Promoting the reuse and recycling of building demolition materials

The demolition of constructed structures has earned a negative reputation for the construction industry due to the enormous amount of waste that is sent to landfills. Demolition waste reuse and recycling is, therefore, significant; it is a new and illustrative perspective on demolition waste management from the viewpoint of the building material lifecycle. It is discovered that demolition waste reuse and recycling plays important roles in value transformation for building material lifecycle, local economics,
sustainable environment and nature resource conservation. In this research article, the authors aim to pinpoint demolition waste management in the lifecycle of building materials, and to examine various economic and environmental aspects of demolition waste reuse and recycling. In addition, the barriers, limitations and solutions for improving the implementation of demolition waste reuse and recycling are discussed in the article.

Use of plastic and textile media in polishing primary treated effluent

The majority of on-site sewage management systems in Australia fail to perform to expectations. About 60% to 80% of on-site systems reportedly fail to produce acceptable effluent quality, and there is an increaed concern about the risks associated with public health and environmental pollution. In Victoria, a large proportion of septic tank installations have been reported to discharge highly polluted waste to drains and streams. Users, often considered by regulators as operators, have to bear the costs of upgrade/replacement of their old systems to meet stringent water quality guidelines. Some of the common problems include clogging of the disposal fields due to solids and organic overloading and surfacing of highly polluted effluent. Large land application area is subsequently required for irrigating the effluent and/or installation of upgraded disposal fields.
This paper investigates the effectiveness of various types of textile and plastic media, in polishing primary tank effluent, downstream from a typical two-compartment septic tank system. Results to date show that high biochemical oxygen demand removal rates are achieved from the textile and plastic media (up to 86% and 83% respectively). At these removal levels, the performance of a combined conventional septic tank system and plastic/textile filters is comparable to that of an advanced aerated wastewater treatment system. This approach, subject to further investigation, could provide a less costly upgrade.

Superplasticity and cavitation of recycled AZ31 magnesium alloy fabricated by solid recycling process

Superplastic behaviour of Mg-alloy AZ31 was investigated to clarify the possibility of its use for superplastic forming (SPF) and to accurately evaluate material characteristics under a biaxial stress by utilizing a multi-dome test. The material characteristics were evaluated under three different superplastic temperatures , 643, 673, and 703 K in order to determine the most suitable superplastic temperature. Finite Element Method (FEM) simulation of rectangular pan forming was carried out to predict the formability of the material into a complex shape. The superplastic material properties are used for the simulation of a rectangular pan. Finally, the simulation results are compared with the experimental results to determine the accuracy of the superplastic material characteristics. The experimental results revealed that the m values are greater than 0.3 under the three superplastic temperatures, which is indicative of superplasticity. The optimum superplastic temperature is 673 K, at which a maximum m value and no grain growth were observed. The results of the FEM simulation revealed that certain localized thinning occurred at the die entrance of the deformed rectangular pan due to the insufficient ductility of the material. The simulation results also showed that the optimum superplastic temperature of AZ31 is 673 K.

Deformation behavior of nanostructured aluminum alloy processed by severe plastic deformation

Microstructure and deformation behavior of the commercial aluminum-based Al7.5%Zn–2.7%Mg–2.3%Cu–0.15%Zr alloy subjected to high pressure torsion (HPT) were studied in the present work. A small grain size less than 100 nm, high level of internal stresses and presence of second phase nanoparticles were revealed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The nanostructured alloy processed by HPT exhibits tensile strength of 800 MPa and ductility of 20% at optimal temperature-strain rate conditions. Unusual influence of a short pre-annealing on tensile strength and ductility of as-processed alloy is discussed.

Public environmental consumerism : recycling behaviour and its impact on intentions to purchase green products

Recycling behaviour has been used as indicators of green behavior since research has indicated that there is a positive relationship between environmental concern and ecologically responsible behavior such as recycling. The objective of this study is to find out if there is a difference between recyclers and non-recyclers and heavy and light recyclers with respect to their willingness to pay more for green products despite the perception of green products being of a lower quality in comparison to alternative products. The answers to this will help us to better understand environmentally conscious consumerism of both groups of consumers i.e. the light and heavy recyclers. The results indicate that willingness to pay somewhat higher prices and accepting somewhat lower quality of green products appears to be, generally, independent of recycling and non-recycling, as well as heavy and light recycling behaviour. It also addresses the implications of these findings for business managers.

Plastic deformation in Zr41 Ti14 Cu12.5 Ni10 Be22.5 bulk metal glass under vickers indenter

Vickers indentation was conducted on an as-cast Zr41Ti14Cu12.5Ni10Be22.5 bulk metal glass (BMG) to study shear band formation using a bonded interface technique. The results indicate that the plastic deformation in the BMG is accommodated by the semi-circular (primary) and radial (secondary) shear bands. The inter-band spacing of the semi-circular shear bands is found to be independent of the applied load. The measured size of the deformation zone is in good agreement with the prediction of the theoretical model proposed by Zhang et al.

