Migrating Corrosion Inhibitor Research Articles

Determination of the ability of migrating steel corrosion inhibitors to passivate corroding reinforcement in reinforced concrete structures

Introduction. The corrosion condition of steel reinforcement in reinforced concrete structures and products is the main factor determining their bearing capacity and durability. The alkalinity of the pore liquid of concrete (at pH > 11.8) in reinforced concrete structures and products under normal conditions ensures the passive state of steel reinforcement. In the presence or when chloride, sulfate and other analogous ions enter the concrete, the steel reinforcement of reinforced concrete structures and products depassives, despite the pH value > 11.8, and begins to corrode. In addition, depassivation and subsequent corrosion of steel reinforcement occur during carbonation (neutralization) of the protective layer of concrete due to a decrease in pH < 11.8. One of the promising options for slowing down or stopping the corrosion processes of steel reinforcement is currently the use of migrating corrosion inhibitors.
 
 The aim of the work was to obtain experimental data on the ability of migrating steel corrosion inhibitors to inhibit or completely stop the corrosion of reinforcement in reinforced concrete structures and products initiated by the presence of chloride ions (Cl-) in concrete or neutralization of the protective layer of concrete in relation to steel reinforcement.
 
 Materials and methods. The following types of migrating steel corrosion inhibitors were used for testing:
 
 – Cortec MCI-2020 (manufacturer – KORTEK RUS (KORTEK) LLC, suppliers – Ettrilat LLC, MONUMENT LLC);
 
 – IFKHAN-80 (manufacturer and supplier – IFKHAN LLC);
 
 – Basf Master-Protect 8000 CI (former name Protectosil ® CIT. Suppliers – MBS Construction Systems LLC, MPKM LLC, LKM-FLEET LLC).
 
 The determination of the ability of migrating steel corrosion inhibitors to inhibit or completely stop the corrosion of reinforcement was carried out by accelerated electrochemical research methods in accordance with State Standard 31383-2008 "Protection of concrete and reinforced concrete structures from corrosion. Test methods".
 
 Results. All three types of migrating steel corrosion inhibitors inhibit corrosion of steel reinforcement initiated by the presence of chloride ions in concrete by the age of 90 days. All three types of migrating steel corrosion inhibitors by the age of 30 days do not inhibit the corrosion of steel reinforcement initiated by concrete carbonation.
 
 Conclusions. According to the results of the work, it was revealed that the migrating steel corrosion inhibitors inhibit the corrosion of steel reinforcement initiated by the presence of chloride ions in concrete, while the corrosion initiated by the carbonation of concrete is not slowed down or stopped by migrating steel corrosion inhibitors.

On the depth of penetration of migrating corrosion inhibitor Haenytex Protectoseal CI into concrete

On the depth of penetration of migrating corrosion inhibitor Haenytex Protectoseal CI into concrete

Smart Inhibition Action of Amino Acid-Modified Layered Double Hydroxide and Its Application on Carbon Steel.

Surface impregnation of concrete structures with a migrating corrosion inhibitor is a promising and non-invasive technique for increasing the lifetime of existing structures that already show signs of corrosion attack. The main requirement for inhibitors is their ability to diffuse the rebar at a sufficient rate to protect steel. The use of smart nanocontainers such as layered double hydroxides (LDH) to store corrosion inhibitors significantly increases efficiency by providing an active protection from chloride-induced corrosion. The addition of LDH to reinforced mortar can also improve the compactness and mechanical properties of this matrix. Here, we report the synthesis of a magnesium-aluminum LDH storing glutamine amino acid as a green inhibitor (labeled as Mg-Al-Gln), which can be used as a migrating inhibitor on mortar specimens. The corrosion behavior of the specimens was determined via electrochemical techniques based on measurements of corrosion potential and electrochemical impedance spectroscopy. A cell containing a 3.5% NaCl solution was applied to the mortar surface to promote the corrosion of embedded rebars. The specimens treated with Mg-Al-Gln presented an improved corrosion protection performance, exhibiting an increase in polarization resistance (Rp) compared to the reference specimens without an inhibitor (NO INH). This effect is a consequence of a double mechanism of protection/stimuli-responsive release of glutamine and the removal of corrosive chloride species from the medium.

