Service Life Extension Of Virginia Bridge Decks Afforded By Epoxy Coated Reinforcement
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| Author | : MC. Brown |
| Publisher | : |
| Total Pages | : 13 |
| Release | : 2006 |
| Genre | : Concrete |
| ISBN | : |
A study was conducted on concrete core samples each containing a single top-mat reinforcing steel bar from ten bridge decks in Virginia. Two of the bridges contained conventional, uncoated mild reinforcing steel (Bare), and eight of the bridges were constructed with epoxy-coated reinforcement (ECR). The bridges ranged in age from 4 to 18 years, and were built under same specifications for concrete water-to-cement ratio (w/c) and cover depth. In the laboratory, the subject cores were prepared and corrosion activity was monitored via electrochemical impedance spectroscopy while subject to cyclic ponding of a 3 % NaCl solution over a 22-month exposure period. The relative corrosion performance of the Bare and ECR bars were evaluated, by comparison of the time to corrosion initiation and time to failure, as designated by visible cracking of the concrete cover. A stochastic model was employed, using bootstrap resampling techniques, to project the corrosion protection service life extension provided by epoxy-coated reinforcement as compared to Bare steel for the population of Virginia bridge decks. Less than 25 % of all Virginia bridge decks built under specifications in place since 1981 were projected to corrode sufficiently to require rehabilitation within 100 years, regardless of bar type. The corrosion service life extension attributable to ECR in bridge decks was found to be approximately 5 years beyond that of Bare steel.
| Author | : Michael Carey Brown |
| Publisher | : |
| Total Pages | : 63 |
| Release | : 2003 |
| Genre | : Concrete bridges |
| ISBN | : |
The corrosion protection service life extension provided by epoxy-coated reinforcement (ECR) was determined by comparing ECR and bare steel bars from 10 Virginia bridge decks built between 1981 and 1995. The objective was to determine the corrosion protection service life time extension provided by ECR field specimens with various degrees of coating adhesion: disbonded, partially disbonded, and wholly bonded coatings. The size and length distributions of cracks in Virginia bridge decks were investigated to assess the frequency and severity of cracks. Correlation of cracks with chloride penetration was used to characterize the influence of cracking on deck deterioration. Cracks influence the rate of chloride penetration, but the frequency and width distributions of cracks indicate that cracks are not likely to shorten the overall service life of most bridge decks in Virginia. Altogether, 141 drilled cores, 102 mm (4 inches) in diameter, were employed in this study. For each of the decks built with ECR, 10 to 12 cores were drilled through a top reinforcing bar adjacent to the previous study core locations. In addition, approximately 3 cores were drilled through a top reinforcing bar at a surface crack location. Laboratory testing involved nondestructive monitoring using advanced electrochemical techniques to periodically assess the corrosion state of the steel bars during cyclic exposure to chloride-rich solution over 36 months of treatment. Time of corrosion initiation and time of cracking (where applicable), as well as chloride content of the concrete before and after treatment, were used in the analysis. Analysis of the epoxy coating after treatment showed the presence of micro cracks in the surface of some coatings, and moisture uptake and glass transition temperatures, as related to curing of the coatings, were investigated. Less than 25 percent of all Virginia bridge decks built under specifications in place since 1981 is projected to corrode sufficiently to require rehabilitation within 100 years, regardless of bar type. The corrosion service life extension attributable to ECR in bridge decks was found to be approximately 5 years beyond that of bare steel and, therefore, ECR is not a cost-effective method of corrosion prevention for bridge decks. Deleting the requirement for ECR in decks would save Virginia approximately $845,000 per year.
