Impressed Current Cathodic Protection System Research Articles

Flexural performance of seawater sea sand concrete composite beams enhanced by dual-functional C-FRCM jackets

The flexural performance of seawater sea sand concrete (SSC) composite beams enhanced by the dual-functional carbon-fabric reinforced cementitious matrix (C-FRCM) jackets was experimentally investigated. Five SSC composite beams were constructed and tested in flexure under four-point loading, including one control specimen, one C-FRCM enhanced beam without the presence of the impressed current cathodic protection (ICCP) system, and three C-FRCM jacketed beams implementing the ICCP system (three different current densities: 25, 75 and 125 mA/m2). The failure modes observed and the performance of the strengthened beams with the dual-functional C-FRCM jackets were discussed in details. The results indicated that the C-FRCM jacketing effectively increased the cracking load up to 46.43% and delayed yielding. The C-FRCM jacket had a relatively small impact on the initial stiffness of the specimens but significantly increased the load-carrying capacity (up to 18%) and improved ductility. With the increase in current density, the load-carrying capacity gradually decreased, the crack inhibitory effect gradually weakened, but the ductility coefficient increased notably (up to 98%). Regarding the failure modes of the composite beams, both fiber fracture and fiber slippage coexisted, and with the increase of current density, the latter became more predominant. Based on the design guidelines provided by ACI 549.4R-13, an analytical formula for bending moment was proposed and compared with the experimental results, providing a reference for the design of such components.

2-D shape optimization of auxiliary anode for ICCP

In this paper, to determine the influence of the shape of the auxiliary anode on the protection potential distribution in an impressed current cathodic protection (ICCP) system, an electrochemical and a level-set optimization method were combined to optimize the shape of the auxiliary anode. To accomplish this, the square of the deviation between the potential of the structure and the protection potential was used as the objective function, and the level set theory was employed to develop the anode shape. Following a set number of iterations, the optimized anode shape was obtained. Using the optimized anode, a current was injected into the anode surface, and the potential distribution was calculated. The experimental results showed that the potential distribution of the protected surface was uniform, and it could fully protect the protected structure’s surface, which helped to avoid overprotection or underprotection.

Corrosion behavior of austenitic stainless steel and nickel-based welded joints in underwater wet welding

Marine structures such as ports, bridges, pipelines, vessels, and platforms are an essential part of modern infrastructure, where the use of higher-strength steel provides savings in logistics and construction. However, the repair of higher-strength steels can be challenging, especially underwater. Wet shielded metal arc welding is the most widely used and least expensive method for underwater welding repairs, but is very susceptible to hydrogen-induced cracking. Thus, researchers and welding engineers aim to reduce the amount of hydrogen in the weld material. Recent success has been achieved through the use of austenitic welding consumables, such as austenitic stainless steel and nickel-based electrodes. The use of these consumables drastically reduces the amount of diffusible hydrogen in the weld metal. However, these austenitic materials usually have different corrosion potential as compared to the structural steel the weld beads are applied to. This creates the risk of severe galvanic corrosion. In the presented study, the corrosion behavior of welds created with austenitic stainless steel and nickel-based electrodes were studied. Samples were aged for 1.5 years in the Baltic Sea. Simultaneously, the effectiveness of corrosion protection systems such as coating and Impressed Current Cathodic Protection (ICCP) were evaluated. Localized corrosion occurred in the heat-affected zone when austenitic electrodes were used in the corrosive environment. The localized corrosion depth after 1.5 years in the Baltic Sea and in the salt spray layer was approximately 250 µm and 390 µm, respectively. The ICCP system and the use of a coating were effective in preventing localized corrosion. The low pitting corrosion density of 2.5 × 103 m−2 corresponds to grade A1 according to the standard and was found to be negligible as compared to the localized corrosion in the heat-affect zone.

Evaluation of the acoustic performance of a novelty cathodic protection system against guitar steel strings corrosion

This work was conducted to establish the efficiency of an impressed current cathodic protection system for musical instruments’ steel strings in protecting them from corrosion caused by human sweat. To conduct this research, the harmonic content degradation of a guitar string subjected to different corrosion stages by artificial human sweat, with and without cathodic protection by an impressed current, was studied. String corrosion is characterised by not only the electrochemical technique of polarisation resistance, but also by weight loss by gravimetric measurements and FESEM microscopy. From the correlation between the acoustic and electrochemical results, it can be concluded that harmonic content degradation of guitar strings increases corrosion but is less significant in the strings protected by impressed current.

