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| Author | : |
| Publisher | : |
| Total Pages | : 202 |
| Release | : 2002 |
| Genre | : Concrete bridges |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : |
| Release | : 1996 |
| Genre | : |
| ISBN | : |
Thermal-sprayed zinc anodes are being used in Oregon in impressed current cathodic protection (ICCP) systems for reinforced concrete bridges. The U.S. Department of Energy, Albany Research Center, is collaborating with the Oregon Department of Transportation (ODOT) to evaluate the long-term performance and service life of these anodes. Laboratory studies were conducted on concrete slabs coated with 0.5 mm (20 mil) thick, thermal-sprayed zinc anodes. The slabs were electrochemically aged at an accelerated rate using an anode current density of 0.032 A/m2 (3mA/ft2). Half the slabs were preheated before thermal-spraying with zinc; the other half were unheated. Electrochemical aging resulted in the formation at the zinc-concrete interface of a thin, low pH zone (relative to cement paste) consisting primarily of ZnO and Zn(OH)2, and in a second zone of calcium and zinc aluminates and silicates formed by secondary mineralization. Both zones contained elevated concentrations of sulfate and chloride ions. The original bond strength of the zinc coating decreased due to the loss of mechanical bond to the concrete with the initial passage of electrical charge (aging). Additional charge led to an increase in bond strength to a maximum as the result of secondary mineralization of zinc dissolution products with the cement paste. Further charge led to a decrease in bond strength and ultimately coating disbondment as the interfacial reaction zones continued to thicken. This occurred at an effective service life of 27 years at the 0.0022 A/m2 (0.2 mA/ft2) current density typically used by ODOT in ICCP systems for coastal bridges. Zinc coating failure under tensile stress was primarily cohesive within the thickening reaction zones at the zinc-concrete interface. There was no difference between the bond strength of zinc coatings on preheated and unheated concrete surfaces after long service times.
| Author | : Ali Akbar Sohanghpurwala |
| Publisher | : Transportation Research Board National Research |
| Total Pages | : 60 |
| Release | : 2009 |
| Genre | : Technology & Engineering |
| ISBN | : |
At head of title: National Cooperative Highway Research Program.
| Author | : Farid Abooameri |
| Publisher | : |
| Total Pages | : 202 |
| Release | : 1994 |
| Genre | : Concrete bridges |
| ISBN | : |
Steel corrosion in reinforced concrete is a major concern to transportation agencies nationwide because of the expenses incurred for repair and ultimate shortening of bridge life. Cathodic protection (CP), as a remedy, has been applied to reinforced bridges in the US since 1974. However, application of this technique is largely empirical, lacking fundamental understanding. In order to optimize the performance of a CP system, it is important to monitor the rebar potential with respect to a reliable reference electrode. Moreover, because of potential variation in the concrete, reference cell placement is fundamental to ensure effective protection. The work plan was divided into two parts: laboratory scale experimentation and computer simulation. In the experimentation section, the response of graphite probes was compared to that of an Orion silver-silver chloride electrode. Graphite probes behaved as well as the standard electrode. Furthermore, the home-made graphite probes behaved the same as the commercial ones. This will allow much greater experimental latitude since the home-made probes are much more economical than the commercial ones. A finite difference code was developed to assess the performance of cathodic protection. The potential distribution in a two dimensional geometry of a concrete block with a sprayed zinc anode at one boundary and an iron cathode at the other side was calculated under cathodic protection. The equations were solved by means of a Gauss-Seidel iterative method with the help of an overrelaxation factor. An interval halving method was used to solve for nonlinear boundary condition at the iron. The effects of concrete pore saturation, concrete cover, and applied potential were studied to determine the degree of protection and proper placement of the reference electrode in concrete. Furthermore, a sensitivity analysis was performed versus input parameters: concrete conductivity, oxygen mass transfer coefficient, and oxygen reduction polarization parameters. The results of the simulation showed that the center of the rebar is less protected than the other locations. Therefore, the reference electrode should be located as close to the center as possible.
| Author | : Jack E. Bennett |
| Publisher | : Strategic Highway Research Program (Shrp) |
| Total Pages | : 316 |
| Release | : 1993 |
| Genre | : Technology & Engineering |
| ISBN | : |
This document provides explanation, guidance, and direction concerning cathodic protection of concrete bridge elements to the highway engineer who wants to incorporate cathodic protection in a bridge project. The manual which provides background information on corrosion fundamentals, is divided into 3 parts: design, construction, and operation and maintenance. An appendix provides standard specifications for cathodic protection systems for both decks and substructures. The document is intended to be a useful reference for engineers who design and prepare specifications or who oversee turnkey operations.
