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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.
51

Estudo do reaproveitamento de isoladores eletricos de porcelana como agregados em argamassas e concretos / Reutilization study of procelain elestric insulator as aggregates in mortars and concretes

Campos, Marco Antonio 13 August 2018 (has links)
Orientadores: Ana Elisabete Paganelli Guimaraes de Avila Jacintho, Gladis Camarini / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-13T17:50:32Z (GMT). No. of bitstreams: 1 Campos_MarcoAntonio_M.pdf: 4912865 bytes, checksum: 2d984476b2f21673120b306516935fb8 (MD5) Previous issue date: 2009 / Resumo: Todo material de construção após certo tempo de uso apresenta um desgaste que compromete a sua eficiência, fazendo com que a substituição e o descarte sejam imprescindíveis. Os isoladores elétricos de porcelana, após um dado período de uso, perdem suas funções isoladoras, tendo necessidade de serem substituídos, e o seu descarte mensal pelas concessionárias do setor elétrico brasileiro atinge dezenas de toneladas. Em muitos casos o depósito destes isoladores é executado de forma desordenada havendo o comprometimento das áreas de preservação ambientais e de mananciais. Durante o processo de fabricação desses isoladores elétricos também são gerados resíduos, chegando até a 10% do total produzido, cujo descarte é feito no lixo pelas indústrias cerâmicas. Estes dois tipos de rejeitos causam na natureza um passivo de material que leva muitos anos para sua decomposição. Assim, a caracterização deste material cerâmico e o desenvolvimento de um estudo que viabilize seu emprego em substituição aos agregados comumente usados em argamassas e concretos, é uma alternativa para a racionalização do descarte desse material e preservação da natureza. Para o uso de resíduos dos isoladores de porcelana na construção civil é necessário sua moagem em granulometrias similares aos agregados graúdos e miúdos comuns. Este trabalho estudou dosagens de concreto e argamassa com substituições paulatinas de isoladores moídos, comparando algumas de suas propriedades com traços de referência feitos com agregados comuns. Para cada traço foram estudadas as propriedades mecânicas, a trabalhabilidade, a cura e a durabilidade. Pelo fato dos isoladores de porcelana terem características similares aos agregados comuns após a moagem, sua utilização em argamassas e concretos, para os traços moldados e tipos de cura realizados, substituindo parcialmente o agregado, foi bastante satisfatória, principalmente quando o agregado substituído foi o agregado miúdo / Abstract: Every construction material after sometime of using presents wastages which compromises its efficiency and turns indispensable its substitution or disposal. Porcelain electrical insulators, after a certain time of use, lose their insulator functions and are needed to be substituted and its monthly disposal in the brazilian electric sector comes to more than ten tons. In many cases the deposit of these insulators is done in a messy way compromising the environment and springs. During the manufacturing process of these electric insulators, wastes are generated coming up to 10% of the total production and the disposal is done by the pottery industries in the garbage. These two types of rejection cause in nature a passive material which takes many years for its decomposition. Therefore the characterization of this pottery material and the development of a study substituting the aggregate materials used in mortars and concretes, is an alternative of the rationalization of the discard of this material and preservation of the environment. For the use of waste of the porcelain insulators in the civil construction, it is needed to grind them in grinders, similar to great and tiny common aggregates. This work studied concrete and mortar portions with gradual substitutions of ground insulators, comparing some of its properties with reference features done with common aggregates. For each feature were studied the mechanical properties, the working, the cure and the durability. Because of the porcelain insulators have similar characteristics to the common aggregates after the grind, their use in mortar and concretes for the feature patterns and types of cure performed, substituting partially the aggregates, it was quite satisfactory mainly when the substituted aggregate was the small aggregate / Mestrado / Arquitetura e Construção / Mestre em Engenharia Civil
52

Análise microestrutural e das propriedades mecânicas e de durabilidade de argamassas e concretos com isoladores elétricos de porcelana / Microstructural analysis and of mechanical and durability properties of mortars and concretes with porcelain electric insulator

