Stephen R. Yeomans

Bond of ribbed galvanized reinforcing steel in concrete

Abstract The ASTM beam end test (ASTM A944) has been used to compare the bond and slip behaviour of deformed (i.e. ribbed) galvanized, epoxy-coated and black steel bars in concrete. The objective was to determine whether galvanizing adversely affects bond strength. From a series of thirty specimens, the average bond strength of black steel and galvanized steel reinforcement used in these tests has been determined and bond stress has been shown to act uniformly over the embedded bar area. A slip value of approximately 0.4 mm has been confirmed to be associated with bond failure by concrete splitting. The results indicated that while epoxy coating resulted in a significant loss in bond strength of the order of 20% compared to black steel, there is no adverse effect on bond with the use of galvanized steel. Chromate treatment of galvanized bars is deemed unnecessary since there was no evidence of long term reduction in bond due to the possible effects of hydrogen gas evolution resulting from the reaction between zinc and wet concrete.

Bond and slip of coated reinforcement in concrete

Abstract Concrete beams reinforced with black, epoxy coated or galvanized steel were tested to failure in flexure and the slip of the reinforcement was monitored. While there was clear evidence of the influence of bar deformations on the bond capacity of beams reinforced with smooth compared to ribbed black steel bars, the majority of the work concentrated on comparing the load-slip behaviour of ribbed bars as affected by the presence of surface coatings. The ultimate capacity in flexure of beams reinforced with ribbed galvanized or epoxy coated bars was not statistically different to that of black steel reinforced beams. The results from load-slip measurements were indicative of the variation in bond for the different bar coatings. It was found that loads at a slip of 0.05 mm were generally too close to the ultimate load and accordingly lower slip values in the serviceability range, i.e. 0.01 and 0.02 mm, were adopted for the analysis. From this it was found that the mean critical load at these slip values for the ribbed galvanized bars was not statistically different to the black steel. On the other hand, the load at slip for the epoxy coated ribbed bars was significantly lower, by about 20%, than that for both the black and galvanized steel bars. Overall, the results of this work indicated that there was no significant loss in bond with the use of galvanized bars, though a significant reduction was observed with epoxy coated bars.

Galvanized Steel in Concrete: An Overview

Publisher Summary This chapter provides a review of the properties, behavior, processing, and application of galvanized steel reinforcement for use in concrete construction. The past 15-20 years have seen extensive research and field investigations are undertaken of the characteristics and behavior of galvanized reinforcement. This considerable body of work has repeatedly highlighted the benefits of galvanizing in delaying the onset of corrosion in reinforced concrete and in reducing the risks of cracking and rust staining of the concrete mass. It presents the considerable research that the life of the galvanized coating and thus, the reliability of the corrosion protection it provides, depends on many factors. These include the morphology and thickness of the coating, the quality of the concrete in which it is placed, and the severity of the environment to which the concrete is exposed. In circumstances where the underlying steel is exposed, such as at breaks in the coating or at cut edges, the zinc sacrificially protects the steel, thereby further extending the life of the reinforcement. The chapter addresses these issues and summarizes a detailed treatment of the electrochemistry and corrosion behavior of zinc and the galvanized coating.Publisher Summary This chapter provides a review of the properties, behavior, processing, and application of galvanized steel reinforcement for use in concrete construction. The past 15-20 years have seen extensive research and field investigations are undertaken of the characteristics and behavior of galvanized reinforcement. This considerable body of work has repeatedly highlighted the benefits of galvanizing in delaying the onset of corrosion in reinforced concrete and in reducing the risks of cracking and rust staining of the concrete mass. It presents the considerable research that the life of the galvanized coating and thus, the reliability of the corrosion protection it provides, depends on many factors. These include the morphology and thickness of the coating, the quality of the concrete in which it is placed, and the severity of the environment to which the concrete is exposed. In circumstances where the underlying steel is exposed, such as at breaks in the coating or at cut edges, the zinc sacrificially protects the steel, thereby further extending the life of the reinforcement. The chapter addresses these issues and summarizes a detailed treatment of the electrochemistry and corrosion behavior of zinc and the galvanized coating.

Galvanized steel reinforcement

Abstract This chapter reviews the characteristics, performance and use of galvanized steel reinforcement in concrete construction. The traditional method of galvanizing by hot dipping and the recent development of continuous coating of reinforcement will be discussed, and differences in the morphology of the zinc coating will be explained. This chapter discusses the behaviour of zinc in concrete, including coating behaviour in alkaline environments, passivation, carbonation resistance and chloride tolerance. There will also be brief coverage of design considerations for galvanized reinforced concrete, including bond-slip considerations and typical applications of galvanized reinforcement.

Coated Steel Reinforcement for Corrosion Protection in Concrete

Coated steel reinforcement is widely used in new concrete construction to provide enhanced corrosion protection to the embedded steel. While concrete itself provides natural corrosion protection to steel, this may be lost as a result of degradation of the concrete mass andlor the penetration of aggressive species from the environment through the cover concrete to the reinforcement. Coating of the reinforcement reduces the risk of corrosive attack in concrete and two coating systems are widely applied to steel for this purpose; namely, fusion bonded epoxy coatings and hot-dip galvanized coatings. An overview is presented of the characteristics and use of epoxy coated steel and galvanized steel reinforcement in concrete. The nature of the protection afforded by these coating systems is explained together with their method of application and relevant codes and standards. A discussion and comparison of typical characteristics of the two systems is given. The results of recent research comparing both the accel...

