Experimental study on strength and ductility of steel tubular stub columns filled with geopolymeric recycled concrete

Geopolymeric recycled concrete (GRC) is a new construction material which takes environmentalsustainability into account, by using alkali solution and fly ash to completely substitute Portland cementas well as by replacing natural coarse aggregate with recycled coarse aggregate. GRC could be used togetherwith steel hollow sections to form composite section. There is very limited study on such GRC filledtubular sections. This paper presents an experimental study on GRC filled tubular stub columns. A total of 12specimens were tested. The main parameters varied in the tests are: (1) two section sizes of square hollow sections(B × t) with 200mm×6mm and 150mm×5mm; (2) different concrete types: GRC and recycled aggregateconcrete (RAC); (3) different recycled aggregate (RA) replacement ratios of 0%, 50% and 100%. The relationshipof load versus axial strain was recorded and analysed to compare the ultimate strength and failuremechanism. Meanwhile, the ductility of the columns was investigated by a ductility index (DI). The resultsshow that the ultimate strength decreased with increasing RA contents for both GRC and RAC filled columns.The influence of RA content on the strength was greater in GRC than that in RAC. The effect of RA contenton the ductility of the columns was further investigated. Simulation method for predicting load versus strainrelationship is discussed for RAC and GRC filled steel tubular columns with different RA replacement ratios.

Recycled effluent irrigation in vineyards : an Australian case study. I. issues and monitoring

The viticultural industry is becoming an increasingly significant part of the Australian agricultural sector, with gross earnings of over $4 billion in 2002. Expansion of the industry in the last decade has been rapid, however its heavy reliance on irrigation has resulted in further expansion in many wine growing regions being limited by the availability of water. This problem is not confined to the viticultural industry, with ever increasing pressures on water resources worldwide. As demands for water continue to rise, new strategies to meet demands must be adopted. One of the strategies being increasingly employed is the recycling of waste waters for a number of applications such as irrigation and industrial uses. The use of recycled water for vineyard irrigation provides a number of benefits. Among them are the reduced demands on potable supplies, reduced waste discharges to surface waters, and the opportunity for expansion of production. Recycled waters however, contain constituents which have the potential to cause deleterious effects to both production and the environment. Therefore, the use of recycled water for irrigation requires targetted monitoring and management to ensure the long-term sustainability of both the vineyard and the surrounding environment. Traditional monitoring techniques including water quality monitoring and soil testing can be complimented by new technologies and techniques which provide large quantities of information with relatively less labour and time. Such techniques can be used to monitor the vineyard environment to identify impacts arising from management practices, allowing vineyard managers to adjust management for sustainable production

Variability of soil chemistry following irrigation with recycled municipal effluent: a Great Western vineyard case study

In areas of Australia where viticultural operations have been limited by lack of an acceptable irrigation water source, considerable expansion has occurred through the use of recycled wastewater. Despite this rapid expansion, little is known of the potential impacts of the water’s chemical constituents on soil properties, or the long-term sustainability of the vineyards using the water. In order to establish the impacts of drip irrigated recycled wastewater on a vineyard in Great Western, Australia, a study comparing the soils from the vineyard inter-row and row area was undertaken. Chemical and physical properties of the soil with varying distances from the drip emitter were also investigated. During the irrigation season, significant differences between the inter-row and row area were found for several chemical parameters including pH(1:5soil/water) (P<0.001), electrical conductivity (EC1:5) (P<0.001), water-soluble sodium (WS Na+) (P<0.001), and water-soluble chloride (WS Cl-) (P<0.001). This paper will discuss differences observed between soil properties of the inter-row and vine row area, as well as the spatial distribution of solutes under the drip emitter.

An analysis of factors influencing waste minimisation and use of recycled materials for the construction of residential buildings

Residential building construction activities, whether it is new build, repair or maintenance, consumes a large amount of natural resources. This has a negative impact on the environment in the form depleting natural resources, increasing waste production and pollution. Previous research has identified the benefits of preventing or reducing material waste, mainly in terms of the limited available space for waste disposal, and escalating costs associated with landfills, waste management and disposal and their impact on a  building company's profitability. There has however been little development internationally of innovative waste management strategies aimed at reducing the resource requirement of the construction process. The authors contend that embodied energy is a useful indicator of resource value. Using data provided by a regional high-volume residential builder in the State of Victoria, Australia, this paper identifies the various types of waste that are generated from the construction of a typical standard house. It was found that in this particular case, wasted amounts of materials were less than those found previously by others for cases in capital cities (5-10 per cent), suggesting that waste minimisation strategies are successfully being implemented. Cost and embodied energy savings from using materials with recycled content are potentially more beneficial in terms of embodied energy and resource depletion than waste minimisation strategies.

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.

Competitive sorbtion of metals in water repellent soils: implications for irrigation recycled water

Australia is a water-stressed nation and demand on potable water supply is increasing. Consequently water conservation and reuse are increasingly becoming important. Irrigation of recycled wastewater on water repellent soils is a technology that is being trialled as a means of improving crop production and conserving potable supply. However, recycled water contains potentially harmful heavy metals. This paper reports the competitive sorption and desorption of several common heavy metals found in soils collected from a farm located in the south-east of South Australia. The soil from this location is severely water repellent, but some sites were amended with kaolinite clay (Si₄Al₄O₁₀(OH)₈) about 7 and 15 years ago. The metals studied were Cu, Pb, Cd, Cr, Ni, and Zn. Competitive sorption of the metals was distinctly observed. For all heavy metals, the quantity of metal sorbed was higher in amended soil, and there was a strong correlation between the specific sorption to total sorption ratio and the amount of clay in the soil. The sorption intensities varied with metal, Cr, Pb, and Cu having a high sorption tendencies and Zn, Cd, and Ni having comparatively low sorption tendencies. The total sorption capacity for all metals increased in clay-treated soils compared with non-treated soils. On average, clay-amended water repellent soils had a 20–40% increased capacity to adsorb total metals; however, this increase was largely caused by the increased capacities to adsorb Zn, Cd, and Ni. The effect of clay treatment largely enhanced the sorption capacity of relatively weakly adsorbing heavy metals. The implications for using recycled wastewater on the long-term sustainable agro-environmental management of these soils are discussed.