Campos, Marco Antonio 19 August 2018 (has links)
Orientador: Vladimir Antonio Paulon / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-19T08:41:17Z (GMT). No. of bitstreams: 1 Campos_MarcoAntonio_D.pdf: 29342134 bytes, checksum: 387aea50293d1fe1cbb0bd9758e9bab3 (MD5) Previous issue date: 2011 / Resumo: Pesquisas para utilização de materiais reciclados e/ou inservíveis da construção civil em seus insumos, concretos e argamassas, é prática recorrente há seis décadas no mundo. No Brasil este uso vem ganhando destaque a cerca de vinte anos principalmente com os entulhos de construção e da cerâmica vermelha. Há uma lacuna a ser preenchida pela cerâmica branca, em especial pelos isoladores elétricos de porcelana, pois seu passivo nacional anual é de 25.000 toneladas proveniente sobretudo da substituição de peças obsoletas. O objetivo deste trabalho foi comprovar a utilização desta porcelana em concretos e argamassas através de sua incorporação com diferentes graus de moagem, variando de granulometria similar ao cimento até aos agregados, miúdo e graúdo, além do estudo referente a influência da camada de esmalte externa aos isoladores através de ensaios mecânicos, de durabilidade e de imagens por MEV e EDS. Para a adição da cerâmica ao cimento nos teores em massa de 5%, 10%, 25%, 50% e 70%, nas argamassas a melhora nos resultados dos ensaios realizados comprovam sua atividade pozolânica e sua potencialidade de uso. Nos ensaios dos concretos com isoladores de porcelana substituindo o agregado miúdo comum ou ambos os agregados, nos teores de 25%, 50%, 75% e 100%, os aumentos de resistências à compressão simples e à tração por compressão diametral obtidos foram superiores a 50% quando comparados aos valores do concreto de referência. A influência da camada de esmalte superficial dos isoladores não foi constada nos ensaios realizados, sendo este mais um fator pró-utilização desta porcelana. As melhoras conferidas às argamassas e aos concretos, quando moldados com agregados ou aglomerantes cerâmicos em suas propriedades mecânicas e de durabilidade acompanhadas dos ensaios de imagens comprovam a utilização dos isoladores elétricos de porcelana nos insumos da construção civil oferecendo com isso às indústrias cerâmicas uma alternativa de uso a esta porcelana e diminuindo a produção de cimento e a extração dos agregados / Abstract: Researches for using recycled materials and/or useless for civil building in input, concretes and mortars, is a practice used for six decades in the world. In Brazil this use is standing out for about20 years mainly with the construction waste and the red ceramic. There is a gap to be fulfilled by the white ceramic especially by the porcelain electric insulators, because of its national passive which is of 25,000 tons proceeded from the substitution of obsolete parts. The purpose of this work is to confirm the utility of this porcelain in concretes and mortars through its incorporation with different degrees of grinding, varying its grinding similar to cement till the aggregates, tiny and great, besides the study referring to the external enamel surface influence to isolators through mechanical test, durability and by SEM and EDS images. Increasing the ceramic to cement in the mass theors of 5%, 10%, 25%, 50% and 70% in the mortar, the improvement in the test results performed, confirm its pozzolanic activity and its potential use. In the concrete test with porcelain insulator substituting the tiny common aggregate or both the aggregates, in theors of 25%, 50%,75% and 100%, the increase in resistance to compressive strength and traction by diametral compression obtained were superior to 50% when compared to the value of the referenced concrete. The influence of the superficial enamel of the insulator was not noticed in the performed tests, therefore being this one more factor for the use of this porcelain. The improvements noticed to the mortars and the concretes, when molded with aggregates or ceramic waste in their mechanical properties and durability followed by image test, confirm the utility of porcelain electric insulator in the input of civil construction offering with this to the ceramic industries an alternative of use to this porcelain and decreasing the cement production and the extraction of aggregates / Doutorado / Recursos Hidricos, Energeticos e Ambientais / Doutor em Engenharia Civil
53

