Impressed Current Cathodic Protection Research Articles

The coupling effect of calcined layered double hydroxides and impressed current cathodic protection system on chloride ion binding and migration of sea sand mortar

Chloride introduced by sea sand and sea water leads to steel bar corrosion. Calcined Layered double hydroxides (CLDH) and impressed current cathodic protection (ICCP) system were used to adsorb chloride ion and control steel bar corrosion in chloride abundant environment. In this research, chloride binding effect of two kinds of CLDH were investigated in simulated concrete pore solution. Besides, chloride absorption capacity and steel bar corrosion resistance of Mg-Al CLDH was explored in mortar. Further, hydration degree of mortar installed ICCP system and migration of ions around the anode and cathode were detected. Results show that Mg-Al CLDH exhibits excellent chloride binding capacity and corrosion resistance. After installing the ICCP system, corrosion of steel bars in mortar mixed Mg-Al CLDH was controlled. And ions in mortar specimen around anode or cathode exhibits migration phenomenon in different degree. A two stage-four step model was established to explain the degradation of hydration products and ion migration in CLDH-ICCP system. Under the ICCP system, Cl− in pore solution increased at early stage and then decreased both around anode and cathode, the increment process was controlled by desorption of Mg-Al CLDH and decreased process was controlled by degradation of hydration products. Therefore, the CLDH-ICCP system was recommended to solve the problem of steel bar corrosion introduced by marine environment.

Research on the Optimal Protection Parameters of Graphene Composite Conductive Coatings Combined with Impressed Current Cathodic Protection Technology in Marine Atmospheric Environments

Based on the principle of a micropore-filling electrolyte, a graphene composite conductive coating combined with impressed current cathodic protection (ICCP) technology was constructed and applied in a marine atmospheric environment. To further explore the optimal protection parameters of the graphene composite conductive coating combined with ICCP technology in a marine atmospheric environment, the effects of the coating damage area (A), impressed voltage (B), and distance from the contact point (C) on the protective performance of the coating were investigated via orthogonal experiments. The optimal protection voltage and effective protection distance were verified by super-depth-of-field morphology observations and electrochemical tests. The orthogonal experimental results show that the primary and secondary orders affecting the protective performance of the conductive graphene composite coating are as follows: applied voltage (B) > coating damage area (A) > distance from the point of contact (C). The optimal protective parameters of the coating in the marine atmospheric environment are an applied voltage of 0.7 V, a damage rate of ≤1%, and a distance from the point of contact of 190 mm. The experimental results show that the corrosion potential of the sample is the highest under an applied voltage of 0.7 V, and the corrosion products do not diffuse to the surface of the coating. When the polarization resistance (Rp) values at 110 mm and 190 mm from the negative electrode at the point of contact are greater, the corrosion rate is lower, and the coating protection performance is better.

Advancing the assessment of ICCP efficiency for steel reinforcement: A novel electrochemical investigation

Impressed current cathodic protection (ICCP) is an electrochemical technique employed to mitigate corrosion. The evaluation of its effectiveness has traditionally relied on qualitative criteria such as protection potential and potential decay. This study proposes a novel electrochemical setup to enable measurements during current-controlled ICCP treatment. The experimental outcomes demonstrate that the proposed approach, in conjunction with protection potential analysis, allows for the quantitative determination of the optimal ICCP current density. As the protection current density increased, the fitted charge transfer resistance (Rct) initially showed an upward trend, followed by a gradual decline. To accurately interpret the results, it is crucial to discern whether the Rct values correspond to oxidation reactions (referred to as corrosion reactions in this context) or reduction reactions. Furthermore, it was observed that the optimal current density was closely associated with the severity of initial corrosion, in line with previous findings. This consistency serves to further validate the efficacy of the proposed method.

Hull Coating Damage Location Prediction Using an Improved Annealing Particle Swarm Optimization Algorithm

Damaged hull coatings can exacerbate corrosion to the ship body and timely detection and repair of defects are necessary to prevent further corrosion. Due to the large size of the ship, detection of the defects is not easy, especially those located below the waterline. When the impressed current cathodic protection detection system is combined with specialized software, this problem can be solved. This article has developed a software system that can predict damaged locations. The system adopts an improved annealing particle swarm optimization algorithm, combined with electrochemical theory, which can search for defects through iteration. Simulation results show that the system can locate the defects accurately in situations, where there are only one or two damaged parts with high accuracy.

