Proceedings of International Structural Engineering and Construction
There is a global shift towards circular economies, which concentrate on reducing waste, extendin... more There is a global shift towards circular economies, which concentrate on reducing waste, extending the useful life of materials or transforming wastes into another useful material. Every year, Australia generates around 2.54 million tonnes (Mt) of waste plastics, 1.16 Mt of waste glass, and 0.45 Mt of end-of-life tires. Of these about 85% of the plastic, 41% of the glass, and 24% of the tires are disposed of in either licensed or unlicensed landfills at significant financial and environmental cost. The 2021 ban on the export of mixed plastics, glass, and tires has put tremendous pressure on Australia's resource recovery sector, as around 500,000 tonnes of additional landfill waste per year must be processed onshore as a consequence. This paper discusses the technical and environmental challenges associated with these landfill wastes and determines whether they can be made or recreated into useful resources. A summary of the current initiatives in value-adding landfill waste for ...
Abstract A novel form of thin-walled composite beams has been developed by bonding cold-formed st... more Abstract A novel form of thin-walled composite beams has been developed by bonding cold-formed steel (CFS) and engineered cementitious composites (ECC). Apart from the superior material strength and ductility of CFS and ECC, the proposed CFS/ECC composite system also benefits from the lightweight concept of thin-walled sections and improved buckling performance due to the ECC restraints on CFS. An experimental study, utilising cold-formed steel sections with a yield strength of 450 MPa and engineered cementitious composites with an ultimate tensile strength of 7 MPa, was conducted to investigate the improvement of the innovated structural system over the traditional CFS structures. Two series of composite CFS/ECC beams, namely, short- and long-span Series, were prepared and tested to monitor the shear and flexural behaviours of the novel composite system. Three locations of thin-layered ECC; outside, inside, and in–out of the CFS section were proposed to determine the perfect composite action between ECC and CFS. The load capacity of the composite beams (ECC—in composite beams) increased to eight times those of the bare CFS members in the short-span Series and up to four times in the long-span Series. The failure modes of the novel composite beams were more ductile compared to the bare CFS. Numerical modelling was conducted and validated using the results obtained from the experimental study. This FE model was employed in a small-scale parametric study to investigate the influence of beam spans on the structural behaviour of the composite CFS/ECC beams.
The use of rubber particles as partial fine aggregate replacement to produce crumb rubber concret... more The use of rubber particles as partial fine aggregate replacement to produce crumb rubber concrete (CRC) can have an adverse effect on some of its mechanical properties, such as strength. Researchers have used a range of methods to overcome the material deficiencies, however the results have often been contradictory and highly variable. In this paper, the effects of many different rubber chemical pre-treatments on CRC workability, compressive strength, tensile strength, and flexural strength were measured. The rubber pretreatments utilized chemicals such as Sodium Hydroxide (NaOH), Hydrogen Peroxide (H2O2), Sulfuric acid (H2SO4), Calcium Chloride (CaCl2), Potassium Permanganate (KMnO4), Sodium Bisulfite (NaHsO3), and Silane Coupling Agent. Soaking rubber particles in tap water or running them through water before mixing were also tried as pre-treatment of rubber particles. X-ray photoelectron spectroscopy (XPS) analysis and scanning electron microscope (SEM) imaging of some of the pre-treated rubber particles were carried out. The results showed that mixing rubber with dry cement before adding to the mix increased the compressive strength by up to 3%. Pretreatment using water was more effective than other chemicals in enhancing the CRC workability. Regardless of the treatment material type, the longer the time of the treatment the more cleaning of rubber occurred.
Abstract Rubberised concrete is an eco-friendly material with reasonable mechanical strengths for... more Abstract Rubberised concrete is an eco-friendly material with reasonable mechanical strengths for potential civil engineering applications. Recent research has proved that rubberised concrete has superior properties at high strain rates such as dynamic compressive strength, dynamic splitting tensile strength, dynamic flexural strength, impact and collision resistance, repeated and reversed cyclic loads, and seismic loads. This paper presents in depth classification and summary of over ninety published articles on rubberised concrete dynamic properties and its structural applications where the dynamic properties are dominant and high strength of concrete is not necessary. The results show that structural applications such as reinforced concrete slabs, columns, beams, and walls with rubberised concrete exhibit better performance under high velocity impact and collision, bullet resistance, and blast loads compared with traditional concrete. In addition, rubberised concrete has high sensitivity to strain loading rates, high energy dissipation and ductile performance under dynamic loads compared to traditional concrete. A significant improvement in the behaviour of structural members under cyclic and seismic loads, including ductility, energy dissipation, stiffness degradation was observed. On the other hand, the reduction in load carrying capacity is significantly smaller than the reduction in the concrete strength of rubberised concrete compared with traditional concrete.