Shear Strength And Volume Change Characteristics Of Granular Materials And Aggregate Mixtures

Kurien, Susan 08 1900 (has links) (PDF)
No description available.
54

Near aggregation: a time and frequency domain analysis using state trajectories and transfer function residues

Babendreier, Justin Eric January 1987 (has links)
In this thesis we investigate concepts associated with aggregation. The basic idea of aggregation is that there exists a reduced order model such that, for an appropriate initial condition, the trajectories of the reduced-order model are linear combinations of the trajectories of the ful 1-order model. We study systems which do not aggregate exactly, but which "nearly aggregate". It is shown that for "nearly aggregable" systems there exists a reduced-order model such that, for an appropriate initial condition, the trajectories of the reduced-order model are near a linear combination of the trajectories of the full-order model. Under certain conditions it has also been shown that near-aggregation is equivalent to near-unobservability (roughly, an invariant subspace close to the null space of C). Here we establish a relationship between near-unobservability and modal measures of observability as suggested by Selective Modal Analysis. With this result we then obtain an upper bound on the norm of the transfer function residue using near-unobservability measures. The Generalized Hessenberg Representation (GHR) and Dual GHR are examined throughout this analysis. It is finally shown that for SISO systems, the residue norm may be expressed in terms of certain parameters of the Dual GHR. / M.S.
55

Durability of a recycled aggregate concrete base course material under coupled environmental exposure and cyclic

Unknown Date (has links)
Long term durability is a major concern for wide-scale use of recycled aggregate materials in civil engineering construction. The purpose of this study is to provide an insight into the damaging effects of combined wet-dry cycles and repeated mechanical loading in a recycled aggregate concrete (RAC) base course material made from recycled crushed concrete aggregate and cement. A coordinated experimental program followed by a mechanistic pavement modeling and life cycle analysis was conducted as part of this research study. This laboratory investigation was divided into three phases each consisting of both wet-dry exposed specimens (WD), and control or non wet-dry exposed specimens (NWD). Phase I experiments involved monotonic loading tests under compression and flexure to evaluate the strength properties. Phase II involved testing a total of 108 cylindrical specimens in cyclic compressive loading at three different stress ratios. After each regime of cyclic loading, residual compressive strengths were determined. In addition, the load-deformation hysteresis loops and the accumulated plastic deformation were continuously monitored through all loading cycles. Phase III included a flexural fatigue test program on 39 beam specimens, and fracture testing program on 6 notched beam specimens, each one having 19-mm initial notch. Traditional SR-N curves, relating the Stress Ratio (SR) with the number of cycles to failure (N or Nf), were developed. Fatigue crack growth rate and changes in Stress Intensity Factors were obtained to determine Paris Law constants and fracture toughness. A mechanistic analysis of a typical highway pavement incorporating RAC base was performed with KENPAVE program, followed by a Life Cycle Analysis (LCA) using the GaBi software. It was found that the specimens subjected to wet-dry cycles suffered significantly higher damage expressed in terms of accumulated plastic deformation, and loss of residual compressive strength, modulus, fatigue endurance limit, and design life, compared to specimens not exposed to wet-dry cycles. Although such degradation in material properties are important considerations in pavement design, a concurrent Life Cycle Analysis demonstrated that recycled aggregate concrete base course still holds promise as an alternative construction material from environmental stand point. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection
56

Partnering with suppliers for quality improvement

Baliso, Unathi January 2010 (has links)
A dissertation submitted in fulfillment of the requirements for the degree Master Technology: Quality in the Faculty of Engineering at the Cape Penisula University of Technology / Uneven surfaces on national roads that often lead to difficulty and even danger can be extremely hazardous when wet, due to mud and cracks, and also create dust pollution for motorists, pedestrians, residents and business. The continuing use of low quality raw materials in producing hot mix asphalt for national roads, leads to regular maintenance at a very high cost. The quality aggregates (stone that is used to produce asphalt), and the quality of bitumen are often inadequate for the correct composition of hot mix asphalt. The mst important factors affecting initial and long term performance of the highways is the inferior pavement structure and condition, due to poor aggregates (raw material)from suppliers. The performance of asphalt i s largely determined by the characteristics of its constituents, the asphalt binder and aggregates.
57

