Introduction to the recycling of construction and demolition waste (CDW)
01 Jan 2013-pp 1-6
TL;DR: The chapter starts with an overview on the recycling of construction and demolition wastes (CDW), followed by a brief analysis on the EU 70% recycling target for 2020.
Abstract: The chapter starts with an overview on the recycling of construction and demolition wastes (CDW), followed by a brief analysis on the EU 70% recycling target for 2020. The chapter also includes a book outline.
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TL;DR: In this paper, a framework based on 10 common circular economy strategies (i.e. recover, recycling, repurpose, remanufacture, refurbish, repair, reuse, reduce, rethink, refuse) is applied to scrutinise the selected targets.
Abstract: The transition to a circular economy requires actions and policies. In the praxis of governance, a common way to steer the transition to a different state proceeds through the setting of targets. Thus far, no study has investigated circular economy targets in a systematic way. To bridge this gap, this study examines which targets can facilitate the transition towards a circular economy. The analysis focuses both on existing and new targets; the latter complement existing targets which are limited to a few discrete cases addressing only partially the goal of a more circular economy. A framework based on 10 common circular economy strategies (i.e. recover, recycling, repurpose, remanufacture, refurbish, repair, re-use, reduce, rethink, refuse) is applied to scrutinise the selected targets. The study clarifies that existing targets for recovery and recycling do not necessarily promote a circular economy, though they are the most commonly applied targets so far. Because of lack of efficacy of recovery and recycling, targets should instead favour other more powerful circular economy strategies. In relation to these, the study looks into new and existing targets showing how they can reduce waste, increase efficiency, close production loops, and maximise retention of the economic value of materials and products. In particular, the study proposes an expanded set of brand new targets for the transition to a circular economy together with a fresh view on targets aimed at scholars and decision-makers alike.
466 citations
Cites background from "Introduction to the recycling of co..."
...Conversely, they can encourage low-quality recycling, because yield rates are typically higher, owing to a higher tolerance of impurities or contaminants (Allwood et al., 2012; Pacheco-Torgal, 2013)....
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TL;DR: In this article, the authors used concrete demolition waste (CDW) as precursors to obtain geopolymer cements, which achieved a maximum compressive strength of 25MPa.
87 citations
TL;DR: The use of recycled aggregates, manufactured from several by-products, to replace virgin aggregates in the production of pavement asphalt mixtures needs to be encouraged as mentioned in this paper, however, there are some concerns and uncertainties about the actual environmental, economic and mechanical performance resulting from the incorporation of recycling aggregates.
Abstract: The use of recycled aggregates, manufactured from several by-products, to replace virgin aggregates in the production of pavement asphalt mixtures needs to be encouraged. Nevertheless, there are some concerns and uncertainties about the actual environmental, economic and mechanical performance resulting from the incorporation of recycled aggregates in asphalt mixtures. Therefore, this paper has the goal of discussing important features to help decision makers to select recycled aggregates as raw materials for asphalt mixtures. Based on the literature review carried out and the own previous experience of the authors, the article’s main findings reveal that incorporating some of the most common recycled aggregates into asphalt mixtures is feasible, even in a life-cycle analysis perspective. Although some specific technical operations are sometimes necessary when using recycled aggregates in asphalt mixtures, some benefits in terms of environmental impacts, energy use and costs are likely to be achieved, as well as in what concerns the mechanical performance of the asphalt mixtures.
37 citations
Cites background from "Introduction to the recycling of co..."
...Although more than 140 million tons per year of construction and demolition waste (CDW) have been produced in recent years in the US and over 970 million tons per year in Europe [51], only 30 to 40% are potentially reused in pavements [52]....
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TL;DR: In this paper, the authors compared two use cycles of natural aggregate concrete and recycled aggregate concrete, which is another way to compare the environmental impacts of recycled materials, and obtained results confirm the potential use of high-quality recycled aggregate originating from local sources in some applications in building structures.
Abstract: The main goal of this study was to compare two use cycles of natural aggregate concrete and recycled aggregate concrete, which is another way to compare the environmental impacts of recycled materials. A series of concrete mixtures with various replacement ratios of primary resources with recycled ones were prepared for this study. The mechanical properties of concrete mixtures were examined and were used for the design of structural elements in the same utilized properties. The two use cycles of a structural element were compared using life cycle assessment (LCA). In the first use cycle, the LCA of the structural element containing only primary raw materials was assessed. In the second use cycle, the LCA of a structural element in which primary materials were partially replaced by recycled ones was assessed. The obtained results confirm the potential use of high-quality recycled aggregate originating from local sources in some applications in building structures. Furthermore, the environmental assessment indicates the benefits of using recycled materials, such as environmental savings, especially the reduction of primary resource use, embodied energy, and embodied emissions, as well as reduction of the pressure on landfill sites.
