Effect of Accelerated Corrosion on the Bond Strength of Corrosion Resistant Reinforcing Bars Embedded in Concrete PDF Download
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Author: Sourav Khatua Publisher: ISBN: Category : Adhesives Languages : en Pages :
Book Description
Corrosion of steel reinforcing bars embedded in concrete applications is a major problem all over the world. Effect of corrosion causes metal loss at sections, cracks in the concrete surrounding the reinforcing steel, spalling of cover concrete also leads to de-bonding of reinforcing bar from the concrete. Corrosion cracks in the surrounding concrete leads to loss in bond strength and finally reduce the structural strength and service life of the structure. This problem is consistently observed in structural slab bridges that are exposed to deicing salts during the winters. In the era of 1980's, black convention steel was replaced with epoxy-coated bars as a solution to prevent corrosion in bridge decks. However the advantage of using epoxy coated bars is still uncertain as the bond strength of these type of bars is a concern. Several researchers in the past have highlighted deleterious effect of corrosion on epoxy-coated bars that are damaged during handling. It is necessary to study the use of alternative reinforcing bars as means of corrosion protection in bridge deck applications. There are several corrosion resistant bars that are readily available in the market, but performance of these bars under accelerated corrosion conditions is still unclear. Six different types of bars which include, conventional black bars, epoxy-coated bars, hot dipped galvanizing bars, continuously galvanized bars, stainless steel bars and MMFX bars were studied in this thesis. The objective of this study is to investigate the effect of accelerated corrosion on bond strength of concrete. The bond between concrete and reinforcement bars play a major role in transfer of stresses from concrete to steel. However, corrosion weakens this bond, resulting in weakening of the Reinforced Concrete member. So, it was necessary to investigate the performance of CRR (Corrosion Resistant Bars) embedded in concrete and s ubjected to accelerated corrosion. The effect of addition of polypropylene fibers on the bond strength was studied. A total of 48 prism specimens were cast with CRR bars including the ones with fibers, of which 24 specimens were subjected to accelerated corrosion. The prisms were 6-inch cube with a reinforcing bar at the centre of each specimen. The embedment length of the bar was 2.5 inches at the mid-height of the section. An electrochemical cell was adopted by placing the specimens in a tank containing 5% salt solution with stainless steel cathode surrounding the specimen. The circuit was completed by connecting the cathode and the reinforcing bar to an external power supply. The specimens were subjected to accelerated corrosion for total of 21 days which includes a two-day wetting and one day drying cycle. Impressed current of 0.02A, calculated using Faraday's law to achieve 5% corrosion damage was supplied during the wetting cycle using external power source. The corroded specimens were then tested to investigate the loss of bond strength due to corrosion and capture any improvement in bond strength using polypropylene fibers. It was observed that, corrosion of bars showed serious bond loss leading to reduced pull-out strength with larger slip of the bars relative to the embedded concrete prisms. Addition of polypropylene fibers showed an improvement in the overall performance of the corroded specimens by increasing the load capacity, reducing slip and improving failure mode from brittle to more ductile mode, compared to un-corroded specimens..
Author: Sourav Khatua Publisher: ISBN: Category : Adhesives Languages : en Pages :
Book Description
Corrosion of steel reinforcing bars embedded in concrete applications is a major problem all over the world. Effect of corrosion causes metal loss at sections, cracks in the concrete surrounding the reinforcing steel, spalling of cover concrete also leads to de-bonding of reinforcing bar from the concrete. Corrosion cracks in the surrounding concrete leads to loss in bond strength and finally reduce the structural strength and service life of the structure. This problem is consistently observed in structural slab bridges that are exposed to deicing salts during the winters. In the era of 1980's, black convention steel was replaced with epoxy-coated bars as a solution to prevent corrosion in bridge decks. However the advantage of using epoxy coated bars is still uncertain as the bond strength of these type of bars is a concern. Several researchers in the past have highlighted deleterious effect of corrosion on epoxy-coated bars that are damaged during handling. It is necessary to study the use of alternative reinforcing bars as means of corrosion protection in bridge deck applications. There are several corrosion resistant bars that are readily available in the market, but performance of these bars under accelerated corrosion conditions is still unclear. Six different types of bars which include, conventional black bars, epoxy-coated bars, hot dipped galvanizing bars, continuously galvanized bars, stainless steel bars and MMFX bars were studied in this thesis. The objective of this study is to investigate the effect of accelerated corrosion on bond strength of concrete. The bond between concrete and reinforcement bars play a major role in transfer of stresses from concrete to steel. However, corrosion weakens this bond, resulting in weakening of the Reinforced Concrete member. So, it was necessary to investigate the performance of CRR (Corrosion Resistant Bars) embedded in concrete and s ubjected to accelerated corrosion. The effect of addition of polypropylene fibers on the bond strength was studied. A total of 48 prism specimens were cast with CRR bars including the ones with fibers, of which 24 specimens were subjected to accelerated corrosion. The prisms were 6-inch cube with a reinforcing bar at the centre of each specimen. The embedment length of the bar was 2.5 inches at the mid-height of the section. An electrochemical cell was adopted by placing the specimens in a tank containing 5% salt solution with stainless steel cathode surrounding the specimen. The circuit was completed by connecting the cathode and the reinforcing bar to an external power supply. The specimens were subjected to accelerated corrosion for total of 21 days which includes a two-day wetting and one day drying cycle. Impressed current of 0.02A, calculated using Faraday's law to achieve 5% corrosion damage was supplied during the wetting cycle using external power source. The corroded specimens were then tested to investigate the loss of bond strength due to corrosion and capture any improvement in bond strength using polypropylene fibers. It was observed that, corrosion of bars showed serious bond loss leading to reduced pull-out strength with larger slip of the bars relative to the embedded concrete prisms. Addition of polypropylene fibers showed an improvement in the overall performance of the corroded specimens by increasing the load capacity, reducing slip and improving failure mode from brittle to more ductile mode, compared to un-corroded specimens..
