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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Uso de finos de resíduos de construção e demolição em concreto autoadensável

Santos, Iago Lopes dos January 2018 (has links)
O concreto autoadensável (CAA) é um concreto especial com a capacidade de fluir e preencher completamente todos os espaços das fôrmas pela ação de seu peso próprio, sem que haja ocorrência de bloqueio e segregação da mistura. Contudo, para alcançar essas características, normalmente esse concreto é dosado com um maior teor de materiais finos e/ou com aditivo modificador de viscosidade. Os agregados provenientes de Resíduos de Construção e Demolição (RCD) já estão sendo utilizados na produção de concretos, porém o uso dos materiais finos de agregados reciclados não é recomendado para a produção de concretos convencionais. Entretanto, acredita-se que em CAA esses materiais finos podem ser uma oportunidade interessante, tanto para a questão da reutilização desses resíduos, conseguindo uma destinação nobre para esses materiais com baixa demanda no mercado, como na manutenção das propriedades deste concreto, sendo os principais agentes do controle de segregação. Desta forma, o presente trabalho consistiu em estudar a influência da utilização de finos de RCD (concretos, argamassas e tijolos cerâmicos), separadamente, em substituição parcial ao agregado miúdo natural, nas principais propriedades do concreto autoadensável no estado fresco (fluidez, habilidade passante e resistência à segregação) e no estado endurecido (resistência à compressão e módulo de elasticidade), bem como avaliar seu desempenho quanto à durabilidade (absorção de água e penetração de íons cloretos). Os resultados demostraram perda de fluidez e boa coesão nos concretos autoadensáveis que empregaram agregados reciclados. No entanto, ainda conferem boas características de autoadensabilidade, atendendo as condições normativas para uso em estruturas correntes de engenharia. No que tange às propriedades mecânicas, foi observado aumento de resistência à compressão e decréscimo do módulo de resistência para concretos com finos de RCD. No quesito de durabilidade, os concretos com agregados reciclados apresentaram valores mais elevados para absorção de água por capilaridade e penetração de íons cloretos em comparação aos concretos de referência. / Self-compacting concrete (SCC) is a special concrete with the ability to flow into and completely fill all spaces within the formworks only by the action of their own weight, without blocking and segregation of the mixture. However, to achieve these characteristics, normally this concrete needs to be mixed with more content of fine materials and/or viscosity modifiers additives. The aggregates from Construction and Demolition Wastes (CDW) are used for concrete production, but the use of fine recycled aggregate is not recommended for the production of conventional concrete. Although, it is believed that in SCC these fine aggregates can be an interesting opportunity for the reuse of these wastes, achieving a noble destination for these materials with low demand in the market, as for the maintenance of the properties of this concrete, being the main agents of segregation control. So, the present research consisted in studying the influence of the use of CDW fines aggregates (concretes, mortars and ceramic bricks, separately) to replace the natural sand in the main properties of the self-compacting concrete in the fresh state (flowability, passing ability and segregation resistance) and in the hardened state (compressive strength and modulus of elasticity), as well as to evaluate its performance in terms of durability (water absorption and chloride penetration). The study results showed loss of flowability and increased cohesion in the self-compacting concretes that used recycled aggregates. However, they still confer good characteristics for self-compacting concrete, taking into account the normative conditions for using current engineering structures. With respect to the mechanical properties, it was observed an increase of compressive strength and decrease of the modulus of elasticity for concrete with CDW fines aggregates. In terms of durability, concretes with recycled aggregates presented higher values for capillarity water absorption and penetration of chloride ions compared to the references concretes.
22

Caracterização tecnológica de resíduos de construção e demolição. / Technological characterization of construction and demolition waste.

