The A1-Zn-Mg (7000 series) wrought alloys are very attractive alloys for commercial use principal... more The A1-Zn-Mg (7000 series) wrought alloys are very attractive alloys for commercial use principally due to their high strength-to-weight ratios. They have been used in many engineering applications including structural assemblies; components and members in road and rail transportation and military vehicles. However, there is some lack of confidence towards a wider usage of these medium-to-high strength aluminium alloys due to difficulties sometimes encountered in welding and their susceptibility to stress corrosion cracking, especially in the as-welded condition. In this paper, a brief survey is given of the structure, properties and characteristics of some commercial Al-Zn-Mg (7000 series) alloys. Special emphasis is given to the welding and weld properties of these versatile alloys as a guide to their use in welded structural applications. (Author/TRRL)
This paper describes preliminary results obtained from a study of the fracture resistance of weld... more This paper describes preliminary results obtained from a study of the fracture resistance of weldments containing lack of penetration defects. The fracture toughness parameters, crack opening displacement and j-contour integral were determined at the onset of cracking from tests on single edge notched specimens tested in three-point bending. Results showed that the fracture resistance of defective weldments made by a gas-shielded arc process (gma) was greater than that of welds made using manual covered electrodes (mma). This difference was found to decrease as the proportion of lack of penetration increased. It can be inferred that, at levels of lack of penetration typically encountered in fabrication practice, the tolerance of gma welds would be about twice that of mma welds. (Author/TRRL)
The use of galvanized reinforcement should not be considered simply as an alternative to the prov... more The use of galvanized reinforcement should not be considered simply as an alternative to the provision of an adequate cover of dense impermeable concrete, unless specific design criteria have to be met. Galvanizing of the reinforcement is a complementary measure of corrosion prevention - a form of insurance against the failure of the concrete mass to isolate and protect the steel (a).
An assessment of the primary factors determining the corrosion protection offered by plain cement... more An assessment of the primary factors determining the corrosion protection offered by plain cement (PC) versus fly ash (FA) concrete is presented. Corrosion model testing has shown that the dominant factors controlling the occurrence and progress of reinforcement corrosion are the state of hydration and the microstructural characteristics of the concrete. In this context the beneficial effect of the incorporation of fly ash may be better utilized in quality concrete, wherein an effective pozzolanic reaction is possible along with the optimum use of Portland cement and mixing water.(A) For the covering abstract of the conference see IRRD 828897.
This paper discusses the use of galvanizing for the corrosion protection of steel reinforcement i... more This paper discusses the use of galvanizing for the corrosion protection of steel reinforcement in bridges and coastal structures exposed to deicing salts or the marine environment. Whilst providing both barrier and sacrificial protection to the base steel, the galvanized coating is also effectively immune to carbonation effects in concrete. More importantly, zinc has a significantly higher chloride tolerance than black steel and a chloride threshold some 2-3 times higher than that for uncoated “black” steel is widely accepted. This combination of factors provides for a significant life extension with the use of galvanized reinforcement and is fundamental to achieving a 50-100 year service life for concrete infrastructure exposed to high-chloride conditions.The characteristics and behaviour of traditional hot dipped galvanized reinforcement in concrete and the recent development of the continuous coating of steel reinforcement are explored. The important role of the presence of pure zinc for the passivation of galvanized steel in concrete and the long-term behaviour of the coating are discussed. Design and construction issues specific to galvanized reinforcement are briefly reviewed. Field studies of existing infrastructure and recent applications of galvanized reinforcement in new bridge and coastal construction are presented.
A conceptual model for the behaviour of galvanized steel reinforcement in concrete is presented. ... more A conceptual model for the behaviour of galvanized steel reinforcement in concrete is presented. Based on traditional service life models which include both initiation and propagation stages for the corrosion of steel, the model incorporates an additional stage, namely the protection stage, between initiation and propagation. (A) For the covering abstract see IRRD 867793.
Coated steel reinforcement is widely used in new concrete construction to provide enhanced corros... more 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...
