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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.
1

Indicadores de sustentabilidade como ferramenta de apoio a gestão pública de resíduos da construção civil em municípios de pequeno porte / Sustainability indicators as assessment tool to support the RCC management in small cities

Gehrke, Amanda Elisa Barros January 2012 (has links)
Introdução: Apesar de a Resolução n°307/2002 exigir a existência de um Plano Integrado de Gestão de Resíduos da Construção Civil (RCC), em todos os municípios brasileiros, desde o ano de 2003, poucos o possuem. Quando desenvolvidos, muitos são pensados para um horizonte de curto prazo e com função meramente corretiva ou, ainda, são adaptações de experiências de outros contextos, sem considerar a realidade local de onde estão sendo implantados. Estudos anteriores apontam dificuldades, principalmente nos municípios de pequeno porte, em implantar as práticas desta resolução. Nesse contexto, identificou-se que indicadores de sustentabilidade poderiam auxiliar na elaboração de políticas públicas mais sustentáveis, fornecendo dados para o planejamento. Objetivos: O objetivo principal desta pesquisa foi o de se desenvolver indicadores de sustentabilidade para a avaliação da gestão de RCC, em municípios de pequeno porte, a fim de se analisar a situação destes e auxiliá-los no processo de decisão, frente a alternativas mais sustentáveis. Esse objetivo foi desdobrado em objetivos secundários: verificar as particularidades do manejo de RCC em municípios de pequeno porte; investigar a utilidade e a eficiência da ferramenta proposta e; identificar oportunidades de inserção dos resultados do diagnóstico no desenvolvimento de políticas públicas de gestão de RCC mais sustentáveis. Método: A estratégia de pesquisa adotada foi a pesquisa construtiva. A construção da ferramenta de apoio à tomada de decisões foi realizada em três etapas: compreensão, desenvolvimento e análise. A primeira etapa teve como objetivo compreender a realidade do manejo de RCC em municípios de pequeno porte brasileiros e, para isto, um estudo exploratório foi realizado em três municipalidades localizadas na Região do Vale do Caí, Rio Grande do Sul. A segunda etapa, a de desenvolvimento dos indicadores, foi realizada a partir do estudo da legislação brasileira, de diretrizes mais sustentáveis de gestão de RCC e das particularidades de municípios de pequeno porte brasileiros. Nesta etapa, contou-se com a participação de três especialistas da área, para avaliação dos indicadores. Após a sua construção, a ferramenta foi implementada e testada no município de Feliz-RS, e seus resultados foram analisados a partir da sua utilidade e aplicabilidade. Na última etapa, foram discutidas as possíveis correções da ferramenta e as adequações necessárias para aplicação em outros municípios. Resultados: A falta de estrutura de municípios de pequeno porte, e consequente falta de dados referentes ao sistema pesquisado, foi determinante para a escolha dos indicadores. Foram desenvovlvidos quinze dicadores, divididos entre cinco dimensões da sustentabilidade, que foram incorporados em uma planilha eletrônica ExcelTM a ser utilizad por gestores municipais. Esse programa, além de fornecer um diagnóstico ao município, sobre a sua inclinação em direção ao desenvolvimento sustentável, para cada um dos indicadores, fornece orientações para que as situações desfavoráveis sejam convertidas em favoráveis. Através da aplicação dos indicadores no município de Feliz-RS, verificou-se que, além de auxiliar no processo de tomada de decisão e direcionar ações, a ferramenta possui caráter educativo. / Introduction: In spite of Resolution No. 307/2002 requirements for the development of an Integrated Management Plan for Construction and Demolition Waste (C&D), in all Brazilian municipalities, few have it done. And, when developed, many are designed with a short time horizon and with purely corrective function, or are adaptations of experiences from other contexts, without considering the local reality where they are developed for. Previous studies indicate difficulties, especially in small municipalities, in implementing the practices of this resolution. In this context, the author understands that sustainability indicators could help on developing more sustainable public policies, thus providing data for planning. Objectives: The main objective of this research was to develop sustainability indicators for assessing the C&D management in small municipalities, in order to analyze their situation and to assist them in the process of making more sustainable decisions. This objective was divided into three secondary objectives: to verify the details of the C&D management in small municipalities; to investigate the usefulness and efficiency of the proposed tool and to identify opportunities for integration of diagnosis results in the development of public policies for more sustainable C&D management. Method: The research strategy adopted was the constructive research. The construction of the tool to support decision-making was done in three stages: understanding, development and analysis. The first step was aimed at understanding the reality of C&D management in small municipalities, and for this intent, an exploratory study was conducted in three locations with this scale. The second step, the development of indicators, was conducted from the study of Brazilian legislation, guidelines of more sustainable C&D management and the particularities of small municipalities in Brazil. construction, the tool was implemented and tested in the municipality of Feliz, in the state of Rio Grande do Sul, Brazil, and its results were analyzed, based on their usefulness and applicability. In the last step, the possible corrections on the tool and its settings, for the application process in other municipalities, were discussed. Results: The lack of structure in small municipalities and consequent lack of data on the investigated system was crucial to the choice of indicators of sustainable development. Fifteen indicators, divided into five dimensions of sustainability, were found and incorporated into a electronic worksheet to be used by municipal managers. This program, in addition, provides data to convert unfavorable situations. Through the application of indicators in the municipality of Feliz-RS, it was found that, in addition to helping in the process of decision making and of directing actions, the tool has an educational character.
2