Ulsen, Carina 22 August 2006 (has links)
Os resíduos de construção e demolição (RCD) representam cerca de 50% de todo o resíduo sólido gerado, sendo que cerca de 90% deste é de origem mineral e pode ser reciclado através de processos de beneficiamento mineral. Para se atingir a reciclagem massiva torna-se imperativo o desenvolvimento de novos mercados e melhorias de usina capazes de tornar o resíduo uma matéria prima de qualidade adequada. Dessa forma a caracterização tecnológica é imprescindível para obtenção de informações fundamentais sobre o processo de beneficiamento e as especificações para os produtos. O programa experimental foi desenvolvido em três amostras de RCD britados de duas usinas de reciclagem do Estado de São Paulo, Itaquera cinza (IT-C), Itaquera vermelho (IT-V), Vinhedo vermelho (VI-V). As atividades desenvolvidas foram: amostragem, cominuição, determinação das composições químicas e mineralógicas por faixa granulométrica, determinação de propriedades físicas relevantes para reciclagem de RCD como agregados para uso em concreto, determinação das curvas de separabilidade por densidade e análise de sua composição química e mineralógica e estudos microscópicos para avaliação do teor de aglomerantes por faixa densitária. Os resultados de análises químicas mostram que as composições químicas das três amostras são semelhantes; os teores variam com a granulometria, com marcantes diferenças na fração mais fina. A composição mineralógica predominante é de silicatos, provenientes de agregados e rochas naturais, cerâmicas e aglomerantes, com menores teores de alumina e óxido de cálcio; a perda ao fogo está diretamente relacionada ao teor de aglomerantes, uma vez que representa a água combinada e o gás carbônico presente. A separação do RCD em classes de densidade permitiu identificar que os produtos obtidos apresentam composições diferentes e pode ser empregada para se obter agregados de melhor qualidade e, portanto, para aplicações mais nobres, uma vez que se verifica que cerca de 80% em massa dos resíduos possuem densidades superiores a 2,2 g/cm3 com qualidades físicas adequadas para uso em concreto estrutural. Adicionalmente, a massa específica aparente e absorção de água estão diretamente relacionadas com os intervalos de densidade. O teor de aglomerantes aumenta significativamente para os produtos de menor densidade, sendo que as partículas cerâmicas estão isentas de pasta de cimento endurecida e cal. / Construction and demolition waste (CDW) represents around 50% of the total solid waste and are essentially constituted by mineral fraction (>90%); therefore it?s possible to recycle it through mineral processing techniques. The development of different uses and the improvement of the typical technologies applied to CDW recycling are essential to achieve a satisfactory level of recycling. Applied mineralogy tools are fundamental to characterize the studied raw material and support the mineral processing in order to obtain products according to its specifications. This research was carried out in three crushed samples from two different plants close to Sao Paulo; they were named according to its classification: grey Itaquera (IT-C), red Itaquera (IT-V) and red Vinhedo (VI-V). The method involved basically sampling, crushing, characterization of the relevant physical properties for a concrete recycled aggregate approach, evaluation of the specific gravity separability curves and chemical and mineralogical analyses for each grain size fraction and gravity classes, and so microscope analyses to verify the binder contents. The results show that the chemical composition of the three samples is very similar, the grades change according to the grain size fractions, specially for the finest fraction. The mineral composition is also quite akin, it is mostly represented by silicates (mainly aggregates and natural rocks), ceramics and binder; minor amounts of Al2O3 and CaO were also detected. The loss of ignition is directly related to the binder and clay minerals (basically OH and CO2). Specific gravity classes are very different regarding their chemical, mineralogical and physical properties, despite their similarity among the samples. Thus the specific gravity separation is more effective to classify the recycled CD debris than its color and could be applied to obtain high quality recycled aggregates, while a significant amount (80%) is recovered above 2.2 g/cm3 and may be used as high strength concrete aggregates. In addition, the physical properties, like specific gravity and water absorption are strictly related to the specific gravity classes.
23

Comportamento mecânico de agregado reciclado de resíduo sólido da construção civil em camadas de base e sub-base de pavimentos. / Mechanical behavior of recycled aggregate of construction and demolition waste in base and sub base layers of pavements.