The authors have investigated some structural fatigue cracking in a fleet of aluminium vessels. A... more The authors have investigated some structural fatigue cracking in a fleet of aluminium vessels. A set of experiments were undertaken during sea trial conditions and the results are generally discussed in the paper. The importance of good design and fabrication detail in the avoidance and management of fatigue cracking has been identified as a result of the study conducted and the specific issues observed are addressed. Of particular interest is the apparent influence of prolonged elevated temperature operation in inducing high stress levels leading to premature fatigue cracking.
This paper describes preliminary results obtained from a study of the fracture resistance of weld... more This paper describes preliminary results obtained from a study of the fracture resistance of weldments containing lack of penetration defects. The fracture toughness parameters, crack opening displacement and j-contour integral were determined at the onset of cracking from tests on single edge notched specimens tested in three-point bending. Results showed that the fracture resistance of defective weldments made by a gas-shielded arc process (gma) was greater than that of welds made using manual covered electrodes (mma). This difference was found to decrease as the proportion of lack of penetration increased. It can be inferred that, at levels of lack of penetration typically encountered in fabrication practice, the tolerance of gma welds would be about twice that of mma welds. (Author/TRRL)
"SP-126: Durability of Concrete: Second International Conference, Montreal, Canada 1991"
This study describes comparisons of the corrosion performance and pullout strength of black, hot ... more This study describes comparisons of the corrosion performance and pullout strength of black, hot dip galvanized and fusion bonded epoxy coated steel reinforcement in concrete. Accelerated exposure testing confirmed that zinc coating was able to considerably delay the onset of corrosion and epoxy coating effectively eliminated corrosion provided the coating was not damaged. Where coated reinforcement was left with cut ends unrepaired, the epoxy coated bars showed early corrosion of the exposed steel with corrosion progressing along the bar under the coating. Even where cut ends were repaired, the epoxy coated bars showed many sites of breakdown of the repair and corrosion of the underlying steel. For plain reinforcement, the ultimate bond strength of epoxy coated bars is some 17 percent less than that for black steel bars, while that for galvanized bars is some 31 percent greater than for black steel. The ultimate bond strength of deformed bars is up to 50 percent higher than that of plain bars. The passivation of galvanized plain bars by chromate additions to the concrete mix water in the range 15-150 ppm could not be shown to significantly improve the bond strength.
40 INTRoDUCTIoN When writing about contemporary South African military issues, scholars face some... more 40 INTRoDUCTIoN When writing about contemporary South African military issues, scholars face some difficulty. Firstly, very little, if any, scholarly research emanating from within the military is being published in South Africa or elsewhere at present. On the surface it appears as if ...
Engineering curriculum innovators face a range of formidable barriers which, singly or in combina... more 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 ...
The authors have investigated some structural fatigue cracking in a fleet of aluminium vessels. A... more The authors have investigated some structural fatigue cracking in a fleet of aluminium vessels. A set of experiments were undertaken during sea trial conditions and the results are generally discussed in the paper. The importance of good design and fabrication detail in the avoidance and management of fatigue cracking has been identified as a result of the study conducted and the specific issues observed are addressed. Of particular interest is the apparent influence of prolonged elevated temperature operation in inducing high stress levels leading to premature fatigue cracking.
International Journal of Engineering Education, 2001
A methodology and framework for discipline-specific curriculum development in a local context is ... more A methodology and framework for discipline-specific curriculum development in a local context is described. These activities, as part of the Thailand-Australia Science and Engineering Assistance Project, were in response to a needs analysis for curriculum assistance to a number of publicly-funded Thai universities in the engineering priority area of Materials Processing and Manufacturing. The paper outlines a strategy for the delivery of a centralised curriculum development workshop for academic staff follow-up visits and local curriculum activities with participating universities, and the presentation of technical short courses as guidance for such activity in other settings and/or discipline areas. This paper is part of a process of documentation so that others can apply the developed methodology and framework for curriculum development. While the paper is a report on curriculum activities in a particular setting, it is written in a manner that allows application of the methodolog...