Indicadores de sustentabilidade como ferramenta de apoio a gestão pública de resíduos da construção civil em municípios de pequeno porte / Sustainability indicators as assessment tool to support the RCC management in small cities

Gehrke, Amanda Elisa Barros January 2012 (has links)
Introdução: Apesar de a Resolução n°307/2002 exigir a existência de um Plano Integrado de Gestão de Resíduos da Construção Civil (RCC), em todos os municípios brasileiros, desde o ano de 2003, poucos o possuem. Quando desenvolvidos, muitos são pensados para um horizonte de curto prazo e com função meramente corretiva ou, ainda, são adaptações de experiências de outros contextos, sem considerar a realidade local de onde estão sendo implantados. Estudos anteriores apontam dificuldades, principalmente nos municípios de pequeno porte, em implantar as práticas desta resolução. Nesse contexto, identificou-se que indicadores de sustentabilidade poderiam auxiliar na elaboração de políticas públicas mais sustentáveis, fornecendo dados para o planejamento. Objetivos: O objetivo principal desta pesquisa foi o de se desenvolver indicadores de sustentabilidade para a avaliação da gestão de RCC, em municípios de pequeno porte, a fim de se analisar a situação destes e auxiliá-los no processo de decisão, frente a alternativas mais sustentáveis. Esse objetivo foi desdobrado em objetivos secundários: verificar as particularidades do manejo de RCC em municípios de pequeno porte; investigar a utilidade e a eficiência da ferramenta proposta e; identificar oportunidades de inserção dos resultados do diagnóstico no desenvolvimento de políticas públicas de gestão de RCC mais sustentáveis. Método: A estratégia de pesquisa adotada foi a pesquisa construtiva. A construção da ferramenta de apoio à tomada de decisões foi realizada em três etapas: compreensão, desenvolvimento e análise. A primeira etapa teve como objetivo compreender a realidade do manejo de RCC em municípios de pequeno porte brasileiros e, para isto, um estudo exploratório foi realizado em três municipalidades localizadas na Região do Vale do Caí, Rio Grande do Sul. A segunda etapa, a de desenvolvimento dos indicadores, foi realizada a partir do estudo da legislação brasileira, de diretrizes mais sustentáveis de gestão de RCC e das particularidades de municípios de pequeno porte brasileiros. Nesta etapa, contou-se com a participação de três especialistas da área, para avaliação dos indicadores. Após a sua construção, a ferramenta foi implementada e testada no município de Feliz-RS, e seus resultados foram analisados a partir da sua utilidade e aplicabilidade. Na última etapa, foram discutidas as possíveis correções da ferramenta e as adequações necessárias para aplicação em outros municípios. Resultados: A falta de estrutura de municípios de pequeno porte, e consequente falta de dados referentes ao sistema pesquisado, foi determinante para a escolha dos indicadores. Foram desenvovlvidos quinze dicadores, divididos entre cinco dimensões da sustentabilidade, que foram incorporados em uma planilha eletrônica ExcelTM a ser utilizad por gestores municipais. Esse programa, além de fornecer um diagnóstico ao município, sobre a sua inclinação em direção ao desenvolvimento sustentável, para cada um dos indicadores, fornece orientações para que as situações desfavoráveis