Corrosion Resistance Of Steel Reinforcement Research Articles

The Influence of Using Recycled Waste Aggregates and Adding TiO2 Nanoparticles on the Corrosion Resistance of Steel Reinforcement Embedded in Cementitious Composite.

The aim of this paper was to examine the effects of adding TiO2 nanoparticles to cementitious compositions and partially substituting natural aggregates with recycled aggregates consisting of glass, brick, slag, or textolite, and to examine the material's ability to resist corrosion under the action of chloride ions existent in the environment that attack the steel reinforcement. The results show that the changes in the cementitious composite when it comes to the composition and microstructure influence the formation of the oxide passivating layer of the reinforcement. The addition of TiO2 nanoparticles and recycled aggregates impacts the kinetics and corrosion mechanism of the reinforcement. An addition of 3% TiO2 was found to be optimal for reinforcement protection. Electrochemical impedance spectroscopy confirmed the results obtained by open-circuit potential and linear polarization tests. The classification of favorable conditions indicates that compositions with recycled aggregates and 3% TiO2 are the most effective, with compositions in which the natural aggregates were partially substituted with slag being the most effective.

Investigating the Synergistic Corrosion Protection Effect of an Alloy Element and Corrosion Inhibitor on Steel Reinforcement Using Machine Learning and Electrochemical Impedance Spectroscopy

Steel reinforcement in marine concrete structures is vulnerable to chloride-induced corrosion, which compromises its structural integrity and durability. This study explores the combined effect of the alloying element Cr and the smart corrosion inhibitor LDH-NO2 on enhancing the corrosion resistance of steel reinforcement. Employing a machine learning approach with a support vector machine (SVM) algorithm, a predictive model was developed to estimate the polarization resistance of steel, considering Cr content, LDH-NO2 dosage, environmental pH, and chloride concentration. The model was rigorously trained and validated, demonstrating high accuracy, with a correlation coefficient exceeding 0.85. The findings reveal that the addition of Cr and application of LDH-NO2 synergistically improve corrosion resistance, with the model providing actionable insights for selecting effective corrosion protection methods in diverse concrete environments.

Improving Corrosion Resistance and Prolonging the Service Life of High-performance Concrete Structures Using Fly Ash and Ground Granulated Blast-furnace Slag

This study investigates the impact of ground granulate blast-furnace slag (GGBFS) and fly ash (FA) on both the corrosion resistance of steel reinforcement, assessed through the accelerated macrocell corrosion test (AMCT), and the durability characteristics of high-performance concrete (HPC). Additionally, the study encompasses an analysis of various concrete properties, including the pH of fresh concrete mixtures as well as water absorption, chloride permeability, and surface resistivity (SR) in hardened concrete specimens. Microstructure analysis on HPC specimens as well as the service life prediction of RCS were also performed in this study. Test results show that the HPC incorporating 35% GGBFS or 35% GGBFS + 20% FA as cement replacement resulted in a lowered pH of fresh mixtures while water absorption and chloride permeability of these specimens increased significantly. In addition, the incorporation of 35% GGBFS or 35% GGBFS + 20% FA concurrently enhanced the SR of HPC specimens. Moreover, these HPC specimens exhibited better corrosion resistance ability as their respective AMCT values were about 1.54 and 1.45 times higher than that of the control specimen. Further, the research highlighted a substantial extension in the corrosion initiation time of concrete structures employing 35% GGBFS or 35% GGBFS + 20% FA, about 3 and 6 times longer than the HPC without GGBFA and FA, respectively. The experimental results, confirmed by the substantial microstructural enhancement in the HPC containing GGBFS and FA, also demonstrated a close interplay between durability and other concrete properties such as water absorption, chloride permeability, and SR.

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.

WHY ARE EPOXY-COATED STEEL REBARS PROHIBITED IN BRIDGE STRUCTURES IN SOME REGIONS?

