Global climate change related to anthropogenic CO2 emissions is one of the most significant chall... more Global climate change related to anthropogenic CO2 emissions is one of the most significant challenges for the future of human life on Earth. There are many potential options for reducing or even eliminating atmospheric CO2 emissions including underground sequestration, carbon mineralization and ocean storage. One of the most promising materials for carbon mineralization is Mg(OH)2 which is highly reactive and capable of forming stable carbonates. Here we show a novel low-carbon method of producing Mg(OH)2, from globally abundant olivine-rich silicate rocks. A combination of acid digestion and electrolysis of olivine were used to produce Mg(OH)2 in a fully recoverable system. The use of Mg(OH)2 from olivine provides a viable pathway for significant industrial scale reductions in global anthropogenic greenhouse gas emissions.
An experimental study was conducted on reinforced and steel fibre–reinforced concrete composite s... more An experimental study was conducted on reinforced and steel fibre–reinforced concrete composite slabs with steel decking under negative bending moment to quantify the ultimate behaviour, loading capacity and crack width under short-term loading. Eight full-scale slab specimens were cast with different types and amounts of reinforcement in the concrete (e.g. mesh, steel fibre or normal reinforcing bars) but with the same type of steel decking. Each slab was simply supported and tested in four-point bending under increasing load until failure. The deflections at mid-span and under the applied point loads were monitored together with the end interface slip. The crack widths were obtained for each slab for different levels of applied load. It was found that the end slip was quite negligible and complete interaction on the steel decking–concrete slab interface existed at service loads and ultimate limit states. Compared to the slab with 20 kg/m3 steel fibre, the application of steel fibr...
... Abstract: An investigation of fly ash (FA) produced from various blends of coal and petroleum... more ... Abstract: An investigation of fly ash (FA) produced from various blends of coal and petroleumcoke (pet coke) fired at Belledune Generating Station, New Brunswick, Canada, was conducted to establish its performance relative to FA derived from coal-only combustion and its ...
ABSTRACT Self-compacting concrete (SCC) has gained substantial attention since its advent for its... more ABSTRACT Self-compacting concrete (SCC) has gained substantial attention since its advent for its ability to compact without the need for either internal or external vibration even in areas of highly congested reinforcement such as beam-column joints. During the past two decades, extensive research has been conducted on both the fresh and hardened properties of normal strength SCC; however, only recently has interest in high-strength self-compacting concrete (HSSCC) gained momentum. This study investigates bond properties between reinforcement and HSSCC as well as conventionally vibrated high-strength concrete (CVHSC). Appropriate mix designs for both HSSCC and CVHSC were first developed to achieve comparable concrete compressive strength of about 90 MPa. The effects of bar grade, diameter, bond length, and concrete type were investigated by means of pull-out tests for both concrete types; where, special attention was paid to the post-yield slip behaviour of different steel grades. It was found that the difference in ductility of bars with different grades results in different rate of diameter reduction due to axial tensile stress which consequently affects their bond performance; especially in the post-yield range. Available bond models were applied to the experimental outcomes of this study and modifications and/or new expressions are suggested where possible.
This paper describes a test programme at the University of Canterbury to evaluate the performance... more This paper describes a test programme at the University of Canterbury to evaluate the performance of elements of concrete slabs that are reinforced in different ways. The reinforcing includes steel fibre, brittle mesh, ductile mesh and two grades of reinforcing bars. The percentage of reinforcing varies. Shear and flexural tests are conducted. The work described is in the initial stages of testing, so this paper concentrates on the methodology for selecting the test types and parameters.
