Corrosion Protection Performance of Corrosion Inhibitors and Epoxy-coated Reinforcing Steel in a Simulated Concrete Pore Water Solution PDF Download
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Author: Wioleta A. Pyć
Publisher:
ISBN:
Category : Epoxy coatings
Languages : en
Pages : 58
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Book Description
We used a simulated concrete pore water solution to evaluate the corrosion protection performance of concrete corrosion-inhibiting admixtures and epoxy-coated reinforcing bars (ECR). We evaluated three commercial corrosion inhibitors, ECR from three coaters removed from job sites, one ECR shipped directly from the coater's plant, and one ECR removed from a job site plus a corrosion inhibitor. The corrosion inhibitors were calcium nitrite, an aqueous mixture of esters and amines, and a mixture of alcohol and amine. Corrosion protection performance was based on the amount of visually observed corroded surface area. For bare steel tested with and without corrosion inhibitors, corrosion increased with increasing chloride concentration, and specimens saturated with oxygen were more corroded than specimens saturated with breathing air. The amount of corrosion over the 90-day test period was controlled by the amount of oxygen in solution at the higher chloride concentrations. The ester-amine and alcohol-amine did not inhibit corrosion. Calcium nitrite inhibited corrosion at all levels of chloride concentration. For ECR, corrosion occurred both at sites where the coating was damaged and underneath the coating. Coating debondment was greatest in pore water solutions containing chloride. The least coating debondment and corrosion occurred in the solution containing calcium nitrite and the ECR shipped directly from the manufacturer. Coating debondment and corrosion of ECR are directly related to the amount of damage as holes; mashed, dented, and cracked areas; and holidays. The researchers recommend that the developed test method be adopted as a standard test for concrete corrosion inhibitors and that calcium nitrite remain the only concrete corrosion inhibitor approved for use in Virginia.
Author: Wioleta A. Pyć
Publisher:
ISBN:
Category : Epoxy coatings
Languages : en
Pages : 58
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Book Description
We used a simulated concrete pore water solution to evaluate the corrosion protection performance of concrete corrosion-inhibiting admixtures and epoxy-coated reinforcing bars (ECR). We evaluated three commercial corrosion inhibitors, ECR from three coaters removed from job sites, one ECR shipped directly from the coater's plant, and one ECR removed from a job site plus a corrosion inhibitor. The corrosion inhibitors were calcium nitrite, an aqueous mixture of esters and amines, and a mixture of alcohol and amine. Corrosion protection performance was based on the amount of visually observed corroded surface area. For bare steel tested with and without corrosion inhibitors, corrosion increased with increasing chloride concentration, and specimens saturated with oxygen were more corroded than specimens saturated with breathing air. The amount of corrosion over the 90-day test period was controlled by the amount of oxygen in solution at the higher chloride concentrations. The ester-amine and alcohol-amine did not inhibit corrosion. Calcium nitrite inhibited corrosion at all levels of chloride concentration. For ECR, corrosion occurred both at sites where the coating was damaged and underneath the coating. Coating debondment was greatest in pore water solutions containing chloride. The least coating debondment and corrosion occurred in the solution containing calcium nitrite and the ECR shipped directly from the manufacturer. Coating debondment and corrosion of ECR are directly related to the amount of damage as holes; mashed, dented, and cracked areas; and holidays. The researchers recommend that the developed test method be adopted as a standard test for concrete corrosion inhibitors and that calcium nitrite remain the only concrete corrosion inhibitor approved for use in Virginia.
Author:
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 96
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Book Description
Eleven systems combining epoxy coated reinforcement with another corrosion protection system are evaluated using the rapid macrocell, Southern Exposure, cracked beam, and linear polarization resistance tests. The systems include bars that are pretreated with zinc chromate to improve the adhesion between the epoxy and the reinforcing steel; two epoxies with improved adhesion to the reinforcing steel; one inorganic corrosion inhibitor, calcium nitrite; two organic corrosion inhibitors; an epoxy coated bar with a primer containing microencapsulated calcium nitrite; the three epoxy coated bars with improved adhesion combined with the corrosion inhibitor calcium nitrite; and multiple coated bars with an initial 2 mil coating of 98 percent zinc and 2 percent aluminum followed by a conventional epoxy coating. The systems are compared with conventional uncoated reinforcement and conventional epoxy coated reinforcement. The results presented in this report represent the findings obtained during the first half of a 5 year study that includes longer term ASTM G 109 and field tests. In the short term tests used to date, the epoxy coatings evaluated provide superior corrosion protection to the reinforcing steel. The results also indicate that the bars will continue to perform well in the longer term, although the tests do not evaluate the effects of long term reductions in the bond between the epoxy and the reinforcing steel. The corrosion rate on the exposed regions of damaged epoxy coated reinforcement is somewhat higher than the average corrosion rate on the surface of uncoated reinforcement subjected to similar exposure conditions. The use of concrete with a reduced water cement ratio improves the corrosion performance of both conventional and epoxy coated reinforcement in uncracked concrete but has little effect in cracked concrete. Increased adhesion between the epoxy and reinforcing steel provides no significant improvement in the corrosion resistance of epoxy coated reinforcement. It appears that corrosion inhibitors in concrete and the primer coating containing microencapsulated calcium nitrite improve the corrosion resistance of the epoxy coated steel in uncracked concrete, but not in cracked concrete. The zinc coating on the multiple coated bars acts as a sacrificial barrier and provides some corrosion protection to the underlying steel in both uncracked and cracked concrete. The degree of protection, however, cannot be evaluated based on the results available to date.