IoT for Cathodic Protection System as Iron Concrete’s Corrosion Protection

Iron concrete or reinforcement steel is steel used for reinforcement of concrete construction or known as reinforced concrete. Iron concrete can undergo a corrosion process caused by chemical or electrochemical reactions between reinforcement steel and its environment. One way to protect concrete from corrosion is cathodic protection. There are two types of cathodic protection, namely sacrificial anodes and impressed current cathodic protection (ICCP). ICCP is more commonly used for protection in reinforced concrete structures. In ICCP, negative current flows to the iron concrete and positive current flows to the anode. This is to protect the concrete from corrosion. In addition to the corrosion protection system, there is also a half-cell potential test to measure the chance of corrosion of the concrete. The project used IoT to monitor and control the ICCP. Measurements are made by reading the potential difference between the reference electrode and the iron concrete. The probability of corrosion can be determined by reading the corrosion probability table with ASTM C879-09 standard. The ICCP system in general still uses the manual method so that there are time efficiency problems in controlling the voltage and current for ICCP purposes, cannot schedule the provision of electric current and monitor it at any time, especially if the electric current flowing in the concrete is higher than the standard it should be. Based on the results of the tests carried out, the IoT system can regulate the power supply by setting the voltage and current and can schedule the power supply to provide electric current to the iron concrete and can provide notifications if the electric current flowing in the concrete is more than or less than ICCP standard.

Experiments on shear behavior of reinforced concrete continuous beams strengthened by C‐FRCM

AbstractThe dual‐function retrofitting system that uses the carbon‐fabric reinforced cementitious matrix (C‐FRCM) as both the anode of impressed current cathodic protection (ICCP) system and the structural strengthening (SS) material, that is, an ICCP‐SS system, is investigated. The experimental program mainly focused on the shear behavior of C‐FRCM strengthened reinforced concrete (RC) continuous beam under the dual‐function retrofitting system. The influence of anode polarization on the shear strengthening of RC continuous beams is analyzed. Shear tests were conducted on a total of 14 corroded RC continuous beams to investigate the influence of key parameters, including anode polarization degree of prefabricated C‐FRCM plate, layer of carbon fiber mesh and side‐wrapping. The failure modes, shear capacities, and load‐deflection curves of the shear‐strengthened RC continuous beams are reported. Based on the test results, the applicability of relevant design codes was evaluated and found to provide rather conservative predictions for the shear capacity of the examined C‐FRCM strengthened RC continuous beams.

Development of a novel and specialised cementitious matrix overlay for anode embedment in impressed current cathodic protection (ICCP) systems for reinforced concrete bridges

Impressed Current Cathodic Protection (ICCP) is a widely utilised method for safeguarding reinforced concrete (RC) structures, including bridges, in marine environments. However, certain ICCP systems encounter degradation of the backfill mortar caused by acid formation at the anode. The acid produced reacts with the anode backfill mortar, compromising the functioning of the cathodic protection system. Rectifying the acidification issue typically involves replacing the backfill mortar and, in some cases, even the anode when it is negatively impacted by acid attack. This paper presents, for the first time, a specialised sustainable cementitious matrix that exhibits excellent acid resistance, intended for use as the anode's backfill material in ICCP systems. The proposed mortar effectively mitigates the effects of acidification around the anode, significantly enhancing the durability of the mortar and, consequently, the service life of bridges equipped with ICCP systems. The mechanical and durability performance of the mortar in an acidic environment is evaluated through various tests, including gravimetric analysis, dimensional changes, diffusion depth, compressive strength, direct tension, slant shear, impact resistance, and interface integrity assessments. Additionally, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques are employed to investigate the material's performance. Subsequently, the specialised mortar is applied to cover Mixed Metal Oxide (MMO) activated titanium mesh anodes of the ICCP system in a reinforced concrete bridge, while its performance is continuously monitored. The results demonstrate that the proposed mortar effectively eliminates acidification issues and improves the performance and longevity of ICCP systems in harsh marine environments.