Gestão de agregados minerais = análise e subsídios para políticas públicas / Management ggregates : comparite analysis betwen Canada and Brazil and subsidies for public policies

Fantin, Marcel, 1979- 18 August 2018 (has links)
Orientador: Hildebrando Herrmann, Richard Poulin / Tese (Doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-18T20:45:27Z (GMT). No. of bitstreams: 1 Fantin_Marcel_D.pdf: 24079682 bytes, checksum: 859c31d723a91364d5f0a38679cb7e96 (MD5) Previous issue date: 2011 / Resumo: Os impactos biofísicos e sociais causados pela mineração de agregados têm colocado este ramo da mineração no centro de situações de conflito, seja por causa do avanço da urbanização sobre áreas de mineração ou por causa de pressões da sociedade civil para impor restrições ao seu desenvolvimento. A busca de soluções para este problema tem exigido do poder público uma grande capacidade de conciliar os interesses divergentes e de assegurar o equilíbrio entre a oferta e a demanda por estes bens minerais. Para este fim, Política e Gestão desempenham um papel fundamental, pois estas são um instrumento eficaz de planejamento e ação. O objetivo desta tese é analisar e comparar experiências de políticas e gestão aplicada aos agregados minerais no Canadá e Brasil. Foram analisados os instrumentos dessas políticas, o desenho organizacional do Estado e o conflito entre o planejamento local e regional. Os resultados da pesquisa mostraram que os casos canadenses analisados são baseados em um forte planejamento provincial, que visa proteger os depósitos dos agregados minerais da esterilização, a fim de atender a demanda futura. Por outro lado, as províncias têm feito grandes esforços para garantir a recuperação de áreas degradadas pela mineração, utilizando, para isso, instrumentos econômicos, tais como cauções e seguros. Especialmente na Província de Ontário, a sua política de agregados minerais é mais eficiente em termos de seus principais objetivos e tem uma postura pró-ativa do setor de produção de agregados minerais. No entanto, seu foco não é o caminho do desenvolvimento sustentável. Para isso seria necessário alterar sua política baseada na garantia da oferta de agregados minerais por uma política baseada em uma gestão econômica da demanda. No Brasil, observou-se que, diferentemente do Canadá, a base legislativa do país permite uma participação muito pluralista das diferentes esferas de poder quando se trata de leis e elaboração de políticas ambientais para os agregados minerais. Entretanto, os resultados dessas políticas nos estudos de caso analisados têm sido bastante limitados devido a problemas como a falta de normas constitucionais que definam claramente as competências legislativas e materiais no âmbito federal, estadual e municipal. Tal situação tem levado à promulgação de leis contraditórias e ações desconexas entre os órgãos públicos responsáveis pela execução das políticas relacionadas com agregados minerais. Ainda, a falta de garantias para a recuperação de áreas degradadas pela mineração de agregados é um problema a ser resolvido a fim de garantir operações em sintonia com as modernas exigências ambientais / Resumé: Les perturbations biophysiques et sociaux causés par l'exploitation en carrière des granulats a placée dans le centre de scénarios de conflit, que ce soit en raison des progrès de l'urbanisation sur les ressources en granulats ou en raison de pressions de la société civile pour imposer des restrictions à leur développement. La recherche de solutions à ce problème a en outre demandé aux gouvernements public une grande habileté pour concilier les intérêts divergents et à assurer l'équilibre entre l'offre et la demande pour ces produits minéraux. À cette fin, la politique et la gestion jouent un rôle fondamental, car elles sont un outil efficace pour la planification et l'action. L'objectif de ce papier est d'analyser et de comparer leurs expériences de politiques appliquées aux granulats minéraux en provenance du Canada et du Brésil. Nous avons analysé les instruments de ces politiques, la conception de l'état d'organisation, le conflit entre la planification locale et régionale et les différences entre les points de vue de l'industrie et les intervenants. Les résultats de recherche illustré que les politiques canadiennes relatives aux granulats minéraux sont fondées sur une solide planification provinciale qui cherche à protéger les dépôts des granulats minéraux de la stérilisation afin de répondre à la demande future. D'autre part, les provinces ont fait