Author: Asko Sarja
Publisher: RILEM Publications
ISBN: 9789517584081
Category : Building materials
Languages : en
Pages : 584
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Book Description
Author: Jerzy Zemajtis
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 80
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Book Description
Corrosion inhibitor admixtures (CIA) and galvanized reinforcing steel (GS) are used for the corrosion protection for reinforced concrete bridges. The results of a 3.5-year evaluation of exposure specimens containing CIA from three different manufacturers and GS are presented. The specimens were built to simulate four exposure conditions typical for concrete bridges located in the coastal region or inland where deicing salts are used. The exposure conditions were Horizontal, Vertical, Tidal, and Immersed Zones. The specimens were kept inside the laboratory and were exposed to weekly ponding cycles of 6% sodium chloride solution by weight. The methods used to assess the condition of the specimens included chloride concentration measurements, corrosion potentials, and corrosion rates. Additionally, visual observations were performed for identification of rust stains and cracking on concrete surfaces. The results of chloride testing indicate that the amount of chlorides present at the bar level is more than sufficient to initiate corrosion. Chloride and rapid permeability data indicate no significant difference either in a rate of chloride ingress or in the diffusion coefficients for concretes with and without CIA. Corrosion potentials were the most negative for the Bare Steel (BS) specimen prepared with the Armatec 2000 corrosion inhibitor and generally indicated a 90% probability of active corrosion. Corrosion potentials were similar for the two BS control specimens and the BS specimen prepared with Rheocrete 222 and generally indicated an uncertain probability of corrosion. Corrosion potentials were the least negative for the BS specimen prepared with DCI-S corrosion inhibitor and generally indicated a 90% probability of no corrosion. Rate of corrosion measurements were the highest for the BS control specimens and the one prepared with A2000 and the most recent data suggest corrosion damage in 2 to 10 years. Although early rate of corrosion measurements were higher or about the same as for BS control specimens, recent measurements were slightly lower for the specimen prepared with Rheocrete 222 and suggest corrosion damage in 10 to 15 years. Rate of corrosion measurements were consistently the lowest for the BS specimens prepared with DCI-S and indicate corrosion damage is expected in 10 to 15 years. The corrosion potential and rate of corrosion data indicate that DCI-S is the only CIA evaluated that clearly provides some level of corrosion protection. A direct comparison of the GS specimens to the BS specimens is not possible because the measured potential refers to the zinc oxide and not to the steel. Nevertheless, the potential data agree with the chloride and permeability data, as well as with the visual observations, and indicate the damaging effect of a high concentration of chloride ions on the GS. At low and moderate chloride exposures, however, GS does provide corrosion protection. Recommendations are to continue monitoring until sufficient cracking has occurred in all specimens to provide for making a better estimate of the service lives of CIA and GS used in the construction of concrete bridge components in Virginia. The specimens with CIA and one control (continuous reinforcement in the legs) should be taken to the Hampton Road North Tunnel Island and placed in the brackish water to a depth of the Immersed Zone at low tide for further exposure to chloride. The specimens with GS and the other control (non-continuous reinforcement in the legs) should remain in an outdoor exposure in Southwest Virginia like the Civil Engineering Materials Research Laboratory in Blacksburg, Virginia.
Author: El Kacimi, Younes
Publisher: IGI Global
ISBN: 1799827771
Category : Technology & Engineering
Languages : en
Pages : 304
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Book Description
Metals are used at an extremely high rate in the industrial and manufacturing fields. Exemplary properties including strength and ductility have made this material highly dynamic; however, the risk of corrosion remains a vital issue. The study of corrosion prevention has attracted interest from researchers and professionals as new technologies are emerging that can assist in the prevention of material destruction. However, research is lacking on the application of these protective technologies within specific fields. New Challenges and Industrial Applications for Corrosion Prevention and Control provides emerging research exploring the theoretical and practical aspects of protective methods against corrosion and the implementation of these techniques within a wide span of professional disciplines. Featuring coverage on a broad range of topics such as molecular modeling, surface treatments, and biomaterials, this book is ideally designed for engineers, industrial chemists, material scientists, researchers, engineers, academicians, practitioners, and students seeking current research on the technological advancements in corrosion protection in various professional scopes.