Inhibition resistance and mechanism of migrating corrosion inhibitor on reinforced concrete under coupled carbonation and chloride attack

Corrosion of steel bars in the marine environment is an important reason to reduce the service life of reinforced concrete structures. In this study, an amino alcohol migrating corrosion inhibitor (MCI) was coated on the concrete surface, which was then subjected to a simulated marine atmospheric environment by carbonation and salt spraying. The carbonation depth, chloride concentration of concrete, electrochemical performance of steel bars and mass loss rate of steel bar were determined to evaluate the corrosion inhibition performance of MCI. NELD-BS610 hardened concrete bubble spacing coefficient analyzer and scanning electron microscopy (SEM) were applied to analyze the pore structure parameters in concrete and the corrosion behavior of steel bar, respectively. The test results showed that MCI could alleviate the deterioration of concrete induced by accelerated carbonation and chloride attack, and delay the carbonation effect. After 7 days of accelerated carbonation and 35 days of chloride attack, the carbonation depth and chloride concentration of concrete coated with MCI were 16.07% and 16.93% lower than those of concrete uncoated with MCI, respectively. MCI could migrate to the steel bar surface of steel bar to form a protective film, significantly improving the electrochemical performance of the steel bar, and the inhibition efficiency of MCI was about 66.07 ∼ 97.91%. Besides, MCI could also reduce the mass loss rate of steel bars and porosity of concrete induced by carbonation and chloride attack. For the specimens coated with MCI, the mass loss rates of steel bar decreased by 20.31 ∼ 39.78%, and pores with sizes of 1.0 ∼ 0.2 μm in concrete reduced by 59.10 ∼ 76.38%. The results of this research are purposeful for alleviating the corrosion damage problems of reinforced concrete in marine areas.

Influence of migrating inhibitor concentration on corrosion resistance of steel reinforcement in concrete

To increase the service life and durability of reinforced concrete structures, new technologies have been developed, such as cathodic protection, re-alkalinization, chloride extraction, and the use of corrosion inhibitors. This study evaluated the influence of cement type, concrete cover thickness, and the addition of organic migrating corrosion inhibitor (MCI) on the corrosion resistance of the embedded steel in concrete against the induced action of chloride ions. To accomplish this, corrosion tests were carried out using electrode potential techniques simultaneously with acceleration cycles of chloride attack. Four mixtures with two levels of reinforcement cover (25 and 40 mm) were subjected to 30 weekly cycles of chemical attack: a reference mixture (without inhibitor) and three others adopting concentration levels of 0.30%, 0.45%, and 0.60% of MCI in the volume of concrete. The concrete properties (compressive strength, voids, specific gravity, and water absorption by immersion and capillarity) were verified. In the corrosion tests on reinforced concrete with lower cover thickness, the mixture with 0.60% MCI addition showed the best results: corrosion potential values less negative than -200 mV, with less than 10% probability of corrosion.

Effect of corrosion inhibitor on service life of cracked and non-cracked concrete

Corrosion of steel in reinforced concrete structures can cause damage and costs involved and attracts researchers to look for solutions that delay the onset of corrosion initiation or slow its development. The effectiveness of four corrosion inhibitors in cracked and non-cracked sections of reinforced concrete was studied: Migrating Corrosion Inhibitor (MCI-2005) based on amine carboxylate; CNCI 1.37 based on calcium nitrite Ca (NO)2 at a concentration of at least 30%; and two lab-made green corrosion inhibitors based on recycled materials – fluorosilicates obtained from fluorosilicic acid (H2SiF6), the by-product of the phosphate industry, and from LABS (Linear Alkyle Benzene Sulphonate), the by-product of the detergent industry. The study followed the guidelines of the ASTM G-109 standard which examines materials intended to inhibit chloride-induced corrosion of steel in concrete, and the ASTM C-876 standard which evaluates the electrical corrosion potential of uncoated reinforcing steel, for the purpose of determining the corrosion activity of the reinforcing steel. Controlled artificial cracks of different depth were created to speed up the corrosion process in the steel. Such cracks allowed a direct penetration of chlorides into the depth of concrete. As was expected, the cracked concrete samples exhibited a significantly higher level of corrosion than the non-cracked samples. In the non-cracked samples, the effectiveness of the CNCI 1.37 commercial corrosion inhibitor was the highest. However, in the cracked samples it appears that its efficiency has decreased, while the recycled corrosion inhibitor based on K2SiF6 has shown the best performance. This result can be explained by the fact that fluorosilicate reacts with calcium hydroxide present in concrete and creates a non-permeable protective layer that inhibits the movement of chlorides to the steel bar.

