Performance of Epoxy-coated Reinforcing Steel in Highway Bridges PDF Download
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Author: Kenneth C. Clear
Publisher: Transportation Research Board
ISBN: 9780309053709
Category : Bridges, Iron and steel
Languages : en
Pages : 164
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Book Description
Author: Kenneth C. Clear
Publisher: Transportation Research Board
ISBN: 9780309053709
Category : Bridges, Iron and steel
Languages : en
Pages : 164
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 94
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Book Description
The primary function of an epoxy coating is to act as a barrier to prevent corrosion-causing chloride ions and oxygen from reaching steel surfaces. For more than a decade, epoxy-coated reinforcing steel has generally been effective in reducing or preventing chloride-induced corrosion in bridges and other concrete structures. Recently, however, instances of corrosion problems or premature failures in Florida, Oregon and New York have focussed attention on the product and its quality. This report was initiated as a result of the questions raised by these failures. In the first section of the report, a state of the art review of epoxy-coated reinforced steel is presented. It details the research performed on epoxy coating, and the results of this research both in the lab and in the field. As well, the authors highlight several areas to be considered for future investigation. The second section examines the fundamentals of epoxy, and the coating process. It provides an overview of the theory, technology, testing and practice as these presently exist for fusion bonded epoxy coatings on steels. The significance of the tests available for use on epoxy-coated rebars and epoxy-coated pipe is described. The report contains numerous figures.
Author: Kenneth C. Clear
Publisher:
ISBN: 9781895102901
Category : Epoxy coatings
Languages : en
Pages : 94
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Book Description
The primary function of an eposy-coating is to act as a barrier to prevent corrosion-causing chloride ions and oxygen from reaching steel surfaces. For more than a decade, epoxy-coated reinforcing steel has generally been effective in reducing or preventing chloride-induced corrosion in bridges and other concrete structures. Recently, however, instances of corrosion problems or premature failures in Florida, Oregon and New York have focussed attention on the product and its quality. This report was initiated as a result of the questions raised by these failures.
Author: Richard E. Weyers
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 32
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Book Description
From 1992 to 2006, the Virginia Transportation Research Council and its contract researchers conducted a long-term systematic series of investigations to evaluate the corrosion protection effectiveness of epoxy-coated reinforcement (ECR) and to identify and recommend the best and most cost-effective corrosion protection system for Virginia bridge decks. This report summarizes this research and subsequent efforts to implement alternative reinforcement. The work was conducted, and is reported, in this general order: review of historical performance of ECR, ECR performance in solutions and concrete, and preliminary field investigations; investigation of field performance of bridge decks built with ECR; assessment of alternative corrosion protection methods; development of probabilistic service life models for bridge decks and laboratory assessment of ECR cores extracted from bridge decks to determine service life extension; efforts to implement alternative reinforcement. The series of studies demonstrated that the epoxy coating on ECR naturally degrades in the highly alkaline moist environment within concrete. The subsequent loss of bond, coupled with the inevitable flaws in the coating induced by construction, leads to an estimated service life benefit of ECR of as little as 3 to 5 years. Further, non-critical decks, beams, and substructure elements not exposed to marine environments, particularly on secondary and rural routes, can be cost-effectively constructed and maintained using low-permeability concrete and black reinforcing bar. However, because the Federal Highway Administration requires the use of corrosion-resistant reinforcement, and because ECR cannot provide adequate corrosion protection for structures designed for a 100-year+ service life as currently recommended by FHWA, the report recommends that the Virginia Department of Transportation amend its specifications regarding the use of ECR to require the use of corrosion-resistant metallic reinforcing bars such as MMFX2, stainless steel clad, and solid stainless steel.
Author: S. Ray Taylor
Publisher:
ISBN:
Category : Epoxy coatings
Languages : en
Pages : 66
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Book Description
Epoxy coating is widely used to mitigate the access of chloride ions to the surface of a rebar. However, corrosion at the point of physical defects in the coating necessitates rehabilitation. Based on its effectiveness in mitigating corrosion of uncoated rebars, we examined cathodic protection (CP) as a method for rehabilitating epoxy-coated rebars (ECR). Although it is well established that cathodic polarization of epoxy coatings on steel in aqueous conditions leads to disbondment of the coating, neither the conditions that lead to this phenomenon nor the actual occurrence of this disbondment process has been determined for ECR in concrete. Since the integrity of the bond between the rebar and the concrete is essential to the composite strengthening by the rebar, the relationships among CP, the integrity of the epoxy coating, and the strength of the rebar/concrete bond must be investigated. The objectives of this study were (1) to determine if CP can effectively mitigate corrosion of coated rebar without adversely affecting the rebar/concrete interface, and (2) to examine the effect of cathodic polarization on the disbonding characteristics of the epoxy coating/rebar interface in concrete. Fifty-five samples of No. 5 ECR with coating defects were exposed to CP. Tensile loading produced splitting failures of all samples. This mode of failure allows greater sensitivity to the contributions of concrete/rebar adhesion and friction than do pullout failures. All electrochemical tests indicated that the cathodic polarization levels and times of application used in this study were effective in preventing corrosion of embedded ECR. An important finding was that the CP protection levels and times had no effect on the splitting failure characteristics based on comparisons of 95 percent confidence intervals. Multiple parameters within the electrochemical impedance spectra indicated that the epoxy coating was delaminating from the steel at the periphery of the defects. This phenomenon was verified in a post mortem analysis of the samples using scanning electron microscopy. The immediate significance of this result is that CP current demands could increase over time. Even though the levels of delamination in this study did not affect mechanical performance, a protective CP level that does not induce film delamination should be explored.