Abstract This study presents a systematic investigation of the bond behaviour of rubberized concr... more Abstract This study presents a systematic investigation of the bond behaviour of rubberized concrete. The local and global bond behaviours of rubberized concrete are studied experimentally using concentric pull-out test and beam end test, respectively. The test parameters include concrete strength grade, bar embedded length, bar diameter and rubber content. In addition to the bond tests and the ancillary material property tests, six large-scale reinforced rubberized concrete beams are also tested under flexural bending to evaluate the influence of the alteration of bond behaviour owing to rubber incorporation on the flexural performance of the beams. The higher deformability of rubberized concrete compared to conventional concrete at each strength grade results in altered local and global bond behaviour, where the reduced peak bond stress and an increase in the slip at the peak bond stress are observed. The altered bond in conjunction with the other reduced mechanical properties of rubberized concrete subsequently led to a reduction in the flexural stiffness at the elastic stage and a reduction in ductility at the post-peak stage of a corresponding reinforced concrete beam containing rubber. The results of the mechanics-based and code-based models for predicting the development length for a reinforced bar in rubberized concrete indicated that the code-based model to design the anchorage length in rubberized concrete could be used with confidence.
Calcium aluminate cement (CAC)—based strain hardening cementitious composites (SHCC) has been dev... more Calcium aluminate cement (CAC)—based strain hardening cementitious composites (SHCC) has been developed and used for the rehabilitation of sewerage pipelines. In addition to well-known microbiologically induced corrosion, CO2 concentration in the sewerage environment is high, which may cause significant carbonation of pipelines. Thus, this paper aims to investigate the effects of carbonation on the mechanical performance of CAC-based SHCC. Two types of CAC-based SHCC with different strength grades and a referenced OPC-based SHCC were prepared. The accelerated carbonation test was conducted in a carbonation chamber with a 5% CO2 concentration. The compressive and tensile behaviour of SHCC was tested first, and microstructure analysis, e.g., X-ray diffraction and scanning electron microscopy, was then performed. The results showed that CAC-based SHCC specimens exhibited robust strain-hardening performance as well as large deformation capacity in tension due to the fiber-bridging effec...
Proceedings of International Structural Engineering and Construction
There is a global shift towards circular economies, which concentrate on reducing waste, extendin... more There is a global shift towards circular economies, which concentrate on reducing waste, extending the useful life of materials or transforming wastes into another useful material. Every year, Australia generates around 2.54 million tonnes (Mt) of waste plastics, 1.16 Mt of waste glass, and 0.45 Mt of end-of-life tires. Of these about 85% of the plastic, 41% of the glass, and 24% of the tires are disposed of in either licensed or unlicensed landfills at significant financial and environmental cost. The 2021 ban on the export of mixed plastics, glass, and tires has put tremendous pressure on Australia's resource recovery sector, as around 500,000 tonnes of additional landfill waste per year must be processed onshore as a consequence. This paper discusses the technical and environmental challenges associated with these landfill wastes and determines whether they can be made or recreated into useful resources. A summary of the current initiatives in value-adding landfill waste for ...
Abstract A novel form of thin-walled composite beams has been developed by bonding cold-formed st... more Abstract A novel form of thin-walled composite beams has been developed by bonding cold-formed steel (CFS) and engineered cementitious composites (ECC). Apart from the superior material strength and ductility of CFS and ECC, the proposed CFS/ECC composite system also benefits from the lightweight concept of thin-walled sections and improved buckling performance due to the ECC restraints on CFS. An experimental study, utilising cold-formed steel sections with a yield strength of 450 MPa and engineered cementitious composites with an ultimate tensile strength of 7 MPa, was conducted to investigate the improvement of the innovated structural system over the traditional CFS structures. Two series of composite CFS/ECC beams, namely, short- and long-span Series, were prepared and tested to monitor the shear and flexural behaviours of the novel composite system. Three locations of thin-layered ECC; outside, inside, and in–out of the CFS section were proposed to determine the perfect composite action between ECC and CFS. The load capacity of the composite beams (ECC—in composite beams) increased to eight times those of the bare CFS members in the short-span Series and up to four times in the long-span Series. The failure modes of the novel composite beams were more ductile compared to the bare CFS. Numerical modelling was conducted and validated using the results obtained from the experimental study. This FE model was employed in a small-scale parametric study to investigate the influence of beam spans on the structural behaviour of the composite CFS/ECC beams.