| Author | : Raman Singh |
| Publisher | : John Wiley & Sons |
| Total Pages | : 448 |
| Release | : 2019-04-09 |
| Genre | : Technology & Engineering |
| ISBN | : 1118350057 |
A comprehensive text to the non-destructive evaluation of degradation of materials due to environment that takes an interdisciplinary approach Non-Destructive Evaluation of Corrosion and Corrosion-assisted Cracking is an important resource that covers the critical interdisciplinary topic of non-destructive evaluation of degradation of materials due to environment. The authors—noted experts in the field—offer an overview of the wide-variety of approaches to non-destructive evaluation and various types of corrosion. The text is filled with instructive case studies from a range of industries including aerospace, energy, defense, and processing. The authors review the most common non-destructive evaluation techniques that are applied in both research and industry in order to evaluate the properties and more importantly degradation of materials components or systems without causing damage. Ultrasonic, radiographic, thermographic, electromagnetic, and optical are some of the methods explored in the book. This important text: Offers a groundbreaking interdisciplinary approach to of non-destructive evaluation of corrosion and corrosion-assisted cracking Discusses techniques for non-destructive evaluation and various types of corrosion Includes information on the application of a variety of techniques as well as specific case studies Contains information targeting industries such as aerospace, energy, processing Presents information from leading researchers and technologists in both non-destructive evaluation and corrosion Written for life assessment and maintenance personnel involved in quality control, failure analysis, and R&D, Non-Destructive Evaluation of Corrosion and Corrosion-assisted Cracking is an essential interdisciplinary guide to the topic.
| Author | : |
| Publisher | : |
| Total Pages | : 38 |
| Release | : 2000 |
| Genre | : Concrete bridges |
| ISBN | : |
In this study, the corrosion protection performance of epoxy-coated reinforcing steel (ECR) was evaluated using approximately 250 concrete cores from 18 bridge decks in Virginia. The decks were 2 to 20 years old at the time of the investigation. The deck field inspections included a crack survey and cover depth determination in the right traffic lane. A maximum of 12 cores with the top reinforcement randomly located in the lowest 12th percentile cover depth were taken from each bridge deck. Because of the safety concerns associated with taking cores from the lower steel mat, and to minimize damage to the bridge, a maximum of only 3 cores were taken through the truss bars. The laboratory evaluation of the concrete cores included a visual examination and a determination of the carbonation depth, moisture content, absorption, percent saturation, and chloride content at a 13-mm depth. The rapid chloride permeability test was also performed for the surface and base concrete on samples obtained from the cores taken through the truss bars to determine chloride permeability. The ECR inspection consisted of a visual examination, a damage evaluation, and a determination of coating thickness and adhesion. The condition of the steel underneath the epoxy coating was also evaluated. Adhesion loss of the epoxy coating to the steel surface was detected in all but one deck that was 4 years old and older. The epoxy coatings were debonding from the reinforcing bars. Whereas a bonded coating can be expected to protect the steel, a debonded coating allows chlorides, moisture, and oxygen to reach the steel and initiate a rapid corrosion mechanism. Reinforcing bars in various stages of adhesion loss showed visible signs of a corrosion process underneath the coating, suggesting that ECR will provide little or no additional service life for concrete bridge decks in comparison to bare steel. Other systems that will provide longer protection against chloride-induced corrosion of the reinforcing steel with a higher degree of reliability should be considered.
| Author | : Yunping Xi |
| Publisher | : |
| Total Pages | : 166 |
| Release | : 2004 |
| Genre | : Concrete bridges |
| ISBN | : |
Corrosion of reinforced concrete structures has been a significant problem for many state and transportation agencies since the application of deicing salts was introduced. Much research has been conducted to develop corrosion protection systems that can prolong the life span of reinforced concrete structures. The Colorado Department of Transportation (CDOT) has several routine and experimental measures to prevent corrosion of the rebar including epoxy-coated rebar, calcium nitrite admixture, organic corrosion inhibitors, a thick cover of quality concrete, and a waterproofing membrane covered by an asphalt overlay. An extensive literature review was performed to collect information on various corrosion protection systems that have been used in the U.S. and around the world. Current CDOT practices in terms of corrosion protection measures were reviewed. A draft inspection plan for Colorado's bridge structures was proposed.
