Dissertations / Theses on the topic 'Pozzolanic Activity'

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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares
A destinação final ambientalmente adequada para os resíduos sólidos industriais é uma problemática que veio ganhando maior importância ao longo dos anos. O setor da construção civil consome grandes quantidades de insumos, gerando paralelamente grandes quantidades de resíduos. Quando o assunto é reciclagem de resíduos industriais, o setor da construção civil exerce um papel importante, reciclando resíduos de diversos setores da economia. Tendo em vista a existência do polo cerâmico no Rio Grande do Sul, e totalidade de resíduos de cerâmica vermelha (RCV) resultante desse polo, buscou-se através deste estudo, verificar qual é o percentual de geração de RCV em uma empresa específica, devido a grande variabilidade dos dados apresentados pela literatura. E em paralelo buscou-se avaliar o potencial pozolânico do RCV e comparar o seu desempenho com o metacaulim, material já consagrado como pozolana. Os aglomerantes (cimento CP II-F-32, Ca(OH)2 – P.A., CH-I) e os materiais pozolânicos (RCV e metacaulim) empregados na pesquisa foram caracterizados quimicamente por ensaios de fluorescência de raios X (FRX) e Perda ao Fogo (PF), mineralogicamente por ensaios de difração de raios X (DRX) e fisicamente por ensaios de, granulometria a laser, massa específica e área superficial específica (BET). Além disso, o RCV e o metacaulim foram submetidos a ensaios para determinação do teor de umidade e finura. Para avaliar a atividade pozolânica do RCV e comparar seu desempenho ao metacaulim foram realizados ensaios de condutividade elétrica, termogravimetria e ensaios de resistência à compressão, orientados pelas NBR 5752:2014, NBR 5751:2015 e NBR 15894:2010. Mediante os resultados obtidos, verificou-se que o percentual de geração de RCV na empresa objeto de estudo, com os ensaios de caracterização foi possível verificar que o RCV atende aos requisitos químicos estabelecidos pela NBR 12653:2014. O procedimento de moagem conferiu ao RCV uma granulometria adequada para uso como pozolona. Quanto a atividade pozolânica, verificou-se que o RCV atendeu ao requisito da NBR 12653:2014, no que diz respeito à resistência com o aglomerante Ca(OH)2 P.A., já quando ensaiado com o aglomerante CH-I, o RCV apresentou resistência à compressão consideravelmente superior ao metacaulim. Já nas argamassas moldadas com cimento, o RCV não atingiu o índice de atividade pozolânica (IAP) exigido na NBR 12653:2014, impedindo sua classificação como material pozolânico. Nas argamassas ensaiadas sob as prescrições da NBR 15894:2010, contendo 15% de substituição do cimento pelo RCV, os resultados de resistência à compressão não apresentaram diferenças significativas em relação às argamassas referência, apontando indícios de melhor desempenho em menores teores de substituição. As análises térmicas evidenciaram o consumo de Ca(OH)2 das pastas. As pastas formuladas com 25% de substituição do cimento por metacaulim apresentaram maior consumo de Ca(OH)2 em relação as pastas formuladas com 25% de RCV, evidenciando a atividade pozolânica dos materiais.
The final destination environmentally suitable for industrial solid waste is a problem that came gaining more importance over the years. The construction industry consumes large amounts of supplies, generating parallel large quantities of waste. When it comes to recycling of industrial waste, the construction sector plays an important role, recycling waste from various sectors of the economy. Considering the existence of the ceramic polo at the Rio Grande do Sul, and all red ceramic waste (RCV) resulting from this pole, we sought through this study, find what is the percentage of RCV generation in a specific company due the great variability of the data presented in the literature. And in parallel we sought to evaluate the potential of pozzolan RCV and compare their performance with metakaolin, material already recognized as pozzolan. The binder (cement CP II-F-32, Ca(OH)2 – P.A., CH-I) and pozzolanic materials (RCV and metakaolin) employed in the study were chemically characterized by X-ray fluorescence assays (XRF) and Loss Fire (PF), mineralogically by testing X-ray diffraction (XRD) and physically by tests of laser granulometry, specific gravity and specific surface area (BET). Furthermore, the RCV and metakaolin were subjected to tests for determination of humidity content and fineness. To evaluate the pozzolanic activity of the RCV and compare its performance to metakaolin were performed electrical conductivity tests, thermogravimetry and compressive strength tests, guided by the NBR 5752:2014, NBR 5751:2015 and NBR 15894:2010. From the results obtained, found to the percentage of RCV generation in study subject company with the characterization tests it was verified that the RCV meets chemical requirements of the NBR 12653:2014. The grinding procedure gave the RCV adequate particle size for use as pozolona. As the pozzolanic activity, it was found that the RCV met requirement the NBR 12653:2014 with regard to resistance to Ca(OH)2 P.A. agglomerating, since when tested with CH-I agglomerating, the RCV showed compression resistance the considerably higher than metakaolin. Already in the cast with cement mortar, the RCV has not reached the pozzolanic activity index (IAP) required in NBR 12653:2014 preventing classification as pozzolanic material. In mortars tested under the requirements of NBR 15894:2010, containing 15% replacement of cement by RCV, the compressive strength results showed no significant differences from the reference mortar, indicating better performance indications in lower replacement levels. The thermal analysis showed the consumption of Ca(OH)2 pastes. The pastes formulated with 25% of the cement replaced by metakaolin showed increased consumption of Ca(OH)2 relative pastes formulated with 25% RCV, showing the pozzolanic activity of the materials.