de grands efforts pour assurer la réhabilitation des zones dégradées par l'exploitation minière, en utilisant, pour cela, des instruments économiques tels que les dépôts de garantie et les assurances. Ces politiques sont plus efficaces en termes de leurs principaux objectifs et ont a une posture pro-active du secteur de la production de granulats mineraux. Cependant, ce modèle a été vivement contestée par la société civile, surtout dans la province de l'Ontario, qui a pressé le gouvernement provincial de modifier l'approche traditionnelle de politique que qui se concentre sur le approvisionnement de granulats minéraux et la réhabilitation des zones dégradées pour une politique basée sur la conservation de l'environnement et la gestion de la demande de ces minéraux. Au Brésil, il a été observé que, contrairement au Canada, la base législative du pays permet une participation très pluraliste des différentes sphères du pouvoir quand il s'agit de l'élaboration de lois et de politiques pour les granulats mineraux. Cependant, les résultats de ces politiques ont été plutôt limités, malgré les efforts considérables déployés ces dernières années. Des problèmes tels que l'absence de règles constitutionnelles qui définissent clairement les pouvoirs législatifs et matériaux aux niveaux fédéral, étatique et municipal ont conduit à la promulgation de lois contradictoires et des actions disjointes entre les entités publiques chargées de la mise en oeuvre des politiques relatives aux granulats mineraux. Pourtant, l'absence de garanties pour le récupération des zones dégradées par l'exploitation minière des granulats est un problème être résolus afin d'assurer une extraction plus efficace et qu'il est en conformité avec les exigences environnementales modernes / Abstract: The biophysical and social disruption caused by aggregates mining has placed it at the center of conflict scenarios, either because of advancing urbanization on the aggregates resources or because of pressures from civil society to impose restrictions on their development. The search for solutions to this problem has required of the governments a large ability to reconcile the divergent interests and to ensure a balance between the supply and demand of these mineral goods. To this end, policy and management play a fundamental role, since they are an efficient tool for planning and action. The aim of this thesis is to analyze and compare experiences of policy and management applied to mineral aggregates in Canada and Brazil. We analyzed the instruments of these policies, the state organizational design and the conflict between the local and regional planning.The research results showed that the Canadian policies related to mineral aggregates are based on a strong provincial planning that seeks to protect the deposits of mineral aggregates from sterilization in order to meet future demand. On the other hand, the provinces have made great efforts to ensure the rehabilitation of areas degraded by mining, using, for this, economic instruments such as deposits and insurances. Such policies are more efficient in terms of their main goals and have a pro-active posture of the mineral aggregates producing sector. However, this model has been hotly contested by civil society, especially in the Province of Ontario, which has pressed the provincial government to change the traditional policy approach that focuses on the provision of mineral aggregates and the rehabilitation of degraded areas to a policy based on environmental conservation and the management of demand for these mineral inputs. In Brazil, it has been observed that, unlike Canada, the country's legislative basis allows a very pluralistic participation of the different spheres of power when it comes to drafting laws and policies for mineral aggregates. However, the results of these policies have been rather limited, despite the great efforts made in recent years. Problems such as the lack of constitutional rules that clearly define the legislative and materials powers at the federal, state and municipal levels have led to the enactment of conflicting laws and disjointed actions between the public entities responsible for the implementation of policies related to mineral aggregates. Still, the lack of guarantees for the recovery degraded areas by aggregates mining is a problem to be faced in order to ensure a more efficient extraction and that it is in line with modern environmental requirements / Doutorado / Geologia e Recursos Naturais / Doutor em Ciências
58