The A1-Zn-Mg (7000 series) wrought alloys are very attractive alloys for commercial use principal... more The A1-Zn-Mg (7000 series) wrought alloys are very attractive alloys for commercial use principally due to their high strength-to-weight ratios. They have been used in many engineering applications including structural assemblies; components and members in road and rail transportation and military vehicles. However, there is some lack of confidence towards a wider usage of these medium-to-high strength aluminium alloys due to difficulties sometimes encountered in welding and their susceptibility to stress corrosion cracking, especially in the as-welded condition. In this paper, a brief survey is given of the structure, properties and characteristics of some commercial Al-Zn-Mg (7000 series) alloys. Special emphasis is given to the welding and weld properties of these versatile alloys as a guide to their use in welded structural applications. (Author/TRRL)
This paper describes preliminary results obtained from a study of the fracture resistance of weld... more This paper describes preliminary results obtained from a study of the fracture resistance of weldments containing lack of penetration defects. The fracture toughness parameters, crack opening displacement and j-contour integral were determined at the onset of cracking from tests on single edge notched specimens tested in three-point bending. Results showed that the fracture resistance of defective weldments made by a gas-shielded arc process (gma) was greater than that of welds made using manual covered electrodes (mma). This difference was found to decrease as the proportion of lack of penetration increased. It can be inferred that, at levels of lack of penetration typically encountered in fabrication practice, the tolerance of gma welds would be about twice that of mma welds. (Author/TRRL)
The use of galvanized reinforcement should not be considered simply as an alternative to the prov... more The use of galvanized reinforcement should not be considered simply as an alternative to the provision of an adequate cover of dense impermeable concrete, unless specific design criteria have to be met. Galvanizing of the reinforcement is a complementary measure of corrosion prevention - a form of insurance against the failure of the concrete mass to isolate and protect the steel (a).
An assessment of the primary factors determining the corrosion protection offered by plain cement... more An assessment of the primary factors determining the corrosion protection offered by plain cement (PC) versus fly ash (FA) concrete is presented. Corrosion model testing has shown that the dominant factors controlling the occurrence and progress of reinforcement corrosion are the state of hydration and the microstructural characteristics of the concrete. In this context the beneficial effect of the incorporation of fly ash may be better utilized in quality concrete, wherein an effective pozzolanic reaction is possible along with the optimum use of Portland cement and mixing water.(A) For the covering abstract of the conference see IRRD 828897.
This paper discusses the use of galvanizing for the corrosion protection of steel reinforcement i... more This paper discusses the use of galvanizing for the corrosion protection of steel reinforcement in bridges and coastal structures exposed to deicing salts or the marine environment. Whilst providing both barrier and sacrificial protection to the base steel, the galvanized coating is also effectively immune to carbonation effects in concrete. More importantly, zinc has a significantly higher chloride tolerance than black steel and a chloride threshold some 2-3 times higher than that for uncoated “black” steel is widely accepted. This combination of factors provides for a significant life extension with the use of galvanized reinforcement and is fundamental to achieving a 50-100 year service life for concrete infrastructure exposed to high-chloride conditions.The characteristics and behaviour of traditional hot dipped galvanized reinforcement in concrete and the recent development of the continuous coating of steel reinforcement are explored. The important role of the presence of pure zinc for the passivation of galvanized steel in concrete and the long-term behaviour of the coating are discussed. Design and construction issues specific to galvanized reinforcement are briefly reviewed. Field studies of existing infrastructure and recent applications of galvanized reinforcement in new bridge and coastal construction are presented.
A conceptual model for the behaviour of galvanized steel reinforcement in concrete is presented. ... more A conceptual model for the behaviour of galvanized steel reinforcement in concrete is presented. Based on traditional service life models which include both initiation and propagation stages for the corrosion of steel, the model incorporates an additional stage, namely the protection stage, between initiation and propagation. (A) For the covering abstract see IRRD 867793.
Coated steel reinforcement is widely used in new concrete construction to provide enhanced corros... more 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...
