1,721,250 research outputs found
Circular construction and demolition waste?: Barriers and opportunities for creating circular business models in the EU C&DW sector
No full textThe main goal of this paper is to identify barriers and opportunities for creating the circular business models in the EU C&DW sector. Having in mind this fact, author of the paper describes market, social, governance and regulatory failures which may limit opportunities for achieving market success in the EU C&DW sector. The presentation will take into account current economic situation of the sector which is under the pressure of both global economic challenges and the EU policy aiming at popularization of the circular economy approach. As a result, different recommendations that may determine the final shape of the business models will be identified, including key resources that have to be used for successful commercialization of the different circular C&DW solutions
Characterization of construction and demolition wastes (C&DW)/geogrid interfaces
No full textOver the last years the environmental sustainability has been demanding a progressive increase in the waste valorisation. The valorisation of Construction and Demolition Wastes (C&DW), reduces the use of natural resources and avoids congesting landfills with these inert materials. Although some studies have been carried out on the application of recycled C&DW, the valorisation of C&DW in geosynthetic reinforced embankments is almost an unexplored field. A research project on the assessment of the use of recycled C&DW as backfill material in geosynthetic reinforced structures is being developed at University of Porto. This work presents and discusses results of direct shear and pullout tests carried out to characterise the behaviour of C&DW/geogrid interfaces. The results have evidenced that C&DW, properly compacted, could exhibit shear strength similar to the natural soils commonly used in the construction of geosynthetic reinforced embankments. High values of the interaction coefficient for the geogrid/C&DW interfaces were achieved. (c) 2015 Taylor & Francis Group, London
Characterization of construction and demolition wastes (C&DW)/geogrid interfaces
No full textOver the last years the environmental sustainability has been demanding a progressive increase in the waste valorisation. The valorisation of Construction and Demolition Wastes (C&DW), reduces the use of natural resources and avoids congesting landfills with these inert materials. Although some studies have been carried out on the application of recycled C&DW, the valorisation of C&DW in geosynthetic reinforced embankments is almost an unexplored field. A research project on the assessment of the use of recycled C&DW as backfill material in geosynthetic reinforced structures is being developed at University of Porto. This work presents and discusses results of direct shear and pullout tests carried out to characterise the behaviour of C&DW/geogrid interfaces. The results have evidenced that C&DW, properly compacted, could exhibit shear strength similar to the natural soils commonly used in the construction of geosynthetic reinforced embankments. High values of the interaction coefficient for the geogrid/C&DW interfaces were achieved. (c) 2015 Taylor & Francis Group, London
Novel circular economy business model of high-added value products for energy efficiency: from C&DW to aerogels
Get PDFSince the Industrial Revolution, humanity’s use of natural resources has been basically the same: TAKE, MAKE and THROW AWAY; which consequently led to the indispensable problems of waste materials. Around 461 million tons of Construction & Demolition Waste (C&DW), excluding excavation materials, are yearly generated in EU28. This undoubtedly gives a call to novel closed-loop circular business models which reshape the Eco-system in a way the waste is 'designed out'. Here, we present a novel closed-loop circular economy model of a high-performance building insulation material from silica containing C&DW materials to silica aerogels with λ≈0.015 W/mK. In the present model, the benefit comes with the use of massive construction waste to a silica precursor and thereby aerogel production guaranteeing at least 40% product cost reduction and 40% reduction in energy consumption in real construction environment
Global Patterns in Construction and Demolition Waste (C&DW) Research: A Bibliometric Analysis Using VOSviewer
No full textC&DW is contributing to exceeding all planetary boundaries and presents a range of other issues. In order to better understand the existing research on C&DW, a global bibliographic analysis was undertaken through seven groups of keyword searches of Scopus and the results visualised using VOSviewer. The study identifies phases in discussion of C&DW in terms of volume and themes and examines how search terms influence what is found. The results show that C&DW receives only a modest research attention compared to other areas of waste, and this is despite an exponential increase in C&DW research since 2016. The analyses also show that concrete is the most researched material in terms of C&DW, and that reuse, recycling, and circular economy are so far attracting only proportionally modest research attention. This signals a need for further acceleration of the C&DW research, and specifically for more research on reuse, recycling, and circular economy for materials other than concrete. One important finding are differences observed when using different search terms related to C&DW, which suggests that single search studies might provide limited insights