Laboratory characterisation of pavement foundation materials

Edwards, Jonathan Paul January 2007 (has links)
Pavement foundations for major roads in the UK were historically designed on an empirical basis, related to a single design chart, restricting the incorporation of superior performing materials or materials for which the empirical data sets were not available. The adoption of performance based specifications was promoted as they are perceived to 'open up' the use of alternative materials (including 'local' sources of primary materials) or techniques, and allow for the incorporation of superior performance into the overall pavement design. Parallel developments to the performance based design of pavement foundations (allowing for superior performance) and in situ testing required the support of laboratory based performance tests. These laboratory based tests were required to determine material performance parameters (elastic modulus and resistance to permanent deformation) for both unbound and hydraulically bound pavement foundation materials. A review of the available laboratory apparatus indicated that they were either; unrealistic (and hence unable to provide the required material performance parameters), or overly complex and more suited to fundamental research. Therefore, the requirement for developmental research work was identified. The research reported herein details the development, manufacture and initial evaluation of simplified laboratory apparatus (the Springbox for unbound materials and static stiffness test for hydraulically bound mixtures) designed to produce the performance parameters of elastic modulus and relative resistance to permanent deformation for pavement foundation materials. The equipment and test procedure evaluation was undertaken across a range of materials, giving initial guidance on likely in situ performance. The innovative laboratory apparatus and materials guidance (including the potential to use recycled and secondary aggregates) was incorporated into key Highways Agency specification and guidance documents, which in turn influence construction practice outside of motorways and major trunk roads. This research concludes by outlining a number of recommendations for continued development and evaluation, including feeding back data sets from long term in situ performance testing for subsequent refinement of assumptions.
59

Alkali-silica reaction in concrete containing recycled concrete aggregates

Adams, Matthew P. 09 January 2012 (has links)
Using recycled concrete aggregate (RCA) as a replacement for natural aggregate in new concrete is a promising way to increase the overall sustainability of new concrete. This has been hindered, however, by a general perception that RCA is a sub-standard material due to the lack of technical guidance, specifically related to long-term durability, on incorporating RCA into new concrete. The goal of this research project was to determine whether current testing methods could be used to assess the potential alkali-silica reactivity of concrete incorporating RCA. The test methods investigated were ASTM C1260 and ASTM C1567 for assessing natural aggregate susceptibility to alkali-silica reactivity (ASR), and the ability of supplementary cementitious materials (SCMs) to mitigate ASR, respectively. Seven different RCA sources were investigated. It was determined that ASTM C1260 was effective in detecting reactivity but expansion varied based on RCA processing. Depending on the aggregate type and the extent of processing, up to a 100% increase in expansion was observed. Replicate testing was performed at four university laboratories to evaluate repeatability and consistency of results. The authors recommend modification to the mixing and aggregate preparation procedures, when testing the reactivity of RCA using ASTM C 1260. This study also investigated the efficacy of replacing portland cement with supplementary cementitious materials (SCMs), known to mitigate alkali-silica reaction (ASR) in concrete with virgin aggregates, to control ASR in concrete incorporating reactive RCA. The SCMs investigated as part of this study included: fly ash (class F), silica fume, and metakaolin. The results of modified alkali-silica reactivity tests, ASTM C1260 and ASTM C1567 (AMBT), are presented for two different recycled concrete aggregates when using 100% portland cement, binary blends of portland cement and fly ash, and ternary blends of portland cement, fly ash and metakaolin or silica fume. The results indicate that SCMs can effectively mitigate ASR in concrete made with RCA. A 40% replacement of portland cement with class F fly ash was able to reduce expansions to below 0.10% in the AMBT for concrete containing 100% of a highly reactive recycled concrete aggregate. A ternary blend, however, of portland cement with a class F fly ash and metakaolin was most effective for both RCAs tested in this study. Higher levels of mitigation may be required for some RCAs, compared to the level required to mitigate ASR in concrete made with their original natural aggregates, depending on the age and composition of the RCA. / Graduation date: 2012
60

Comportamento do cimento álcali ativado em ambientes sulfatados / Behavior of alkali-activated cements in sulphated environments