Author: fib Fédération internationale du béton
Publisher: fib Fédération internationale du béton
ISBN: 2883940894
Category : Technology & Engineering
Languages : en
Pages : 123
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Book Description
It has long been recognised that corrosion of steel is extremely costly and affects many industry sectors, including concrete construction. The cost of corrosion of steel reinforcement within concrete is estimated at many billions of dollars worldwide. The corrosion of steel reinforcement represents a deterioration of the steel which in turn detrimentally affects its performance and therefore that of the concrete element within which it has been cast. A great amount of work has been undertaken over the years concerning the prevention of corrosion of steel, including the application of coatings, which has included the study of the process of corrosion itself, the properties of reinforcing steels and their resistance to corrosion as well as the design of structures and the construction process. The objective of fib Bulletin 49 is to provide readers with an appreciation of the principles of corrosion of reinforcing steel embedded in concrete and to describe the behaviour of particular steels and their coatings as used to combat the effects of such corrosion. These include galvanised reinforcement, epoxy coated reinforcement, and stainless reinforcing steel. It also provides information on the relative costs of the materials and products which it covers. It does not deal with structure design or the process of construction or with the post-construction phase of structure management including repair. It is hoped that it will nevertheless increase the understanding of readers in the process of corrosion of reinforcing steels and the ability of key materials and processes to reduce its harmful effects.
Author: Brian D. Chambers
Publisher:
ISBN:
Category : Corrosion and anti-corrosives
Languages : en
Pages : 68
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Book Description
The corrosion of reinforcing steel in concrete is estimated to affect more than 50% of the 575,000 bridges in the United States. One approach to mitigating this problem is to use corrosion-inhibitive compounds admixed into the concrete paste. This study sought to examine the corrosion inhibition performance of a series of compounds admixed into high-quality concrete and to delineate the effects of these compounds on the concrete with regard to the corrosion process. A series of eight compounds were admixed into Type A4 concrete. The compounds tested were aminoethylethanolamine, aminothiophenol, di-sodium Beta-glycerophosphate, calcium nitrite, di-n-butyl sulfoxide, lithium nitrate, sodium metasilicate, and nitrilotriphosphonic acid. Concrete blocks were cast, into which were placed 0.009-in.-diameter 1040 steel wires. The corrosion rate was assessed via a resistance change measurement (RCM) of these wires over time using a temperature-corrected four-point resistance measurement. The time-to-open circuit for the wires was also monitored. RCM was compared to (1) electrochemical impedance spectroscopy results of tests conducted in a simulated pore solution, and (2) chloride permeability measurements of the concrete as per ASTM C 1202. The effect of the admixtures on the compressive strength and density of the concrete was also assessed. RCM and time-to-open circuit results showed that four test inhibitors had equal or better corrosion prevention at 2 years of testing compared to a widely used commercial mix (DCI). These test inhibitors included di-sodium Beta-glycerophosphate (0.283 mol/cu ft and 0.815 mol/cu ft), aminoethylethanolamine (0.815 mol/cu ft), lithium nitrate (0.815 mol/cu ft), and sodium metasilicate (0.815 mol/cu ft). After 100 weeks, 33% to 44% of the wires were active in concrete admixed with these test compounds, whereas only 25% of the wires were active in concrete admixed with DCI. This research has also shown that the performance of a corrosion inhibitor in high-quality concrete is a function of numerous interrelated factors that are not predicted from any single laboratory test. These tests provide promising results for alternative inhibitive admixtures for standard Type A4 concrete. It is recommended that additional tests be conducted on concrete mixtures containing slag and fly ash using multiple concentrations of the four most promising inhibitors. Further testing may lead to the implementation of a better corrosion-inhibiting admixture, thus increasing the service life of bridges.