sejam convertidas em favoráveis. Através da aplicação dos indicadores no município de Feliz-RS, verificou-se que, além de auxiliar no processo de tomada de decisão e direcionar ações, a ferramenta possui caráter educativo. / Introduction: In spite of Resolution No. 307/2002 requirements for the development of an Integrated Management Plan for Construction and Demolition Waste (C&D), in all Brazilian municipalities, few have it done. And, when developed, many are designed with a short time horizon and with purely corrective function, or are adaptations of experiences from other contexts, without considering the local reality where they are developed for. Previous studies indicate difficulties, especially in small municipalities, in implementing the practices of this resolution. In this context, the author understands that sustainability indicators could help on developing more sustainable public policies, thus providing data for planning. Objectives: The main objective of this research was to develop sustainability indicators for assessing the C&D management in small municipalities, in order to analyze their situation and to assist them in the process of making more sustainable decisions. This objective was divided into three secondary objectives: to verify the details of the C&D management in small municipalities; to investigate the usefulness and efficiency of the proposed tool and to identify opportunities for integration of diagnosis results in the development of public policies for more sustainable C&D management. Method: The research strategy adopted was the constructive research. The construction of the tool to support decision-making was done in three stages: understanding, development and analysis. The first step was aimed at understanding the reality of C&D management in small municipalities, and for this intent, an exploratory study was conducted in three locations with this scale. The second step, the development of indicators, was conducted from the study of Brazilian legislation, guidelines of more sustainable C&D management and the particularities of small municipalities in Brazil. construction, the tool was implemented and tested in the municipality of Feliz, in the state of Rio Grande do Sul, Brazil, and its results were analyzed, based on their usefulness and applicability. In the last step, the possible corrections on the tool and its settings, for the application process in other municipalities, were discussed. Results: The lack of structure in small municipalities and consequent lack of data on the investigated system was crucial to the choice of indicators of sustainable development. Fifteen indicators, divided into five dimensions of sustainability, were found and incorporated into a electronic worksheet to be used by municipal managers. This program, in addition, provides data to convert unfavorable situations. Through the application of indicators in the municipality of Feliz-RS, it was found that, in addition to helping in the process of decision making and of directing actions, the tool has an educational character.
3

Indicadores de sustentabilidade como ferramenta de apoio a gestão pública de resíduos da construção civil em municípios de pequeno porte / Sustainability indicators as assessment tool to support the RCC management in small cities