The extent of the benefits provided by use of SCMs in cementitious systems increases as their percentage amounts in total binder increases. However, the proportion of SCMs in cementitious systems is limited, especially for natural pozzolans, by some factors such as increase in water requirement and decrease in rate of strength development. Therefore investigations are needed to increase the amount of natural pozzolans in blended cements or in concrete as much as possible without decreasing their performance. This aim requires studies on cementitious systems with more reactive natural pozzolans than widely-used ones. The objective of the study was to investigate the pozzolanic activity of natural zeolites (clinoptilolite) from two localities in Turkey, and properties of cementitious systems containing low (15%), moderate (35%) and high (55%) amount of them. The study covers characterization of the natural zeolites used, evaluation of their pozzolanic activity in comparison with some popular mineral admixtures, and properties of pastes, mortars, and concrete mixtures containing low, moderate, and high amounts of natural zeolites. Reactivity of the natural zeolites with Ca(OH)2 was found to be higher than those of the fly ash and the non-zeolitic pozzolan, but lower than that of the silica fume. Natural zeolite blended cements were characterized with the following highlighted properties
faster setting than portland cement, low amounts of Ca(OH)2 and capillary pores larger than 50 nm in hardened pastes, relatively dense microstructure of hardened paste than portland cement, more compatibility with melamine-based superplasticizer than being with naphthalene-based one, and excellent compressive strength performance. Concrete mixtures containing natural zeolites as partial replacement for portland cement were characterized with the following properties
7-day compressive strength of ~25 MPa and 28-day strength of 45-50 MPa with only 180 kg/m3 portland cement and 220 kg/m3 zeolite dosages (55% replacement), comparable modulus of elasticity with plain portland cement concrete, &ldquo
low&rdquo
and &ldquo
very low&rdquo
chloride-ion penetrability for low and large levels of replacement, respectively.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Universidade Politecnica de Valencia- Espanha
O presente trabalho apresenta um método de produção de cinza de casca de arroz (CCA) altamente reativa e de coloração clara, bem como o seu comportamento em matrizes de cimento Portland com o intuito de avaliar a atividade pozolânica da CCA. O trabalho está dividido em quatro etapas, a saber: construção de um forno e produção da cinza de casca de arroz, caracterização físico-química da CCA, verificação da atividade pozolânica do material através de métodos instrumentais e, finalmente, ensaios mecânicos em argamassas de cimento Portland. O forno utilizado para a produção da cinza de casca de arroz não apresenta controle de temperatura e, o tempo de queima é bastante longo, aproximadamente 36 horas. Neste método obtém-se cerca de 1,5Kg de cinza por processo de queima. A cinza obtida apresenta uma coloração clara e o seu caráter amorfo foi determinado através de diferentes métodos: difração de Raio-X, determinação do teor de sílica amorfa, análise termogravimétrica, Microscopia Eletrônica de Varredura (MEV) e ensaios mecânicos em argamassas de cimento Portland. O programa experimental também abrange estudos de variação da finura da CCA e estudos com diferentes porcentagens, em substituição ao cimento Portland. Os resultados obtidos foram comparados...