Author: fib Fédération internationale du béton Publisher: fib Fédération internationale du béton ISBN: 2883940894 Category : Technology & Engineering Languages : en Pages : 123
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: fib Fédération internationale du béton Publisher: fib Fédération internationale du béton ISBN: 9782883940505 Category : Technology & Engineering Languages : en Pages : 448
Book Description
"In 1993, the CEB Commission 2 Material and Behavior Modelling established the Task Group 2.5 Bond Models. It's terms of reference were ... to write a state-of-art report concerning bond of reinforcement in concrete and later recommend how the knowledge could be applied in practice (Model Code like text proposal)... {This work} covers the first part ... the state-of-art report."--Pref.
Author: Marina Cabrini Publisher: MDPI ISBN: 3036502904 Category : Technology & Engineering Languages : en Pages : 496
Book Description
This book contains thirty articles on various topics related to the corrosion and protection of metallic materials. This topic is of strong actuality both due to the aging of plants and infrastructures that require checks and maintenance, and to the use of traditional materials in increasingly aggressive environments, added to the need of changing the current anti-corrosion systems with less environmental impact methods. Finally, the new development of innovative materials, such as additive manufacturing or high-entropy alloys, needs the characterization of their corrosion behavior. In this issue, there are works on new alloys obtained for additive manufacturing or high entropy, on the study of corrosion and stress corrosion cracking and hydrogen embrittlement mechanisms, through electrochemical and microscopical techniques, studies on low environmental impact inhibitors and biocides, as well as ceramic and metal protective coatings. Finally, there are works on the study of the residual mechanical resistance of corroded infrastructures and on monitoring and non-destructive control. In this way, the book therefore offers a somewhat varied panorama of research trends in the field.
Author: Luca Bertolini Publisher: John Wiley & Sons ISBN: 3527651713 Category : Technology & Engineering Languages : en Pages : 389
Book Description
Steel-reinforced concrete is used ubiquitously as a building material due to its unique combination of the high compressive strength of concrete and the high tensile strength of steel. Therefore, reinforced concrete is an ideal composite material that is used for a wide range of applications in structural engineering such as buildings, bridges, tunnels, harbor quays, foundations, tanks and pipes. To ensure durability of these structures, however, measures must be taken to prevent, diagnose and, if necessary, repair damage to the material especially due to corrosion of the steel reinforcement. The book examines the different aspects of corrosion of steel in concrete, starting from basic and essential mechanisms of the phenomenon, moving up to practical consequences for designers, contractors and owners both for new and existing reinforced and prestressed concrete structures. It covers general aspects of corrosion and protection of reinforcement, forms of attack in the presence of carbonation and chlorides, problems of hydrogen embrittlement as well as techniques of diagnosis, monitoring and repair. This second edition updates the contents with recent findings on the different topics considered and bibliographic references, with particular attention to recent European standards. This book is a self-contained treatment for civil and construction engineers, material scientists, advanced students and architects concerned with the design and maintenance of reinforced concrete structures. Readers will benefit from the knowledge, tools, and methods needed to understand corrosion in reinforced concrete and how to prevent it or keep it within acceptable limits.
Author: Sourav Khatua
Author: Sourav Khatua
Author: fib Fédération internationale du béton
Author: J. Tonini
Author: United States. Federal Highway Administration. Offices of Research and Development
Author: D. E. Tonini
Author: fib Fédération internationale du béton
Author: Marina Cabrini
Author: 
Author: Luca Bertolini
Author: Kyle David Stanish