Cathodic protection for prestressed concrete structures

Ishii, Kouji; Seki, Hiroshi; Fukute, Tsutomu; Ikawa, Kazuhiro

doi:10.1016/s0950-0618(97)00014-7

Cited by 23 publications

(14 citation statements)

References 4 publications

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“…However, since CP is also accompanied by various side effects [22][23][24][25][26], alternatives of the conventional CP have been reported [5,6,19,[27][28][29], some more recently introduced and studied [1,14]. Discussing these alternatives is not subject to this contribution.…”

Section: Chloride-induced Corrosion and Impressed Current Cpmentioning

confidence: 99%

Electrochemical behavior of corroded and protected construction steel in cement extract

Koleva

2011

Materials & Corrosion

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The corrosion behavior of corroded, cathodically protected and control (reference) construction steel, previously embedded in concrete, was studied in cement extract (pH 12.6, considered as concrete pore water), using cyclic voltammetry (CVA) and potentiodynamic polarization (PDP). The necessity for this investigation occurred from the previously observed and commented discrepancies in the recorded corrosion parameters for corroded and protected steel in embedded conditions [1]. Therefore this study aimed to evaluate how the ''naturally'' formed in concrete product layers (after 460 days) will influence the electrochemical behavior of the steel in cement extract. The PDP measurements reveal the lowest corrosion resistance to be for the previously corroded steel samples, for which the most active corrosion potential (À0.7 V SCE) and the highest anodic current in the potential region 0 to 0.6 V (SCE) were recorded. The CVA tests support the results from PDP and correlate the properties of the naturally formed layers with the recorded peak current densities and peak potentials with cycling. For all specimens, except the corroded ones, the peak potential initially shifts anodically, which denotes for a high corrosion resistance in the former and low corrosion resistance in the latter case. For the control and protected specimens, the passive current in the potential region of 0 to 0.6 V (SCE) remains almost unchanged with cycling, i.e. the protective properties of the initial layers remain unchanged. Thickening of the film with cycling does not influence the corrosion resistance of the previously formed layers. For the protected specimens, however, a tendency to reach a steady state and change of peak currents' height only were observed, without a pronounced shift to more anodic values. An increase in the peak current only, not accompanied by anodic shift of the peak potential, suggests that the layers in the cathodically protected specimens are more homogeneous and compact. Overall it can be stated that in cement extract, the product layer with lowest corrosion resistance is the one on the surface of the corroded steel reinforcement. The product layers in the protected specimens (although similar to control conditions) are with the highest corrosion resistance.

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Section: Chloride-induced Corrosion and Impressed Current Cpmentioning

confidence: 99%

Electrochemical behavior of corroded and protected construction steel in cement extract

Koleva

2011

Materials & Corrosion

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“…A major part of the possible side effects actually results from microstructural and physico-chemical alterations at the steel/cement paste interface, leading to a reduced adhesion of the cement paste layer to the steel surface [18,23], and thus finally results in bond strength weakening (the latter reported to reach 55% [24]). The reason for bond-strength degradation is still unclear, despite the reported data for changes in microstructure, pore size distribution, and micro-cracking [18,25,26].…”

Section: Technical Backgroundmentioning

confidence: 99%

Conventional and pulse cathodic protection of reinforced concrete: Electrochemical behavior of the steel reinforcement after corrosion and protection

