Corrosion Protection Of Reinforcement Research Articles

EVA enhanced cementitious materials based coatings for the improvement of steel reinforcement corrosion protection performance

EVA enhanced cementitious materials based coatings for the improvement of steel reinforcement corrosion protection performance

In-situ grafted graphene oxide-based waterborne epoxy curing agent for reinforcement corrosion protection of waterborne epoxy coating

Abstract Well-dispersed graphene oxide (GO) in resin matrix has been found for improving corrosion protection performance of the coatings. In this paper, a new strategy relying on waterborne epoxy curing agent contained GO (GO-WCA) was developed, which was prepared via endcapping, modifying and in-situ grafting process. Wherein, endcapping includes blocking the high-activity hydrogen which is used to modulate curing activity. And the modifying process introduces homologous epoxy segment so as to improve compatibility between curing agent, resin matrix and GO. Attributing to this evolvement of WCA and superior barrier effects of GO, the epoxy coatings cured by GO-WCA exhibit desirable corrosion protection capacity. Besides, the failure mode is discovered as bubbling. This environmentally-friendly waterborne curing agent, only with 4.2 g/L VOC content, is anticipated to become available in diverse waterborne epoxy coatings system with excellent barrier property.

Assessment of chloride-induced reinforcement corrosion protection of modified sulfur polymer composites

The present study deals with the corrosion behavior assessment of steel reinforcing bars embedded in modified sulfur polymer-based mortars with and without microfillers. Modified sulfur was used as the primary binder, while silica fume, metakaolin, and fly ash were used as the microfillers in the sulfur polymer composites. The comparison was made with Portland cement mortar (CM). The modified sulfur polymer mortars formulations used were plain sulfur mortars (SM), sulfur-silica fume mortar (SSM), sulfur-metakaolin mortar (SMM), and sulfur-fly ash mortars (SFM). The reinforced samples were exposed to 5% calcium chloride (CaCl2) solution for 52 weeks (~365 days). The corrosion states of rebars embedded in sulfur, as well as Portland cement mortars, were estimated in terms of electrical resistivity (ER), half-cell potentials, corrosion current density based on linear polarization resistance (LPR) test, and visual inspection of steel rebars and mortar samples. Besides, comprehensive analysis based on Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy were also performed on samples collected from the steel-mortar interface of all specimens. The results revealed that the rebars embedded in sulfur-based mortars underwent less corrosion-related deterioration compared to Portland cement mortars. Moreover, the inclusion of microfillers improved the corrosion inhibition performance of sulfur-mortars. Furthermore, deterioration effects were observed to be lower due to improved sorptivity values. The corrosion inhibition effect of mortars was observed to be decreasing in the order SSM > SMM > SM > SFM > CM.

Corrosion protection of reinforcement with phosphate coatings

As a method of protection against corrosion, the application of phosphate coatings to the surface of steel reinforcement before the manufacture of a reinforced concrete product can be considered. The influence of modifiers introduced into the cold phosphating solution on the structure and protective properties of phosphate coatings was studied. It is established that from solutions with the addition of saccharin, glucose, Trilon A, Trilon B and washing preparations, fine crystalline, dense phosphate films are obtained. The introduction of the proposed additives also reduces the time of formation of a phosphate coating on the surface of the steel and leads to a decrease in their porosity. It has been established that phosphate coatings are resistant to the effects of aqueous, salt and acidic environments. Films deposited from modified cold phosphating solutions provide better corrosion protection compared to films obtained from a traditional cold phosphating solution. Presented phosphate coatings have high protective properties, because, due to their lower porosity, they well prevent the penetration of aggressive particles to the surface of the protected reinforcement.

Study of Lower Temperature–Sintered Enamel Coating on Steel Bars: Effect of Coating Cycles

AbstractEnamel coating is a novel type of coating for the corrosion protection of reinforcement in concrete. Recently, improved enamel coating was achieved using low-temperature sintering. This stu...

Corrosion protection of reinforcing steel reinforced concrete structures of transport structures

The influence of reinforcing steel corrosion on the durability of reinforced concrete structures of transport structures and the degree of knowledge of this problem is considered. It is specified that the protection of reinforcing steel from corrosion is not able to completely replace the correct design and use of high-strength concrete. But it is able to extend the life of reinforced concrete structures. It is noted that corrosion of the reinforcement leads to a decrease in the structural strength due to wear and tear and by a third of the period of operation of reinforced concrete structures, as a result of which transport structures collapse. As an example of the detrimental effect of corrosion of reinforcing steel on the durability of transport structures, examples of accidents of bridges and overpasses caused by this type of corrosion are given. As a result, a conclusion is drawn on the advisability of ensuring a sufficient level of corrosion protection of reinforcing steel to achieve the required durability of reinforced concrete structures of transport structures. The types and causes of corrosion processes in reinforcing steel reinforced concrete structures are described. The compositions and technologies of anticorrosive protection are examined and analyzed. Comparison of the compositions of anticorrosive protection of reinforced concrete structures is carried out according to the following criteria: consumption, density, viability, curing temperature and the number of components of the composition. A comparison of anti-corrosion protection technologies is carried out on the basis of the following indicators: line dimensions, productivity and consumption of energy resources. A comparison is also made of the cost of using various anti-corrosion protection technologies. Based on the data obtained, the advantages and disadvantages of the considered compositions and technologies of corrosion protection are determined. As a result, the most effective and technologically advanced method of corrosion protection of steel reinforcement of reinforced concrete structures of transport structures is selected.