One of the common ways in many countries to protect steel reinforcement from corrosion in reinforced concrete structures is to cover its surface with a thin layer of epoxy resin. However, in practice, in many cases, the anti-corrosion effect of epoxy coating was not significant, and the durability of reinforced con-crete bridge structures was lower than those where steel reinforcement was not coated with epoxy resin. Ex-perts believe that one of the factors that affects the corrosion resistance of steel reinforcement with epoxy coat-ing in reinforced concrete is the presence of mechanical damage in the epoxy coating of the reinforcing rod, through which moisture can penetrate. Therefore, in some countries, instructions have been developed for the prevention of such damage at the stages of applying an epoxy coating to the armature, its storage, transporta-tion, and construction and assembly work in the manufacture of reinforced concrete structures. This article discusses the thermomechanical mechanism of violation of the internal structural integrity of concrete rein-forced with steel rods with an epoxy coating, which is caused by a high value of its coefficient of linear thermal expansion and the epoxy coating itself. Using the methods of the theory of thermoelasticity, a mathematical model of this phenomenon was developed, a system of solving differential equations was formed, and its solu-tion was constructed. It was established that even with relatively minor temperature changes in the concrete environment in the area of its contact with the reinforcement, cracks and damages occur along the entire length of the steel reinforcement. All this contributes to further destructive processes and reducing the durabil-ity of reinforced concrete bridge structures.

КОМПОЗИТНА АРМАТУРА В БУДІВЕЛЬНІ ГАЛУЗІ:ТЕНДЕНЦІЇ РОЗШИРЕННЯВИКОРИСТАННЯ

Scientific and technical progress largely ensures the production and use of new effective building construction materials with predetermined properties. The article considers the prospects of using a relatively new modern material in construction -composite reinforcement (AC), which has anumber of advantages compared to traditional metal reinforcement and at the same time is characterized by properties that limit its use in the production technology of modern concrete structures. In connection witha number of circumstances associated with the expansion of the operating conditions of reinforced concrete structures in highly aggressive environments, where it is difficult to ensure the corrosion resistance of steel reinforcement, composite reinforcement is used. The prospects of using composite reinforcement in ensuring the dielectric properties of some products and structures are shown. The global experience of using AK is summarized, the modern regulatory framework for its use in modern construction isgiven. It is shown that the use of AK on a par with steel reinforcement according to current standards regarding mechanical, technological and operational properties is sufficient to solve the vast majority of construction tasks. Reasons for the expansion of the use of composite reinforcement,taking into account the high energy intensity of traditional steel reinforcement and the inevitability of reducing greenhouse gas emissions in accordance with Ukraine's international obligations, are given.

Effect of mineral additives on the adherence strength of reinforced concrete with increased corrosion resistance

The purpose of this study was to evaluate the corrosion resistance of steel reinforcement in concrete samples containing modifying additives using an accelerated electrochemical corrosion method. It was found that the adhesion strength between the reinforcement and the cement stone of concrete largely depends on the corrosion resistance of the reinforcement in concrete. At the same time, the best result from the tested concretes was shown by the developed concrete of optimal composition, in which the adhesion strength between concrete and reinforcement is 1.7 times higher than that of control concrete without mineral additives. The obtained results can be explained by the fact that an increase in the density of concrete due to the modification of its structure with organo-mineral additives leads not only to an increase in its strength, but also to a better protection of steel reinforcement in concrete from corrosion. This will help to increase the durability of reinforced concrete structures of offshore hydraulic structures in Vietnam and increase the period of their maintenance-free operation.

The Effect of Mineral Additives on the Corrosion Resistance of Steel Reinforcement in Reinforced Concrete Structures

The Effect of Mineral Additives on the Corrosion Resistance of Steel Reinforcement in Reinforced Concrete Structures

Preparation of inorganic-polymer nano-emulsion inhibitor for corrosion resistance of steel reinforcement for concrete