33 citations
01 Jan 2015
TL;DR: In this article, the types of recycled aggregates and the properties of recycled aggregate concretes, both fresh and hardened states, are discussed and the subject of alkali-activated recycled aggregate concrete is still at a very early stage and a lot more research is needed.
Abstract: The need to reduce emissions of greenhouse gases leads to the efficient utilization of resources especially in the construction industry. The endeavor to use environmentally friendly materials such as alkali-activated binders and recycled aggregate concretes is a good example. In this chapter, the types of recycled aggregates and the properties of recycled aggregate concretes, both fresh and hardened states, are discussed. Much information is available on both alkali-activated binders and recycled aggregate concretes, but the subject of alkali-activated recycled aggregate concrete is still at a very early stage and a lot more research is needed. Information on normal strength, lightweight and pervious alkali-activated concrete containing recycled aggregates is provided in this chapter.
22 citations
References
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TL;DR: In this paper, the authors present an assessment of the global use of materials since the beginning of the 20th century based on the conceptual and methodological principles of material flow accounting (MFA).
944 citations
TL;DR: In this article, four major strategies for reducing material demand through material efficiency are discussed: longer-lasting products; modularization and remanufacturing; component re-use; designing products with less material.
Abstract: For most materials used to provide buildings, infrastructure, equipment and products, global stocks are still sufficient to meet anticipated demand, but the environmental impacts of materials production and processing, particularly those related to energy, are rapidly becoming critical. These impacts can be ameliorated to some extent by the ongoing pursuit of efficiencies within existing processes, but demand is anticipated to double in the next 40 years, and this will lead to an unacceptable increase in overall impacts unless the total requirement for material production and processing is reduced. This is the goal of material efficiency, and this paper aims to stimulate interest in the area. Four major strategies for reducing material demand through material efficiency are discussed: longer-lasting products; modularisation and remanufacturing; component re-use; designing products with less material. In industrialised nations, these strategies have had little attention, because of economic, regulatory and social barriers, which are each examined. However, evidence from waste management and the pursuit of energy efficiency suggests that these barriers might be overcome, and an outline of potential mechanisms for change is given. In bringing together insights into material efficiency from a wide range of disciplines, the paper presents a set of 20 open questions for future work.
702 citations
TL;DR: In this paper, the authors investigated the available literature on every step in the LCA of concrete and found that the adopted functional unit for which the environmental impact is calculated, influences the outcome significantly.
Abstract: With the current focus on sustainability, it is necessary to evaluate concrete’s environmental impact properly, especially when developing new ‘green’ concrete types. Therefore, we investigated the available literature on every step in the LCA of concrete. The adopted functional unit for which the environmental impact is calculated, influences the outcome significantly. When comparing different concrete compositions, this unit should incorporate differences in strength, durability and service life. Hence, a cradle-to-grave or modified cradle-to-gate approach is advised as system boundary. When using industrial by-products as cement replacing material in ‘green’ concrete, an economical allocation of impacts is recommended. Inventory data on energy use, CO2, PM10, SOx and NOx emissions were collected and assigned to the impact categories of the problem oriented CML 2002 and the damage oriented Eco-indicator 99 impact method. Compared to Portland cement, the impact of blast-furnace slag and fly ash is about an order of a magnitude lower.
531 citations
TL;DR: In this article, the authors provide a context for innovative development through a review of what is meant by a hydraulic cementitious binder, identification of key physico-chemical properties of successful binders and how novel systems generally rely on similar factors.
293 citations
TL;DR: In this paper, the authors examined some of the routes that may be followed to further improve the environmental performance of concrete, which is the largest volume material used by man and is irreplaceable for innumerable large infrastructure developments.
Abstract: Concrete is the largest volume material used by man and is irreplaceable for innumerable large infrastructure developments. From the point of view of natural resources, ecology and economy, it is virtually impossible to imagine substituting concrete by any other material. However, because of the large volumes used, its total energy and CO2 footprint is important. This material therefore needs to be improved and small steps can have a big impact, once again because of the large volumes involved. This review paper examines some of the routes that may be followed to further improve the environmental performance of concrete.
287 citations