Determination of plastic yield stress from spherical indentation slope curve

The indentation slope curve from a spherical indentation on elastic-plastic materials is examined. By comparing it with that of an linear elastic material of the same elastic properties, we found that the start point of plastic yielding for an elastic-plastic material can be easily located from the indentation slope curve. Based on this analysis, a simple but effective method is proposed to measure the plastic yield stress of very small samples from a spherical nano-indentation slope curve.

Polyhedral : recycling boundary ecologies

Foregrounding the extent to which 'place' remains resistant to the politics and poetics of 'network culture', this essay approaches place as a boundary ecology rather than as an instance of cultural invariance. It calls on readers to think about attempts to actively recycle cultural 'debris' or 'waste' through an ethics of passage instead of the kind of instrumentalist statics that prevents the development of an ontology of mobility. Con-tending that such a capacity to inhabit passage is compromised by the eschatological language used to communicate the implications of environmental disaster, as well as by languages of consultation that (con-ceptually) empty place of any creative power to incubate alternatives – events, modes of relation –, the essay stresses the mythopoetic techniques that produce places as knots or nodal points within a network of pas-sage. The designer's task is to create the hinge mechanisms that render such boundary ecologies inhabitable imaginatively, and by materialising the nexus between creativity and change to alter our position vis-a-vis our ethical responsibilities as citizens of a shared biosphere.

Effect of structure relaxation on the plastic deformation behaviour in a Zr-based BMG under indenter

Vickers and nano indentations were performed on a structurally relaxed Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5 bulk metallic glass (BMG), and the evolution of the shear bands in the relaxed BMG was investigated and compared to that in the as-cast alloy. Results indicate that the plastic deformation in the BMG with structure relaxation is accommodated by the semicircular (primary) and radial (secondary) as well as tertiary shear bands. Quantitatively, the shear band density in the relaxed alloy was much lower than that in the as-cast alloy. The annihilation of free volume caused by the annealing was responsible for the embrittlement of the sample with structure relaxation.

Plastic deformation in the annealed Zr41Ti14Cu12.5Ni10Be22.5 bulk metal glass under indenter

Vickers and nanoindentationswere carried out on an annealed Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5 bulk metallic glass (BMG), and the evolution of the shear bands in the annealed BMG was investigated and compared to that in the as-cast alloy. Results indicate that the plastic deformation in the BMG with the structure relaxation is accommodated by the semicircular (primary) and radial (secondary) as well as tertiary shear bands. Quantitatively, the shear band density in the annealed alloywas much lower than that in the as-cast alloy. The load-displacement curve of nanoindentation test for the annealed alloy exhibited a more flat serrated flow. The annihilation of free volume caused by the annealing was responsible for the embrittlement of the annealed sample.

Plastic deformation in a partially crystallized Zr-based BMG under Vickers indenter

Vickers indentations were carried out on an anneal-introduced partially crystallized Zr₄₁Ti₁₄Cu_12.5 Ni₁₀Be_22.5 bulk metallic glass (BMG), and the evolution of the shear bands in this samplewas investigated and compared to the as-cast, aswell as the structurally relaxed counterparts. The results indicate that the plastic deformation in the partially crystallized BMG was accommodated by the semi-circular (primary) and radial (secondary) shear bands. A full crack or flake that was produced due to the spring back during the load removal was observed. The shear band density in the annealed alloy which was dispersed with crystalliteswas significantly lower than that of the as-cast alloy. The difference of the shear band features among the three kinds of alloy status, i.e., partially crystallized, structurally relaxed and as-cast alloys was discussed in terms of the free volume in the BMGs and the characteristics of nano-composites. It has been demonstrated that the plasticity for the three statuses of alloys queues in the descending order as the as-cast, annealed with partial crystallization, and annealed without crystallization.

Plastic flow properties and microstructural evolution in an ultrafine-grained Al-Mg-Si alloy at elevated temperatures

An AA6082 alloy was subjected to eight passes of equal channel angular pressing at 100 °C, resulting in an ultrafine grain size of 0.2 to 0.4 µm. The tensile deformation behavior of the material was studied over the temperature range of 100 °C to 350 °C and strain rate range of 10¯⁴ to 10¯¹ s¯¹. The evolution of microstructure under tensile deformation was investigated by analyzing both the deformation relief on the specimen surface and the dislocation structure. While extensive microshear banding was found at the lower temperatures of 100 °C to 150 °C, deformation at higher temperatures was characterized by cooperative grain boundary sliding and the development of a bimodal microstructure. Dislocation glide was identified as the main deformation mechanism within coarse grains, whereas no dislocation activity was apparent in the ultrafine grains.