Corrosion prevention of storage tank bottom using impressed current cathodic protection – Experimental and simulation study

Underside failure of storage tank bottoms is a serious industrial problem which is induced by various corrosion phenomena such as under deposit, microbial and stray current corrosion and can lead to leakage of hazardous materials and explosion. Impressed current cathodic protection (ICCP) is a widely used technique to hinder these types of corrosion. However, undue design of the ICCP system can accelerate the corrosion. Therefore, it is necessary to make sure that the tank bottom is totally and properly under protection before implementation. For this aim, a FEM model is designed in this study for validating this presumption. The model is based on the potential and current density distribution of the tank bottom and is designed using the data of a real storage tank being protected in practice. Simulation results showed that the tank bottom's potential with the ICCP applied (considering voltage drop) and its polarized potential at the very first instant of current interruption both are at least −0.850 V vs Cu/CuSO4. Furthermore, based on the calculations, 0.260 to 0.280 V polarization is experienced by the tank bottom. These results confirm full protection of the tank bottom. Effects of anode arrangement, coating application and soil resistance on the system performance are also investigated and the most optimal design is proposed based on the potential distribution. Conducting such a simulation in advance can significantly increase the life time of the structure.

Carbon enhanced cementitious coatings: Alternative anode materials for impressed current cathodic protection systems intended for reinforced concrete

AbstractIn this study, the functionality of self‐formulated carbon‐based conductive coatings (CBCCs) with incorporation of graphite as the anode in an impressed current cathodic protection system is studied. The anode materials are tested and evaluated for long‐term durability and performance by an accelerated durability test method. The results show that the functional time is highly dependent on the acceleration factor, and thus the charge passed through the material during testing, as well as the material composition. From the results, there are also indications that the addition of graphene into the CBCC matrix has a positive effect on the homogeneity of the material, but without any major influence on the conductivity and performance.

Factors Governing the Failure of Subsea Critical Connector Bolts

Impressed current cathodic protection (ICCP) systems are commonly used to shield offshore drilling rigs, pipelines, and subsea equipment in the oil and gas industry. In underwater service conditions, water temperature, salinity and velocity play a major role in the longevity of subsea applications. Interactions between the preceding factors can induce catastrophic failure to critical systems while the underlying cause is unclear. This paper proposes an approach for elucidating the corrosion process accompanying underwater applications. The service conditions of underwater application are simulated in a multidisciplinary system that records various parameters such as water temperature, reference-electrode potential, and electric current at five-minute intervals during the 21 d of the experiment. This novel, experimental, and inexpensive ICCP system was developed on an “Arduino” microcontroller and applied to an actual ASTM A193 B7 bolt tightened on an ASTM A105 flange at different torque levels. Experimental results indicate a direct relationship between the water day-night temperature profile and the cathodic protection performance. Specifically, the ICCP performance declines with increasing temperature. When the ICCP system was activated, gas bubbles are generated on the metal surface. Presumably these bubbles could induce hydrogen embrittlement cracks which were observed in scanning electron microscope images of the bolt cross-sections.

Investigation of residual protection of a 55 years old marine structure after 20 years subject to impressed current cathodic protection

It has been reported that structures to which impressed current cathodic protection (ICCP) has been applied for a long period have displayed evidence of residual protection when ICCP has been halted, ranging from several days up to significantly longer periods. To study this phenomenon this paper reports the de-activation of a 20 years old ICCP system installed on a 55 years old wharf structure. The ICCP was de-activated for 84 days and the reinforcing steel potentials at locations on the front pile cap and front wall were monitored via the existing installed reference electrodes (RE). The results showed that all the RE installed in the structure initially demonstrated a positive shift in potential, with 61% maintaining a positive trend over the entire trial period.

Effect of seawater pH variation on the growth of calcareous deposits and its effect on an impressed current cathodic protection system

Effect of seawater pH variation on the growth of calcareous deposits and its effect on an impressed current cathodic protection system

Electrochemical Performance of Concrete Conductive Anode Paint Used as an Impressed Current Anode Material

The impressed current cathodic protection (ICCP) technique is a widely accepted technique to control corrosion of steel in reinforced concrete structures exposed to a high chloride environment. With the growing applicability of the technique, this research focused on developing a new anode material for the system. The author’s previous zinc-rich paint (ZRP) anode is further modified to improve its properties and its performance to be suitable for ICCP. The new concrete conductive anode paint (CAP) was evaluated for various concrete elements with varying steel: concrete ratios. Results showed that concrete CAP possesses excellent electrical conductivity as the anode for the ICCP system irrespective of specimen size. Compared with other available commercial anode paint materials and ZRP anode, concrete CAP is more promising as an ICCP anode material and satisfies the required polarization requirement. Polarization performance showed anode is capable to protect reinforced concrete structure with varied steel: concrete or steel: anode ratio. With an anode current density of 20 mA/m2, the service life was evaluated as 45 years.