This research show a method of production white amorphous Rice Husk Ash (RHA), therefore, the behaviour of RHA in Portland cement matrix to evaluate the pozzolanic activity of this material. The research can be shared in four steps, to know: construction of an oven and production of rice husk ash, physical-chemical analysis of the rice husk ash, evaluation of pozzolanic activity of the pozzolan though instrumental analysis and, finally, mechanical properties of Portland cement mortars. The oven used for production of rice husk ash didn't have a control of temperature and, the time of burning is so longer, approximately 36 hours. In this method is obtained for about 1,5Kg of ash. The obtained ash has white colour and its amorphous phase were determined though different methods: X-ray diffractometry, determination of amorphous silica, Termogravimetric Analysis (TA), scanning electron microscopy (SEM) and mechanical properties of Portland cement mortars. Besides that, the experimental procedure involves studies on fineness variation of rice husk ash and different degrees of Portland cement substitution. The obtained results were compared with silica fume, because this is the most similar pozzolanic material with rice husk ash. The RHA produced under this method can be used... (Complete abstract click electronic access below)

Orientador: Jorge Luis Akasaki
Banca: Marco Antonio Moraes Alcantara
Banca: Antônio Alberto Nepomuceno
Resumo: O presente trabalho apresenta um método de produção de cinza de casca de arroz (CCA) altamente reativa e de coloração clara, bem como o seu comportamento em matrizes de cimento Portland com o intuito de avaliar a atividade pozolânica da CCA. O trabalho está dividido em quatro etapas, a saber: construção de um forno e produção da cinza de casca de arroz, caracterização físico-química da CCA, verificação da atividade pozolânica do material através de métodos instrumentais e, finalmente, ensaios mecânicos em argamassas de cimento Portland. O forno utilizado para a produção da cinza de casca de arroz não apresenta controle de temperatura e, o tempo de queima é bastante longo, aproximadamente 36 horas. Neste método obtém-se cerca de 1,5Kg de cinza por processo de queima. A cinza obtida apresenta uma coloração clara e o seu caráter amorfo foi determinado através de diferentes métodos: difração de Raio-X, determinação do teor de sílica amorfa, análise termogravimétrica, Microscopia Eletrônica de Varredura (MEV) e ensaios mecânicos em argamassas de cimento Portland. O programa experimental também abrange estudos de variação da finura da CCA e estudos com diferentes porcentagens, em substituição ao cimento Portland. Os resultados obtidos foram comparados... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This research show a method of production white amorphous Rice Husk Ash (RHA), therefore, the behaviour of RHA in Portland cement matrix to evaluate the pozzolanic activity of this material. The research can be shared in four steps, to know: construction of an oven and production of rice husk ash, physical-chemical analysis of the rice husk ash, evaluation of pozzolanic activity of the pozzolan though instrumental analysis and, finally, mechanical properties of Portland cement mortars. The oven used for production of rice husk ash didn't have a control of temperature and, the time of burning is so longer, approximately 36 hours. In this method is obtained for about 1,5Kg of ash. The obtained ash has white colour and its amorphous phase were determined though different methods: X-ray diffractometry, determination of amorphous silica, Termogravimetric Analysis (TA), scanning electron microscopy (SEM) and mechanical properties of Portland cement mortars. Besides that, the experimental procedure involves studies on fineness variation of rice husk ash and different degrees of Portland cement substitution. The obtained results were compared with silica fume, because this is the most similar pozzolanic material with rice husk ash. The RHA produced under this method can be used... (Complete abstract click electronic access below)
Mestre

The doctoral thesis deals with the reactivity of burnt clays in connection with modified lime mortars. The theoretical part of the doctoral thesis provides an overview of the properties of lime mortars, their quality and ways of their degradation. The different types of burnt clays (brick powder, bentonites and burnt clay shale), their origin, properties and factors affecting their reactivity and methods of its evaluation are stated. The properties and reactivity of burnt clays are evaluated on the basis of determination of pozzolanic activity, mineralogical and chemical composition, surface area, density, content of the amorphous phase and granulometry in the experimental part of the doctoral thesis. The compositions of lime mortars containing burnt clays and evaluation of an impact of burnt clay on the properties of mortars in the fresh and hardened state are given. Consistency, bulk density, workability and air content of mortars in the fresh state are evaluated. Strength characteristics depending on the time, water absorbability, porosity, capillary attraction, adhesion, coefficient of diffusion resistance, frost resistance, shrinkage, mineralogical composition and microstructure of mortars in the hardened state are evaluated. Attention is also paid to the influence of the cellulose ether addition into the modified lime mortars.