Gehrke, Amanda Elisa Barros January 2012 (has links)
Introdução: Apesar de a Resolução n°307/2002 exigir a existência de um Plano Integrado de Gestão de Resíduos da Construção Civil (RCC), em todos os municípios brasileiros, desde o ano de 2003, poucos o possuem. Quando desenvolvidos, muitos são pensados para um horizonte de curto prazo e com função meramente corretiva ou, ainda, são adaptações de experiências de outros contextos, sem considerar a realidade local de onde estão sendo implantados. Estudos anteriores apontam dificuldades, principalmente nos municípios de pequeno porte, em implantar as práticas desta resolução. Nesse contexto, identificou-se que indicadores de sustentabilidade poderiam auxiliar na elaboração de políticas públicas mais sustentáveis, fornecendo dados para o planejamento. Objetivos: O objetivo principal desta pesquisa foi o de se desenvolver indicadores de sustentabilidade para a avaliação da gestão de RCC, em municípios de pequeno porte, a fim de se analisar a situação destes e auxiliá-los no processo de decisão, frente a alternativas mais sustentáveis. Esse objetivo foi desdobrado em objetivos secundários: verificar as particularidades do manejo de RCC em municípios de pequeno porte; investigar a utilidade e a eficiência da ferramenta proposta e; identificar oportunidades de inserção dos resultados do diagnóstico no desenvolvimento de políticas públicas de gestão de RCC mais sustentáveis. Método: A estratégia de pesquisa adotada foi a pesquisa construtiva. A construção da ferramenta de apoio à tomada de decisões foi realizada em três etapas: compreensão, desenvolvimento e análise. A primeira etapa teve como objetivo compreender a realidade do manejo de RCC em municípios de pequeno porte brasileiros e, para isto, um estudo exploratório foi realizado em três municipalidades localizadas na Região do Vale do Caí, Rio Grande do Sul. A segunda etapa, a de desenvolvimento dos indicadores, foi realizada a partir do estudo da legislação brasileira, de diretrizes mais sustentáveis de gestão de RCC e das particularidades de municípios de pequeno porte brasileiros. Nesta etapa, contou-se com a participação de três especialistas da área, para avaliação dos indicadores. Após a sua construção, a ferramenta foi implementada e testada no município de Feliz-RS, e seus resultados foram analisados a partir da sua utilidade e aplicabilidade. Na última etapa, foram discutidas as possíveis correções da ferramenta e as adequações necessárias para aplicação em outros municípios. Resultados: A falta de estrutura de municípios de pequeno porte, e consequente falta de dados referentes ao sistema pesquisado, foi determinante para a escolha dos indicadores. Foram desenvovlvidos quinze dicadores, divididos entre cinco dimensões da sustentabilidade, que foram incorporados em uma planilha eletrônica ExcelTM a ser utilizad por gestores municipais. Esse programa, além de fornecer um diagnóstico ao município, sobre a sua inclinação em direção ao desenvolvimento sustentável, para cada um dos indicadores, fornece orientações para que as situações desfavoráveis sejam convertidas em favoráveis. Através da aplicação dos indicadores no município de Feliz-RS, verificou-se que, além de auxiliar no processo de tomada de decisão e direcionar ações, a ferramenta possui caráter educativo. / Introduction: In spite of Resolution No. 307/2002 requirements for the development of an Integrated Management Plan for Construction and Demolition Waste (C&D), in all Brazilian municipalities, few have it done. And, when developed, many are designed with a short time horizon and with purely corrective function, or are adaptations of experiences from other contexts, without considering the local reality where they are developed for. Previous studies indicate difficulties, especially in small municipalities, in implementing the practices of this resolution. In this context, the author understands that sustainability indicators could help on developing more sustainable public policies, thus providing data for planning. Objectives: The main objective of this research was to develop sustainability indicators for assessing the C&D management in small municipalities, in order to analyze their situation and to assist them in the process of making more sustainable decisions. This objective was divided into three secondary objectives: to verify the details of the C&D management in small municipalities; to investigate the usefulness and efficiency of the proposed tool and to identify opportunities for integration of diagnosis results in the development of public policies for more sustainable C&D management. Method: The research strategy adopted was the constructive research. The construction of the tool to support decision-making was done in three stages: understanding, development and analysis. The first step was aimed at understanding the reality of C&D management in small municipalities, and for this intent, an exploratory study was conducted in three locations with this scale. The second step, the development of indicators, was conducted from the study of Brazilian legislation, guidelines of more sustainable C&D management and the particularities of small municipalities in Brazil. construction, the tool was implemented and tested in the municipality of Feliz, in the state of Rio Grande do Sul, Brazil, and its results were analyzed, based on their usefulness and applicability. In the last step, the possible corrections on the tool and its settings, for the application process in other municipalities, were discussed. Results: The lack of structure in small municipalities and consequent lack of data on the investigated system was crucial to the choice of indicators of sustainable development. Fifteen indicators, divided into five dimensions of sustainability, were found and incorporated into a electronic worksheet to be used by municipal managers. This program, in addition, provides data to convert unfavorable situations. Through the application of indicators in the municipality of Feliz-RS, it was found that, in addition to helping in the process of decision making and of directing actions, the tool has an educational character.
4

Agregado reciclado de construção e demolição com adição de aglomerantes hidráulicos como sub-base de pavimentos. / The use construction and demolition waste aggregate with hydraulic binders for pavement subbase.