Assessment of the Impressed Current Cathodic Protection system after 4 years operation: Case study of the Saint-Cloud Viaduct (France)

Impressed Current Cathodic Protection (ICCP) is an electrochemical technique widely used, especially for repairing reinforced concrete structures contaminated with chlorides. This paper represents the results of the feedback of the ICCP system implemented on a road bridge, the Viaduct of Saint-Cloud in France. In 2012, a field trial was conducted in order to evaluate the effectiveness and the reliability of an ICCP system with embedded anodes designed for impressed current. The full-scale ICCP system was energized in 2018. Results of the four years monitoring including the variations of the applied current density and the polarization of the various anodic zones are presented. The ICCP data analysis is performed taking into consideration the initial degradation level of the span segments and the presence of prestressed tendons ducts. The electrical resistance of the circuit is influenced by several factors, the most important of which is the temperature. Considerations about the heterogeneity of the concrete resistivity are discussed.

Microstructure and interface analyses of novel external anode mortar incorporated calcined hydrotalcite nanoparticles towards an enhanced impressed current cathodic protection

BackgroundDuring Impressed current cathodic protection (ICCP), acidification around the mortar is occurred by anodic reactions including the transfer of hydroxide to oxygen, and significantly influences the expected lifetime of the utilized external anodes. MethodsIn this study, calcined hydrotalcite (CLDH NPs) were designed by a simple and single step and were presented to stabilize the pH around anode mortar in the ICCP system. The modified ICCP system by CLDH or its external anode was evaluated by surface, mechanical, and electrochemical analyses (impedance (EIS) and potentiodynamic polarization (PDP)) besides different techniques such as X-ray powder diffraction (XRD), thermal gravimetric analysis (TGA), and scanning electron microscope (SEM) morphology at the investigated anode mortar interface. Significant findingsThe obtained results indicated that CLDH NPs enhanced the lifetime of the external anode in ICCP by decreasing the acidification around the mortar. The corrosion current (Jcorr) went down from 1.78 to 1.62 µA/cm2 due to the CLDH NPs incorporation, which indicated the impact of CLDH NPs on the electrochemical stability of the utilized mortar. Besides, the presented CLDH NPs could potentially be applied for the engineering fabrication of the anode mortars in ICCP systems.

Test Study of the Bridge Cable Corrosion Protection Mechanism Based on Impressed Current Cathodic Protection

The cable system is an important bearing element of a bridge with stay cables or slings and a matter of major concern in the safety of the bridge structure. Bridge cables are vulnerable to corrosion induced by leakage and soaking during their service life. To solve this problem, and based on the idea of proactive control by means of the impressed current cathodic protection (ICCP) of bridge cables, this study designs and develops an ICCP system device for bridge cable protection. In this study, an accelerated corrosion test was conducted to test the ICCP system of steel wires inside the cables and the cables under acid rain conditions. The corrosion protection behavior of ICCP was analyzed to reveal the corrosion protection mechanism of bridge cable ICCP. The results show that in the cable ICCP system, the impressed current generated by a more negative voltage may improve the efficiency of corrosion protection, but an excessively negative voltage may cause hydrogen embrittlement of the cable steel wire due to overprotection. The rational range of −1.13 V to −1.15 V was set as the result of the overall consideration. Within this range, the cable is subject to the joint protection of ICCP and sacrificial anode cathodic protection (SACP). Corrosive products can delay the development of cable corrosion to a certain degree; the SACP protection efficiency of the galvanized coat reduces gradually with corrosion development; and cable ICCP protection efficiency increases gradually. The ICCP for cable corrosion protection is transformed from joint protection using both a sacrificial anode and impressed current into protection, mainly using an impressed current.