The equivalent quantization method of corrosion damage of reinforcement cage for concrete beam and its durability in island and reef environment

• The equivalent quantization method of corrosion damage of concrete beam was proposed and verified. • Effects of four factors with twelve levels on durability of concrete beam were studied. • Three types of self-produced protective materials were tested. • The relation between the linear polarization resistance and electrochemical impedance spectroscopy methods was established. The electrochemical measurement technique was used to conduct a non-destructive test the corrosion degree of reinforcement cage for concrete beam in tidal environment of island and reef region in real-time. Apart from this, the corrosion resistance of concrete beam with different concrete strength grades, steel bar, darex and migrating corrosion inhibitors, including three types of self-produced protective materials, was studied. Furthermore, based on electrochemical parameters, the relation of electrochemical measurement techniques was established. The results showed that the proposed equivalent quantization method of corrosion damage could be available for the reinforcement cage in concrete beam. In addition, the durability of concrete beam in tidal environment of island and reef region can be effectively improved by improving the concrete strength grade and the corrosion resistance of steel bar and using darex and migrating corrosion inhibitors. The polarization resistance obtained by the linear polarization resistance method and charge transfer resistance obtained by the electrochemical impedance spectroscopy method were linear. This study provides a key technology for actual reinforcement corrosion in concrete structure and some protective measures.

Modeling of Chloride Binding Capacity in Cementitious Matrices Including Supplementary Cementitious Materials

The improvement in the chloride binding capacity of concrete has been shown to increase corrosion resistance. The addition of supplementary cementitious materials (SCMs) to Portland cement has been proven to increase the binding capacity, except for silica fume, whereas the impact of chemical additives is not extensively addressed in the literature. This work studies the influence of SCMs and chemical additives, i.e., calcium nitrite inhibitor (CNI), migrating corrosion inhibitor (MCI), and Caltite as a hydrophobic material, on binding capacity. The addition of both corrosion inhibitors (MCI and CNI) has minimal effect on the binding capacity, while the addition of Caltite reduces the binding capacity by limiting the contact of the samples with the salt in water due to its hydrophobic nature. In addition, the study compares the performance of the available fitting–binding models against the available experimental work in the literature, and shows that the Freundlich isotherm is the best fitting model for describing the relationship between the binding capacity and the free chloride. The study further relates the binding capacity to different compositions in cement and SCMs, and shows, by conducting quantitative analysis, that the Al2O3 content is the dominant factor affecting the binding capacity. Finally, this work proposes a new model, which uses Al2O3 content and free salt concentration to predict the bound chloride. The model shows adequate correlations to the experimental work and, further, can be used in service-life modeling of concrete.