Beja, Igor Amorim 06 December 2013 (has links)
O uso de resíduos de construção e demolição (RCD) vem ganhando espaço crescente em aplicações na engenharia. Este material adquiriu maior importância a partir da década de 70, com seu emprego ampliado como material granular em concretos de cimento para obras civis e no setor de infraestrutura, principalmente como camadas de pavimentos. O presente trabalho tem por objetivo compreender o comportamento físico e mecânico do agregado reciclado de resíduos de construção e demolição com adição de aglomerantes, a cal hidratada e cimento Portland. Foram construídos três trechos experimentais de uma via urbana com uso de RCD misto na sub-base dos pavimentos: (i) um sem aglomerantes adicionais, (ii) um com adição em usina de 3% de cal hidratada, e (iii) um com adição em usina de 3% de cimento Portland. Todas as amostras coletadas em usina foram caracterizadas em laboratório e foram analisados os comportamentos mecânicos das três diferentes misturas por meio de ensaios de (i) resistência à compressão simples aos 7 dias de cura para os materiais com aglomerantes, (ii) ensaios de módulo de resiliência a 7, 28 e 60 dias de cura para todas as misturas, e (iii) ensaios de deformação permanente com diferentes tensões. Analisando os resultados das misturas a 60 dias de cura, a mistura em RCD apresentou com o menor ganho em módulo de resiliência, enquanto que a mistura de RCD com 3% cimento, apresentou os maiores módulos, e a mistura RCD com adição em 3% de cal obteve um valor pouco abaixo daquele com cimento. Quanto ao comportamento à deformação permanente, verificou-se que a baixos níveis de tensão, todas as misturas apresentaram baixas deformações e comportamento similar. Em maiores níveis de diferença de tensões principais, as misturas estabilizadas apresentaram comportamento estável e as misturas em RCD obtiveram deformação permanente mais significativa. Com o monitoramento deflectométrico foi possível realizar retroanálise, e estimar os módulos de resiliência in situ, cujos valores foram similares aos encontrados em laboratório. Passados quase dois anos, o comportamento funcional e estrutural dos trechos experimentais é satisfatório. / The use of construction and demolition waste (CDW) has been increasing in engineering applications the use of CDW has become more important since the 70s as granular material in cement concrete applications in civil engineering and transportation infrastructure, mainly as pavement layers. This study aims to understand the physical and mechanical behavior of recycled aggregate from construction and demolition waste with the addition of hydraulic binders, as hydrated lime and Portland cement. Three experimental urban pavement sections were constructed using CDW as subbase material: (i) the first one using CDW, (ii) the second one using CDW with 3% of hydrated lime (mixed in the plant), and (iii) the third one employing CDW with 3% of cement (also mixed in the plant). All samples collected in the plant were characterized in laboratory. The mechanical behavior of these materials and mixtures were analyzed through the following tests: (i) compressive strength after 7 days of curing for materials with hydraulic binders, (ii) resilient moduli after 7, 28, and 60 days of curing for all mixes, and (iii) permanent deformation. By analyzing the responses of the mixture after 60 days of curing, the CDW mixture presented, as a crushed stone, the smallest gain on resilient modulus, whereas mixture with 3% cement with CDW had the highest modulus. The mixture with 3 % hydrated lime with CDW showed resilient modulus smaller than the mixture with cement. The permanent deformations at low stress levels were low and similar for the three tested materials. On the other hand, at higher stress level, the stabilized mixtures exhibited stable behavior, and the mixture with CDW shows a significant permanent deformation. The backcalculation based on the measurement of field deflections showed values of resilient moduli in situ similar to the laboratory results. After almost two years, the performance of the experimental sections is considered satisfactory.
5

Agregado reciclado de construção e demolição com adição de aglomerantes hidráulicos como sub-base de pavimentos. / The use construction and demolition waste aggregate with hydraulic binders for pavement subbase.

