. O 2 + 2H 2 O + 4e 4OH -

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1 16 1 Vol 16 No ELECTROCHEMISTRY Feb * O646 A 1 2 ph > ph Fe Fe e Cl - 4 O 2 + 2H 2 O + 4e 4OH - Cl - CO 2 / 8 Cl - CO 2 H 2 O O * Tel cjlin@ xmu eud cn BAB27B04

2 mm 10 μm Fig 1 Schematic diagram showing the array electrode for 1 2 simulating measurement corrosion behavior of reinforcing steel in concrete 0 9mm mm 60 mm 10 mm 24 h 28 d % NaCl / 2 3 5% NaCl Fig 2 Variations of corrosion potential of array electrode GS510 with the electrode position in concrete immerging in 3 5% NaCl solution Autolab Potentiostat Galvanostat Autolab 10 d 4# mv ± 15 mv vs OCP 1 mv /s 2 4# 25 d # 2 3 5% NaCl / 1 d mv 10# 1# 10# 7d 2 2 4# mv

3 d 4# 21 d 1# 2# 3# 4# 30 d 1# ~ 4# 4# / 4 Fig 4 Variations of microcell current density of array electrode with the electrode position in concrete immerging in 3 5% NaCl solution 3 Fig 3 Variations of macrocell current density of array electrode with the electrode position in concrete immerging in 3 5% NaCl solution ~ 3 7 d 4# 1# 2# 3# 10# 30 d 5# ~ 9# 1# ~ 4# 5 ~ 9# 4 Autolab 7 d 10 d 4# 30 d 1# ~ 5# 6# 7# 9# 7 d 4# 8# 10# 4 0 / 2 4

4 1 63 1# 14 d 21 d 5# 6 # 7# 9# d 4# 21 d 4# 1# 2# 3# 30 d 1# ~ 4# 10# / ph Cl - / 5 3 5% NaCl Fig 5 Distributions of macrocell corrosion current microcell corrosion current and corrosion potential of ar- ray electrode in concrete immersed in 3 5% NaCl / at different time a 10 d b 21 d c 30 d / / References 1 Hong D H Corrosion and protection of rein-

5 forced steel in concrete J Beijing China Railway Publishing House Vinod K Protection of steel reinforcement for concrete-a review J Corrosion Reviews Koleva D A de Wit J H W van Breugel K et al Investigation of corrosion and cathode protection in reinforced concrete J Journal of Electrochemical Society C261 4 Schiessl P Corrosion of steel in concrete RILEM technical committee 60-CSC M New York Chapman & Hall Elsener B Macrocell corrosion of steel in concrete-implications for corrosion monitoring J Cement and Concrete Composites Qian S Y Zhang J Y Qu D Y Theoretical and experimental study of microcell and macrocell corrosion in patch repairs of concrete structures J Cement and Concrete Composites Hansson C M Poursace A Laurent A Macrocell and microcell corrosion of steel in ordinary Portland cement and high performance concretes J Cement and Concrete Research Hansson C M Comments on electrochemical measurements of the rate of corrosion of steel in concrete J Cement and Concrete Research Yang L Dunn D S Pan Y M et al Real-time monitoring of carbon steel corrosion in crude oil and brine mixtures using coupled multielectrode sensors A In Corrosion Houston NACE International Yang L Sridhar N Coupled multielectrode array systems and sensors for real-time corrosion monitoring-a review A In Corrosion NACE International Lin Chang-Jian Zhuo Xiang-Dong Chen Ji-Dong et al Corrosion potential imaging at interface of polymeric coating / metal by array electrode technique J Journal of Chinese Society for Corrosion and Protection Hu Rong-Zong Lin Chang-Jian He Rui-Yan et al Investigation of iron corrosion process beneath coating in different kinds of anion solution using the technique of array electrode J Journal of Xiamen University Natural Science Lin C J Zhuo X D Nguyen T An array electrode technique for mapping corrosion potential at the polymer / metal interface A In Comizzoli R B Frankenthal R B Sinclair J D Corrosion and Reliability of Electronic Materials and Devices C Hu Rong-Zong Lin Chang-Jian Zhou Xiang et al An Investigation on the corrosion potential imaging at the interface of concrete / reinforcing bar in corrosion media J Electrochemistry Legat A Monitoring of steel corrosion in concrete by e- lectrode arrays and electrical resistance probes J Electrochimica Acta Studied Corrosion Behaviors of Reinforcing Steel in Concrete by a Single-dimensional Array Electrode LI Lan-qiang DONG Shi-gang DU Rong-gui LIN Chang-jian * State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen Fujian China Abstract A single-dimensional array electrode was developed as a new electrochemical technique to image corrosion potential galvanic current and polarization curves of reinforcing steel in concrete during corrosion process Combining with the polarization behavior for each micro-electrode the interactions between corrosion macrocell and corrosion microcell of the steel in concrete were evaluated It was noticed that the corrosion macrocell and microcell occurred independently in difference regions at the initial stage of corrosion The corrosion macrocell current can be in situ followed by corrosion potential imaging The corrosion propagation of steel in concrete is closely related to the interactions between corrosion macrocell and corrosion microcell Key words array electrode concrete corrosion macrocell microcell