АНАЛІЗ ЕФЕКТИВНОСТІ ЗАСТОСУВАННЯ МІГРУЮЧИХ ІНГІБІТОРІВ КОРОЗІЇ (МІК) ДЛЯ ПІДВИЩЕННЯ ЕКСПЛУАТАЦІЙНОЇ ДОВГОВІЧНОСТІ ЗАЛІЗОБЕТОНУ

Currently, concrete and reinforced concrete structures are an indispensable component of any construction. However, during operation due to the active influence of aggressive components of the atmosphere and the environment, there is a destruction of the protective layer of concrete and corrosion of metal reinforcement.The porous structure of cement stone, which is the basis of concrete, determines the degree of its hydration and, accord-ingly, penetration into it together with moisture aggressive components of the environment (various chlorides, sulfates, carbon dioxide, etc.). The latter leads to a change in the pH of the pore fluid and the development of low destructive processes in the structure of the concrete and metal reinforcement.The detailed analysis of the situation showed that the most favorable conditions, in terms of complete coverage in scien-tific journals, have developed around primary corrosion protection of reinforced concrete structures, which consists in the use of corrosion inhibitors (substances based on various amino compounds, salts of benzoic acids and nitrites of benzoate compo-sitions) at the stage of manufacturing reinforced concrete structures and products from them. The secondary protection of reinforced concrete structures that have been in operation for some time with the use of migrating inhibitor mixtures with good passivation ability and diffusion permeability is less studied, but very relevant.However, to date, there is still no systematic material on the mechanism of their protective action and the effective ratio of molar concentrations of their individual components despite the large number of publications on thedevelopment of migrat-ing corrosion inhibitors as corrosion protection of reinforcing elements of reinforced concrete structures,.In this regard, the purpose of this work is to determine the mechanism for ensuring effective corrosion resistance of metal elements of reinforced concrete structures with the use of migrating corrosion inhibitors.It is shown that the effectiveness of migrating corrosion inhibitors will be determined not only by the nature of its com-ponents, but also by the ratio of concentrations of its passivators of anodic and cathodic reactions, as well as the adsorption component. Monoethanolamine and triethanolamine have been found to be typical surfactants with low surface tension with a satisfactory ability to passivate cathodic reactions, while NaNO2 serves as a passivator for the anodic reaction of steel ioni-zation. The results show that the most effective anticorrosive effect is provided by mixtures with equal ratio of concentrations of adsorption and corrosion inhibiting components (15TEA + 15NaNO2 and 15MEA + 15NaNO2, respectively).Thus, research in the field of corrosion protection of reinforced concrete structures that have been in operation for some time has identified promising ways to develop migratory corrosion inhibitors, mainly related to the creation of synergistic composite compounds that will contain adsorption and passivation components. The effectiveness of inhibitory compositions, which include surfactants based on amine-type compounds, which in combination with sodium nitrites are able to penetrate into the pores of cement stone, reaching the metal reinforcement to inhibit both existing corrosion centers and prevent its occurrence in the future.

Corrosion Inhibition Mechanism of Steel Reinforcements in Mortar Using Soluble Phosphates: A Critical Review.

The corrosion inhibition mechanism of soluble phosphates on steel reinforcement embedded in mortar fabricated with ordinary Portland cement (OPC) are reviewed. This review focuses soluble phosphate compounds, sodium monofluorophosphate (Na2PO3F) (MFP), disodium hydrogen phosphate (Na2HPO4) (DHP) and trisodium phosphate (Na3PO4) (TSP), embedded in mortar. Phosphate corrosion inhibitors have been deployed in two different ways, as migrating corrosion inhibitors (MCI), or as admixed corrosion inhibitors (ACI). The chemical stability of phosphate corrosion inhibitors depends on the pH of the solution, H2PO4− ions being stable in the pH range of 3–6, the HPO42− in the pH range of 8–12, while the PO43− ions are stable above pH 12. The formation of iron phosphate compounds is a thermodynamically favored spontaneous reaction. Phosphate ions promote ferrous phosphate precipitation due to the higher solubility of ferric phosphate, thus producing a protective barrier layer that hinders corrosion. Therefore, the MFP as well as the DHP and TSP compounds are considered anodic corrosion inhibitors. Both types of application (MCI and ACI) of phosphate corrosion inhibitors found MFP to present the higher inhibition efficiency in the following order MFP > DHP > TSP.