L’incorporation de sous-produits agricoles ou de matériaux naturels dans la matrice cimentaire confère des propriétés intéressantes aux composites élaborés. L’objectif de cette thèse est d’élaborer un matériau pouvant répondre aux exigences mécaniques, thermiques et de durabilité des matériaux de construction en zone tropicale humide. Dans un premier temps, l’activité pouzzolanique d’une pouzzolane naturelle, de cendres de tronc de bambou et de cendres de bagasse de canne à sucre ont été évaluées. L’influence de leur incorporation a été ensuite étudiée sur les propriétés mécaniques et la durabilité des mortiers exposés à des ions chlorures et sulfates. Dans un second temps, l’influence de l’ajout de fibres de bagasse sur les propriétés thermiques et mécaniques des composites a été étudiée en fonction de différents paramètres (teneur en fibres, environnement de vieillissement, type de matrice cimentaire).Les résultats obtenus ont permis de montrer que les matériaux étudiés possèdent une activité pouzzolanique et qu’il est possible de les incorporer au ciment afin de lutter contre la corrosion. De plus, les composites élaborés avec des fibres de bagasse sont plus isolants que ceux élaborés sans fibres. Cependant, du point de vue des propriétés mécaniques, l’incorporation de fibres de bagasse diminue les contraintes à la flexion des composites
The incorporation of crop wastes or natural materials in the cement matrix confers interesting properties to composites prepared. The aim of this thesis is to develop a material that can reach the mechanical, thermal and durability requirements for building materials in the humid tropical zone. Firstly, pozzolanic activity of a natural pozzolan, bamboo stem and sugar cane bagasse ashes has been determined. Influence of their incorporation on mechanical properties and durability of mortars exposed to chloride and sulphate ions was studied. Secondly, influence of addition of bagasse fibers on thermal and mechanical properties of composites was studied as a function of various parameters (fibers content, curing, type of cement matrix).These results has shown that the materials studied have pozzolanic activity and it is possible to incorporate them into the cement to fight against corrosion. Moreover, composites elaborated with bagasse fibers are more insulating than those elaborated without fibers. However, from the viewpoint of mechanical properties, incorporation of bagasse fibers decreases flexural strength of composites in the present work and under the conditions producing procedures that were adopted

The corrosion of steel reinforcement is probably the most frequent type of degradation of reinforced concrete structures. Reinforcing bars are protected from corrosion by a thin iron oxide layer which is formed on their surface due to a high alkalinity of the surrounding concrete. Corrosion may start when this layer is destroyed (i) either by chloride ion penetration (when the concentration of dissolved chloride at the depth of the reinforcing steel exceeds a critical value) or (ii) by a reduction in the pH value of pore solution to values below 9.5. Such a reduction in alkalinity is the result of carbonation of the Ca(OH)2 in the concrete mass, i.e. of its reaction with the atmospheric CO2. The main aim of this work is an experimental investigation and modelling of carbonation process. The effect of relative humidity, curing period and replacement of Portland cement by supplementary cementing materials (SCM - fly ash, blast furnace slag and metakaolin) on carbonation process has been studied. Calcium hydroxide content in the presence of SCM and their pozzolanic activities have been also determined. Furthermore, lots of parametric studies and comparison of carbonation models have been provided. The software tools based on the introduced models and considering the input data to be statistically independent random variables have been described and used for other parametric studies.

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A incorporação de resíduos diversos dentro de seus processos produtivos tem sido uma tendência na construção civil, esse processo visa a diminuição dos custos de produção e da deposição de resíduos no meio ambiente, dentro desta ótica as cinzas vegetais tem sido bastante estudadas devido as suas possíveis propriedades pozolânica. Para este estudo foi utilizada a cinza do bagaço da cana-de-açúcar (CBCA) proveniente do estado de Pernambuco, esse material foi submetido a um processo de secagem em estufa a 100°C e um peneiramento para retirar matérias contaminantes como folhas, madeiras e outros. O material foi dividido em quatro partes e submetido a um processo de calcinação nas temperaturas de 300°C, 400°C, 500°C e 600°C e chamadas de CB 300, CB 400, CB 500 e CB 600, a parte do material que não passou por esse tratamento foi denominada de CAN. Posteriormente a CBCA passou por um peneiramento em peneiras de malha #200 e #400 e a moagem em um moinho de bolas e por fim essas amostras foram submetidas aos ensaios de caracterizações físicas (Área específica, BET (BrunauerEmmett-Teller) e Massa específica) e caracterização química (D.R.X. e termogravimetria) e ensaios de consistência e resistência a compressão. A existência de atividade pozolânica foi testada através dos ensaios de D.R.X. e resistência a compressão segundo as normas da ABNT NBR 5751 (2012). No ensaios químicos (D.R.X.) ficou constatada a possível existência de atividade pozolânica do material estudado apenas nas cinzas moídas a sete horas, no ensaio de resistência a compressão apenas as cinzas moídas a sete horas apresentaram desempenho satisfatório. O estudo mostrou a importância do processo de moagem do material e de como o mesmo influencia na atividade pozolânica, já o processo de calcinação teve resultados abaixo do esperado principalmente nas temperaturas a partir de 500°C, já que as amostras apresentaram resultados melhores nas temperaturas de 300°C e 400°C.