Author:
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages :
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Book Description
The application of a mineral admixture or a combination of a mineral admixture with corrosion inhibitor are the methods used for the corrosion protection for reinforced concrete bridges. The results of a 1.5-year study on evaluation of three concretes with fly ash, slag cement (SC), and silica fume (SF) and one concrete with silica fume and a corrosion inhibitor (SFD) are presented. The specimens were built to simulate four exposure conditions typical for concrete bridges located in the coastal region or inland where deicing salts are used. The exposure conditions were horizontal, vertical, tidal, and immersed zones. The specimens were kept inside the laboratory and were exposed to weekly ponding cycles of 6% sodium chloride solution by weight. In addition, cover depth measurements from 21 bridge decks and chloride data from 3 bridge decks were used, together with laboratory data, in modeling the service lives of investigated corrosion protection methods. The methods used to assess the condition of the specimens included chloride concentration measurements, corrosion potentials, and corrosion rates (3LP). Additionally, visual observations were performed for identification of rust stains and cracking on concrete surfaces. The results of chloride testing indicate that the amount of chlorides present at the bar level is more than sufficient to initiate corrosion. Chloride and rapid permeability data demonstrate that for low permeable (LP) concretes there appears to be significant difference both in a rate of chloride ingress and in the diffusion coefficients in comparison to the controls. Corrosion potentials agree with corrosion rates and suggest the possibility of an active corrosion process development on control specimens during indoor exposure. The structural cracks that were observed in some specimens appeared to have no influence on the corrosion development on the bars in the vicinity of the these cracks. It was concluded that the silicone and duct tape protection was adequate. The cracking, other than structural, appeared to be related to the reinforcing steel corrosion, except the cracks in the horizontal zone of the specimen with slag cement which were probably caused by the subsidence cracking. The least number of cracks was observed on the SF and SFD specimens. Modeling the time as a function of probability of the end of functional service life (EFSL) was presented. It has been shown that the distributions of surface concentrations of chloride ions (C0) and diffusion constants (Dc) are key elements in the model. Model predictions show that the LP concretes provide much better level of protection against moisture and chlorides than the A4 concrete alone. Application of a corrosion inhibitor causes an elevation of the chloride threshold resulting in an additional increase in time to EFSL. Recommendations are to continue monitoring until cracking has occurred in all specimens to a greater extent to better estimate the service lives of LP concretes than is presently known in the construction of concrete bridge components in Virginia. The specimens with LP concretes and one control (continuous reinforcement in the legs) should be taken to the Hampton Road North 1 Tunnel Island and placed in the brackish water to a depth of the immersed zone at low tide for further exposure to chloride. The other control (non-continuous reinforcement in the legs) should remain in an outdoor exposure in Southwest Virginia like the Civil Engineering Materials Research Laboratory in Blacksburg, Virginia. Also more field studies are needed to better estimate distributions of surface chloride concentration and diffusion coefficient of Virginia bridge decks, and to confirm predicted times to EFSL for LP concretes.
Author: M Raupach
Publisher: Woodhead Publishing
ISBN: 1845692284
Category : Technology & Engineering
Languages : en
Pages : 337
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Book Description
Given the widespread use of reinforced concrete in infrastructure, understanding the corrosion of this material is of major importance. As a result there has been a wealth of research into catalysts, inhibitors and effective means of monitoring the rate of corrosion. Corrosion of reinforcement in concrete: mechanisms, monitoring, inhibitors and rehabilitation techniques summarises some of the most significant research and its implications.The book begins by reviewing findings from various experiments designed to test the corrosion rate of metals induced by a range of factors. Later chapters discuss techniques for monitoring and testing for corrosion. The book concludes by assessing important methods of prevention, including corrosion inhibitors, protective coatings and electrochemical methods for protection, together with rehabilitation procedures for susceptible structures.Filled with practical examples and written by a distinguished team of international contributors, Corrosion of reinforcement in concrete: mechanisms, monitoring, inhibitors and rehabilitation techniques is an essential reference for civil engineers using reinforced concrete. Summarises research into catalysts, inhibitors and effective means of monitoring the rate of corrosion Concludes by assessing important methods of prevention
Author: Adrienne Accardi
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
ABSTRACT: This investigation is an examination of the behavior of dual coated reinforcing steel (DCR) with defects in the polymer coating exposing the only zinc layer in simulated concrete pore solution with and without chlorides. The intentional defects simulated the condition typically experienced by the rebar in service. Specimens were tested at open circuit potential, +100 mV, -500 mV, and -1000 mV for 30 to 100 days. The results were compared with that from previous DCR investigation with to-steel defects and epoxy-coated rebar (ECR). DCR with to-zinc defects had extensive corrosion damage when under strong anodic polarization and exposed to chlorides and was similar to that seen for DCR with to steel defects. The freely corroding (OCP) to-zinc DCR specimens in solutions both with and with no-chlorides experienced initially very active dissolution which ended after ~1 day. The zinc exposed at the coating breaks was not completely consumed even after 100 days and there was no visible corrosion product accumulation. This may be due to the formation of a calcium hydroxyzincate passive film and shows that the zinc passivates in alkaline solutions without the benefit of a crevice environment. The DCR with to-steel defects and the DCR with to-zinc defects had similar amounts of disbondment for all test conditions. Notable disbondment was seen only in highly anodic polarization regime with chlorides and was due to large amounts of solid corrosion product formation. These results suggest then that the overall process of zinc wastage in DCR in concrete pore water is not likely to be rapid, which would be beneficial to extending the period in which the barrier and galvanic properties of the zinc are maintained.