Assessment of reinforcement corrosion protection of self-curing concrete

The curing of concrete requires high water demand. In this study reinforcement corrosion protection of self-curing concrete (SC) mixtures incorporating two water-soluble polymers; polyethylene glycol (PEG) and polyacrylamide (PAM) have been evaluated. Durability indices; electrical resistivity, chloride ion penetrability and water permeability, were evaluated and compared to that of control concrete mixture with no self-curing agents under different curing regimes. Reinforcement corrosion monitoring was conducted by exposing reinforced concrete prisms at the age of 28 days to wet-dry cycles for a total period of 96 weeks. In the wetting cycle, the prisms were partially immersed in 5% sodium chloride solution at ambient temperature. The corrosion activity was evaluated by measuring the corrosion potential and corrosion current density. Self-curing concrete mixtures showed better reinforcement protection and durability indices than those of air-cured control mixture. Short water curing period of 3 days significantly improved the reinforcement protection and durability indices of the self-curing concrete mixtures to a level comparable to that of the control mixture that was moist-cured for 28 days. Self-curing concrete represents a step towards a new construction material due to its lower demand for curing water and hence can reserve the limited water resources in many parts of the world.

Maintenance of structural integrity using cathodic protection

Cathodic protection has been applied to reinforced concrete structures in the UK as a reinforcement corrosion protection technique since the 1980s. It is now well established in the toolbox of repair techniques available for chloride-contaminated reinforced concrete structures. Cathodic protection is an ‘active’ technique and includes an ongoing operation and performance-monitoring commitment. The technique works by introducing an anode through which a small direct current is applied to protect the reinforcement. Monitoring is required to ensure that the current is maintained at the correct level to maintain the reinforcement adequately. This paper provides a brief history of the use of cathodic protection on reinforced concrete in the UK, including the trials and subsequent wholesale use of the technique on the Midland Links motorway viaducts. Also described are the operating and performance-monitoring requirements for cathodic protection systems, including the sensors and monitoring and control equipment used. The paper also discusses the use of monitoring data in the management of cathodic protection systems, and the structures to which they are applied, to predict future performance and life, allowing future maintenance interventions to be planned and providing best value for structure owners.

Ground Granulated Blast-Furnace Slag and its Activation Methods

. The ground granulated slag is a wide spread component of various types of cement and binding substances. Its pozzolanic activity depends on different factors. It is searched out, that there are no minerals able to liquid maturing in the slag under consideration, the slag activity data according to domestic and foreign standards specifies it as low-active, third rate. Altering the chemical composition to a small degree, specific to a definite type of slag, does not alter its functioning much. The same stands for the slag dispersiveness at the high rate of amorphous state – the dispersiveness rise increases slag activity and water demand, and more dispersed slag does not increase the resistibility of matrix samples in high-flow concrete mix. Thus, this type of slag is supposed to be grounded up to BET surface area equal to 250-300 m2/kg, compared to dispersive capacity СEM 1, and the substitution of a part of cement by slag would not have a significant ifluence on mix water demand. With the increase in the slag content within the cementing component the slag effectiveness index increases and reaches its maximum at 70% cement replacement by slag. A large portion of slag can substantially decrease the hydration of lime in the hardened cement paste of the concrete and lessen the solidity of reinforcement corrosion protection in concrete structures. The article deals with different methods of ground granulated blastfurnace slag activation within the mixed cementing substance: Portland-cement CEM1 + GGBFS. The most widely used way of activation – the usage of sodium and potassium alkalies and liquid glass is quite effective, but it demands expensive artificial components, while the alkali compounds forming at hardening of such a cementing component would be soluble.

Limestone-filled pozzolanic cement

Fillers are specially selected, natural or artificial inorganic materials, which improve the physico-chemical and mechanical properties of the cement such as workability or water retention. They can be inert or have slightly hydraulic, latent hydraulic or pozzolanic properties. They cause no appreciable increase of the water demand of the cement, in addition to not impairing the resistance of the concrete or mortar to deterioration in any way or reducing the corrosion protection of reinforcement. Fillers are normally either limestone or any inert material such as sand. The aim of this investigation is to study the effect of substitution of limestone for Homra in pozzolanic cement. The effect of limestone replacement was studied by the determination of the combined water, free lime contents, bulk density, total porosity and compressive strength. The results show that the addition of limestone reduces the initial and final setting time, as well as total porosity, whereas the free lime and combined water increase with limestone content. It can be concluded that limestone fills the pores between cement particles due to formation of carboaluminate, which may accelerate the setting of cement pastes.

Corrosion Protection of Reinforcement in Modified High-Alumina Cement Concrete

Corrosion characteristics of reinforcement in modified high-alumina cement (HAC) containing a conversion-preventing additive (CPA) was studied. An investigation was carried out using ordinary Portland cement, high-alumina cement, and modified high-alumina cement. Results including compressive strength, bond strength, porosity. Cl - permeability, and extent of steel bar corrosion are presented. The effect of a deicing salt, calcium chloride, on formation of hydrogarnet and stratlingite in HAC and modified HAC mortars is also reported. This work indicates that HAC mortar, after conversion, is unable to protect the reinforcement from corrosion in an environment containing chloride ions. Conversion-inhibited high-alumina cement has the capability of protecting the reinforcement from corrosion under severe test conditions due to its effective resistance to the penetration of chloride ions.