sidering the number of structures in need of maintenance and the size of the staff, the Corrosion Laboratory uses consul- tants as and when needed, and districts also have begun to use local consultants for the same purpose. FDOT has a formal policy for the use and application of cathodic protection system technology. Standards have been developed for several different types of cathodic protection systems that are a part of the Bridge Repair Manual. The bridge owners hire local consultants for the repair and rehabi- litation programs, who use FDOT standards to design cathodic protection systems for the project. The Corrosion Laboratory reviews all cathodic protection systems designed for imple- mentation on state-owned structures. Many of the local bridge consultants in the state have acquired sufficient exper- tise to design cathodic protection systems and there are sev- eral Corrosion Consultants who either provide services to the bridge consultants, the districts, or to the Corrosion Labora- tory. This policy of allowing consultants to design cathodic

protection systems has created a significant pool of skilled manpower that the state can access for the implementation of this technology. The installation of the cathodic protection systems can be done by any qualified contractor. However, each project is required to have the services of an independent NACE-certified Cathodic Protection Specialist to provide quality control and quality assurance services. The indepen- dent specialist not only provides inspection services, but also trains and provides guidance to the contractors with the installation of the cathodic protection system. Because many contractors in the state have acquired experience in the instal- lation of the cathodic protection systems, competition in the marketplace has been maintained. Monitoring and routine maintenance of all cathodic pro- tection systems is performed by the Corrosion Laboratory. If a major repair is required, then either the bridge crew or a con- tractor is used. As the inventory of cathodic protection sys- tems in the state grows, FDOT is finding it difficult to manage all the systems in-house and is starting to use consultants for this purpose. The galvanic cathodic protection systems are monitored once a year. When the work load cannot be han- dled by the manpower available, the best performing systems are temporarily dropped from the monitoring program. The impressed current systems are monitored using remote moni- toring technology. There is only one impressed current sys- tem in the inventory that does not have a remote monitoring unit and the Corrosion Laboratory staff visit the system once each month. Data from the remote monitoring systems are reviewed weekly. To ensure that it is able to properly monitor the impressed current cathodic protection systems, a remote monitoring unit was specifically designed for their needs. The Corrosion Laboratory, in an interview, indicated that because of its experience and expertise in the area of corro- sion, it is not subject to extensive sales and marketing efforts. Many of the products used in the state are first evaluated by the Corrosion Laboratory. The anode materials available in the marketplace do address their present needs; however, innovation and more competition in the anode marketplace would be welcome. With the use of cathodic protection technology, FDOT has experienced a reduction in maintenance costs. Its inven- tory includes impressed current systems that have been in operation for 20 years and galvanic systems that have been operational for 10 to 15 years. Oregon Oregon has many historic structures and much of their cor- rosion problem stems from exposure to the marine environ- ment. Its need to protect superstructure elements on many of its marine structures has resulted in the state being the largest users of surface-applied cathodic protection systems such as arc sprayed zinc. With the completion of ongoing construc- tion, Oregon will have 1.17 million square feet of concrete 32 under cathodic protection. They pioneered the practical appli- cation of cathodic protection for preservation of existing major historic coastal bridges. The historic Alsea Bay Bridge suffered significant corrosion-induced damage and had to be replaced. The pub- lic process for the replacement was difficult and it cost the Oregon DOT (ODOT) $24 million more than the simpler bridge it had planned to use for replacement. This prompted it to search for technologies to preserve its other historic bridges and avoid replacement for as long as possible. One of the crews in the DOT had electrical and mechanical engi- neers who were familiar with cathodic protection technology used on pipelines, marine vessels, and offshore oil platforms, and they proposed its use on reinforced concrete structures. At that time, Caltrans had just completed a research project to test thermal-sprayed zinc as an anode on the surface of the reinforced concrete components. Oregon selected the arc sprayed zinc anode for application on historic structures and completed its first application on the Cape Creek Bridge in 1990. Including the ongoing project on Coos Bay South Approaches, there are a total of 11bridges with cathodic pro- tection systems in the state. Although the number of bridges is not large, the surface area protected is. ODOT has a Bridge Preservation Group that includes struc- tural, electrical, geotechnical, hydraulics, and corrosion posi- tions and is charged with the preservation of all bridge struc- tures in the state. There are two corrosion positions: Corrosion Protection Engineer and Corrosion Design in the group. This group has developed specifications for design and application of the arc sprayed cathodic protection systems, and has also experimented with various other surface-applied anodes. Cor- rosion consultants are used in conjunction with their in-house staff for design and to provide quality control during installa- tion. Monitoring and maintenance is done in-house. California Caltrans was the pioneer in the application of cathodic pro- tection to reinforced concrete structures. It was the first to install cathodic protection systems on bridge decks. Cathodic protection is best suited for its marine structures. Deicing salt exposure is limited to the mountainous regions of the state, where the overlay systems on bridge decks are often dam- aged by the chains on heavy trucks during the winter and are not preferred in those applications. Cathodic protection is considered to be last option and is used only when the expo- sure environment is such that no other corrosion control sys- tem will provide the desired service-life extension. Caltrans developed the coke breeze cathodic protection system and experimented with several coating systems including arc sprayed zinc. It has also experimented with a conductive polyester concrete bridge deck cathodic protection system. The Caltrans Corrosion Technology Branch (CTB) is cur- rently staffed by four engineers and two technicians. The exis-

