Evaluation of Mechanical and Corrosion Properties of MMFX Reinforcing Steel for Concrete PDF Download
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Author: Lien Gong
Publisher:
ISBN:
Category : Chromium alloys
Languages : en
Pages : 138
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Book Description
The corrosion performance of MMFX and conventional reinforcing steels is compared based on macrocell and bench-scale tests. The conventional steel includes epoxy-coated and uncoated bars. Macrocell tests are conducted on bare bars and bars symmetrically embedded in a mortar cylinder. Specimens are exposed to a simulated concrete pore solution with a 1.6 or 6.4 molal ion concentration of sodium chloride. Bench-scale tests include the Southern Exposure and cracked beam tests. A 15% (6.04 m ion) NaCl solution is ponded on the top of both the Southern Exposure and cracked beam specimens. Mechanical properties are compared with the requirements of ASTM A 615. The uniformity and consistency in chemical composition is evaluated using a scanning electron microscope and an energy dispersive spectrometer. The microstructure of corrosion products is analyzed using a scanning electron microscope. The results indicate that MMFX steel exhibits better corrosion resistance than conventional uncoated steel, but lower corrosion resistance than epoxy-coated bars. In both the macrocell and bench-scale tests, MMFX steel exhibits a macrocell corrosion rate between one-third and two-thirds that of uncoated conventional reinforcing bars, while epoxy-coated reinforcement with the coating penetrated corrodes at a rate between 5% and 25% that of conventional steel. MMFX reinforcing steel is not recommended as a replacement for epoxy-coated reinforcement unless it is used in conjunction with a supplementary corrosion protection system.
Author: Lien Gong
Publisher:
ISBN:
Category : Chromium alloys
Languages : en
Pages : 138
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Book Description
The corrosion performance of MMFX and conventional reinforcing steels is compared based on macrocell and bench-scale tests. The conventional steel includes epoxy-coated and uncoated bars. Macrocell tests are conducted on bare bars and bars symmetrically embedded in a mortar cylinder. Specimens are exposed to a simulated concrete pore solution with a 1.6 or 6.4 molal ion concentration of sodium chloride. Bench-scale tests include the Southern Exposure and cracked beam tests. A 15% (6.04 m ion) NaCl solution is ponded on the top of both the Southern Exposure and cracked beam specimens. Mechanical properties are compared with the requirements of ASTM A 615. The uniformity and consistency in chemical composition is evaluated using a scanning electron microscope and an energy dispersive spectrometer. The microstructure of corrosion products is analyzed using a scanning electron microscope. The results indicate that MMFX steel exhibits better corrosion resistance than conventional uncoated steel, but lower corrosion resistance than epoxy-coated bars. In both the macrocell and bench-scale tests, MMFX steel exhibits a macrocell corrosion rate between one-third and two-thirds that of uncoated conventional reinforcing bars, while epoxy-coated reinforcement with the coating penetrated corrodes at a rate between 5% and 25% that of conventional steel. MMFX reinforcing steel is not recommended as a replacement for epoxy-coated reinforcement unless it is used in conjunction with a supplementary corrosion protection system.
Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 162
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Book Description
Author: Terry J. Wipf
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 84
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Book Description
The corrosion of steel reinforcement in an aging highway infrastructure is a major problem currently facing the transportation engineering community. In the United States alone, maintenance and replacement costs for deficient bridges are measured in billions of dollars. The application of corrosion-resistant steel reinforcement as an alternative reinforcement to existing mild steel reinforced concrete bridge decks has potential to mitigate corrosion problems, due to the fundamental properties associated with the materials. To investigate corrosion prevention through the use of corrosion-resistant alloys, the performance of corrosion resistance of MMFX microcomposite steel reinforcement, a high-strength, high-chromium steel reinforcement, was evaluated. The study consisted of both field and laboratory components conducted at the Iowa State University Bridge Engineering Center to determine whether MMFX reinforcement provides superior corrosion resistance to epoxy-coated mild steel reinforcement in bridge decks. Because definitive field evidence of the corrosion resistance of MMFX reinforcement may require several years of monitoring, strict attention was given to investigating reinforcement under accelerated conditions in the laboratory, based on typical ASTM and Rapid Macrocell accelerated corrosion tests. After 40 weeks of laboratory testing, the ASTM ACT corrosion potentials indicate that corrosion had not initiated for either MMFX or the as-delivered epoxy-coated reinforcement. Conversely, uncoated mild steel specimens underwent corrosion within the fifth week, while epoxy-coated reinforcement specimens with induced holidays underwent corrosion between 15 and 30 weeks. Within the fifth week of testing, the Rapid Macrocell ACT produced corrosion risk potentials that indicate active corrosion for all reinforcement types tested. While the limited results from the 40 weeks of laboratory testing may not constitute a prediction of life expectancy and life-cycle cost, a procedure is presented herein to determine life expectancy and associated life-cycle costs.