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.

Implementation of a control and monitoring system for a cathodic protection cell to mitigate localized corrosion in fixed and mobile steel structures

The current study introduces a novel technique to handle electrochemical localized corrosion in certain limited regions rather than applying comprehensive cathodic protection (CP) treatment. An impressed current cathodic protection cell (ICCPC) was fabricated and firmly installed on the middle of a steel structure surface to deter localized corrosion in fixed or mobile steel structures. The designed ICCPC comprises three essential parts: an anode, a cathode, and an artificial electrolyte. The latter was developed to mimic the function of the natural electrolyte in CP. A proportional-integrated-derivative (PID) controller was designed to stabilize this potential below the ICCPC at a cathodic potential of −850 mV, which is crucial for protection efficacy. The controller of the protection system was designed to automatically activate the ICCPC when the environment of the steel structure is exposed to humidity. At a temperature range from 27 °C to 35 °C, the protection potential, current, and power showed an increase in percentage by 411 %, 688.74 %, and 2842.3 %, respectively when the humidity level rose from 10 % to 100 %. The intended spraying of sodium chloride (NaCl) solution on the structure at different concentrations from 1.5 % to 5 % showed excellent protection against corrosion, notable improvements in electrical conductivity, and reduction in resistance between the anode and cathode. The energy dispersive spectroscopy and scanning electron microscopy (SEM-EDS) analyses confirm effective corrosion inhibition under ICCPC coverage compared to unprotected areas. These tests revealed an absence of oxidation beneath the ICCPC compared with areas outside of its coverage. The areas outside of ICCPC protection showed a reduction in iron and carbon contents from 57.1 % to 47.0 % and 41.4 %–22.4 %, respectively, and an increase in oxygen from 1.6 % to 30.6 %.

Effect of ICCP on bond performance and piezoresistive effect of carbon fiber bundles in cementitious matrix

The purpose of this study is to lay a foundation for developing a triple-functional system of impressed current cathodic protection, structural strengthening, and structural health monitoring (ICCP-SS-SHM) regarding carbon fabric reinforced cementitious matrix (CFRCM) material performance, and promote the utilization of seawater sea-sand resources to alleviate the shortage of freshwater river sand resources. In recent years, CFRCM, ICCP, and the piezoresistive effect have been widely studied in strengthening reinforced concrete structures, corrosion protection of steel reinforcement, and SHM, respectively. This study used two types of matrix materials: normal matrix (ISO standard sand) and seawater sea-sand matrix. The effect mechanism of the ICCP procedure on the bond performance degradation of CFRCM with the two types of matrix and the bond performance differences between them were investigated through carbon fiber bundle tensile tests and CFRCM bundle pull-out tests. Prediction formulas for bond performance were established based on the different charge densities, mechanical parameters, and resistance parameters, respectively. The piezoresistive effects of CFRCM with the two types of matrix after the ICCP procedure and the effect of ICCP on the piezoresistive effect were analyzed. The seawater sea-sand environment has a positive impact on delaying the degradation of CFRCM by ICCP.

Effect of ICCP on tensile performance of carbon fiber bundles in seawater sea-sand cementitious matrix

Impressed current cathodic protection (ICCP), carbon fabric reinforced cementitious matrix (CFRCM) composites, and piezoresistive effect have been widely studied in delaying steel bar corrosion, strengthening steel-reinforced concrete structures, and structural health monitoring, respectively. In this study, the effect mechanism of the ICCP procedure on the tensile performance degradation of CFRCM bundles with the two types of matrix (normal matrix (i.e., sand conforming to ISO standard) and seawater sea-sand matrix), as well as the tensile performance differences between them, were investigated through carbon fiber bundle tensile tests and CFRCM bundle tensile tests. The piezoresistive effects of CFRCM with the two types of matrix after the ICCP procedure and the effect of ICCP on the piezoresistive effect were analyzed. Prediction formulas for the tensile performance were established based on the different charge densities. Based on the dual functionality of carbon fiber strengthening and self-sensing, this study lays a foundation for the development of a triple-functional system of impressed current cathodic protection, structural strengthening, and structural health monitoring (ICCP-SS-SHM). The study indicates that seawater sea-sand positively influences the delay of CFRCM degradation through ICCP. This is advantageous in tackling the issue of scarce freshwater river sand resources.