The incorporation of various waste in their production processes has been a trend in the construction industry, this process is aimed at reducing production costs and waste disposal on the environment, within this perspective plant ash has been widely studied because of its potential pozzolanic properties. For this study we used sugar cane bagasse ashes (CBCA) from the state of Pernambuco, this material was subjected to a drying process in oven at 100 ° C and sieving to remove contaminating materials such as leaves, wood and others. The material was divided into four parts and subjected to a calcination process at temperatures of 300 ° C, 400 ° C, 500 ° C and 600 ° C and calls CB300, BC400, BC500 and BC600, the portion of the material which has not undergone this treatment was designated CAN. Subsequently the CBCA passed a sieve of sieve mesh # 200 and # 400 and grinding in a ball mill and finally the samples were subjected to physical characterization assays (specific surface area, BET (Brunauer-EmmettTeller) and Mass specific) and chemical (DRX and thermogravimetry) and consistency tests and compressive strength. The existence of pozzolanic activity was tested by the D.R.X. tests, thermogravimetry and compressive strength according to ABNT NBR 5751 (2012). In chemical assays (XRD and thermogravimetric analysis) was found to contain the reactivity of the material studied compared to pozzolan reference metakaolin (TCM), as compared to compressive strength testing only the ash grinded to seven hours (M7H) showed satisfactory performance. The study showed the importance of the process of grinding the material and how the same influence on the pozzolanic activity, since the calcination process results below mainly expected at temperatures from 500 ° C, since the samples showed better results in temperatures 300 ° C and 400 ° C.

Natural pozzolanic materials played an important role in Ancient architecture. In the last decades and nowadays it is artifical pozzolan which especially finds its use as an additive to mortar and concrete to improve some, especially the mechanical properties. This master thesis deals with study of pozzolan type of fine brick powder which is a by-product of the production of calibrated bricks. Along with studying pozzolanic activity of brick powder, lime mortar with different proportions of brick powder as an additive or replacement of lime dust are investigated. What is observed is its impact on the consistency of these mortar, water absorption, strength in time or fracture-mechanical parameters of mortar. The results may indicate the possible potential use of this source of pozzolanic admixture in lime mortar and plaster which are nowadays mainly used for the restoration of facades of historic buildings.

Orientador: Jorge Luís Akasaki
Resumo: Nos últimos anos, tem havido um crescente interesse em substituir parcialmente ou totalmente o uso do cimento Portland por materiais com baixo impacto ambiental; logo o estudo de aglomerantes ativados alcalinamente obtidos a partir da mistura de um precursor sólido, rico em aluminossilicato, e uma solução alcalina de alta concentração, tem se mostrado uma alternativa viável, uma vez que o consumo de energia e a emissão de CO2 durante a produção dessas matrizes são reduzidas, e ainda, ocorre a possibilidade de inserção de subprodutos agroindustriais, na matriz desses aglomerantes. Assim a presente tese apresenta um estudo de viabilidade do uso da cinza do bagaço de cana-de-açúcar (CBC), subproduto da indústria sucroalcooleira, na produção de aglomerantes ativados alcalinamente. A CBC foi obtida a partir da queima não controlada do bagaço de cana-de-açúcar e apresentou uma composição química predominantemente constituída de dióxido de silício. A cinza foi submetida a ensaios de caracterização física e química, de modo a avaliar a viabilidade do uso da cinza na produção de matrizes ativadas. Os ensaios de caracterização e de reatividade indicaram que a cinza apresenta grande parte da sua sílica no estado cristalino, além de apresentar baixa solubilidade e reatividade pozolânica. Porém, os ensaios térmicos e mecânicos das argamassas e pastas produzidas com a CBC, demostraram que, a CBC apresenta boa reatividade para períodos de cura prolongados, possibilitando o seu uso em matriz... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In recent years, there has been a growing interest in partially or totally replacing the use of Portland cement with materials with low environmental impact; Therefore, the study of alkaline activated binders obtained from the mixture of an aluminosilicate rich solid precursor and a high concentration alkaline solution, proved to be a viable alternative since energy consumption and CO2 emission during production of these matrices are reduced, and also, there is the possibility of insertion of agroindustrial byproducts in the matrix of these binders. Thus, this thesis presents a viability study of the sugarcane bagasse ash (SCBA) use, a by-product of the sugar and alcohol industry, in the production of alkaline activated binders. The SCBA was obtained from the uncontrolled calcination of the sugarcane bagasse and presented a chemical composition predominantly constituted of silicon dioxide. The ash was physically and chemically characterized, in order to assess the viability of the ash use in the production of activated matrices. Characterization and reactivity analysis indicated that ash presents a great part of its silica in the crystalline state, low solubility and pozzolanic reactivity. However, the thermal and mechanical analysis of mortars and pastes produced with SCBA showed that ash presented good reactivity for long curing periods, allowing its use in Portland cement matrices and activated matrices. Two types of systems were analyzed in the activated matrices studies:... (Complete abstract click electronic access below)
Doutor