Koleva¹,

Guo²,

Breugel³

et al. 2009

Materials & Corrosion

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The applicability and efficiency of an alternative for impressed current cathodic protection (CP) for reinforced concrete, based on pulse technology, was investigated. The technique, denoted as pulse CP (pCP), was evaluated on the basis of a comparative analysis to reference (non-corroding), corroding, and conventional CP conditions, in terms of long-term monitoring of electrochemical parameters for the embedded steel with time of corrosion and protection. The hereby reported results are for the total duration of the experiment, i.e., 460 days of conditioning, also presented in comparison with earlier stages. Protection was applied after corrosion was initiated (using corrosion medium of 5% NaCl), at different time intervals (here reported are starting points 60 and 150 days of age). Both CP regimes used current density of 5 or 20 mA/m 2 steel surface. The pulse CP was applied as a pulse-shaped block current (square wave) with the current itself being the feedback control signal, using 12.5-50% duty cycle at 500 Hz to 1 kHz frequency. Under equal environmental conditions and for a comparatively long period of application, the pulse CP was found to perform as effectively as the conventional CP with regard to electrochemical behavior of the steel reinforcement. Furthermore, the pulse CP technique was found to achieve more rapidly the so called ''open circuit potential (OCP) passivity'' as a result of an enhanced ion transport (chloride withdrawal) and more favorable cement chemistry (increased alkalinity around the steel reinforcement).

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“…Side effects, however, are known in these applications as well, e.g., bond-strength degradation, alkali ion accumulation, and possible concrete degradation due to alkali-silica reaction, etc. 22,23 The present study aimed at:…”

mentioning

confidence: 99%

Investigation of Corrosion and Cathodic Protection in Reinforced Concrete

Koleva¹,

Wit

Breugel³

et al. 2007

J. Electrochem. Soc.

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The electrochemical behavior of steel reinforcement in conditions of corrosion and cathodic protection was studied, using electrochemical impedance spectroscopy ͑EIS͒ and compared to reference ͑noncorroding͒ conditions. Polarization resistance ͑PR͒ method and potentiodynamic polarization ͑PDP͒ were employed as well, in addition to ac 2 pin electrical resistance monitoring, thus deriving a comparison of the involved parameters, mainly polarization resistance and bulk electrical properties, obtained by all methods. It was found out that EIS is readily applicable for evaluating electrochemical behavior of the steel surface not only for corroding or passive state, but also in conditions of cathodic protection, although the interpretation of derived parameters is not straightforward and is related to the properties of the product layers, formed on the steel surface in the different conditions. For verification of the latter dependence, EIS, PDP, and PR measurements were performed additionally in cement extract solution, using steel samples from the previously embedded rebars in all technical conditions. The bulk matrix properties in passive, corroding, or under-protection conditions can be well defined by EIS. The evaluation of the electrochemical behavior of the steel surface, in terms of deriving polarization resistance, should take into account the crystallinity, morphology, and composition of the surface layers, which were investigated by scanning electron microscopy and energy dispersive X-ray analysis. In nondamaged reinforced concrete, steel remains passive due to the high alkalinity of the concrete pore solution ͑pH 12.5-13.5͒. If damages of the concrete cover and the concrete bulk matrix occur, depending on the aggressiveness of the environment, corrosion of the steel reinforcement will be initiated. The initiation and further evolution of the corrosion process will depend on the concrete pore network permeability and connectivity on one hand and the rate of penetration, amounts and concentration of aggressive substances in the environment ͑CO 2 , chlorides, sulfates͒ on the other. In the presence of chlorides, localized corrosion takes place as a consequence of passive layer breakdown. The rate of the process depends to a significant extent on the initial surface state of the steel surface, the chloride concentration, the chloride binding capacity of the bulk concrete matrix, etc. The chloride-induced corrosion process on steel reinforcement has been largely studied in concrete and in simulated pore solutions as well.1-21 Along with the localized corrosion on the steel surface, physico-chemical and structural transformations are taking place on the steel/cement paste interface. Further, the morphological alterations and certain distribution of product layers are influencing the mechanical properties of the reinforced concrete system as a whole.Impressed current cathodic protection ͑ICCP͒ is one of the protection techniques applied to such systems. Along with minimizing the corrosion process and preventing f...

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Cathodic protection for prestressed concrete structures

Cited by 23 publications

References 4 publications

Electrochemical behavior of corroded and protected construction steel in cement extract

Electrochemical behavior of corroded and protected construction steel in cement extract

Conventional and pulse cathodic protection of reinforced concrete: Electrochemical behavior of the steel reinforcement after corrosion and protection

Investigation of Corrosion and Cathodic Protection in Reinforced Concrete

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