The use of rubber particles as partial fine aggregate replacement to produce crumb rubber concret... more The use of rubber particles as partial fine aggregate replacement to produce crumb rubber concrete (CRC) can have an adverse effect on some of its mechanical properties, such as strength. Researchers have used a range of methods to overcome the material deficiencies, however the results have often been contradictory and highly variable. In this paper, the effects of many different rubber chemical pre-treatments on CRC workability, compressive strength, tensile strength, and flexural strength were measured. The rubber pretreatments utilized chemicals such as Sodium Hydroxide (NaOH), Hydrogen Peroxide (H2O2), Sulfuric acid (H2SO4), Calcium Chloride (CaCl2), Potassium Permanganate (KMnO4), Sodium Bisulfite (NaHsO3), and Silane Coupling Agent. Soaking rubber particles in tap water or running them through water before mixing were also tried as pre-treatment of rubber particles. X-ray photoelectron spectroscopy (XPS) analysis and scanning electron microscope (SEM) imaging of some of the pre-treated rubber particles were carried out. The results showed that mixing rubber with dry cement before adding to the mix increased the compressive strength by up to 3%. Pretreatment using water was more effective than other chemicals in enhancing the CRC workability. Regardless of the treatment material type, the longer the time of the treatment the more cleaning of rubber occurred.
Abstract Rubberised concrete is an eco-friendly material with reasonable mechanical strengths for... more Abstract Rubberised concrete is an eco-friendly material with reasonable mechanical strengths for potential civil engineering applications. Recent research has proved that rubberised concrete has superior properties at high strain rates such as dynamic compressive strength, dynamic splitting tensile strength, dynamic flexural strength, impact and collision resistance, repeated and reversed cyclic loads, and seismic loads. This paper presents in depth classification and summary of over ninety published articles on rubberised concrete dynamic properties and its structural applications where the dynamic properties are dominant and high strength of concrete is not necessary. The results show that structural applications such as reinforced concrete slabs, columns, beams, and walls with rubberised concrete exhibit better performance under high velocity impact and collision, bullet resistance, and blast loads compared with traditional concrete. In addition, rubberised concrete has high sensitivity to strain loading rates, high energy dissipation and ductile performance under dynamic loads compared to traditional concrete. A significant improvement in the behaviour of structural members under cyclic and seismic loads, including ductility, energy dissipation, stiffness degradation was observed. On the other hand, the reduction in load carrying capacity is significantly smaller than the reduction in the concrete strength of rubberised concrete compared with traditional concrete.
Abstract This study presents a systematic investigation of the bond behaviour of rubberized concr... more Abstract This study presents a systematic investigation of the bond behaviour of rubberized concrete. The local and global bond behaviours of rubberized concrete are studied experimentally using concentric pull-out test and beam end test, respectively. The test parameters include concrete strength grade, bar embedded length, bar diameter and rubber content. In addition to the bond tests and the ancillary material property tests, six large-scale reinforced rubberized concrete beams are also tested under flexural bending to evaluate the influence of the alteration of bond behaviour owing to rubber incorporation on the flexural performance of the beams. The higher deformability of rubberized concrete compared to conventional concrete at each strength grade results in altered local and global bond behaviour, where the reduced peak bond stress and an increase in the slip at the peak bond stress are observed. The altered bond in conjunction with the other reduced mechanical properties of rubberized concrete subsequently led to a reduction in the flexural stiffness at the elastic stage and a reduction in ductility at the post-peak stage of a corresponding reinforced concrete beam containing rubber. The results of the mechanics-based and code-based models for predicting the development length for a reinforced bar in rubberized concrete indicated that the code-based model to design the anchorage length in rubberized concrete could be used with confidence.
Calcium aluminate cement (CAC)—based strain hardening cementitious composites (SHCC) has been dev... more Calcium aluminate cement (CAC)—based strain hardening cementitious composites (SHCC) has been developed and used for the rehabilitation of sewerage pipelines. In addition to well-known microbiologically induced corrosion, CO2 concentration in the sewerage environment is high, which may cause significant carbonation of pipelines. Thus, this paper aims to investigate the effects of carbonation on the mechanical performance of CAC-based SHCC. Two types of CAC-based SHCC with different strength grades and a referenced OPC-based SHCC were prepared. The accelerated carbonation test was conducted in a carbonation chamber with a 5% CO2 concentration. The compressive and tensile behaviour of SHCC was tested first, and microstructure analysis, e.g., X-ray diffraction and scanning electron microscopy, was then performed. The results showed that CAC-based SHCC specimens exhibited robust strain-hardening performance as well as large deformation capacity in tension due to the fiber-bridging effec...
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