In this work, the effect of inorganic–organic corrosion inhibitor composition on corrosion inhibition rate was studied through electrochemical accelerated corrosion experiments and ambient atmosphere corrosion experiments. The corrosion inhibitor performance was analyzed to establish the relationship between inhibitor composition, steel temperature, inhibitor temperature, treatment time and corrosion inhibition rate. The effect of nano-emulsion type on the corrosion inhibition rate of reinforcing steel shows that different types of nano-emulsions can increase the self-corrosion potential and reduce the corrosion current of reinforcing steel, improving the corrosion resistance of reinforcing steel. The highest corrosion inhibition rate of 72.1% could be achieved with the addition of fluorocarbon nano-emulsion DF-1 to the corrosion inhibitor. This indicates that among the studied polymer nano-emulsions, fluorocarbon nano-emulsion DF-1 is the best polymer nano-emulsion corrosion inhibitor with a better content of 5%.

Corrosion Processes of Steel Reinforcement in Concrete Structures Based on Secondary Resources of Metallurgical Production

The study of the influence of the physical and mechanical properties of concrete on various hydraulic binders on the corrosion resistance of steel reinforcement has been carried out. As a binder, the following were considered: CEM I 42.5 N and a slag-alkaline binder (SAB) based on ground granulated blast-furnace slag of Novolipetsk Metallurgical Plant (NMP). For comparative tests, concretes of class B 25 (M300) were used on granite aggregate with a fraction of 2,5-7,5 mm. Indicators of physical and mechanical properties such as: compressive strength, porosity, water absorption coefficient and weight loss coefficient of reinforcement at the age of 28, 90 and 180 days are criterial. 5 % aqueous solutions of NaCl, Na2S04 were used as working media in assessing the corrosion resistance of reinforcing steel; MgS04. It has been established that steel reinforcement in slag-base concrete (SBC) has high corrosion resistance, both in an aqueous solution of NaCl and in solutions of Na2S04 and MgSO4. Slag-alkali concretes are characterized by low porosity, lower water absorption coefficient in comparison with concretes based on Portland cement.

The Effect of Shot Blasting Process on Mechanical Properties and Anti-Corrosive Behavior of Steel Reinforcement

The need to confront the problem of corrosion resistance of steel reinforcement is an issue of major importance and a perpetual challenge to the structural integrity and reliability in reinforced concrete (RC) structures. The current experimental study presents the results of the combined effect of shot blasting and coating on steel reinforcing bars in respect to their anticorrosive resistance and their mechanical behavior, at various times of exposure to corrosive environment. In the present manuscript, a comparison of different abrasive materials was primarily conducted, via electrochemical measurements (Tafel tests), to estimate the corrosion current (icorr) for each abrasive material. After the indication that corrosion resistance can be modified by shot blasting with corundum, the method of Zn85Al15 coating was chosen to further investigate the combined effect of shot blasting with coating, in terms of percentage mass loss and mechanical behavior of steel reinforcement. The results demonstrated that, upon the completion of the surface treatment process with corundum, the mechanical performance of steel bars was improved in terms of ductility. Moreover, the Zn85Al15 coating provided a satisfactory anticorrosive protection to steel bars in the entire exposure period of accelerated corrosion. The combined contribution of shot blasting and coating processes was deemed to be very encouraging and may trigger further investigation and research, for the production of a better corrosion resistance of B500c steel.

Electrochemical Investigations of Steels in Seawater Sea Sand Concrete Environments.

Seawater and sea sand concrete (SWSSC) is an environmentally friendly alternative to ordinary Portland cement concrete for civil construction. However, the detrimental effect of high chloride content of SWSSC on the corrosion resistance of steel reinforcement is a concern. This study undertook the electrochemical corrosion behaviour and surface characterizations of a mild steel and two stainless steels (AISI type 304 and 316) in various simulated concrete environments, including the alkaline + chloride environment (i.e., SWSSC). Open circuit potential (OCP), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were employed. Though chloride is detrimental to the corrosion resistance of mild steels, a simultaneous presence of high alkalinity in SWSSC negate the detrimental effect of chloride. In the case of stainless steels, a high level of alkalinity is found to be detrimental, whereas chloride seems to have less detrimental effect on their corrosion resistance.