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.

Effect of ICCP on tensile performance and piezoresistive effect of CFRCM plates

Currently, extensive research has been conducted on carbon fabric−reinforced cementitious matrix (CFRCM) composites, impressed current cathodic protection (ICCP), and the piezoresistive effect in the field of strengthening of reinforced concrete (RC) structures, corrosion protection of steel reinforcement, and structural health monitoring, respectively. This study utilized two types of matrix materials: normal matrix (sand conforming to ISO standard) and seawater sea-sand matrix. The mechanism by which the ICCP procedure affects the degradation of tensile performance in CFRCM plates with these two types of matrix materials was investigated in the study. Additionally, the piezoresistive effects of CFRCM with the two types of matrix materials after the ICCP procedure were analyzed, and the impact of ICCP on the piezoresistive effect was also investigated. By observing the piezoresistive effect of each CFRCM segment, the sequence of crack propagation and an approximate crack location can be inferred. Finally, the tensile performance of CFRCM with charge density was investigated. Leveraging the dual functionality of carbon fiber reinforcement and sensing, this study lays the groundwork for the development of a triple-functional system encompassing impressed current cathodic protection, structural strengthening, and structural health monitoring (ICCP-SS-SHM). Seawater sea-sand has the potential to be used as an alternative to freshwater river sand, which is beneficial for addressing the shortage of freshwater river sand resources.

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.

Corrosion protection failure test analysis of the initial damaged cable ICCP mechanism

Given the corrosion protection failure of the cable-stayed bridge cable in the actual project, the impressed current cathodic protection (ICCP) technology was used to carry out the anti-corrosion tests from steel wire scale to cable scale, analyze the corrosion protection characteristics of steel wire ICCP, deduce the corrosion factor ICCP diffusion model, and reveal the space ICCP mechanism of the initial damaged cable. The analysis shows that ICCP can effectively inhibit the corrosive effect of steel wires and cables, and reduce the loss of mechanical properties of steel wires. Its protective efficiency increases with an increase in the absolute value of its protective potential and decreases with an increase in the dead load level. ICCP has a blocking effect on the diffusion of corrosion factors in the cable space, and the corrosion spatial distribution range, corrosion factor concentration, and diffusion coefficient of the initial damaged cable decrease significantly with the increase in the absolute value of the protection potential. The open circuit potential moves in a positive direction with the development of the corrosion process, and the blocking effect of corrosive factor diffusion is transformed from the joint participation by sacrificial anode cathodic protection and ICCP to the dominance of ICCP.

Shedding Light on the Failure Factors of Subsea Critical Fastener Bolts

Offshore facilities, such as oil and gas rigs, wind turbines, and related subsea equipment, typically use flanges fastened using bolts and nuts as the main connectors. In this study, multidisciplinary parameters, namely the preload torque used to tighten bolts, simulated subsea water currents, water temperature, and impressed current cathodic protection, were applied to ASTM A193 B7 bolts. An experimental supervisory control and data acquisition system was designed to obtain measurements every 5 min throughout a 21-day experiment. Finite element analysis was performed to predict the structurally vulnerable areas of the bolts. A strong correlation was found between the reference electrode readings and the measured electrical current, tightening torque, and water temperature. As the water temperature rises during the day, the reference electrode reading becomes less negative and the electrical current decreases. Subsea water currents cause about a four-time increase in the bolt corrosion rate, with unprotected bolts suffering a nine-time-higher corrosion rate than protected bolts. A unique supply–demand interaction is observed; less protection is supplied to areas with lower corrosion rates (lower demand for protection). Finally, scanning electron microscopy examination reveals new insights into the failure mechanisms of subsea bolts.

