Durability of Concrete Bridge Decks

Durability of Concrete Bridge Decks
Author: National Research Council (U.S.). Transportation Research Board
Publisher: Transportation Research Board National Research
Total Pages: 80
Release: 1979
Genre: Technology & Engineering
ISBN:

"This synthesis will be of special interest and usefulness to bridge engineers and others seeking information on design, construction, and maintenance of bridge decks. Detailed information is presented on the causes, prevention, evaluation, and rehabilitation of deck deterioration related to corrosion of steel reinforcement."--Avant-propos.

Innovations in Bridge Engineering Technology

Innovations in Bridge Engineering Technology
Author: Khaled Mahmoud
Publisher: CRC Press
Total Pages: 302
Release: 2014-04-21
Genre: Technology & Engineering
ISBN: 1482266180

In the last few years, remarkable technological advances have been achieved in bridge engineering technology. These cover a wide spectrum of issues, ranging from design, maintenance, and rehabilitation methodologies to material and monitoring innovations.Within an international framework of exchanging the state-of-the-art in the field of bridge eng

Multiple Corrosion Protection Systems for Reinforced Concrete Bridge Components

Multiple Corrosion Protection Systems for Reinforced Concrete Bridge Components
Author:
Publisher:
Total Pages: 260
Release: 2011
Genre: Concrete bridges
ISBN:

Eleven systems containing epoxy-coated reinforcement (ECR) in combination with another corrosion-protection system are evaluated using the rapid macrocell, southern exposure, cracked beam, linear polarization resistance, and field tests. The systems include bars 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 (Rheocrete® 222+ and HycreteTM), an epoxy-coated bar with a primer containing microencapsulated calcium nitrite, three epoxy-coated bars with improved adhesion combined with the corrosion inhibitor calcium nitrite, and multiple-coated (MC) bars with an initial 50-microm (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 ECR. The coatings on all bars are penetrated to simulate the effects of damage during fabrication and placement in the field. The results presented in this report indicate that the coated bars provide superior corrosion protection to the reinforcing steel and that bars with damaged coatings initiate corrosion at chloride contents within concrete that are several times greater and corrode at rates that are typically two orders of magnitude below those exhibited by conventional reinforcement. Limited additional protection is achieved using bars with the primer coating, MC bars, and concrete containing the corrosion inhibitors calcium nitrite and one of the organic corrosion inhibitors, although the latter resulted in reduced compressive strength and reduced resistance to surface scaling. The differences in costs over a 75-year design life are relatively small for coated bars. Cracks in concrete directly over and parallel to the reinforcement, such as found in bridge decks, result in earlier corrosion initiation and higher corrosion rates than obtained with intact concrete for all systems. Epoxies that provide initially high adhesion to the underlying steel provide no advantage over conventional epoxy coatings. All coated bars that were evaluated exhibited corrosion losses at openings through the coating. A reduction in adhesion between an epoxy coating and the reinforcing steel occurs after a period of exposure to corrosive conditions. This reduction increases with increasing chloride content in the concrete and in the presence of cracks and decreases with the use of corrosion inhibitors, with the use of MC reinforcement, and with electrical isolation of the epoxy-coated bars from each other. Corrosion products form under the coating where adhesion has been reduced. For periods up to five years under exposure conditions representative of those in bridge decks, the reduction in adhesion between an epoxy coating and the reinforcing steel did not affect the rate at which coated bars corrode.

Coating Protection for Reinforcement

Coating Protection for Reinforcement
Author: C. Andrade
Publisher: Thomas Telford
Total Pages: 64
Release: 1995
Genre: Concrete coatings
ISBN: 9780727720214

This report provides a technical survey of the most common coating protection systems for steel reinforcement, the use of which is rapidly increasing at present. The text also evaluates the practical effect of the systems and is the result of a research project conducted by a CEB task group which was specifically assembled to address the need for more information in this subject area.

Evaluation of Multiple Corrosion Protection Systems for Reinforced Concrete Bridge Decks

Evaluation of Multiple Corrosion Protection Systems for Reinforced Concrete Bridge Decks
Author: Matthew O'Reilly
Publisher:
Total Pages: 522
Release: 2011
Genre: Concrete bridges
ISBN:

"The performance of corrosion protection systems for reinforcing steel in concrete is evaluated. In addition to conventional and conventional epoxy-coated reinforcement, the corrosion protection systems tested include epoxy coatings with improved adhesion to the underlying steel, conventional and conventional epoxy-coated reinforcement used in conjunction with concrete containing one of three corrosion inhibitors, DCI-S, Rheocrete 222+, or Hycrete, epoxy-coated reinforcement with a microencapsulated calcium nitrite primer, multiple-coated reinforcement with a layer of zinc between the epoxy and steel, and pickled 2205 duplex stainless steel. The systems are evaluated using bench-scale and field tests. Two bridges in Kansas, cast with 2205 stainless steel, are monitored using corrosion potential mapping. Epoxy-coated and multiplecoated bars are evaluated to determine the effect of corrosion loss and time on the disbondment of the epoxy coating. Conventional, galvanized, and epoxy-coated reinforcement are evaluated using impressed current to determine the corrosion loss required to crack concrete for each system. A finite element model is developed to represent general and localized corrosion, and the results are used to develop a relationship between concrete cover, bar diameter, and area of bar corroding, and the corrosion loss required to crack concrete. An analysis of pore solutions expressed from cement pastes containing corrosion inhibitors is performed, with pH and selected ion concentrations measured from solutions collected one and seven days after casting. The results obtained from bench-scale and field test specimens are used to estimate cost effectiveness for each system under a 75-year service life. The results show epoxy coatings significantly reduce the corrosion rate compared to conventional reinforcement. Corrosion inhibitors significantly reduce corrosion rates in uncracked concrete. In cracked concrete, corrosion inhibitors also reduce corrosion rates, but their relative effectiveness is reduced. Specimens containing Hycrete exhibit the lowest corrosion rates; however, field specimens containing Hycrete also show signs of scaling. Epoxies with improved adhesion exhibit no improvement over conventional epoxy-coated reinforcement in terms of corrosion rate or disbondment of the epoxy coating. Multiple-coated reinforcement exhibits significantly less disbondment than epoxy-coated reinforcement. Pickled 2205 reinforcement exhibits the least corrosion among all systems tested. Testing of conventional and galvanized reinforcement indicates galvanized reinforcement requires more than twice as much corrosion loss to crack the surrounding concrete compared to conventional reinforcement."--Technical report documentation page.

Materials and Methods for Corrosion Control of Reinforced and Prestressed Concrete Structures in New Construction

Materials and Methods for Corrosion Control of Reinforced and Prestressed Concrete Structures in New Construction
Author: J. L. Smith
Publisher:
Total Pages: 90
Release: 2000
Genre: Concrete bridges
ISBN:

Salt-induced reinforcing steel corrosion in concrete bridges has undoubtedly become a considerable economic burden to many State and local transportation agencies. Since the iron in the steel has a natural tendency to revert eventually to its most stable oxide state, this problem will, unfortunately, still be with us, but to a much lesser degree due to the use of various corrosion protection strategies currently used in new construction. The adoption of corrosion protection measures in new construction, such as the use of good design and construction practices, adequate concrete cover depth, low-permeability concrete, corrosion inhibitors, and coated reinforcing steel is significantly reducing the occurrence of reinforcing steel corrosion in new bridges.