The Reinforced Concrete Reinforcement Corrosion Degradation Inhibition with Nitrates of Alkali and Alki-Earth Metals

In order to determine the inhibitory additives concentration influence degree on the corrosion degradation rate, we studied the anode behavior of steel reinforcement made of steel grade St3 in a 10% solution NaCl with and without the inhibitors additives of various concentrations. As inhibitory additives, nitrates of potassium, sodium, magnesium, calcium and zinc were introduced into the aggressive environment, since they are often introduced into concrete compositions to accelerate their hardening. Polarization curves have been obtained for steel reinforcement in an aggressive environment, allowing the corrosion rate calculation. It was established that the introduction of potassium and zinc nitrates in an amount of 0.5% into an aggressive environment has the greatest effect on the corrosion processes’ inhibition. When nitrates of alkali and alkali-earth metals are introduced into an aggressive environment, the change in the reinforcing bars mass made of St3 steel occurs 7-8 times slower. Increasing the concentration to 1 and 1.5% is shown to be impractical, due to the small difference in the effect on the reinforcing steel anodic dissolution. A study on the effect of combining inhibitory additives on the corrosion resistance of steel reinforcement in a 10% solution NaCl was made. It was found that the combined action of inhibitors is less effective than the single effect of additives on the corrosion rate.

Corrosion resistance of steel reinforcement in polymer silicate shyngizite concrete

Polymersilicate concrete is used for structures of industrial buildings in many industries, where production processes form an acidic wet- gas operating environment. The lightweight polymer silicate shungizite concrete, proposed by the author for external walls, can also be attributed to these materials. The polymersilicate composition is based on the components of schungite and schungizite. The composition also included liquid glass, sodium silicofluoride and furyl alcohol. These ingredients are usually adopted for polymersilicate concrete. Previously, the author carried out the research of physical and mechanical properties of the composition. The components based on schungite and schungizite were chosen because of their high acid resistance. The issue of the corrosion resistance of reinforcement in light polymer-silicate concrete has not been studied enough. This article presents the results of investigations of the corrosion resistance of steel reinforcement in polymer silicate shungizit concrete. The investigations were carried out in an airy environment of high humidity and in solutions of sulfuric acid of various concentrations. After the established time limits for corrosion testing, the corrosion of reinforcement in samples was not observed. Such a result was obtained due to the dense structure of the material and high acid resistance of the constituent components on the basis of schungite and shungizite. There is no need for additional protection of the concrete surface to prevent corrosion of the reinforcement in it . The author recommends the use of the material for reinforced structures of external walls exposed to an acidic wet- gas operating environment.

Effect of Copper Tailing Content on Corrosion Resistance of Steel Reinforcement in a Salt Lake Environment.

With the increasing proportions of copper tailings of concrete in the Qinghai Salt Lake area of China, there arises the problem of corrosion of steel reinforcement in concrete structures. In this study, we determine the corrosion rate (CR), crack width, and corrosion potential of the steel reinforcement with copper tailing. This was achieved by conducting the constant-current accelerated corrosion test with different proportions of copper tailing in the brine environment of the Qinghai province. The results demonstrate that the corrosion potential (Ecorr) and the passivation area of the polarization curve decrease with the increase in the corrosion time, and the corrosion rate and crack width increase with the increase in the corrosion time. When the corrosion time is the same, the corrosion potential, crack width, and corrosion depth of the reinforcement decrease first and then increase with the increase in the copper tailing powder content. When the copper tailing powder content is 20%, the above parameters reach the minimum value. In the salt lake environment of Qinghai, China, the copper tailing powder content is recommended to be 20%.

