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| Effect of chloride cation type on chloride threshold value for steel corrosion in concrete |
| 1.College of Mechanics and Materials, Hohai University, Nanjing, Jiangsu 210098, China; 2.State Key Laboratory of HydrologyWater Resources and Hydraulic Engineering, Hohai University, Nanjing, Jiangsu 210098, China |
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Abstract Four kinds of chloride deicing salt, KCl, NaCl, CaCl2and MgCl2, were chosen to study the corrosion of steel reinforcement. The halfcell potential, electrochemical impedance spectroscopy, electrochemical titration and Xray diffraction methods were used to investigate the effect of cation type on the corrosion behavior of steel reinforcement in concrete. Combined the opencircuit potential with corrosion current, the onset of pitting corrosion was detected by electrochemical impedance spectra. The results indicate that the cation type has a marked effect on the chloride threshold value(CTV), and the CTV is varied with its representation. When the CTV is expressed as the mass fraction of free chloride content, the sequence is wf (MgCl2)<wf (CaCl2)<wf (NaCl)<wf(KCl). When the form of c(Cl-)／c(OH-) is close, the relationship is cKCl(Cl-)／cKCl(OH-)≈cNaCl(Cl-)／cNaCl(OH-)<cCaCl2(Cl-)／cCaCl2(OH-)<cMgCl2(Cl-)／cMgCl2(OH-). When the mass fraction of total chloride is used, the sequence is wt (KCl)≈wt (NaCl)<wt (MgCl2)<wt (CaCl2).
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2013, Vol. 34 