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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Com o objetivo de reduzir a geração de resíduos nos processos industriais e agrícolas, bem como melhor reaproveitá-los, seja no próprio processo produtivo ou como matéria-prima na elaboração de outros materiais, tem-se cada vez mais investido em pesquisas para a transformação destes, até então considerados apenas resíduos industriais, em produtos de interesse comercial. Neste sentido, as cascas residuais oriundas do processo de beneficiamento de arroz vêm sendo utilizadas como combustível, visando ao aproveitamento energético. Mediante a queima da casca de arroz é gerada a cinza de casca de arroz composta basicamente de sílica, potencializando o uso deste resíduo em diferentes segmentos industriais. Muitos trabalhos aplicam a cinza de casca de arroz na construção civil, visto que grande parte dessas cinzas apresenta características pozolânicas decorrente da alta concentração de sílica amorfa presente no material. Pesquisas têm demonstrado que estas cinzas também apresentam potencialidade de aplicação como material adsorvente. No entanto, a cinza de casca de arroz apresenta-se, muitas vezes, como um material heterogêneo tanto na sua composição granulométrica quanto na sua composição química. Estas características podem interferir nas aplicações limitando seu aproveitamento. A segregação dos resíduos é uma técnica amplamente aplicada no gerenciamento de resíduos sólidos industriais e pode oportunizar a reciclagem dos materiais segregados. Neste contexto, este trabalho tem como proposta principal contribuir para a valorização do resíduo cinza de casca de arroz como co-produto através da etapa de segregação. Foi estudada a influência da segregação da cinza da casca de arroz nas características fisicoquímicas, bem como no seu desempenho como material pozolânico e adsorvente. As amostras e as frações segregadas foram caracterizadas através de parâmetros físicos (perda ao fogo, massa específica, área superficial, distribuição granulométrica) parâmetros químicos (análise química, difração de raio-X) e parâmetros microestruturais (microscopia eletrônica de varredura com espectro de dispersão de energia-EDS). A atividade pozolânica foi determinada após moagem das amostras e das frações através de ensaios de Pozolanicidade com o cimento e Condutividade Elétrica. Os ensaios de adsorção foram realizados com soluções de Cr(VI). O cromo residual foi quantificado pelo método colorimétrico da 1,5- difenilcarbazida. Resultados obtidos demonstraram que a segregação configura-se numa etapa importante, pois remove impurezas e contaminantes presentes na amostra, bem como origina frações diferentes, evidenciadas nos ensaios de caracterização. Nos ensaios de atividade pozolânica, observou-se que a influência da segregação relaciona-se com o tipo de processo de combustão aplicado para a obtenção da cinza. Nos ensaios de adsorção, observou-se que a segregação influenciou na remoção de cromo hexavalente. O estudo demonstrou, nas condições testadas, a viabilidade do uso de cinza de casca de arroz na adsorção do metal quando ajustados os parâmetros do processo que favoreçam a remoção dos íons de cromo.
The main objective for the industry is to reduce the generation of wastes, or to find better uses to them, such as in the own productive process or as raw material in the elaboration of other materials. Also, a great amount of funds has been invested in researches for the transformation of such wastes, in by-products of commercial interest. In this way, the rice husk from the rice processing have been used as combustible, for producing energy. Rice husk ashes are generated from the rice husk burning, which presents a potential to be used as raw material in the production of several products in different industry sectors. Most of the works apply the rice husk ash in civil construction, because a great part of those ashes present pozzolanic characteristics as a result of their amorphous chemical structure and the high silica content. In fact, between other factors, the pozzolanicity of rice husk ash depends on the thermal process applied to the rice husk during burning. Researches have been demonstrating that the ashes also may be potentiality applied as adsorbent. However, the rice husk ash comes, many times, as a heterogeneous material so much in your particle size distribution as in your chemical composition. These characteristics can interfere in the applications limiting your use. The segregation of the wastes is thoroughly a technique applied in the administration of industrial solid waste and it can guarantee the recycle of the segregated materials. This work has as main objective to contribute for the valorization of the waste rice husk ash as coproduct through the segregation stage. It was studied the influence of the segregation of the rice husk ash, in physical-chemical characteristics, as well as your acting as pozzolanic and adsorbent. The samples and segregated fractions were characterized via physical (fire loss, specific gravity, specific surface area, particle size distribution), chemical (chemical analysis, X Ray diffraction) and microstructural parameters (scanning electronic microscopy with energy dispersion spectroscopy – EDS). The pozzolanic activity was determined after grinding the samples and the fractions via Cement pozzolanic and Electric Conductivity Methods. The adsorption rehearsals were accomplished with Cr(VI) solutions, that was quantified by the colorimeter method using 1,5-difenilcarbazida. Results demonstrated that the segregation became an important step, because removes impurities and contaminants from the samples and also originates fractions with different characteristics. It was observed, in pozzolanic activity, that the influence of the segregation links with the type of applied combustion process for the obtaining of the ash. It was observed, in adsorption rehearsals, that the segregation influenced in the removal of chromium (VI). Adsorption results showed, considering the experimental conditions in this work, the viability of the use of rice husk ash in the adsorption of chromium (VI) when adjusted the process’s parameters that guarantee the removal of chromium.