Beltrame, Neusa Aparecida Munhak 29 September 2017 (has links)
O cimento Portland (CP) é um produto industrializado que não é só consumidor de energia e de matérias-primas, mas também responsável por grandes emissões de CO2. Além do impacto ambiental, a presença de alguns compostos hidratados que em contato com os sulfatos, produzem fases expansivas que reduzem a vida útil das estruturas. Adições minerais, como as escórias de alto-forno, têm sido adicionadas para reduzir o clínquer e aumentar a resistência aos sulfatos, porém nem todas as escórias conferem empregabilidade como adição devido a sua composição química. Cimentos com adições apresentam ganho de resistência muito lento nas primeiras idades, tornando-se desinteressante para a cadeia produtiva da construção civil. Assim, as limitações que o CP apresenta, somada ao aumento dos resíduos, incentivaram a busca por aglomerantes isentos de clínquer. A álcali ativação proporcionou a possibilidade de reaproveitamento de diversos subprodutos, pois a cinética de reação é similar ao CP, devido à semelhança química e liberação de calor. Pesquisas ligadas à durabilidade dos cimentos álcali ativados (CAT) ainda são bastante reduzidas, principalmente a eficácia dos métodos empregados para avaliação da resistência aos sulfatos em ambientais laboratoriais. Portanto, este trabalho teve como objetivo investigar o comportamento das pastas de escórias ativadas com 5% de NaOH e CP resistente a sulfatos (CPIV-RS) em ambientes sulfatados através do método NIST e comparar com o método acelerado em argamassas proposto pela NBR 13583:2014. As avaliações incluíram as análises microestruturais (DRX/MEV/DTG) e macroestrutural através de inspeções visuais, variação dimensional, variação de massa e resistência à compressão. Os resultados indicaram que nas condições ensaiadas, os métodos acelerados de avaliação da resistência aos sulfatos não apresentaram diferenças significativas entre as pastas e argamassas. Os CATs apresentaram desempenho superior antes e depois da exposição ao Na2SO4 comparados aos CPIV-RS, favorecendo a hidratação e a resistência à compressão. Por outro lado, a formação da gipsita parece ser o principal produto de degradação dos CATs na solução de MgSO4, originado pela descalcificação do C-S-H, afetando fortemente as propriedades físicas, químicas e mecânicas dos cimentos álcali ativados. / Portland cement (PC) is an industrialized product that is not so consuming of energy and raw materials, but also responsible for large CO2 emissions. Besides the environmental impact, the presence of some hydrated compounds that in contact with the sulfates, produce expansive phases that reduce the useful life of the structures. Minerals additions, such as blast furnace slag, have been added to reduce clinker and increase resistance to sulphates, but not all slags confer employability as addition because of their chemical composition. Cements with additions show very low resistance gain in the early ages, making it uninteresting for the productive chain of civil construction. Thus, the limitations that PC presents, together with the increase of residues, have encouraged the search for clinker-free binders. Alkali-activation provided the possibility of reuse of several by-products, because the reaction kinetics is similar to PC, due to chemical similarity and heat release. Researches related to the durability of alkaliactivated cements (AAC) are still very low, mainly the efficacy of the methods used to evaluate the resistance to sulfates in laboratory environments. Therefore, the objective of this work was to investigate the behavior of slag pastes activated with 5% NaOH and sulfate resistant PC (PCIV-SR) in sulphated environments using the NIST method and to compare with the accelerated mortar method proposed by NBR 13583:2014. The evaluations included microstructural analysis (XRD/SEM/DTG) and macrostructural analysis through visual inspection, dimensional variation, mass variation and compressive strength. The results indicated that under the conditions tested, the accelerated methods of sulfate resistance evaluation did not present significant differences between pastes and mortars. The AACs presented better performance before and after exposure to Na2SO4 compared to PCPIV-SR, favoring hydration and compressive strength. On the other hand, the formation of gypsum appears to be the main degradation product of the AACs in the MgSO4 solution, caused by the C-S-H decalcification, strongly affecting the physical, chemical and mechanical properties of the activated alkali cements.

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