Beam-column joints of reinforced concrete building frames play an important role under seismic ex... more Beam-column joints of reinforced concrete building frames play an important role under seismic excitations. These are one of the most congested areas in reinforced concrete framed structures; placement of concrete and proper compaction in such areas are hence substantially challenging. This offers a unique area of application for self-compacting concrete which can flow through every corner of extensively reinforced area without any vibration. Therefore if implementing self-compacting concrete in beam-column joints does not compromise seismic performance of the frame, it can be used instead of conventional concrete. This paper focuses on implementation of high-strength self-compacting concrete in beam-column joints and assessment of its seismic behaviour under reversed cyclic loading. Three interior beam-column subassemblies chosen to vary in concrete type and compressive strength are designed as per the New Zealand Standard NZ3101:2006. The specimens are instrumented to measure the load, displacement/drift, ductility, joint shear deformations, and elongation of the plastic hinge zone. The cracking pattern at different load levels and the mode of failure are also recorded and compared among different specimens.
Metal roofing material is commonly used for residential and industrial roofs in volcanically acti... more Metal roofing material is commonly used for residential and industrial roofs in volcanically active areas. Increased corrosion of metal roofing from chemically reactive volcanic ash following ash deposition post-eruption is a major concern due to decreasing the function and stability of roofs. Currently, assessment of ash-induced corrosion is anecdotal, and quantitative data are lacking. Here, we systematically evaluate the corrosive effects of volcanic ash, specifically ash leachates, on a variety of metal roofing materials (i.e. weathered steel, zinc, galvanized steel, and ColorsteelÓ) utilizing weathering chamber experiments and direct acid treatments. Weathering chamber tests were carried out for up to 30 days, and visual, chemical, and surface analyses did not definitively identify significant corrosion in any of the test roofing metal samples. Direct concentrated acid treatments with hydrochloric (HCl), sulphuric (H 2 SO 4 ), and hydrofluoric (HF) acids demonstrate that roofing materials are chemically resilient. Our experimental results suggest that ash-leachate-related corrosion is a longer-term process ([1 month), potentially related to a multitude of factors including increased ash leachate concentrations, the dissolution of the glass matrix of the ash, moisture retention at the ash-surface boundary, and potential reactions involving photo-oxidation. Overall, corrosion is not a simple process related to the short-term release of acid and/or salt leachates from the ash surface, but a product of dynamic interactions involving ash and water at the surface of metal roofing material for extended periods.
Global climate change related to anthropogenic CO2 emissions is one of the most significant chall... more Global climate change related to anthropogenic CO2 emissions is one of the most significant challenges for the future of human life on Earth. There are many potential options for reducing or even eliminating atmospheric CO2 emissions including underground sequestration, carbon mineralization and ocean storage. One of the most promising materials for carbon mineralization is Mg(OH)2 which is highly reactive and capable of forming stable carbonates. Here we show a novel low-carbon method of producing Mg(OH)2, from globally abundant olivine-rich silicate rocks. A combination of acid digestion and electrolysis of olivine were used to produce Mg(OH)2 in a fully recoverable system. The use of Mg(OH)2 from olivine provides a viable pathway for significant industrial scale reductions in global anthropogenic greenhouse gas emissions.
An experimental study was conducted on reinforced and steel fibre–reinforced concrete composite s... more An experimental study was conducted on reinforced and steel fibre–reinforced concrete composite slabs with steel decking under negative bending moment to quantify the ultimate behaviour, loading capacity and crack width under short-term loading. Eight full-scale slab specimens were cast with different types and amounts of reinforcement in the concrete (e.g. mesh, steel fibre or normal reinforcing bars) but with the same type of steel decking. Each slab was simply supported and tested in four-point bending under increasing load until failure. The deflections at mid-span and under the applied point loads were monitored together with the end interface slip. The crack widths were obtained for each slab for different levels of applied load. It was found that the end slip was quite negligible and complete interaction on the steel decking–concrete slab interface existed at service loads and ultimate limit states. Compared to the slab with 20 kg/m3 steel fibre, the application of steel fibr...
... Abstract: An investigation of fly ash (FA) produced from various blends of coal and petroleum... more ... Abstract: An investigation of fly ash (FA) produced from various blends of coal and petroleumcoke (pet coke) fired at Belledune Generating Station, New Brunswick, Canada, was conducted to establish its performance relative to FA derived from coal-only combustion and its ...
