Recycling has proven not only to address today’s economical, environmental and social issues, but also to be imperative for the sustainability of human technology. The current thesis has investigated the feasibility of a new philosophy for Recycling (Alloying-Recycling) using steel 1020 and aluminum 6061T6. The study was limited to the metallurgical aspects only and has highlighted the potential of recycled alloys made of recycled aluminum and steel to exhibit substantially increased wear resistance and strength-to-weight ratio as compared to initial primary materials. Three alloy-mixtures are considered: TN3 (5wt% 1020 +95wt% 6061T6); TN5 (0.7wt% 1020 + 99.3wt% 6061T6); and TN4 (10wt% 6061T6 + 90wt% 1020). A Tucker induction power supply system (3kW; 135-400 kHz) is used to melt the alloy mixtures for casting in graphite crucibles. Heat treatment of the cast samples is done using a radiation box furnace. Microscopy, Vickers hardness and pin-on-disc abrasive wear tests are performed. Casting destroyed the initial microstructures of the alloys leading to a hardness reduction in the as-cast and solution heat-treated aluminum rich samples to 60 Hv from 140 Hv. Ageing slightly increased the hardness of the cast samples and provided a wear resistance two times higher than that of the initial 6061T6 material. On the steel rich side, the hardness of the as-cast TN4 was 480 Hv, which is more than twice as high as the initial hardness of steel 1020 of 202 Hv; this hints to strong internal and residual stress, probably martensite formation during fast cooling following casting. Solution heat treatment lowered the hardness to the original value of steel 1020, but provided about ten (10) times higher wear resistance; this suggests higher ductility and toughness of normalised TN4 as compared to 1020. In addition, TN4 exhibits about 25% weight reduction as compared to 1020. The actual recycling process and the effect of non-metallic impurities shall be investigated in future works. Also, the casting and heat treatment processes need to be improved.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The use of foamed asphalt as a technique that incorporates recycled bases stabilized with RAP is known, because it achieves important structural contributions. However, the component of aggregates, belonging to the fine fraction (through the # 200 mesh) takes special importance. This article seeks to develop a comparative analysis between the stabilizations of recycled foamed asphalt bases and asphalt emulsion. The importance of this study lies in analyzing the structural contribution of the fines fraction when comparing both stabilizations. For the present investigation, 48 pits were examined, where the combined granulometry of the RAP plus the granular base was evaluated. Here it was possible to identify a minimal presence of fines even within the recommended spindle for foamed asphalt mixtures, evidencing a deficit in indirect traction strength (ITS). The results obtained show, that a dry stability of 484.7 kg is achieved, and a conserved strength of 45% in the foamed asphalt. While in the asphalt emulsion a dry stability of 1862.1 kg and a conserved resistance of 70% is achieved. This demonstrates the impact on the structural behavior that have the fines fraction in stabilizations with foamed asphalt.

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The negative environmental impacts of buildings are now recognised as being of great concern. Increasingly, these concerns are being addressed in both the construction and the operational phase of a building's lifecycle. The specification of renewable or low impact materials and the criteria for designing for energy efficiency are now commonplace, but what about the final stage of a building's life-the demolition phase? The construction industry produces 24 kg of waste per person per week in the UK, and the majority of this is caused by decisions taken at the design stage. Conversely most of the current discussion in this area has been focused on dealing with the waste once it has arisen. If we are going to do more than 'end of pipe', remedial clean up of building waste we need to rethink how we design, build, use and demolish our built environment. In effect this means taking the filters out of the pipes and placing then instead in the designers heads. In addressing this situation, the aim of this thesis is to define guideline strategies that will reduce the negative environmental impacts of buildings by designing for the whole lifecycle. The research is presented in four parts. In the first part, the literature is reviewed and developed to define buildings within a cyclical systems context. This entails drawing upon relevant debates within the fields of systems thinking, architecture, bio-mimicry, industrial ecology, and industrial product design. In the second part, an investigation carried out with demolition experts is presented. In this study knowledge and opinions were sought via a number of semi-structured interviews with demolition experts. The conclusions of the case study identify strategies, which if implemented at the design stage could reduce the lifetime impacts and increase the reuse and recycling potential of buildings, their elements and material components. Following the detailed focus on end of life, the research is now expanded to consider the changes that occur throughout a building's lifetime. The aim of this is to determine where the greatest use of resources and major impacts occur throughout the building life cycle. Therefore Part III presents an investigation of the lifetime environmental impacts of office buildings. The building is fragmented into its time dependent layers (foundations, frame, claddings, services and internal fit out) and the impacts of these layers over the building lifetime are investigated. The study also examines the relative impacts of different frames and floors, which allow varying degrees of disassembly. Finally, to complete the lifecycle investigation, the embodied impacts are compared with the operational impacts over a sixty-year lifecycle. Part IV presents the conclusions of this research, based on a synthesis of the findings of the earlier chapters. Finally those areas that would benefit from further research are identified.

published_or_final_version / Botany / Master / Master of Philosophy