Author: Irene K. Battaglia
Publisher:
ISBN:
Category : Dowels
Languages : en
Pages : 52
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Book Description
Author: Milan Joseph Jolley
Publisher:
ISBN:
Category :
Languages : en
Pages : 172
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Book Description
The corrosion of steel reinforcement in an aging highway infrastructure is a major problem currently facing the transportation engineering community, in particular bridge engineers. Further, the use of deicing salts has resulted in steady deterioration of bridge decks due to corrosion. In the United States, maintenance and replacement costs of deficient bridges are measured in billions of dollars. These concerns have initiated continual development of protective measures. Application of corrosion-resistant steel reinforcement as an alternate reinforcement for existing mild steel reinforced concrete bridge decks has great potential due to the inherent corrosion resistant properties associated with the materials. To investigate corrosion prevention through the use of corrosion-resistant alloys, the performance of corrosion resistance for MMFX Microcomposite steel reinforcement, a high-strength, high chromium steel reinforcement, is evaluated. The study presented herein presents the separate field and laboratory studies of ongoing research at Iowa State University to determine if in fact MMFX reinforcement provides superior corrosion resistance to epoxy-coated mild steel reinforcement in bridge decks. However, as definitive field evidence of the corrosion resistance of MMFX reinforcement may require several years of monitoring, attention transferred to investigate the reinforcement under accelerated conditions in a laboratory. In the laboratory investigation, the evaluation process was based on using ASTM and Rapid Macrocell accelerated corrosion tests. After 40 weeks of testing, the associated ASTM ACT corrosion potentials indicate corrosion has not initiated for either MMFX or as-delivered epoxy-coated reinforcement. However, the uncoated mild steel underwent corrosion within the fifth week, while epoxy-coated reinforcement with holidays underwent corrosion between 15 and 30 weeks. For the study presented herein, concrete powder specimens were collected at the top reinforcement depth at the first indication of corrosion initiation. While the limited results from 40 weeks of laboratory testing do not constitute a prediction of life expectancy and lifecycle cost, a procedure is presented to determine the life expectancy and lifecycle cost once definitive evidence is attained. The life expectancy of bridge decks constructed with different steel reinforcing systems is estimated by the two-stage, diffusion-spalling model (i.e., the time required for corrosion initiation and the subsequent time period required to cause spalling due to corrosion).
Author: fib Fédération internationale du béton
Publisher: fib Fédération internationale du béton
ISBN: 2883940932
Category : Technology & Engineering
Languages : en
Pages : 391
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Book Description
The second edition of the Structural Concrete Textbook is an extensive revision that reflects advances in knowledge and technology over the past decade. It was prepared in the intermediate period from the CEP-FIP Model Code 1990 (MC90) tofib Model Code 2010 (MC2010), and as such incorporates a significant amount of information that has been already finalized for MC2010, while keeping some material from MC90 that was not yet modified considerably. The objective of the Textbook is to give detailed information on a wide range of concrete engineering from selection of appropriate structural system and also materials, through design and execution and finally behaviour in use. The revised fib Structural Concrete Textbook covers the following main topics: phases of design process, conceptual design, short and long term properties of conventional concrete (including creep, shrinkage, fatigue and temperature influences), special types of concretes (such as self compacting concrete, architectural concrete, fibre reinforced concrete, high and ultra high performance concrete), properties of reinforcing and prestressing materials, bond, tension stiffening, moment-curvature, confining effect, dowel action, aggregate interlock; structural analysis (with or without time dependent effects), definition of limit states, control of cracking and deformations, design for moment, shear or torsion, buckling, fatigue, anchorages, splices, detailing; design for durability (including service life design aspects, deterioration mechanisms, modelling of deterioration mechanisms, environmental influences, influences of design and execution on durability); fire design (including changes in material and structural properties, spalling, degree of deterioration), member design (linear members and slabs with reinforcement layout, deep beams); management, assessment, maintenance, repair (including, conservation strategies, risk management, types of interventions) as well as aspects of execution (quality assurance), formwork and curing. The updated Textbook provides the basics of material and structural behaviour and the fundamental knowledge needed for the design, assessment or retrofitting of concrete structures. It will be essential reading material for graduate students in the field of structural concrete, and also assist designers and consultants in understanding the background to the rules they apply in their practice. Furthermore, it should prove particularly valuable to users of the new editions of Eurocode 2 for concrete buildings, bridges and container structures, which are based only partly on MC90 and partly on more recent knowledge which was not included in the 1999 edition of the Textbook.
Author: Zachary Wayne Ashcraft
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 306
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Book Description
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:
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 92
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Book Description
Author: H. G. Russell
Publisher: Transportation Research Board
ISBN: 0309070112
Category : Bridges
Languages : en
Pages : 188
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Book Description
At head of title: National Cooperative Highway Research Program.