Study on the durability improvement of cracked concrete based on bidirectional electromigration rehabilitation

In order to study the effect of Bidirectional Electromigration (BIEM) in cracked coastal concrete, the influence of the relative position and width of a crack on chloride removal and corrosion inhibition was ascertained through numerical simulation and experimental research. The results showed that, in the power-on state, the current in the crack was higher than that on other positions, leading to current concentration effect. If the BIEM technique was applied, the steel bar corrosion potential in cracked concrete could be restored to a high level. The width of a transverse crack had no significant influence on the corrosion potential restoration, while a longitudinal crack had better corrosion potential restoration effect as the cracks became wider. When the crack width was less than 0.1 mm, BIEM presented a similar chloride removal and corrosion inhibition effect to that in the uncracked concrete. If more than 0.1 mm, the efficiency of removing chloride ions and migrating corrosion inhibitor in the crack increased with the crack width, but decreased on the positions far from the crack.

Corrosion of steel bar in carbonated concrete treated with realkalisation and inhibitor

The combination of realkalisation and migrating corrosion inhibitor (MCI) was proposed as a protective technique for structures subjected to carbonation-induced corrosion; the effects on passivated steel bars in partly carbonated concrete were investigated. The corrosion behaviours of treated steel bars under three exposure conditions (natural indoor environment, accelerated carbonation and simulated carbonated concrete pore solution) were examined and the effects of amino-alcohol-based and amino-carboxylate-based MCIs were compared. The surface morphology of steel bars was observed by scanning electron microscopy, which indicated that MCIs could be adsorbed on the bar surfaces. Moreover, potentiodynamic polarisation curves were obtained and electrochemical impedance spectroscopy was performed. Results corresponding to a natural indoor environment and accelerated carbonation showed that current would destabilise the passivated steel bars but that the corrosion resistance of treated steel bars was significantly enhanced. According to the results in simulated carbonated concrete pore solution, the corrosion behaviour of steel bar was related to the type of MCI and the treatment parameters. Compared with amino-carboxylate-based MCI, the adsorption of amino-alcohol-based MCI was more stable although it was weakened with a decrease in pH. In general, treatment by realkalisation and MCI is more effective than simple application of realkalisation or MCI.

Structure, dynamics and transport behavior of migrating corrosion inhibitors on the surface of calcium silicate hydrate: a molecular dynamics study.

The incorporation of a corrosion inhibitor into a cement-based material can enhance the durability of the reinforced concrete. In this study, molecular dynamics simulation is utilized to study the interfacial structure and dynamic behavior of a solution with three migrating corrosion inhibitors (MCI) functionalized by hydroxyl (-OH), carboxyl (-COO-), and phenyl (-PH) groups in calcium silicate hydrate (CSH) gel pores. The transport rate of inhibitors is greatly dependent on the polarity of the functional group: -PH > -OH > -COO-. The slow migration rate of the inhibitor with -OH and -COO- is attributed to the chemical bond formed between CSH and MCI. The silicate chains near the CSH surface can provide plenty of non-bridging oxygen sites to accept the H-bond from the hydroxyl group in the inhibitor molecule. The surface calcium atom can capture the -COO- by forming an ionic COO-Ca bond. Furthermore, the hydration structure of the inhibitor molecule also influences its transport properties. The inhibitor functionalized by the carboxyl group, associating with the neighboring water molecules, forms ion-water clusters, and the inhibitor molecule and its hydration shell with a long resident time retard the migration rate. Hopefully, this study is able to provide molecules for the development of a migration-type corrosion inhibitor to elongate the service life of cement-based materials.

Effects of corrosion inhibitor and functional components on the electrochemical and mechanical properties of concrete subject to chloride environment