Author: Wallace T. McKeel
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 28
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Book Description
Virginia's first installation of epoxy-coated reinforcing steel, which was opened to traffic in 1977, was evaluated during construction and through 13 years of service. It was apparent at the time of construction that the integrity of the coating application did not meet the requirements of the specifications There were many flaws and holidays in the coatings on all of the bars, and patching with a liquid epoxy compound was not effective. Although the applicability of the findings, which are based on an application that does not represent the best practice, may be limited, useful information on the durability of the coated steel and its role in protecting the deck was developed. It was found that the coated reinforcement was exposed to relatively high chloride concentrations at transverse cracks in the decks early in the life of the structures, but the decks remained in good condition throughout the evaluation period. It was concluded that despite the poor coatings, the coated reinforcing steel contributed to the deck's durability by providing enhanced protection at critical cracked sections. Rebars taken from deck cores showed no signs of rusting, although the steel had a dull dark gray finish that may be underfilm corrosion. No debonding of the coating was evident.
Author: S.Amutha Subramaniam
Publisher:
ISBN:
Category : Corrosion
Languages : en
Pages : 172
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Book Description
The principal cause of degradation of steel reinforced structures is corrosion damage to the rebar embedded in the concrete. The two most common causes of reinforcement corrosion are chloride ions and carbonation. The scale of this problem has reached alarming proportions in various parts of the world. Thus, a lot of money being spent on the rehabilitation of concrete structures i.e. bridges, marine structures etc. In realizing this crucial situation, the corrosion protection methods were emphasized widely in the past. However, the proposed methods somehow failed to be implemented widely due to various factors. Hence this project is trying to look into the potential corrosion protection method on reinforcement steel. Laboratory tests were carried out using small reinforced concrete beam specimens exposed to different corrosive environment namely tap water, chloride, tap water accelerated, marine accelerated and acidic accelerated. Out of total 10 numbers of specimens, 5 specimens contain reinforcement painted with epoxy-coating (Nitoprime Zincrich) having coating thickness of 40 11m. Acceleration tests were carried out on 60% of the specimens to expedite the various environmental effects on the specimens. From the study, it is apparent that coating the reinforcement prior to placing inside concrete plays a key role in protecting the reinforcement from corrosion. However, one needs to study the environment prior to choosing the suitable coating material.
Author:
Publisher:
ISBN:
Category : Cathodic protection
Languages : en
Pages : 67
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Book Description
The purpose of this study was to investigate various epoxy coating and exposure parameters to determine their effects on the corrosion of reinforcing steel. The parameters investigated were: chloride content at the bar depth, coated bar corroded area, corrosion product color under the coating, epoxy coating adhesion, coating color, coating damage (holidays and holes), coating thickness, TGA, DSC and EDS analysis and SEM coating cracking investigation. This study demonstrated that the ECR coating samples extracted from concrete exhibited extensive cracking compared to the new ECR samples in which the coating cracking was limited to only one sample. The coating cracking correlated with the amount of chloride at bar level, residual adhesion of the epoxy to the steel surface, and the percent moisture in the coating. The coating cracking is also related to the change in color of the epoxy and indicates that the epoxy coating degradation in concrete influences the surface condition of the coating. The DSC results showed that both the extracted epoxy coating samples as well as new samples are not fully cured during the manufacturing process. Additionally, the extracted epoxy coated samples investigated presented significant permanent adhesion loss with little or no epoxy coating residue present on the bar surface, while the EDS analysis showed that once adhesion is lost, corrosion will proceed unimpeded under the coating even in the absence of chlorides. The parameters that presented a direct correlation with the observed corrosion activity were the number of holidays and the number of damaged areas per unit length of bar. The results also show a distinct loss of quality control in the handling and possibly storage of new coated bars. The new ECR samples had significantly higher damage density than the samples extracted from concrete, while there was no change in the number of holidays and cure condition.
Author: Kris Peterson
Publisher:
ISBN:
Category : Epoxy coatings
Languages : en
Pages : 36
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Book Description
Author: Seung-Kyoung Lee
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 136
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Book Description