Igor Amorim Beja 06 December 2013 (has links)
O uso de resíduos de construção e demolição (RCD) vem ganhando espaço crescente em aplicações na engenharia. Este material adquiriu maior importância a partir da década de 70, com seu emprego ampliado como material granular em concretos de cimento para obras civis e no setor de infraestrutura, principalmente como camadas de pavimentos. O presente trabalho tem por objetivo compreender o comportamento físico e mecânico do agregado reciclado de resíduos de construção e demolição com adição de aglomerantes, a cal hidratada e cimento Portland. Foram construídos três trechos experimentais de uma via urbana com uso de RCD misto na sub-base dos pavimentos: (i) um sem aglomerantes adicionais, (ii) um com adição em usina de 3% de cal hidratada, e (iii) um com adição em usina de 3% de cimento Portland. Todas as amostras coletadas em usina foram caracterizadas em laboratório e foram analisados os comportamentos mecânicos das três diferentes misturas por meio de ensaios de (i) resistência à compressão simples aos 7 dias de cura para os materiais com aglomerantes, (ii) ensaios de módulo de resiliência a 7, 28 e 60 dias de cura para todas as misturas, e (iii) ensaios de deformação permanente com diferentes tensões. Analisando os resultados das misturas a 60 dias de cura, a mistura em RCD apresentou com o menor ganho em módulo de resiliência, enquanto que a mistura de RCD com 3% cimento, apresentou os maiores módulos, e a mistura RCD com adição em 3% de cal obteve um valor pouco abaixo daquele com cimento. Quanto ao comportamento à deformação permanente, verificou-se que a baixos níveis de tensão, todas as misturas apresentaram baixas deformações e comportamento similar. Em maiores níveis de diferença de tensões principais, as misturas estabilizadas apresentaram comportamento estável e as misturas em RCD obtiveram deformação permanente mais significativa. Com o monitoramento deflectométrico foi possível realizar retroanálise, e estimar os módulos de resiliência in situ, cujos valores foram similares aos encontrados em laboratório. Passados quase dois anos, o comportamento funcional e estrutural dos trechos experimentais é satisfatório. / The use of construction and demolition waste (CDW) has been increasing in engineering applications the use of CDW has become more important since the 70s as granular material in cement concrete applications in civil engineering and transportation infrastructure, mainly as pavement layers. This study aims to understand the physical and mechanical behavior of recycled aggregate from construction and demolition waste with the addition of hydraulic binders, as hydrated lime and Portland cement. Three experimental urban pavement sections were constructed using CDW as subbase material: (i) the first one using CDW, (ii) the second one using CDW with 3% of hydrated lime (mixed in the plant), and (iii) the third one employing CDW with 3% of cement (also mixed in the plant). All samples collected in the plant were characterized in laboratory. The mechanical behavior of these materials and mixtures were analyzed through the following tests: (i) compressive strength after 7 days of curing for materials with hydraulic binders, (ii) resilient moduli after 7, 28, and 60 days of curing for all mixes, and (iii) permanent deformation. By analyzing the responses of the mixture after 60 days of curing, the CDW mixture presented, as a crushed stone, the smallest gain on resilient modulus, whereas mixture with 3% cement with CDW had the highest modulus. The mixture with 3 % hydrated lime with CDW showed resilient modulus smaller than the mixture with cement. The permanent deformations at low stress levels were low and similar for the three tested materials. On the other hand, at higher stress level, the stabilized mixtures exhibited stable behavior, and the mixture with CDW shows a significant permanent deformation. The backcalculation based on the measurement of field deflections showed values of resilient moduli in situ similar to the laboratory results. After almost two years, the performance of the experimental sections is considered satisfactory.
6

Development of ambient-cured geopolymer mortars with construction and demolition waste-based materials