33 tence of the CTB can be traced back to the time of Richard Stratfull who pioneered cathodic protection application on reinforced concrete structures. Stratfull was instrumental in developing the awareness of corrosion and the importance of having DOT staff receive training in cathodic protection. At present, three staff members are experienced and are well- versed with cathodic protection technology; they primarily control the implementation of the technology. In-house- developed technology and research projects funded by the FHWA provided them with much of the experience. CTB staff has also received training from NACE educational programs. Funding for the corrosion laboratory is allocated through the Office of Testing and Technology Services, which is a sub- branch of the Division of Engineering Services. CTB provides its services to the headquarters and the districts. The maintenance groups and structure design engineers decide on the repair and/or rehabilitation strategies. The design of the cathodic protection systems, when used, is done by the CTB. Caltrans does not have any standards; they use the spec- ifications from previous projects and the experience of the staff in designing the systems. Also, it does not interact with the cathodic protection industry and has generally used systems developed in-house. Quality control functions are done by in- house personnel. Monitoring and maintenance of the cathodic protection systems is performed by CTB. Caltrans believes that if better guidelines become available and if its confidence in the newer product is established, it is likely to increase its use of the technology. Connecticut In the 1990s, the Connecticut DOT (ConnDOT) initiated a research study to ascertain the effectiveness of cathodic pro- tection systems in controlling corrosion of its reinforced con- crete bridge elements. The study was lead by a ConnDOT Principal Investigator and the cathodic protection systems were installed under subcontracts in construction projects. A total of 13 structures received cathodic protection under this project. From 1989 to 1993, cathodic protection systems were installed on the decks of 12 bridge structures. In the 1996–1997 time frame, cathodic protection was installed on the caps of one more bridge. All cathodic protection systems installed under this program are impressed current type with titanium-mixed metal oxide mesh or ribbon anodes. The selection and design of the cathodic protection sys- tems were performed in-house by the Research Group with assistance from the FHWA and NACE. The installation spec- ifications were developed by the Research Group in con- junction with their consultants and they in turn received input from system material suppliers and installers. The material suppliers provided a manufacturer’s representative during the installation to ensure that the systems were installed in accordance with the project specifications and requirements. Since installation, all systems have been monitored by the Research Group and are performing satisfactorily. Although they do not have formally trained personnel, the Research Group has acquired sufficient skills to monitor and maintain the systems. All bridges included in the study are within a few hours’ drive of ConnDOT offices and site visits are reg- ularly made to monitor and maintain the systems. When asked to categorize their experience with the catho- dic protection systems, it stated that “ConnDOT’s experience has been highly satisfactory for corrosion prevention and control.”

Next: Chapter Five - Problems Encountered with Cathodic Protection System Application »
Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements Get This Book
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TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 398: Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements examines the use of cathodic protection by state transportation agencies for controlling corrosion on existing reinforced concrete bridge elements. The report also explores the different types of cathodic protection systems, highlights case studies of states using these systems, and reviews reasons why public agencies may or may not employ cathodic protection.

Appendix A: Summaries of Questionnaires and Interview Results is available online.

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