Anticorrosion Method Combining Impressed Current Cathodic Protection and Coatings in Marine Atmospheric Environment

In this study, a new anticorrosion method combining impressed current cathodic protection (ICCP) with coatings that can be applied to marine atmospheric environments is proposed. As the corrosion medium fills the cracks and pores of the coating, an electrolyte film layer is inevitably formed on the metal surface. Therefore, a graphene conductive coating with excellent chemical inertness and shielding performance is selected as the intermediate coating to form an electrolytic cell system with a metal substrate serving as the cathode and a graphene coating serving as the auxiliary anode. By studying the surface corrosion morphologies and electrochemical signals of the coating samples at different protection potentials and coating thicknesses, the optimal potential is determined to be 0.6 V, and the optimal coating thickness is determined to be 20 μm. The samples protected by the joint method have lower corrosion rates and better anticorrosion performance than those protected by the coatings alone.

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.

Comparative study of special iron-silicon-chromium alloy electrode (FeSiCr) and Zinc electrode (Zn)

Corrosion is an oxidation-reduction reaction that occurs mainly in metals in contact and with different potential energies, both subjected to an environment conducive to the circulation of electrons or ions. A widely used method for protecting metals is cathodic protection, which can be galvanic cathodic protection or impressed current cathodic protection. The structure to be protected by cathodic protection is called the cathode and the other metal that will suffer the sacrifice of donating electrons and being worn out is the anode, normally called the sacrificial anode. There are several types of materials that are used as anodes. Zinc (Zn) is a metal highly recommended as an anode for protecting vessels due to its ease of installation and maintenance. Another material used in cathodic protection as an anode is Iron-Silicon-Chrome (FeSiCr), which is a special alloy, considered inert. Comparing the Zn electrode with the FeSiCr electrode for cathodic protection of buried steel pipes, it can be concluded that the FeSiCr electrode is more efficient. The most relevant factor when comparing the two electrodes in the same condition is their material loss rate.

Efficiency of the Impressed Current Cathodic Protection (ICCP) in reinforced concretes: Experimental and numerical investigation

In the present work, the efficiency of the Impressed Current Cathodic Protection (ICCP) applied to reinforced concretes is investigated. A comprehensive approach, combining experimental and numerical methodologies, is employed. The investigation focuses on a simplified system, represented by a reinforced concrete slab subjected to accelerated corrosion.Experimental tests are conducted to evaluate the initial condition of the system and subsequently examine different ICCP scenarios. Various parameters are considered, including the spatial arrangement of reference electrodes and activated titanium anodes, as well as the applied current intensity. The outcomes of these experiments are carefully analyzed to assess the influence of these parameters, and the results are presented for in-depth discussion.Finally, a theoretical model based on electrochemical interactions between the steel and the concrete is developed thanks to virtual work principle. Applied to the system under study, the predictions of the model are shown to give satisfactory results when compared to experimental data, demonstrating its reliability.

Application of impressed current cathodic protection on chain structure: An experimental study combined with COMSOL simulation

Corrosion protection of mooring chain is difficult but of great significance to guarantee the security of deep-sea operation. In consideration of the advantages and limitation of impressed current cathodic protection (ICCP), the feasibility of ICCP application on chain structure was studied through physical experiments combining with COMSOL simulation. The influence of electrical continuity on the protection potential distribution was investigated by potential measurement and numerical simulation. It was demonstrated that the conductivity was the key factor restricting the successful application of ICCP on the chain structure. With improved electrical continuity, the surface potential distribution of the chain structure under ICCP was uniform with a difference less than 12 mV, and the 90-day corrosion rate significantly reduced by 94.8% compared with that without ICCP. Furthermore, the quantitative formula of the relationship between the critical conductivity required for ICCP and the chain diameter was determined to be σc = 0.015d2 + 0.65d + 10.49. The effect of corrosion time and auxiliary anode distance on the potential distribution was also investigated. This work might provide new idea for the corrosion protection of mooring chain and provide reference for the design of mooring chain with improved possibility in corrosion protection.