Yildirim, Gurkan, Ashour, Ashraf F., Ozcelikci, E., Gunal, M.F., Ozel, B.F., Alhawat, Musab M. 21 February 2023 (has links)
No / Degrading infrastructure and applications of structural demolition create tremendous amounts of construction and demolition waste (CDW) all around the world. To address this issue in an effective way, recycling CDW in a most appropriate way has become a global concern in recent years. To this end, this study focused on the utilization of CDW-based materials such as hollow brick (HB), red clay brick (RCB), roof tile (RT), glass (G) and concrete (C) in the production of geopolymer mortars. These materials were first collected from an urban transformation area and then subjected to an identical two-step crushing-milling procedure to provide sufficient fineness for geopolymerization. To investigate the influence of blast furnace slag (S) addition to the CDW-based mixtures, 20% S substituted mixture designs were also made. Fine recycled concrete aggregates (FRCA) obtained from crushing and sieving of the waste concrete were used as the aggregate. A series of mixtures were designed using different proportions of three distinct alkali activators such as sodium hydroxide (NaOH), sodium silicate (Na2SiO3) and calcium hydroxide (Ca[OH]2). To improve their applicability, the mixtures were left to cure at room temperature rather than the heat curing which is frequently applied in the literature. After 28 days of ambient curing, the 100% CDW-based geopolymer mortar activated with three different activators reached a compressive strength of 31.6 MPa, whereas the 20% S substituted geopolymer mortar achieved a compressive strength of 51.9 MPa. While the geopolymer mortars activated with only NaOH exhibited poor performance, it was found that the use of Na2SiO3 and Ca(OH)2 improved the compressive strength. Main geopolymerization products were related to NASH, CASH, and C(N)ASH gel formations. Our results demonstrated that mixed CDW-based materials can be employed in the manufacturing geopolymers, making them potential alternatives to Portland cement-based systems by being eco-friendly, energy-efficient, and comparable in compressive strength. / This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 894100.
7

Development of Concrete Mixtures Based Entirely on Construction and Demolition Waste and Assessment of Parameters Influencing the Compressive Strength

Yildirim, Gurkan, Ozcelikci, E., Alhawat, Musab M., Ashour, Ashraf 22 March 2023 (has links)
Yes / Demolition and reconstruction of degrading structures alongside with the repetitive repair, maintenance, and renovation applications create significant amounts of construction and demolition waste (CDW), which needs proper tackling. The main emphasis of this study has therefore been placed on the development of concrete mixtures with components (i.e., aggregates and binder) coming entirely from CDW. As the binding phase, powdered CDW-based masonry units, concrete and glass were used collectively as precursors to obtain geopolymer binders, which were then incorporated with CDW-based fine and coarse concrete aggregates. Together with the entirely CDW-based concretes, designs were also proposed for companion mixtures with mainstream precursors (e.g., fly ash and slag) occupying some part of the CDW-based precursor combination. Sodium hydroxide (NaOH), sodium silicate (Na2SiO3) and calcium hydroxide (Ca[OH]2) were used at various concentrations and combinations as the alkaline activators. Several factors that have impact on the compressive strength results of concrete mixtures, such as mainstream precursor replacement rate, al-kaline molar concentrations, aggregate-to-binder ratios and curing conditions, were considered and these were also backed by the micro-structural analyses. Our results showed that through proper optimiza-tion of the design factors, it is possible to manufacture concrete mix-tures entirely out of CDW with compressive strength results able to reach up to 40 MPa under ambient curing. Current research is believed to be very likely to promote more innovative and up-to-date techniques to upcycle CDW, which are mostly downcycled through basic practices of road base/sub-base filling, encouraging further research and increas-ing the awareness in CDW issue. / The full-text of this paper will be released for public view at the end of the publisher embargo on 1 Jul 2024.
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Mechanical and microstructural characterization of geopolymers from assorted construction and demolition waste-based masonry and glass