| Author | : David Whiting |
| Publisher | : |
| Total Pages | : 105 |
| Release | : 1995 |
| Genre | : Concrete bridges |
| ISBN | : |
Laboratory evaluations were carried out on a series of anode materials, including aluminum, magnesium, and zinc alloys. Anode/steel couples were placed in simulated concrete environments consisting of sealed containers filled with silica sand treated with a mixed alkali-chloride solution. Measurements of current flow, circuit resistance, potential, and depolarization were made over a period of 18 weeks. Based on results obtained, aluminum and zinc anodes were found to hold the most promise for use as galvanic anodes in reinforced concrete bridge decks. A series of reinforced concrete test slabs were produced for evaluation of the candidate materials. Normal-weight structural concrete, structural lightweight concrete, free-draining concrete, and free-draining latex-modified concrete overlays were placed over the anodes to serve as riding surfaces. Performance of the cathodic protection (CP) systems was evaluated using current flow and depolarization techniques.
| Author | : Xiaoge Gregory Zhang |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 500 |
| Release | : 1996-09-30 |
| Genre | : Science |
| ISBN | : 9780306453342 |
Humankind's use of zinc stretches back to antiquity, and it was a component in some of the earliest known alloy systems. Even though metallic zinc was not "discovered" in Europe until 1746 (by Marggral), zinc ores were used for making brass in biblical times, and an 87% zinc alloy was found in prehistoric ruins in Transylvania. Also, zinc (the metal) was produced in quantity in India as far back as the thirteenth century, well before it was recognized as being a separate element. The uses of zinc are manifold, ranging from galvanizing to die castings to electronics. It is a preferred anode material in high-energy-density batteries (e.g., Ni/Zn, Ag/Zn, ZnJair), so that its electrochemistry, particularly in alkaline media, has been extensively explored. In the passive state, zinc is photoelectrochemically active, with the passive film displaying n-type characteristics. For the same reason that zinc is considered to be an excellent battery anode, it has found extensive use as a sacrificial anode for the protection of ships and pipelines from corrosion. Indeed, aside from zinc's well-known attributes as an alloying element, its widespread use is principally due to its electrochemical properties, which include a well-placed position in the galvanic series for protecting iron and steel in natural aqueous environments and its reversible dissolution behavior in alkaline solutions.
| Author | : John P. Broomfield |
| Publisher | : CRC Press |
| Total Pages | : 305 |
| Release | : 2023-01-31 |
| Genre | : Technology & Engineering |
| ISBN | : 1000822486 |
Corrosion of Steel in Concrete: Understanding, Investigation and Repair is a guide for designing, constructing and maintaining reinforced concrete structures, such as buildings and bridges which are subject to reinforcement corrosion. It presents the basics of theory and practice in steel corrosion in concrete and reviews the latest research and developments, such as progress on measuring the corrosion threshold for chloride-induced corrosion. This third edition compares the currently proliferating major national and international standards and guidance documents. New developments are considered, such as hybrid anodes for electrochemical treatment and the latest research and developments in assessment, such as the use of ground penetrating radar to measure the chloride content of the concrete cover. It overhauls coverage of electrochemical repair and rehabilitation techniques and outlines recent innovations in structural repair and construction and investigates their implications for durability. The book is ideal for practitioners and graduate students in structural engineering and concrete technology.
| Author | : Carlo Pellegrino |
| Publisher | : Springer Nature |
| Total Pages | : 1454 |
| Release | : 2021-12-11 |
| Genre | : Technology & Engineering |
| ISBN | : 3030918777 |
This book gathers the latest advances and innovations in the field of quality control and improvement of bridges and structures, as presented by international researchers and engineers at the 1st Conference of the European Association on Quality Control of Bridges and Structures (EUROSTRUCT 2021), held in Padua, Italy on August 29 – September 1, 2021. Contributions include a wide range of topics such as testing and advanced diagnostic techniques for damage detection; SHM and AI, IoT and machine learning for data analysis of bridges and structures; fiberoptics and smart sensors for long-term SHM; structural reliability, risk, robustness, redundancy and resilience for bridges; corrosion models, fatigue analysis and impact of hazards on infrastructure components; bridge and asset management systems, and decision-making models; Life-Cycle Analysis, retrofit and service-life extension, risk management protocols; quality control plans, sustainability and green materials.
| Author | : John B. Vrable |
| Publisher | : Transportation Research Board National Research |
| Total Pages | : 1304 |
| Release | : 1977 |
| Genre | : Technology & Engineering |
| ISBN | : |