Challenging construction industry with C&DW: opportunities and limits
Get PDFConstruction and Demolition Waste (C&DW) comprises the largest waste stream in the European Union (EU), with relatively stable amounts produced over time and high recovery rates: it is estimated at one third of total wastes generated in the EU. Although this may suggest that the construction sector is highly circular, scrutiny of waste management practices reveals that C&DW recovery is largely based on backfilling operations and low-grade recovery, such as using recycled aggregates in road sub-bases. These wastes are usually recovered as secondary raw materials after a recycling process resulting in the production of recycled sands and aggregates. Researches have been performed to show how it is possible to encourage and support the use of these recycled materials: preparation process and selection are fundamental for increasing capability of recycling. Analysis of recycled bricks and tiles sands and fine particles has also been tested as substitution product in concrete design. A quantitative analysis is proposed for five North West European (NWE) countries: Belgium, France, Germany, Luxembourg and the Netherlands, where barriers are pointed out. The construction industry will be definitively affected by C&DW recycling for promoting circular economy in the coming years
Environmental Effects of C&DW on Landfill environments: A column leaching experiment
No full textThis dataset presents the results of weekly column leaching experiments, along with data analysis, physicochemical characterization, and data visualization. It details the leaching behavior of chemicals of concern and examines how variations in gypsum and C&DW content over time influence this behavior. Additionally, the data highlights the environmental impacts of gypsum and C&DW content on a simulated landfill
Performance of C&DW materials for road applications validated by field monitoring
No full textSUPREMA – Sustainable Application of Construction and Demolition Recycled Materials in Road Infrastructures was a research project developed by the Laboratório Nacional de Engenharia Civil (LNEC), in cooperation with the University of Lisbon (IST). The use of recycled materials has major environmental and economic benefits. Its recycling contributes for a more sustainable construction and rehabilitation of road pavements. The main goals of this project were to achieve a deeper knowledge on recycled materials and correspondent technologies and to increase the confidence of road agencies and construction companies for its application in road pavements. The objective of the paper is to analyse the mechanical performance of recycled aggregates, from construction and demolition waste (C&DW), used in unbound granular layers and evaluated on experimental sections of asphalt pavements. Four sections were instrumented with strain gauges and load cells. The recycled aggregates used in these sections were: crushed concrete, crushed mixed concrete and crushed and milled reclaimed asphalt pavement (RAP). A crushed natural limestone aggregate was used in one section as a reference material. The sections were submitted to in situ load tests performed by the Falling Weight Deflectometer (FWD). In addition, an extensive program of laboratory tests was also performed related to geometrical, physical, mechanical, chemical and environmental characteristics. This paper presents the mechanical behaviour of aggregate layers obtained from the backanalysis of FWD tests results and from the instrumentation measurements. In general, it was concluded that stiffness of unbound granular layers with recycled aggregates could be considered equivalent to the stiffness of layers constructed by natural aggregates. Results of resilient modulus obtained for the studied recycled aggregates could be useful for pavement design purposes
Technical requirements for the use of C&DW recycled aggregates in municipal and rural roads and trenches
No full textThe use of construction and demolition waste (C&DW) in the construction industry is an important contribution to attain sustainability in the sector. The roads are among the civil engineering works which can use larger quantities of C&DW recycled aggregates. In Portugal, the limit values for the properties of C&DW recycled aggregates that can be used in the roads of Portuguese Road Network are defined by two Laboratório Nacional de Engenharia Civil (LNEC) technical specifications (TS), in accordance to Portuguese Decree-law no. 46/2008 of May 12th. Municipal and rural roads and trenches have specific characteristics that can enable the use of C&DW of lower quality than those required by existing LNEC TS, and even then ensuring an adequate performance. However, given the absence of specific regulation for those applications, the Portuguese Environment Agency requires compliance with the existing LNEC TS, which represents an obstacle to recycling a significant part of the C&DW, in particular at a local government level. This paper presents guidelines for the recycling of C&DW in municipal and rural roads and in trenches, which could be considered in a new forthcoming LNEC TS. In the preparation of the guidelines, the bibliography collected and analysed, the information gathered from the application of C&DW in a municipal and rural roads of a Portuguese municipality and in the roadways of a Portuguese resort, and the results of laboratory tests carried out on samples collected in the Portuguese municipality were taken into consideration.Fundação para a Ciência e Tecnologia (FCT
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