Leite, Fabiana da Conceição 19 June 2007 (has links)
Os resíduos de construção e demolição (RCD) são gerados em quantidades expressivas nas cidades de grande e médio portes no Brasil e são comumente descartados de forma irregular. Para os milhares de quilômetros de vias urbanas não pavimentadas, o agregado reciclado de resíduo sólido da construção civil é uma alternativa aos materiais convencionais de pavimentação. Esta dissertação analisa o comportamento mecânico do agregado reciclado para emprego em camadas de base e sub-base. A pesquisa consiste em ensaios laboratoriais, acompanhados de um estudo de caso - o pavimento do novo campus da Universidade de São Paulo (USP Leste). Um trecho de 1.020 metros de extensão foi utilizado no estudo, de um total de aproximadamente dois quilômetros de vias pavimentadas no campus. O pavimento avaliado possui agregado reciclado em sua estrutura; quatro seções-tipo diferentes foram construídas, variando os materiais, as espessuras, a compactação e o subleito. Propriedades físicas e mecânicas do agregado reciclado foram determinadas em laboratório por meio dos seguintes testes: composição, porcentagem de materiais indesejáveis, massa específica, absorção de água, graduação, forma dos grãos, compactação, influência da compactação, índice de suporte Califórnia, módulo de resiliência e deformação permanente. Os ensaios de campo compreenderam: controle de materiais e de execução, resistência à penetração pelo Dynamic Cone Penetrometer e levantamento deflectométrico com o Falling Weight Deflectometer. Baseado na análise das bacias de deflexão das seções-tipo construídas, o trecho estudado é dividido em quatro comportamentos distintos à deformação. Os resultados mostraram que o comportamento mecânico do agregado reciclado apresenta uma forte dependência da eficiência da compactação. Quando submetido a uma compactação adequada, o material reciclado comporta-se tal qual uma brita graduada simples. / Construction and demolition waste (CDW) is generated in significant amounts in medium and large size cities in Brazil and are usually disposed of illegally. For the thousands of kilometers of unpaved urban roads, the recycled aggregate of CDW is an alternative to conventional paving materials. This dissertation analyses the mechanical behavior of the recycled aggregate for use in base and subbase layers. This research consisted of a series of laboratory tests, followed by a case study - the pavement of the new campus of the University of Sao Paulo (USP Leste). A test track of 1,020 meters of extension was used for the study, from a total of approximately two kilometers of paved roads in the campus. The pavement studied contains recycled aggregate in its structure; four different road sections were constructed, varying the materials, thickness, compaction and subgrade. Physical and mechanical properties of the recycled aggregate were characterized through the following laboratory tests: composition, percentage of impurities, bulk density, water absorption, gradation, grain form, compaction, compaction influence, California Bearing Ratio, resilient modulus and permanent deformation. The field tests covered: materials and construction control, bearing capacity using the Dynamic Cone Penetrometer and deflection measurement using a Falling Weight Deflectometer. Based on the analysis of the deflection basins of the built road sections, the test track is divided according to four different deformation behaviors. The results show that the mechanical behavior of the recycled aggregate presents a strong dependence on the compaction effort. When submitted to proper compaction, the recycled material behaves as a crushed-stone.
24

Aplicação de resíduos de construção e demolição reciclados (RCD-R) em estruturas de solo reforçado / Use of recycled construction and demolition wastes (RCDW) as backfill of reinforced soil structures

Santos, Eder Carlos Guedes dos 06 March 2007 (has links)
O intenso crescimento populacional traz consigo uma preocupação ambiental, já que, diante da necessidade de exploração dos recursos naturais, a adoção de políticas de reciclagem faz-se fundamental para alcançar o desenvolvimento sustentável. Neste cenário, apesar dos resíduos de construção e demolição (RCD) possuírem alto potencial de reciclagem, a estes sempre foi dispensado o tratamento de lixo. Além disso, os estudos realizados visando à reciclagem dos RCD mostram-se bastante concentrados na produção de agregados para a fabricação de concreto e para a aplicação em pavimentação. Diante disso, neste trabalho procurou-se definir uma nova aplicação para os resíduos de construção e demolição reciclados (RCD-R), buscando caracterizar suas propriedades geotécnicas como material de construção e verificando o seu desempenho como material de preenchimento de estruturas de solo reforçado. Ensaios de caracterização, de resistência ao cisalhamento e ensaios de arrancamento de geogrelha revelaram que o RCD-R apresentou baixos coeficientes de variação nas suas propriedades e excelente comportamento mecânico, o que justifica a sua utilização na aplicação proposta. / The intense population growth brings some environmental concerns due to the need of exploitation of natural resources, and the adoption of recycling policies is basic principle to reach sustainable development. In this scenario, however, the high potential of recycling the construction and demolition wastes (CDW) has been ignored. Moreover, studies focus mainly on the recycling of CDW for the production of aggregates for use in pavements and concrete. The present study deals with a new application of the recycled construction and demolition waste (RCDW) as backfill of reinforced soil structures. Characterization, direct shear and pullout tests on geogrids has depicted that RCDW shows low coefficients of variation of its properties and excellent mechanical behavior that justify its use for proposed application.
25