ABSTRACT Self-compacting concrete (SCC) has gained substantial attention since its advent for its... more ABSTRACT Self-compacting concrete (SCC) has gained substantial attention since its advent for its ability to compact without the need for either internal or external vibration even in areas of highly congested reinforcement such as beam-column joints. During the past two decades, extensive research has been conducted on both the fresh and hardened properties of normal strength SCC; however, only recently has interest in high-strength self-compacting concrete (HSSCC) gained momentum. This study investigates bond properties between reinforcement and HSSCC as well as conventionally vibrated high-strength concrete (CVHSC). Appropriate mix designs for both HSSCC and CVHSC were first developed to achieve comparable concrete compressive strength of about 90 MPa. The effects of bar grade, diameter, bond length, and concrete type were investigated by means of pull-out tests for both concrete types; where, special attention was paid to the post-yield slip behaviour of different steel grades. It was found that the difference in ductility of bars with different grades results in different rate of diameter reduction due to axial tensile stress which consequently affects their bond performance; especially in the post-yield range. Available bond models were applied to the experimental outcomes of this study and modifications and/or new expressions are suggested where possible.
This paper describes a test programme at the University of Canterbury to evaluate the performance... more This paper describes a test programme at the University of Canterbury to evaluate the performance of elements of concrete slabs that are reinforced in different ways. The reinforcing includes steel fibre, brittle mesh, ductile mesh and two grades of reinforcing bars. The percentage of reinforcing varies. Shear and flexural tests are conducted. The work described is in the initial stages of testing, so this paper concentrates on the methodology for selecting the test types and parameters.
Beam-column joints of reinforced concrete building frames play an important role under seismic ex... more Beam-column joints of reinforced concrete building frames play an important role under seismic excitations. These are one of the most congested areas in reinforced concrete framed structures; placement of concrete and proper compaction in such areas are hence substantially challenging. This offers a unique area of application for self-compacting concrete which can flow through every corner of extensively reinforced area without any vibration. Therefore if implementing self-compacting concrete in beam-column joints does not compromise seismic performance of the frame, it can be used instead of conventional concrete. This paper focuses on implementation of high-strength self-compacting concrete in beam-column joints and assessment of its seismic behaviour under reversed cyclic loading. Three interior beam-column subassemblies chosen to vary in concrete type and compressive strength are designed as per the New Zealand Standard NZ3101:2006. The specimens are instrumented to measure the load, displacement/drift, ductility, joint shear deformations, and elongation of the plastic hinge zone. The cracking pattern at different load levels and the mode of failure are also recorded and compared among different specimens.
Metal roofing material is commonly used for residential and industrial roofs in volcanically acti... more Metal roofing material is commonly used for residential and industrial roofs in volcanically active areas. Increased corrosion of metal roofing from chemically reactive volcanic ash following ash deposition post-eruption is a major concern due to decreasing the function and stability of roofs. Currently, assessment of ash-induced corrosion is anecdotal, and quantitative data are lacking. Here, we systematically evaluate the corrosive effects of volcanic ash, specifically ash leachates, on a variety of metal roofing materials (i.e. weathered steel, zinc, galvanized steel, and ColorsteelÓ) utilizing weathering chamber experiments and direct acid treatments. Weathering chamber tests were carried out for up to 30 days, and visual, chemical, and surface analyses did not definitively identify significant corrosion in any of the test roofing metal samples. Direct concentrated acid treatments with hydrochloric (HCl), sulphuric (H 2 SO 4 ), and hydrofluoric (HF) acids demonstrate that roofing materials are chemically resilient. Our experimental results suggest that ash-leachate-related corrosion is a longer-term process ([1 month), potentially related to a multitude of factors including increased ash leachate concentrations, the dissolution of the glass matrix of the ash, moisture retention at the ash-surface boundary, and potential reactions involving photo-oxidation. Overall, corrosion is not a simple process related to the short-term release of acid and/or salt leachates from the ash surface, but a product of dynamic interactions involving ash and water at the surface of metal roofing material for extended periods.
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Papers by Allan Scott