This study aims to solve the long-term durability issues regarding chloride-induced corrosion of concrete structures. The electrochemical methods were used to investigate the anticorrosion performance of migrating corrosion inhibitor (MCI-0), and the axial compression and electric flux of high performance concrete with different mix formulations incorporating inhibitor, nano-components and functional components were performed. The results showed that the corrosion resistance of steel rebar greatly was improved with the addition of inhibitor. Meanwhile, the corrosion inhibitor revealed a satisfactory electrochemical performance, and the polarization potential of reinforced bar maintained stable when ≥2% of the inhibitor was added to the concrete. While the dosage of nano-components (i.e., nano-SiO2) reached 2%, the strength and electric flux of concrete can meet the performance requirements. And the mechanical and electrochemical properties of reinforced concrete were effectively improved when the electric flux was less than 1000 Coulombs with 15% of compound functional components included. However, the electric flux dropped significantly while mineral admixtures and corrosion inhibitor were incorporated simultaneously, and they present a synergistic effect on the durability of concrete. In view of the field marine environment exposure test in splash zone, the addition of 20% nano-modified cementitious material can improve the strength of concrete and the resistance to chloride ions penetration within samples, indicating the corrosion inhibitor and functional components are promising and applicable in marine engineering.

Corrosion of the infrastructure migrating corrosion inhibitors, “green” bio based technology to extend durability of new and existing infrastructure

Corrosion of embedded steel is a leading cause of deterioration in reinforced concrete structures. While concrete mix designs have become more durable, the possibility of cracking due to shrinkage, movement, or other forces is a consideration when designing for long service life. In addition, preserving integrity and extending the useful service life of existing structures is of paramount importance. Migrating, organic corrosion inhibitors have been used for more than 30 years in construction applications as an economical method of corrosion mitigation. Migrating corrosion inhibitors, based on organic amines have become available with the claimed advantage that, as well as being capable of application as admixtures, they may be applied as remedial agents to the surface of the concrete. This paper will give details on the chemistry of organic corrosion inhibitors, test methods used to assess the efficacy of migrating corrosion inhibitors in concrete and their performance in new construction, repair and specialty applications.

Mass transfer analysis considering gas phase diffusion and experimental verification for surface painting a waterborne MCI in concrete

The mass transfer numerical model including the long-term gas phase diffusion of a waterborne migrating corrosion inhibitor (MCI, named PCI-2016) in concrete was investigated in this study. The PCI-2016 was prepared by using multi-compound and chelate-induced techniques. The concentrations of nitrogen in different thickness of cover concrete after surface-painted different amounts of PCI-2016 were calculated by this mass transfer model. The calculated data were basically consistent with the nitrogen contents tested by Kjeldahl method at interface between steel bar and mortar matrix. To verify the anticorrosion performance of painting PCI-2016 steel bars bedded in mortar specimens containing different content of NaCl painted with relevant amounts of PCI-2016 were also investigated by the linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). The results revealed that the I corr of steel bar in the specimen containing 1.25% NaCl (wt. to cement) after painting with 5 g PCI-2016 for 3 days and 28 days decreased from 0.67 μA·cm –2 (before painting) to 0.25 μA·cm –2 and 0.06 μA·cm –2 , respectively. The numerical analysis and test results supported that the gas phase transfer model is suitable to calculate the weight of PCI-2016 at the interface zone between steel bar and concrete, and the painted the certain amounts of PCI-2016 on the surface of mortar could show an identified repairing effect on the corrosive steel bar.

Evaluation of the effectiveness of migrating corrosion inhibitors and hydrophobizers for protection against corrosion of steel reinforcement in concrete using bimetallic batch sensor

Evaluation of the effectiveness of migrating corrosion inhibitors and hydrophobizers for protection against corrosion of steel reinforcement in concrete using bimetallic batch sensor

Innovative Techniques/Technologies to Enhance the Durability of Civil Infra Structures PART 2: Corrosion Protection Techniques/ Technologies

