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Journal of ZheJiang University (Engineering Science)  2020, Vol. 54 Issue (3): 483-490    DOI: 10.3785/j.issn.1008-973X.2020.03.008
Civil Engineering     
Study on experimental method and morphology of accelerated non-uniform corrosion of steel bars
Nan-guo JIN1(),Jia-hao HE1,Chuan-qing FU2,*(),Xian-yu JIN1
1. College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China
2. College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China
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Abstract  

An innovative test method of non-uniform corrosion was developed to investigate the non-uniformity of steel bar corrosion in concrete. The corrosion of steel bar in concrete was accelerated by the electrification between a pre-embedded stainless steel wire and the steel bar in concrete specimen. The 3D geometric model of steel bar corrosion at different corrosion rates was obtained using the 3D laser scanning technology. Results indicate that the non-uniform corrosion behavior of steel bar obtained by this method was similar to that from the condition of natural corrosion. That is, the corrosion in concrete near the stainless steel wire is much severer than that far away from the stainless steel wire. The probability distribution model of the non-uniform coefficient R, which was established from the longitudinal cross section area of corroded steel bar, agreed well with the Gumbel extreme value distribution. Compared with the probability distribution of the non-uniform coefficient R under natural corrosion, the feasibility of this method in evaluation of the bearing capacity for reinforced concrete members is further verified.



Key wordselectrochemical corrosion      non-uniformity      3D laser scanning      probability distribution     
Received: 24 February 2019      Published: 05 March 2020
CLC:  TU 375  
Corresponding Authors: Chuan-qing FU     E-mail: jinng@zju.edu.cn;chqfu@zju.edu.cn
Cite this article:

Nan-guo JIN,Jia-hao HE,Chuan-qing FU,Xian-yu JIN. Study on experimental method and morphology of accelerated non-uniform corrosion of steel bars. Journal of ZheJiang University (Engineering Science), 2020, 54(3): 483-490.

URL:

http://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2020.03.008     OR     http://www.zjujournals.com/eng/Y2020/V54/I3/483


钢筋加速非均匀锈蚀试验方法和锈蚀形态研究

采用自主发明的通电加速钢筋非均匀锈蚀试验方法,以不锈钢丝作为辅助电极对混凝土试件进行通电加速锈蚀,利用三维激光扫描技术获得不同锈蚀率下锈蚀钢筋的三维几何模型,研究采用该方法时锈蚀钢筋的不均匀性. 研究发现,由此可以得到与实际自然锈蚀情况相似的不均匀锈蚀现象,即靠近不锈钢丝一侧锈蚀比较严重,远离不锈钢丝一侧锈蚀较少. 根据对锈蚀钢筋纵向截面积的分析,建立不均匀系数R的概率分布模型,其值满足Gumbel极值分布;将模型与实际自然锈蚀的钢筋不均匀系数R的概率分布进行比较,进一步验证该方法用于评估钢筋混凝土构件承载力的可行性.


关键词: 通电锈蚀,  不均匀性,  三维激光扫描,  概率分布 
Fig.1 Distance between each point on surface of steel bar and stainless steel wire
Fig.2 Development of non-uniform corrosion of steel bars
水灰比 水泥 细骨料 粗骨料
0.53 370 750 1 112 188
Tab.1 Mix proportion of concrete kg/m3
Fig.3 Schematic diagram of reinforced concrete specimen
试件编号 i/( ${\rm{\mu A}} \cdot {\rm{c}}{{\rm{m}}^{{\rm{ - 3}}}}$ ρ0/ % t/h
A12-1 300 5 74.6
A12-2 10 373
A12-3 15 1 119
Tab.2 Time schedule of electrification for concrete specimen
Fig.4 Test setup for electrochemical accelerated corrosion
Fig.5 Corroded steel bar and 3D reconstructive model
Fig.6 Schematic diagram of steel bars splitting
Fig.7 Corrosion cracks distribution of concrete specimen at different corrosion rates
Fig.8 Partial enlarged view of non-uniform corrosion of steel reinforcement
Fig.9 Corroded steel bar and 3D reconstructive model with different corrosion rate
试件编号 ρ0 ρ ρav w
A12-1 5 4 4.0 0
A12-2 10 8 7.7 3.7
A12-3 15 11 10.7 2.7
Tab.3 Comparison of theoretical corrosion rate, mass corrosion rate and average corrosion rate of 3D scanning calculation %
Fig.10 Distribution of residual area and section corrosion rate of corroded rebar
Fig.11 Contour curve for part of electrified non-uniform corroded steel reinforcement
Fig.12 Contour comparison of uniform and non-uniform corroded steel bars after electrification
Fig.13 Frequency distribution and verification of R value of corroded steel bars at different corrosion rates
Fig.14 Relationship among location parameter μ,scale parameter σ and corrosion rate ρ of Gumbel extreme-value distribution
Fig.15 Probability density distribution of R value at different corrosion rates
Fig.16 Probability density distribution of R value of natural rust and non-uniform rusting
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