Materials Performance

NOV 2018

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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52 NOVEMBER 2018 W W W.MATERIALSPERFORMANCE.COM CM CORROSION MANAGEMENT Conclusions and Lessons Learned Periodic collection of I macro and R data along with sensor temperature is recom- mended to monitor the corrosion state of marin e-reinforced concret e str uctures using a sufficient number of multi-func- tional sensors installed in critical locations. Measurement of corrosion potential can be useful for determining changes in corro- sion tendency, but it is also sensitive to moisture content. Consequently, interpret- ing potential data requires careful consid- erations. The instantaneous rate of corro- sion may not be suitable in the field if the sensor's corrosion potential is not stable before applying potential increments to obtain linear polarization resistance. It is expected that sufficient amounts of chlo- ride ions reaching to the embedded sensors should be detected by noticeable changes in periodically collected data sets. Accord- ing to the collected electrochemical data, the sea side was a more aggressive corrod- ing environment for reinforcing steel than the lake side. As expected, the atmospheric zone is likely to be the least corrosive for dry concrete. Future corrosion monitoring of this structure needs to focus on the sea side's tidal zone and lower section of the splash zone, which are the most vulnerable to corrosion if cathodic protection (CP) is absent. Premature sensor failures and data variability are major challenges to the suc- cessful implementation of any corrosion monitoring project. To mitigate these prob- lems, it is also recommended to install at least three redundant sets of each sensor group within a reasonable proximity of one another and subjected to the same expo- sure conditions. The increased volume of monitoring data provided by multiple sen- sors can extend the duration of effective monitoring even though this approach means higher costs. Thus, when every sen- sor works well, statistically meaning ful data will be available in early phases of the project; when one or two sensors stop func- tioning, the remaining sensor(s) will con- tinue to provide data for a much longer period of time. References 1 S. Lee, et al., "Corrosion Monitoring of a Mas- sive Concrete Structure Exposed to Marine Environment Using Embedded Corrosion S e n s o r s ," N D E / N D T f o r Hi g hw ay s a n d Bridges: Structural Materials Technology (SMT) Conference, Washington, DC (2014). 2 F.J. Ansuini, J.R . Dimond, "Long-Term Field Tests of Reference Electrodes for Concrete— Ten Year Results," CORROSION 2001, paper no. 01296 (Houston, TX: NACE International, 2001). 3 H. Adrup, O. Klinghoffer, J. Mietz, "Long Term Performance of MnO 2 -Reference Electrodes in Concrete," CORROSION 2017, paper no. 97243 (Houston, TX: NACE, 2017). 4 ASTM C876-09, "Standard Test Method for Corrosion Potentials of Uncoated Reinforc- ing Steel in Concrete" (West Conshohocken, PA: ASTM International, 2009). SEUNG-KYOUNG LEE is president of SK Lee & Associates, Fairfax, Virginia, USA, email: skleeinva@gmail.com. He special- izes in concrete corrosion, CP, tendon cor- rosion, corrosion sensors, and steel bridge coatings. A member of NACE International for 26 years, he is a NACE-certified CP4 and Coating Inspector Program (CIP) Level 1 and 2 with Bridge Specialty. He has M.S. and Ph.D. degrees from the Department of Ocean Engineering at Florida Atlantic University. BONG-SEOK JANG is a research engineer at Korea Water Resources Corp., Daejeon, Republic of Korea, email: concrete@ kwater.or.kr. He is a concrete durability expert at K-water and developed a corro- sion monitoring program and concrete mixes for the tidal power plant. He has M.S. and Ph.D. degrees from the Depart- ment of Civil Engineering at Seoul National University. JEONG-HWAN AHN is a project manager at Korea Water Resources Corp., email: ahnjeonghwan@kwater.or.kr. He is a civil engineer at the company and was respon- sible for installing the corrosion monitor- ing system and follow-up testing discussed in this article. KI-CHEOL KIM is a project manager at Korea Water Resources Corp., email: montb@kwater.or.kr. He is a civil engineer at the company and oversaw power plant construction. He was later responsible for facility management, including corrosion monitoring stations. AUTHORS WANTED NACE is looking for industry experts to write and edit NACE-published books and compilations. Contact Jean Broge +1 281-228-6455 jean.broge@nace.org

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