Background: The durability of civil infrastructures is a severe problem faced by Scientists, Engineers and Technologies of 21st Century, due to the increasing pollution of our environments. This paper deals with innovative corrosion protection techniques/technologies to enhance the durability of civil infrastructures. Corrosion resistant rebars manufactured using Cu, P, Ni and Cr are capable of bearing the humid conditions of the coastal areas. TATA TISCON 500D rebars de-signed with diminished levels of impurities like S and P showed better corrosion resistance properties. Compared to CTD rebars, TMT rebars with tempered martensite zone showed improved corrosion re-sistance properties. Cement based coated steel rebars (inhibited cement slurry coated, cement polymer composite coated rebars) found to be more compatible for reinforcement corrosion control, in compari-son to galvinized and epoxy coated rebars. Fly ash, slag or silica fume, blended cements are finer as compared to OPC. The fineness reduced the permeability of blended cement concrete and improved the durability. Ternary blended cements, due to the fineness of the material and increased alumina, silica contents showed improved mechanical properties and better protection for steel in concrete. Owing to the unique molecular structure and high ion exchange capacity, chloride scavengers reduced the corro-sion susceptibility. Epoxy-polyurethane based surface coatings enhanced the durability as barrier type of coatings. Corrosion inhibiting admixtures such as calcium nitrite, citrate and stannate due to the for-mation of an insoluble film enhanced the corrosion resistance properties of reinforcements. Migrating corrosion inhibitors (MCI) based on amino alcohol, amines and nitrites showed superior corrosion resistance properties when compared to admixed inhibitor systems. Depending upon the environmental conditions, the implementation of corrosion protection technologies definitely enhanced the durability of civil infrastructures. Methods: The durability of the civil infrastructures such as National Highway Bridges, Nuclear Reactors, Elevated water tanks, On-shore and Off-shore concrete structures will be enhanced by adopting Innovative Corrosion protection Techniques/ Technologies such as i) Corrosion resistant rebars, ii)Coatings to steel rebars, iii) Blended cements, iv) Chloride scavengers for marine structures and v) Corrosion inhibiting admixtures for fresh structures. For existing structures, the following innovative technologies such as i). Coatings to concrete surface ii). Migrating corrosion inhibitors will be implemented. Results: After adopting the appropriate innovative corrosion protection techniques/technologies, the effect of treated structures will be monitored by conducting NDT techniques. Conclusion: Each and every innovative corrosion protection techniques/technologies have its own merits, demerits and limitations. Proper selection of method of corrosion protection strategies depending upon the environmental conditions can only lead to saving of money and enhancing the durability of civil infrastructures. In order to enhance the service life of civil infrastructures, it is essential to provide additional protective measures. Keywords: Protection strategies, corrosion resistant steel rebars, coatings to steel rebars, blended cements, admixtures, migrating corrosion inhibitors, chloride scavengers, repair/renovation strategy.

Influence of reinforcement mesh configuration for improvement of concrete durability

Steel bar in concrete structures under harsh environmental conditions, such as chlorine corrosion, seriously affects its service life. Bidirectional electromigration rehabilitation (BIEM) is a new method of repair technology for reinforced concrete structures in such chloride corrosion environments. By applying the BIEM, chloride ions can be removed from the concrete and the migrating corrosion inhibit can be moved to the steel surface. In conventional engineering, the concrete structure is often configured with a multi-layer steel mesh. However, the effect of the BIEM in such structures has not yet been investigated. In this paper, the relevant simulation test is carried out to study the migration law of chloride ions and the migrating corrosion inhibitor in a concrete specimen with complex steel mesh under different energizing modes. The results show that the efficiency of the BIEM increases 50% in both the monolayer steel mesh and the double-layer steel mesh. By using the single-sided BIEM, 87% of the chloride ions are removed from the steel surface. The different step modes can affect the chloride ion removal. The chloride ions within the range of the reinforcement protective cover are easier to be removed than those in the concrete between the two layers of steel mesh. However, the amount of migrating corrosion inhibitor is larger in the latter circumstances.

The use of a Phosphate-Based Migrating Corrosion Inhibitor to Repair Reinforced Concrete Elements Contaminated by Chlorides

The use of sodium monofluorophosphate (MFP) was experimented as migrator inhibiting treatment against corrosion of reinforced concrete elements induced by chlorides. The results show that sodium monofluorophosphate, applied by surface impregnation, is able to slow down reinforcement corrosion only for reinforcing steel bars with concrete cover not thicker than 1 cm. This limitation is most probably due to the difficulty, with the type of application adopted, in making MFP to reach concentrations high enough to inhibit the corrosive process at greater depths from the impregnation surface.