Diagnóstico do gerenciamento dos resíduos da construção civil da região metropolitana de São Paulo /

Ribeiro, Simone. January 2008 (has links)
Orientador: Rosane Aparecida Gomes Battistelle / Banca: Adilson Renofio / Banca: Adriana Antunes Lopes / Resumo: O crescimento dos resíduos sólidos vem se transformando em um dos grandes desafios para os órgãos municipais, especialmente dos resíduos sólidos urbanos, decorrentes da indústria da construção civil. Este trabalho teve como objetivo realizar um diagnóstico do gerencimento deste tipo de resíduos na região metropolitana de São Paulo, baseando-se em informações fornecidas pelos órgãos envolvidos e em visitas a locais de armazenamento, triagem, reciclagem e disposição final. Esta investigação decorreu da necessidade de se avaliar estratégias para minimizar os impactos socioambientais negativos, acarretados por esses resíduos. Seu objetivo geral foi coletar dados que delineassem a realidade do descarte de resíduos da construção civil no município de São Paulo e gerar subsídios que pudessem servir de apoio aos agentes envolvidos. Teve também por objetivos específicos: identificar os pontos de descarte na região metropolitana de São Paulo e realizar, por meio de dados e informações obtidas junto a órgãos públicos e empresas privadas, uma estimativa da geração dos resíduos de construção civil nesses pontos. Como resultado, contabilizou-se valores na ordem de 1.366.460,17 t/mês. Conclui-se que há necessidade de uma maior valorização de todos os materiais que constituem as peças de uma construção , no sentido de que não ocorram sobras, nem desperdícios de matéria-prima. Recomenda-se a preservação das áreas de jazidas de materiais e minimização do uso desses locais para destinação final dos resíduos. / Abstract: The growth of solid waste has become one of the greatest challenges for the public authorities, in particular the management of solid urban waste resulting from the construction industry. The purpose of this work is to perfom a diagnosis of the management of this type of waste in the greater São Paulo. This study is based on information supplied by the involved agencies, as well as visits to storage, separation, recycling and final disposition sites. Such investigation results from the need to evaluate strategies to minimize negative social and environmental impacts caused by such waste. The goal was to raise general data to draw the reality of disposal of waste from construction in the municipality of São Paulo and generate subsidies that could serve as a support for the agents involved. He had also by specific objectives: to identify the points of disposal in the greater São Paulo and carry through data and information from the public agencies and private companies, an estimate of the generation of waste from construction at such points. The data totalize a generation of Construction and Demolition Waste (CDW) of 1.366.460,17 metric tons/month in the city of São Paulo. In conclusion, one can mention the need to increase the value of all materials used as construction elements so that no unused materials remain nor raw materials are wasted. It is recommended to preserve the extraction sites of the materials and limit the use of these sites as final waste destination. / Mestre
26

Quantifying the Impact of Circular Economy Applied to the Built Environment: A Study of Construction and Demolition Waste to Identify Leverage Points

January 2019 (has links)
abstract: The built environment is responsible for a significant portion of global waste generation. Construction and demolition (C&D) waste requires significant landfill areas and costs billions of dollars. New business models that reduce this waste may prove to be financially beneficial and generally more sustainable. One such model is referred to as the “Circular Economy” (CE), which promotes the efficient use of materials to minimize waste generation and raw material consumption. CE is achieved by maximizing the life of materials and components and by reclaiming the typically wasted value at the end of their life. This thesis identifies the potential opportunities for using CE in the built environment. It first calculates the magnitude of C&D waste and its main streams, highlights the top C&D materials based on weight and value using data from various regions, identifies the top C&D materials’ current recycling and reuse rates, and finally estimates a potential financial benefit of $3.7 billion from redirecting C&D waste using the CE concept in the United States. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2019
27