Ulugöl, H., Kul, A., Yildirim, Gurkan, Şahmaran, M., Aldemir, A., Figueira, D., Ashour, Ashraf 23 September 2020 (has links)
Yes / Geopolymers are mostly produced with main-stream precursors such as fly ash and slag. These precursors are successfully used and competitively demanded by the cement industry. Development of geopolymers from alternative precursors is appealing. The main aim of this work is the development of geopolymers with construction and demolition waste-based precursors including masonry units (red clay brick, roof tile, hollow brick) and glass. Different curing temperatures (50, 65, 75, 85, 95, 105, 115, 125 oC), curing periods (24, 48, 72 h), and Na concentrations (10, 12, 15%) of alkaline activator (NaOH) were employed. Compressive strength testing and microstructural investigations were performed including X-ray diffraction, thermogravimetry and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Results showed that depending on the type of precursor (hollow brick), curing temperature/period (115 oC/24 h) and concentration of alkaline activator (12%), it is possible to obtain compressive strength results more than 45 MPa. Hollow brick is the most successful precursor resulting in higher compressive strength results thanks to a more compact microstructure. The strength performance of red clay brick and roof tile is similar. The compressive strength results of geopolymers with glass precursor are lower, most probably due to significantly coarser particles of glass used. The main reaction products of red clay brick-, roof tile- and hollow brick-based geopolymers are sodium aluminosilicate hydrate (N-A-S-H) gels with zeolite-like structures while they are sodium silicate gels in the case of glass-based geopolymers. Our findings showed that CDW-based materials can be used successfully in producing geopolymers. Current research is believed to help raise awareness in novel routes for the effective utilization of such wastes which are realistically troublesome and attract further research on the utilization of CDW-based materials in geopolymer production. / The authors gratefully acknowledge the financial assistance of the Scientific and Technical Research Council (TUBITAK) of Turkey and British Council provided under projects: 117M447 and 218M102.
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Development of ambient-cured geopolymer mortars with construction and demolition waste-based materials

Yildirim, Gurkan, Ashour, Ashraf, Ozcelikci, E., Gunal, M.F., Ozel, B.F., Alhawat, Musab M. 22 September 2023 (has links)
Yes / Degrading infrastructure and applications of structural demolition create tremendous amounts of construction and demolition waste (CDW) all around the world. To address this issue in an effective way, recycling CDW in a most appropriate way has become a global concern in recent years. To this end, this study focused on the valorization of CDW-based materials such as tile, bricks, glass, and concrete in the development of geopolymer mortars. CDWs were first collected from demolition zone and then subjected to crushing-milling operations. To investigate the influence of slag (S) addition to the mixtures, 20% S substituted mixture designs were also made. Fine recycled concrete aggregates (FRCA) obtained from crushing and sieving of the waste concrete were used as the aggregate. A series of mixtures were designed using different proportions of three distinct alkali activators such as sodium hydroxide (NaOH), sodium silicate (Na2SiO3), and calcium hydroxide (CH; Ca(OH)2). To improve their applicability, the mixtures were left to cure at room temperature rather than the heat curing which is frequently applied in the literature. After 28 days ambient curing, the 100% CDW-based geopolymer mortar activated with three different activators reached a compressive strength of 31.6 MPa, whereas the 20% S substituted geopolymer mortar showed a 51.9 MPa compressive strength. While the geopolymer mortars activated with only NaOH exhibited poor performance, it was found that the use of Na2SiO3 and CH improved the mechanical performance. Main geopolymerization products were related to NASH (Sodium alumino-silicate hydrate), CASH (Calcium alumino-silicate hydrate), and C(N)ASH gel formations. Results demonstrated that mixed CDWs can be employed in the manufacturing geopolymers, making them potential alternatives to Portland cement (PC)-based systems by being eco-friendly, energy-efficient, and comparable in compressive strength. / This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 894100.
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Developing a self-sustaining secondary construction materials market in South Africa

Macozoma, Dennis Skhumbuzo 11 March 2008 (has links)
ABSTRACT Sustainable development has become part of Government policy across the world. In the construction industry it has been introduced through the promotion of “sustainable construction” or “green construction”. International trends show a gradual move away from wasteful construction industry practices that include high resource consumption, material wastage, inefficiencies in construction processes and a high percentage of waste that find its way to waste disposal sites and illegal dumps. This research report seeks to promote sustainable construction and waste minimisation as preferred models for achieving a balance in the economic, social and environmental impacts of development. It reviews South Africa’s construction and demolition site practice from the perspective of construction and demolition waste management, assessing waste management practice and the resultant waste disposal. To gauge South Africa’s performance it benchmarks South African practice against those of the United States, United Kingdom, Germany and the Netherlands. This approach highlights gaps in South Africa’s current practice and also provides some valuable lessons that can be used to ensure compliance with sustainable construction principles. Finally the research report proposes a framework for developing a self-sustaining secondary construction materials market in South Africa, which can prove to be a valuable tool for ensuring the absorption of sustainable construction in the construction industry.

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