Influence of various parameters on the current distribution and protection degree of impressed current cathodic protection for reinforced concrete with TiMMO mesh anodes

Impressed current cathodic protection (ICCP) is an effective technique to control reinforcement corrosion in concrete structures. The efficiency and design of an ICCP system with titanium mixed metal oxide (TiMMO) anodes in a mortar overlay is strongly influenced by the current distribution to the different reinforcement layers of a reinforced concrete element. An in-depth experimental study is performed to investigate the effect of various parameters on the current distribution and degree of corrosion protection: (i) chloride content, (ii) cement type, and (iii) reinforcement configuration. 24-hour depolarization measurements (EN ISO 12696:2022) indicate that an increase in chloride concentration in the concrete, related to an increase in the rate of reinforcement corrosion, leads to a general decrease in the degree of protection. The use of a CEM III/A cement leads to a large increase in concrete electrical resistivity compared to concrete with an ordinary Portland cement (CEM I). This causes a lower total current output to the reinforcement and a less uniform distribution of current. Finally, a lower steel reinforcement density resulted in a larger current density, as the total current is distributed over a smaller steel surface area, causing higher depolarization values.

Suppression of corrosion on stainless steel 303 with automatic impressed current cathodic protection (a-ICCP) method in simulated seawater

One effective method to slow down metal corrosion rate is the impressed current cathodic protection (ICCP) system. The ICCP system is suitable for coastal applications such as piping systems and offshore structures. In this application, metal surfaces tend to be exposed to seawater. Specific concentrations of seawater can accelerate the occurrence of corrosion of metals, even though they are stainless steel types. This study applied the automatic ICCP system to stainless steel 303. Stainless steel 303 will be immersed in simulated seawater at several concentrations of NaCl (27 ppt, 31 ppt, and 35 ppt). The specimens were immersed in NaCl solution for three weeks or about 504 hours at a constant temperature of 38 °C. After the sample has been soaked, quantitative and qualitative measurements were carried out. Quantitative measures include average weight loss, corrosion rate, and potential value. At the same time, the qualitative measurements include macroscopic, Scanning Electron Microscopy (SEM), and Energy Dispersive X-Ray Spectroscopy (EDS). Based on quantitative measures, it was found that the difference in average weight loss and corrosion rate for each NaCl concentration was not very significant. The difference of each parameter is less than 0.1 % and 0.22 %, respectively. The potential value quickly reaches a steady state at NaCl concentrations of 27 ppt and 31 ppt in less than 10 seconds. The results of the SEM test showed a change in the metal structure. The oxygen (O) content in the metal after the EDS test showed a decrease in this element up to 35 % at a NaCl concentration of 35 ppt. The decrease in oxygen (O) can slow down the corrosion rate in metals when exposed to seawater.

The Effects of Biofouling and Corrosion Products on Impressed Current Cathodic Protection System Design for Offshore Monopile Foundations

The robustness of the cathodic protection systems utilized for offshore wind monopile foundations depends on the surface condition of the steel as well as the environmental conditions. This study investigated how preexisting biofouling and corrosion products on vertical uncoated steel surfaces extending from the intertidal zone to the buried zone affected the cathodic protection requirements when impressed current cathodic protection (ICCP) was applied under tidal conditions. The comparative results between initially clean and previously fouled and corroded panel sets showed that the fouling and corrosion products increased both the initial and mean current densities. They also altered the composition, slowed the formation, and reduced the protective properties of cathodic chalks during nine weeks of deployment in seawater at Port Canaveral, Florida.

Fatigue life of C-FRCM strengthened corroded RC continuous beams under multi-intervention system

A new fatigue life prediction model for reinforced concrete (RC) beams is proposed. The model was applied to carbon-fabric reinforced cementitious matrix (C-FRCM) strengthened corroded RC beams under the impressed current cathodic protection (ICCP) and structural strengthening (SS) multi-intervention system. The stress development of steel bar in the fatigue process was captured by employing the fracture mechanics and finite element (FE) analysis. The concept of equivalent initial flaw size (EIFS) was also introduced to account for the actual initial micro crack size of steel bar. The feasibility of the model was validated through comparisons of the numerical deflection, the strain of steel bar and fatigue life of RC beams against the test results. The validated model was then used to examine the effects of key parameters including load level, corrosion degree of steel bar and polarization degree of C-FRCM. Furthermore, the results of the parametric study were used to fit S-N curve and analyse the reliability. The high accuracy of the model was shown to be suitable for the fatigue life prediction of ICCP-SS system in long-term service. It was also found that the fatigue life of the corroded RC beams was greatly improved through strengthening with C-FRCM.