| Author | : W. Pyc |
| Publisher | : |
| Total Pages | : 4 |
| Release | : 2000 |
| Genre | : Concrete bridges |
| ISBN | : |
| Author | : J. L. Smith |
| Publisher | : |
| Total Pages | : 100 |
| Release | : 1996 |
| Genre | : Bridges |
| ISBN | : |
Epoxy coated rebar (ECR) was introduced in the mid 1970s as a means to minimize concrete deterioration caused by corrosion of the reinforcing steel and to extend the useful life of highway structures. This report summarizes the results of investigations performed by highway agencies in the United States and Canada, academia, and the Canadian Strategic Highway Research Program to evaluate the performance of ECR. A total of 92 bridge decks, two bridge barrier rails, and one noise barrier rail was evaluated in the States of California, Indiana, Kansas, Michigan, Minnesota, New York, Ohio, Pennsylvania, Virginia, West Virginia, and Wisconsin, and the provinces of Alberta, Nova Scotia, and Ontario.
| Author | : Han-Ching Wu |
| Publisher | : |
| Total Pages | : 262 |
| Release | : 1999 |
| Genre | : |
| ISBN | : |
Concrete bridge decks subjected to corrosive environment, due to the application of de-icing chemical, could deteriorate at a rapid rate. In an effort to minimize corrosion of the reinforcement and the corresponding delaminations and spalls, the Iowa Department of Transportation (IADOT) started using epoxy-coated rebars (ECR) in the top mat of reinforcing around 1976 and in both mats about 10 years later. The ultimate objective of this research was to determine the impact of deck cracking on durability and estimate the remaining functional service life of a bridge deck. The overall objectives of this work were obtained by conducting a literature review, visually inspecting several bridge decks, collecting and sampling test cores from cracked and uncracked areas of bridge decks, determining the extent to which epoxy coated rebars deteriorate at the site of cracks, and evaluating the impact of cracking on service life.
| Author | : Soundar S. G. Balakumaran |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2019 |
| Genre | : Bridges |
| ISBN | : |
Overlaying bridge decks has remained one of the best rehabilitation methods to extend their service life, and the Virginia Department of Transportation (VDOT) has been a leader in the use of bridge deck overlays. Although VDOT has extensive experience in overlays, the long-term performance of overlays has not been entirely understood. One of the biggest challenges for studying the performance of overlays is that only minimal information is available in bridge inventory and inspection records. This limits any scientific assessment of this system. Therefore, the purpose of this study was to provide a strong framework for the understanding of the long-term performance of overlays and the factors affecting them. This Phase II report reports on an extensive data collection process that led to the development of a robust database of 133 overlaid bridge decks after verification of historical inspection reports, verification of as-built plans and communication with VDOT district bridge engineers. This helped in developing a model for understanding the amount of time it takes for bridge decks to require the first major rehabilitation and the major factors influencing the durability. A database of information about overlays that were replaced at the end of their functional service life was compiled. This helped develop a multiple regression model for understanding the factors that affected the durability of overlays. Survival analyses were conducted to estimate the service life of overlays and corresponding risk. As a preventive method, epoxy concrete (EC) overlays were predicted to serve an average of 20.9 years, with 18 to 22 years at a 95 percent confidence level. As a rehabilitative method, rigid concrete overlays were predicted to serve an average of 25.9 years, with 21 to 32 years at a 95 percent confidence level. The recent trend of preferred overlay types has been identified as EC and very-early- strength latex-modified concrete (VELMC) overlays. EC overlays have proven to be one of the better performing overlays through extensive VDOT experience. VELMC overlays are an improvement upon latex-modified concrete overlays by vastly reducing the time of construction and thus become more suitable for decreased construction time, reduced traffic disruption, and lessened worker exposure to the field environment. An important discovery was the identification of the influence of the degree of deck damage prior to overlaying on the service life of overlays. Preventive EC overlays should be used in a preventive sense, as the name suggests. If preventive EC overlays are installed on bridge decks with spalls, patches, or delaminations, irrespective of the amount of damage, an increased rate of deterioration in the overlays is likely to follow. The future performance of rehabilitative overlays such as latex-modified concrete, silica fume, and VELMC overlays will not be influenced by the presence of bridge deck damage prior to overlaying. This might be because of the removal of deteriorated concrete before these rigid overlays are constructed. This emphasizes the importance of proper removal of poor quality concrete from bridge decks before overlaying during rehabilitation.
| Author | : |
| Publisher | : |
| Total Pages | : 37 |
| Release | : 1997 |
| Genre | : Concrete bridges |
| ISBN | : |