This diploma thesis mainly tracks the effect of grinding technology on the final properties of portland cement and selected pozzolanic materials. For grinding of portland cement, was also observed the effect of storage time on the final mechanical properties and hydratation process. Pozzolan activity of selected materials was monitored by evaluation of the reaction with CaO by differential thermal analysis.

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Cementing operation is one of the most important stages in the oil well drilling processes and has main function to form hydraulic seal between the various permeable zones traversed by the well. However, several problems may occur with the cement sheath, either during primary cementing or during the well production period. Cements low resistance can cause fissures in the cement sheath and compromise the mechanical integrity of the annular, resulting in contamination of groundwater and producing zones. Several researches show that biomass ash, in particular, those generated by the sugarcane industry have pozzolanic activity and can be added in the composition of the cementing slurries in diverse applications, providing improvements in mechanical properties, revenue and cement durability. Due to the importance of a low cost additive that increases the mechanical properties in a well cementing operations, this study aimed to potentiate the use of sugarcane bagasse ash as pozzolanic material, evaluate the mechanisms of action of this one on cement pastes properties and apply this material in systems slurries aimed to cementing a well with 800 m depth and geothermal gradient of 1.7 ?F/100 ft, as much primary cementing operations as squeeze. To do this, the ash beneficiation methods were realized through the processes of grinding, sifting and reburning (calcination) and then characterization by X-ray fluorescence, XRD, TG / DTG, specific surface area, particle size distribution by laser diffraction and mass specific. Moreover, the ash pozzolanic activity added to the cement at concentrations of 0%, 20% and 40% BWOC was evaluated by pozzolanic activity index with lime and with Portland cement. The evaluation of the pozzolanic activity by XRD, TG / DTG and compressive strength confirmed the ash reactivity and indicated that the addition of 20% in the composition of cement slurries produces improvement 34% in the mechanical properties of the slurry cured. Cement slurries properties evaluated by rheological measurements, fluid loss, free fluid, slurry sedimentation, thickening time and sonic strength (UCA) were satisfactory and showed the viability of using the sugarcane ash in cement slurries composition for well cementing
A opera??o de cimenta??o ? uma das etapas mais importantes no processo de perfura??o de po?os de petr?leo e tem a fun??o primordial de promover a veda??o hidr?ulica entre as diversas zonas perme?veis atravessadas pelo po?o. No entanto, v?rios problemas podem ocorrer com a bainha de cimento, seja durante a cimenta??o prim?ria ou no decorrer do per?odo produtivo do po?o. Cimentos de baixa resist?ncia podem causar trincas na bainha de cimento e comprometer a integridade mec?nica do anular, resultando em contamina??o de len??is fre?ticos e zonas produtoras. V?rias pesquisas comprovam que cinzas de biomassa, em particular, as geradas pela ind?stria sucroalcooleira apresentam atividade pozol?nica e podem ser adicionadas na composi??o das pastas cimentantes em diversas aplica??es, proporcionando benef?cios nas propriedades mec?nicas, no rendimento e na durabilidade do cimento. Dada a import?ncia de um aditivo de baixo custo e que aumenta as propriedades mec?nicas em uma opera??o de cimenta??o de po?os, este trabalho objetivou potencializar o uso da cinza de biomassa da cana-de-a??car (CBCC) como material pozol?nico, avaliar os mecanismos de atua??o desta nas propriedades de pastas de cimento e aplicar este material em sistemas de pastas destinadas ? cimenta??o de um po?o com 800 m de profundidade e gradiente geot?rmico de 1,7 ?F/100 p?s, tanto para as opera??es de cimenta??o prim?ria quanto corretiva (squeeze). Para isso, foram realizados m?todos de beneficiamento da cinza atrav?s dos processos de moagem, peneiramento e requeima (calcina??o) e, em seguida, a caracteriza??o por fluoresc?ncia de raios-X, DRX, TG/DTG, superf?cie espec?fica, granulometria a laser e massa espec?fica. Al?m disso, a atividade pozol?nica da cinza, adicionada ao cimento nas concentra??es de 0% (pasta padr?o), 20% e 40% BWOC, foi avaliada pelo ?ndice da atividade pozol?nica com a cal e com o cimento Portland. A avalia??o da atividade pozol?nica atrav?s das an?lises de DRX, TG/DTG e resist?ncia ? compress?o comprovaram a reatividade do material e indicaram que a adi??o de 20% de cinza na composi??o das pastas produz melhorias em at? 34% das propriedades mec?nicas da pasta endurecida. As propriedades das pastas avaliadas atrav?s dos ensaios de propriedades reol?gicas, perda de filtrado, ?gua livre, estabilidade, tempo de espessamento e resist?ncia ? compress?o (UCA) mostraram-se satisfat?rias e indicaram a viabilidade da utiliza??o da cinza na composi??o das pastas de cimento para po?os de petr?leo

Professional Doctorate - Doctor of Philosophy (PhD)