The authors have investigated some structural fatigue cracking in a fleet of aluminium vessels. A... more The authors have investigated some structural fatigue cracking in a fleet of aluminium vessels. A set of experiments were undertaken during sea trial conditions and the results are generally discussed in the paper. The importance of good design and fabrication detail in the avoidance and management of fatigue cracking has been identified as a result of the study conducted and the specific issues observed are addressed. Of particular interest is the apparent influence of prolonged elevated temperature operation in inducing high stress levels leading to premature fatigue cracking.
This paper describes preliminary results obtained from a study of the fracture resistance of weld... more This paper describes preliminary results obtained from a study of the fracture resistance of weldments containing lack of penetration defects. The fracture toughness parameters, crack opening displacement and j-contour integral were determined at the onset of cracking from tests on single edge notched specimens tested in three-point bending. Results showed that the fracture resistance of defective weldments made by a gas-shielded arc process (gma) was greater than that of welds made using manual covered electrodes (mma). This difference was found to decrease as the proportion of lack of penetration increased. It can be inferred that, at levels of lack of penetration typically encountered in fabrication practice, the tolerance of gma welds would be about twice that of mma welds. (Author/TRRL)
"SP-126: Durability of Concrete: Second International Conference, Montreal, Canada 1991"
This study describes comparisons of the corrosion performance and pullout strength of black, hot ... more This study describes comparisons of the corrosion performance and pullout strength of black, hot dip galvanized and fusion bonded epoxy coated steel reinforcement in concrete. Accelerated exposure testing confirmed that zinc coating was able to considerably delay the onset of corrosion and epoxy coating effectively eliminated corrosion provided the coating was not damaged. Where coated reinforcement was left with cut ends unrepaired, the epoxy coated bars showed early corrosion of the exposed steel with corrosion progressing along the bar under the coating. Even where cut ends were repaired, the epoxy coated bars showed many sites of breakdown of the repair and corrosion of the underlying steel. For plain reinforcement, the ultimate bond strength of epoxy coated bars is some 17 percent less than that for black steel bars, while that for galvanized bars is some 31 percent greater than for black steel. The ultimate bond strength of deformed bars is up to 50 percent higher than that of plain bars. The passivation of galvanized plain bars by chromate additions to the concrete mix water in the range 15-150 ppm could not be shown to significantly improve the bond strength.
40 INTRoDUCTIoN When writing about contemporary South African military issues, scholars face some... more 40 INTRoDUCTIoN When writing about contemporary South African military issues, scholars face some difficulty. Firstly, very little, if any, scholarly research emanating from within the military is being published in South Africa or elsewhere at present. On the surface it appears as if ...
Engineering curriculum innovators face a range of formidable barriers which, singly or in combina... more 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 ...
The authors have investigated some structural fatigue cracking in a fleet of aluminium vessels. A... more The authors have investigated some structural fatigue cracking in a fleet of aluminium vessels. A set of experiments were undertaken during sea trial conditions and the results are generally discussed in the paper. The importance of good design and fabrication detail in the avoidance and management of fatigue cracking has been identified as a result of the study conducted and the specific issues observed are addressed. Of particular interest is the apparent influence of prolonged elevated temperature operation in inducing high stress levels leading to premature fatigue cracking.
International Journal of Engineering Education, 2001
A methodology and framework for discipline-specific curriculum development in a local context is ... more A methodology and framework for discipline-specific curriculum development in a local context is described. These activities, as part of the Thailand-Australia Science and Engineering Assistance Project, were in response to a needs analysis for curriculum assistance to a number of publicly-funded Thai universities in the engineering priority area of Materials Processing and Manufacturing. The paper outlines a strategy for the delivery of a centralised curriculum development workshop for academic staff follow-up visits and local curriculum activities with participating universities, and the presentation of technical short courses as guidance for such activity in other settings and/or discipline areas. This paper is part of a process of documentation so that others can apply the developed methodology and framework for curriculum development. While the paper is a report on curriculum activities in a particular setting, it is written in a manner that allows application of the methodolog...
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