1. Institute of Structural Engineering, Zhejiang University, Hangzhou 310058, China 2. School of Civil Engineering and Architecture, Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, China 3. Hangzhou Bay Cross-sea Bridge Development Co. Ltd, Ningbo 315317, China
The bi-directional electro-migration (BIEM) method was used to repair the cracked concrete in the marine environment, in order to eliminate the chloride enriched in the vicinity of the crack and to prevent corrosion of the steel bars. The effect of BIEM under different crack widths was studied by measuring the concentration of rust inhibitor, mass fraction of chloride ion and the polarization curve of reinforcement. The chloride migration law was verified by the chloride migration characteristic test. Results that the corrosion potential of the steel can be restored to a high level after BIEM of the cracked concrete. When the crack width is small, the migration law of chloride ion in concrete cover is similar to that of the uncracked concrete. When the cracked width in concrete is greater than 0.3 mm, the chloride ion discharge efficiency at the crack increases with the increase of the crack width, while the discharge efficiency of chloride ion farther from the crack decreases.
Fei-bin YUAN,Wei-liang JIN,Jiang-hong MAO,Jin-quan WANG,Wei-jie FAN,Jin XIA. Effect of chloride removal and corrosion prevention for cracked concrete based on bi-directional electro-migration rehabilitation. Journal of ZheJiang University (Engineering Science), 2019, 53(12): 2317-2324.
Fig.1Schematic diagram of bi-directional electro-migration（BIEM）in cracked concrete
Fig.2Schematic diagram of potential distribution in cracked concrete when electrified
编号
ρ /(kg·m?3)
水
水泥
砂子
石子
氯化钠
C30
206.7
406.7
633.3
1050
20.3
Tab.1Mix proportion of C30 concrete specimen
Fig.3Schematic diagram of BIEM specimen and chloride ion migration characteristic test specimen
Fig.4Powder picking position along direction of specimen length and concrete cover
Fig.5Polarization curve of steel bars in specimen groups with different crack widths before and after BIEM
试件组
Ecorr /mV
$ E'_{\rm{corr}}$/mV
单值
均值
单值
均值
A-0
?480
?463
?180
?172
?456
?191
?455
?145
A-0.1
?431
?430
?162
?166
?391
?157
?468
?180
A-0.3
?430
?437
?157
?161
?448
?179
?432
?146
A-0.5
?484
?457
?182
?166
?436
?155
?452
?162
A-0.7
?476
?491
?142
?160
?504
?156
?494
?183
A-1.0
?501
?470
?158
?149
?414
?143
?494
?147
Tab.2Corrosion potential before and after bi-directional electro-migration（BIEM）
Fig.6Distribution of chloride concentration in concrete cover after BIEM
Fig.7Schematic diagram for color boundary of each specimen
Fig.8Distribution of color boundary of specimen with different crack widths
Fig.9Location distribution of each specimen with fixed mass fraction value of chloride ion（0.03%）
Fig.10Comparison of chloride ion mass fractions at different locations on surface layer of steel bar
Fig.11Comparison of molar concentration of TETA in layer near steel bar
w/mm
x0 /mm
R
w/mm
x0 /mm
R
0
0
28.36
0.1
0
26.54
20
27.16
20
26.24
60
28.80
60
25.24
0.3
0
33.05
0.5
0
31.97
20
27.99
20
27.24
60
28.60
60
28.93
0.7
0
36.49
1.0
0
45.13
20
20.72
20
15.13
60
17.70
60
10.8
Tab.3Molar concentration ratio of TETA and chloride ion in layer near steel bar
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