This thesis presented the results of investigations on single and two stage mineral carbonation processes (using heat activated serpentine as feed stock) aimed at producing reactive materials as cement substitutes from mineral carbonation by-products. This study examined the effect of different sample preparation techniques (wet grinding, wet sieving, and heat activation), single and two stage carbonation processes at laboratory and pilot scale and cement substitution studies at a commercial cement manufacturer R&D facility. Chemical and physical characterisation of feed and by-product samples were performed employing a variety of analytical techniques including Thermal Gravimetric Analysis Mass Spectrometry (TGA-MS), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICPAES), Qualitative and semi-quantitative Powder X-ray diffraction (XRD), Malvern Mastersizer PSD analyser, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Surface area and porosity measurement (BET), Fourier-Transform Infrared Spectroscopy (FTIR), Transmission Electronic Microscopy (TEM),29Si Solid State Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) and Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS). Undesired side reactions occurring during single stage aqueous mineral carbonation process using heat activated serpentine (antigorite and lizardite) were investigated. It was found that when heat activated antigorite was used as feed, crystalline serpentine and a silica-rich passivating layer were formed on the surface of reacting particles. In contrast, when using heat activated lizardite as feed, crystalline serpentine was absent and a silica-rich passivating layer was the only undesired side product formed during the carbonation process. These findings disclosed a possible explanation for the relatively low magnesite yields often observed in the aqueous mineral carbonation process using heat activated serpentine as feed. Quiescent soaking of heat activated lizardite under aqueous conditions at ambient temperature and pressure was found to be a very simple and promising approach to increase magnesite yields of single stage carbonation process. Results showed that soaking produced coral shaped nano-structure on the surface of heat activated lizardite. The coral-shaped nanostructure was found to be an amorphous magnesium silicate hydroxide phase with 1:1 mole ratio of magnesium and silicon, which is suggested to be formed in a dissolution/precipitation process. By-products of single and two stage mineral carbonation processes using heat activated lizardite were characterised, to investigate their potentials as cement substitutes. It was found that all samples contained at least 40 wt% of an amorphous silica phase. Experiments were performed to increase the concentration of amorphous silica by magnesium extraction in two stage and acid treatment processes. Treating the solid residue of the two stage process with nitric acid was effective in the quantitative extraction of magnesium and produced a very reactive silica product. The experimental data obtained from a 30 L pilot batch reactor, used for single stage aqueous carbonation and for the dissolution of heat activated lizardite was compared to laboratory scale data obtained under similar reaction conditions. The results of aqueous carbonation experiments in the pilot and the laboratory scale reactors showed less than 5% scatter in repeat experiments. Results indicated that the magnesite yield obtained in the pilot batch reactor were 35±2% higher than that produced in the laboratory scale reactor. The higher yield was attributed to improved mixing and in consequence, removal of passivating phases from the surface of the reacting particles in the pilot reactor compared to the laboratory reactor. The yield of magnesite in mineral carbonation experiments using distilled water and tap water were almost identical. Undertaking reaction in 1 M NaCl solution did not have a significant effect, but adding 0.64 M sodium bicarbonate had a notable effect on magnesite yield. Regrinding of the solid residue remaining after dissolution stage of two stage process and performing a second dissolution step resulted in a 50% increase in the amount of magnesium extracted. The feasibility of utilising feed and by-products of mineral carbonation technology as cement substitutes was investigated. These materials, with and without pre-treatment, were used to substitute 5, 10 and 20 wt% of Portland cement in mortars. Pozzolanic activity tests indicated that acid treated silica-enriched residue from two stage process displayed pozzolanic activity. At 5 wt% cement replacement, all materials showed compressive strengths comparable to the control. When 10 wt% of cement was replaced, only heat activated lizardite showed strength results similar to the control. The compressive strength of mortars containing other samples with 10 wt% or greater cement replacement showed that the extra water demand outweighed any pozzolanic contribution of mineral carbonation materials and resulted in lowering the compressive strength of these mortars compared to controls. Therefore our study showed that replacing up to 5 wt% of Portland cement with mineral carbonation by-products was feasible.