Eco-efficiency and Performance Strategies in Construction and Demolition Waste Recycling Systems

Bohne, Rolf André January 2005 (has links)
<p>This thesis studies the Danish and Norwegian recycling systems for construction and demolition (C&D) waste. The architectural, Engineering and Construction (AEC) industry is a major contributor to societies waste production; accounting for approximately 40% of the waste production. It is therefore important to manage the C&D waste effectively to move society towards sustainability.</p><p>This study applies the Industrial Ecology paradigm. This involved multidisciplinary approach, spanning the fields of Industrial Ecology, Systems Engineering and Organizational and Social Studies.</p><p>The scope of this thesis is threefold. The first scope is to get a better understanding of the processes that are taking place within the socio-technical sphere of a recycling system. Second, what is the nature of the C&D waste and what are the environmental impacts from the various waste fractions. Third, how can this information be used to improve recycling systems for C&D waste.</p><p>The study show that the suggestions in the National Action Plan and the corresponding policies are eco-effective, but that the environmental impact is very transport dependent. The study also shows that there is a great need to focus on future waste composition in the design of recycling systems for C&D waste. However, such waste projections are difficult to perform due to poor data availability.</p><p>There is a need for making more qualified decisions on environmental issues, with regard to long term management of such recycling systems. Long term models combined with environmental and economic information can make a powerful tool for such analysis.</p>
28

Eco-efficiency and Performance Strategies in Construction and Demolition Waste Recycling Systems

Bohne, Rolf André January 2005 (has links)
This thesis studies the Danish and Norwegian recycling systems for construction and demolition (C&amp;D) waste. The architectural, Engineering and Construction (AEC) industry is a major contributor to societies waste production; accounting for approximately 40% of the waste production. It is therefore important to manage the C&amp;D waste effectively to move society towards sustainability. This study applies the Industrial Ecology paradigm. This involved multidisciplinary approach, spanning the fields of Industrial Ecology, Systems Engineering and Organizational and Social Studies. The scope of this thesis is threefold. The first scope is to get a better understanding of the processes that are taking place within the socio-technical sphere of a recycling system. Second, what is the nature of the C&amp;D waste and what are the environmental impacts from the various waste fractions. Third, how can this information be used to improve recycling systems for C&amp;D waste. The study show that the suggestions in the National Action Plan and the corresponding policies are eco-effective, but that the environmental impact is very transport dependent. The study also shows that there is a great need to focus on future waste composition in the design of recycling systems for C&amp;D waste. However, such waste projections are difficult to perform due to poor data availability. There is a need for making more qualified decisions on environmental issues, with regard to long term management of such recycling systems. Long term models combined with environmental and economic information can make a powerful tool for such analysis.
29

