Cathodic protection of new and old reinforced concrete structures

Bertolini, Luca; Bolzoni, F.; Cigada, A.; Pastore, Tommaso; Pedeferri, Pietro

doi:10.1016/0010-938x(93)90393-u

Cited by 76 publications

(48 citation statements)

References 1 publication

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“…When CP is applied to reinforcing steel in concrete however, the objective might not always be to achieve ''immunity'' but to reduce the risk of chloride-induced corrosion, by polarizing the steel from its condition of chloride-induced corrosion (or ''pitting'') to the domain of ''imperfect passivity,'' where pitting is unstable [6,7,13]. In case CP is initially applied within the construction of a structure, i.e., before exposure to aggressive environments, then only a modest polarization of the steel surface will be sufficient for corrosion protection, the technique being applied and denoted as ''cathodic prevention'' [6,14,15].…”

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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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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“…As reported by previous studies (Bertolini et al 1993;Pedeferri 1996), a current density of 0.2 μA/cm 2 is considered sufficient for cathodic prevention of corrosion initiation. From the test results, it can be deduced that after 530 days the current densities of all sacrificial point anodes are still over the range of cathodic prevention for all exposure conditions.…”

Section: Polarization Behavior Of the Sacrificial Point Anodementioning

confidence: 71%

Application of Sacrificial Point Anode for Prevention of Steel Corrosion in Cracked Concrete

Caronge

Hamada

Irmawaty

et al. 2015

ACT

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The effectiveness of a commercially available sacrificial point anode for corrosion prevention of steel in cracked concrete is presented. Reinforced concrete prisms with dimensions of 150 mm x 150 mm x 500 mm were prepared with a water to cement ratio (W/C) of 0.4 showing crack widths ranging from 0.1 to 0.4 mm obtained by pre-cracking. These specimens were exposed to three conditions: (1) laboratory air (temperature of 20±2°C and relative humidity of 60%); (2) immersed in 3% NaCl solution; and (3) dry/wet cycles of above mentioned conditions. Measurements included the free corrosion potential, polarization behavior of the sacrificial point anode, anodic-cathodic polarization curve of the reinforcement steel and visual observation. The test results show that the sacrificial point anode was effective to prevent the embedded steel from corrosion in cracked concrete. Specimens exposed to dry/wet cycles or immersed in 3% NaCl solution demonstrated a better protection than those exposed to laboratory air due to the high moisture condition. Thus, a sacrificial point anode becomes active to protect the steel bars even in cracked concrete.

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“…This has an important practical consequence on the protection of structures with several layers of reinforcement. In fact, in reinforced concrete structures, depending on the conditions of humidity and the concrete composition, 70-90% of the current fed by the anode is absorbed by the nearest layer of reinforcement; only a small fraction of the current reaches the deeper mats of rebars (Bertolini, Bolzoni, Cigada, Pastore, & Pedeferri, 1993). In order to polarize the deeper mats as well, it is necessary to increase the current density applied to the first mat.…”

Section: Cathodic Preventionmentioning

confidence: 99%

Corrosion of Steel in Concrete and Its Prevention in Aggressive Chloride-Bearing Environments

Bertolini¹,

Carsana²,

Gastaldi³

et al. 2016

Proceedings of the 5th International Conference on the Durability of Concrete Structures

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This keynote paper deals with the durability of reinforced concrete (RC) structures exposed to aggressive environments characterized by high concentration of chloride ions, namely, marine environments or the use of de-icing salts. The mechanism of chloride-induced corrosion of steel in concrete is introduced, and its influence on the service life of RC structures is analyzed. Factors affecting the time to corrosion initiation are described with regard to both concrete properties and environmental exposure conditions. Design approaches available for achieving durability targets associated with the design service life are analyzed, focusing on studies carried out by the authors in recent years at the mCD Concrete Durability lab of Politecnico di Milano, which were aimed at improving the protection provided to the steel bars by the concrete cover, investigating the advantages of using corrosion-resistant stainless steel bars and developing the electrochemical technique of cathodic prevention.

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Cathodic protection of new and old reinforced concrete structures

Cited by 76 publications

References 1 publication

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

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

Application of Sacrificial Point Anode for Prevention of Steel Corrosion in Cracked Concrete

Corrosion of Steel in Concrete and Its Prevention in Aggressive Chloride-Bearing Environments

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