Cementitious coatings for improved corrosion resistance of steel reinforcement

The viability of cementitious capillary crystalline waterproofing materials for corrosion protection of steel reinforcing bars for civil engineering infrastructure was evaluated using the half-cell potential method according to ASTM C876. The coatings were characterized by a novel eka-molecular sieve type structure which is breathable yet highly impermeable to water and possesses self-healing characteristics. The test program monitored the corrosion activity of 102 reinforcing bar samples embedded in mortar and immersed in a 3.5% concentration sodium chloride solution for one year. For some samples, the coating was applied directly on the embedded reinforcing bar while for other samples the outside surface of the mortar was coated. Three different types and combinations of coatings were applied. It was found that, in general, the coatings significantly delayed the onset of corrosion compared to the uncoated control samples. Samples that underwent mortar surface coating demonstrated no signs of corrosion after one year of exposure to the chloride solution.

Evaluation of the influence of the pH of concrete pore solution on the corrosion resistance of steel reinforcement

Partial replacement of Portland cement by supplementary cementitious materials results in decreased concentration of calcium hydroxide, leading to a reduction in the pH of the pore solution and influencing the formation of passive films on steel. Decreases in pH are often equated to lower-quality passive films, but, as has been recently shown, that is not always the case. This study evaluates the effect of partial replacement of cement Portland by silica fume, both on the pH of pore solution and corrosion resistance of reinforced concrete. Three concrete mixtures with variations of cement replacement by silica fume (0, 5 and 10% by volume) were produced. Pore solution chemical composition, corrosion current density and polarization resistance were measured up to 91 days. Results show that, especially in early ages—when concrete resistivity remains low and unchanged among the different mixtures tested—partial replacement of cement by silica fume led to an improved passivation process and increased corrosion resistance, even with a related decrease in calcium hydroxide concentration and pH.

The effect of silane-based hydrophobic admixture on corrosion of reinforcing steel in concrete

The influence of a hydrophobic admixture based on silane on the corrosion resistance of steel reinforcement in concrete was studied. Sound or deliberately pre-cracked concrete specimens were manufactured with w/c of 0.45 and 0.80, both in the presence and in the absence of silane. The specimens were fully immersed in a 3.5% NaCl aqueous solution. The results, in terms of electrochemical measurements, visual observations, and weight loss measurements of steel reinforcement, show that silane blocked corrosion process in uncracked concrete specimens. On the other hand, in cracked concrete specimens, corrosion of steel reinforcements was unexpectedly more severe in hydrophobic specimens rather than in the corresponding not hydrophobic ones. It is believed that oxygen, which is needed to feed the corrosion process, diffuses faster in a gaseous phase through the open concrete porosity in the hydrophobic concrete, whereas in concrete without silane, oxygen diffuses much more slowly through the water filling the pores of the saturated concrete.

The effect of thiosemicarbazide on corrosion resistance of steel reinforcement in concrete

This study describes a laboratory investigation of the influence of thiosemicarbazide (TSC) on the corrosion of reinforcing steel and the compressive strength of concrete. The effect of TSC on the corrosion resistance of steel reinforced concrete was evaluated by carrying out electrochemical tests in NaCl and NaCl + TSC solutions for 60 days. Polarisation resistance ( R p) values of TSC added reinforced concrete were much higher than those without TSC. Similarly, AC impedance spectra revealed that the resistance of TSC mixed electrodes were also quite higher than those without. The compressive strength of concrete specimens containing TSC was measured and an increase of 20–25% was observed.

Comparative investigation of corrosion resistance of steel reinforcement in alinite and Portland cement mortars

The corrosion resistance of steel-reinforced mortar specimens made from alinite cement was investigated using ordinary Portland cement (OPC) specimens as reference. The specimens were prepared and exposed in three different environments: continuous exposure in tap water, interrupted exposure in tap water, and interrupted exposure in 3.5% NaCl solution. The steel weight loss and the half cell potential were measured vs. exposure time, up to the age of 12 months. Pore solution extraction and analysis and porosity determination were also performed. In continuous exposure in tap water, alinite cement provided adequate protection against corrosion. In interrupted exposure in tap water, a higher corrosion was observed for alinite cement compared to OPC. In the case of interrupted exposure in 3.5% NaCl solution, the simultaneous action of free chlorides and oxygen resulted in the depassivation of steel reinforcing bars in alinite and Portland cement mortars, and led to severe corrosion effect.