Lokalisering av ytor för hantering av jord- och bergmaterial i Södertörn

Morén, Linda January 2015 (has links)
Syftet med arbetet var att identifiera ytor inom Södertörn där det skulle vara möjligt att etablera materialterminaler för hantering av byggbranschens jord- och bergmaterial. Förhoppningen var att detta kunde bidra till ett planeringsunderlag för en samordnad materialförvaltning inom regionen. Behovet och nyttan av fler materialterminaler har börjat uppmärksammas, men inga studier kring vilka platser som lämpar sig för ändamålet har tidigare genomförts utifrån svenska förhållanden.   För att ta reda på vilka kriterier som definierade en bra materialterminalyta genomfördes en intervjustudie där tio aktörer med anknytning till materialhanteringsbranschen intervjuades. Kriterierna översattes till geografisk information och implementerades i GIS-programmet ArcMAP där det konstruerades en kartbild vilken visualiserade de ytor som var lämpliga respektive olämpliga att använda för ändamålet. Därefter genomfördes ett exempel vilket visade hur kartunderlaget kunde användas för att göra ett första urval av potentiella platser för en terminal inom angivet avstånd från utvalda byggprojektområden. För att ytterligare bidra till planeringsunderlaget identifierades regionens nuvarande materialterminaler, även de redovisades i en geografisk bild konstruerad i ArcMAP. I stort var de intervjuade aktörerna överens om vilka kriterier en materialterminalyta bör uppfylla. De främsta tycktes vara följande; att terminalen har ett bra logistiskt läge som ger korta transporter, att den kan avskärmas från boende och andra som vistas i området, att den har liten konkurrens från andra intressen och ligger utanför miljökänsliga områden samt har en (tillräckligt) stor yta. GIS-analysen och dess resulterande kartbild visade att det fanns stora tillgängliga ytor som uppfyllde kriterierna och som potentiellt skulle kunna användas till nya materialterminaler inom Södertörn. Detta strider mot den vedertagna uppfattningen om att platsbrist är en av de största anledningarna till att terminaler inte har kunnat etableras. Alla kriterier fanns dock inte representerade i analysen, vissa visade sig nämligen vara svåra att översätta till geografisk information. Dessutom fanns det inte alltid tydliga gränser mellan när en markyta kunde användas och inte, i flera fall tycktes det bero på platsspecifika egenskaper. Antaganden och subjektiva bedömningar låg därmed delvis till grund för hur kriterierna representerades i kartbilden. Dessa antaganden och bedömningar baserades dock på intervjuer med kunniga och insatta aktörer samt relevant litteratur, resultaten bedömdes därmed som rimliga och kartbilden möjlig att använda för att få en uppfattning om potentiella materialterminalplatser. GIS-analysen med resulterande kartunderlag skulle kunna användas för att göra ett första urval av potentiella terminalplatser som sedan analyseras vidare innan slutgiltigt val. Rapporten kan användas till att få en bredare kunskap om materialterminaler, vilka kriterier och krav de bör uppfylla och hur berörda aktörer tänker kring dessa. / The purpose of this thesis was to identify areas within Stockholm’s southernmost municipalities (Södertörn) where it was possible to establish terminals where soil and rock material used within the construction industry could be stored and sorted. This should contribute to the planning of a coordinated material management in the region. The need for and usefulness of these hubs have begun to be recognized, but no studies about suitable sites based on Swedish conditions has previously been carried out. In order to find the criteria that define a favourable area for such a site ten stakeholders with connection to the material management were interviewed. The criteria were then translated into geographic information and implemented in the GIS software ArcMap, where a map visualizing the areas that were suitable respectively unsuitable for the purpose was constructed. Thereafter an example which showed how the map could be used to make an initial selection of potential sites within a specified distance from selected construction sites was carried out. In order to further contribute to a coordinated material management the region's current sites for soil and rock handling were identified, also presented in a geographical image constructed in ArcMap. Overall the interviewed stakeholders agreed about which criteria a soil and rock handling site should meet. The most important ones seemed to be the following; a good logistical location which minimizes transportation distances, possibility to shield it from residents and others staying in the area, little competition from other interests, a location outside environmentally sensitive areas, and finally, an area that is (sufficiently) large. The result showed that there existed large accessible areas that could potentially be used for the establishment of new handling sites within Södertörn, which contradict the opinion that the lack of space is one of the major reasons to that these kind of establishments can’t be established. All criteria were not represented in the map though, this since some were not possible to translate into geographic information. Moreover, clear boundaries between when an area could be used and not were sometimes lacking, it seemed to depend on site-specific characteristics. How the criteria were represented in the map was therefore partly based on assumptions and subjective judgments. Assumptions and estimates were however based on interviews with knowledgeable stakeholders and relevant literature and were therefore considered to be reasonable. The map was considered to be able to give an indication of where were soil and rock handling sites potentially could be established. The map could be used to make an initial selection of potential sites, which then can be further analysed before a final choice. The report can be used to gain a broader understanding of these kind of establishments, the criteria and requirements they must meet, and what involved stakeholders think about these.
30

To evaluate the current solid waste issues in Hong Kong's housing process

Kong, Yiu-kuen, Wilson., 江耀權. January 2002 (has links)
published_or_final_version / Housing Management / Master / Master of Housing Management

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