Using Soft Systems Thinking to Confront the Politics of Innovation in Engineering Education

Engineering curriculum innovators face a range of formidable barriers which, singly or in combination, have thwarted countless attempts at sustainable curricular quality improvement initiatives regardless, of their educational efficacy. The often ignored elephant in the room of programmatic quality improvement is the politics of change. The essential point of this chapter is this: a whole-of-programme curriculum innovation demands an intervention strategy capable of effectively responding to multiple stakeholder perspectives and therefore to the politics of change. It is argued that Soft Systems Methodology embedded within a Systemic Action Research approach will give engineering educators that capability.

Laboratory and Field Performance of Galvanized Steel in Concrete

Publisher Summary This chapter provides a review of the diverse range of laboratory and field-based research that has focused on galvanized reinforcement. A level of information is provided to give a sense of the work along with a summary of the pertinent results and conclusions. Reference should be made to the primary sources for full details of the work undertaken. The chapter provides a review of the electrochemical behavior of galvanized steel in aqueous solutions and simulated pore-water conditions and focuses on key laboratory-based research on galvanized reinforcement embedded in mortar and concrete specimens and the field investigations of the longer-term performance of galvanized reinforcement. The conclusions drawn from this large-scale investigation are that galvanized steel reinforcement is, at best, no better than non-galvanized steel reinforcement and the air-entrained concrete inhibited corrosion of either galvanized or non-galvanized steel compared with non-air-entrained concrete.

Galvanized Steel in Concrete

Publisher Summary This chapter provides a review of the properties, behavior, processing, and application of galvanized steel reinforcement for use in concrete construction. The past 15-20 years have seen extensive research and field investigations are undertaken of the characteristics and behavior of galvanized reinforcement. This considerable body of work has repeatedly highlighted the benefits of galvanizing in delaying the onset of corrosion in reinforced concrete and in reducing the risks of cracking and rust staining of the concrete mass. It presents the considerable research that the life of the galvanized coating and thus, the reliability of the corrosion protection it provides, depends on many factors. These include the morphology and thickness of the coating, the quality of the concrete in which it is placed, and the severity of the environment to which the concrete is exposed. In circumstances where the underlying steel is exposed, such as at breaks in the coating or at cut edges, the zinc sacrificially protects the steel, thereby further extending the life of the reinforcement. The chapter addresses these issues and summarizes a detailed treatment of the electrochemistry and corrosion behavior of zinc and the galvanized coating.Publisher Summary This chapter provides a review of the properties, behavior, processing, and application of galvanized steel reinforcement for use in concrete construction. The past 15-20 years have seen extensive research and field investigations are undertaken of the characteristics and behavior of galvanized reinforcement. This considerable body of work has repeatedly highlighted the benefits of galvanizing in delaying the onset of corrosion in reinforced concrete and in reducing the risks of cracking and rust staining of the concrete mass. It presents the considerable research that the life of the galvanized coating and thus, the reliability of the corrosion protection it provides, depends on many factors. These include the morphology and thickness of the coating, the quality of the concrete in which it is placed, and the severity of the environment to which the concrete is exposed. In circumstances where the underlying steel is exposed, such as at breaks in the coating or at cut edges, the zinc sacrificially protects the steel, thereby further extending the life of the reinforcement. The chapter addresses these issues and summarizes a detailed treatment of the electrochemistry and corrosion behavior of zinc and the galvanized coating.

Chapter 1 – Galvanized Steel in Concrete: An Overview

Publisher Summary This chapter provides a review of the properties, behavior, processing, and application of galvanized steel reinforcement for use in concrete construction. The past 15-20 years have seen extensive research and field investigations are undertaken of the characteristics and behavior of galvanized reinforcement. This considerable body of work has repeatedly highlighted the benefits of galvanizing in delaying the onset of corrosion in reinforced concrete and in reducing the risks of cracking and rust staining of the concrete mass. It presents the considerable research that the life of the galvanized coating and thus, the reliability of the corrosion protection it provides, depends on many factors. These include the morphology and thickness of the coating, the quality of the concrete in which it is placed, and the severity of the environment to which the concrete is exposed. In circumstances where the underlying steel is exposed, such as at breaks in the coating or at cut edges, the zinc sacrificially protects the steel, thereby further extending the life of the reinforcement. The chapter addresses these issues and summarizes a detailed treatment of the electrochemistry and corrosion behavior of zinc and the galvanized coating.Publisher Summary This chapter provides a review of the properties, behavior, processing, and application of galvanized steel reinforcement for use in concrete construction. The past 15-20 years have seen extensive research and field investigations are undertaken of the characteristics and behavior of galvanized reinforcement. This considerable body of work has repeatedly highlighted the benefits of galvanizing in delaying the onset of corrosion in reinforced concrete and in reducing the risks of cracking and rust staining of the concrete mass. It presents the considerable research that the life of the galvanized coating and thus, the reliability of the corrosion protection it provides, depends on many factors. These include the morphology and thickness of the coating, the quality of the concrete in which it is placed, and the severity of the environment to which the concrete is exposed. In circumstances where the underlying steel is exposed, such as at breaks in the coating or at cut edges, the zinc sacrificially protects the steel, thereby further extending the life of the reinforcement. The chapter addresses these issues and summarizes a detailed treatment of the electrochemistry and corrosion behavior of zinc and the galvanized coating.