Dissertations / Theses: 'Alumina cement'

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Ding, Jian. "Conversion prevention in high alumina cement products." Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/9683.

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Mechanisms of stratlingite (C$\rm\sb2ASH\sb8)$ formation in the high alumina cement (HAC)--siliceous material--water systems were investigated. Different siliceous materials, e.g. natural zeolites, silica fume, fly ash, ground granulated blast-furnace slag, and different sodium salts, e.g. sodium silicate, sodium sulfate, etc. were employed. Reactions between CAH$\sb $ or C$\rm\sb2AH\sb8$ and dissolved silica occur. Acceleration of the silica dissolution by addition of chemical admixtures promoted the formation of stratlingite. A method for prevention of strength reduction of HAC products due to the conversion of thermodynamically unstable hexagonal calcium aluminates to cubic hydrogarnet is described. New conversion-preventing additives (CPA) to inhibit hydrogarnet formation in HAC products are described. Compressive strength development of HAC mortars containing the CPA additive was studied. The effect of curing conditions on strength development was also investigated. No strength reduction occurs for the HAC/CPA mortar water-cured at 38$\sp\circ$C. Stratlingite preferentially formed in the HAC paste containing the CPA additive. Durability of inhibited HAC products is also studied. Conversion inhibited high alumina cement binders have excellent characteristics for corrosion protection of reinforcement under severe test conditions. The HAC/CPA mortar can effectively resist the penetration of chloride ions. (Abstract shortened by UMI.)

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Baker, Nina Crampton. "High alumina cement in the marine environment." Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316529.

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Zamri, Diyana. "Biogenic and chemical corrosion of calcium aluminate cement in sour media." Thesis, The University of Sydney, 2012. http://hdl.handle.net/2123/19260.

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Gill, Susan Margaret. "The effect of superplasticising admixtures on the performance of ciment fondu." Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279745.

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Kawamura, Mirian Akiko. "Evolução microestrutural de cerâmicas porosas moldáveis à base de alumina e ligadas com cimento de aluminato de cálcio (CAC) e alumina hidratável (AH) durante aquecimento inicial até 1500°C." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-12032018-103724/.

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Cerâmicas porosas encontram um vasto campo de aplicações tecnológicas, tais como isolantes térmicos em equipamentos siderúrgicos, filtros de fluidos em altas temperaturas e biomateriais. A obtenção dessas estruturas por meio de moldagem direta de suspensões aquosas é uma interessante técnica de conformação, pois, peças com geometrias complexas e de grandes volumes podem ser produzidas. Neste caso, a consolidação ocorre, geralmente, pela ação de um ligante hidráulico, cuja função é garantir níveis mínimos de resistência mecânica à verde. Em sistemas refratários, os ligantes mais utilizados são o cimento de aluminato de cálcio (CAC) e alumina hidratável (AH), devido à alta refratariedade e custos competitivos destes materiais. Nas estruturas porosas à base de alumina, particularmente, eles podem proporcionar valores distintos de porosidade e diferentes tipos de microestruturas. Este trabalho teve como objetivo entender como o CAC e a AH interagem com a alumina. Foram avaliados a evolução microestrutural e os efeitos do teor (10 até 40% em volume de ligante hidráulico) e do tamanho das partículas da matriz (alumina fina e grossa) nas amostras à verde e durante o aquecimento inicial até 1500°C. De modo geral, maiores volumes de ligantes permitiram a obtenção de estruturas à verde mais rígidas e resistentes, porém menos porosas. Além da porosidade total (PT), as microestruturas decorrentes das transformações de fases cristalinas ou amorfas também influenciaram os resultados mecânicos. No caso do CAC, as fases formadas durante as reações in situ ajudaram a melhorar as propriedades mecânicas das amostras, mesmo que acompanhado por um acréscimo em porosidade. Em proporções estequiométricas, os cristais de hexaluminato de cálcio (CA6) formados após tratamento a 1500°C inibiram a densificação, ajudando na manutenção da PT (36,7-46,5%), ainda com boa resistência (acima de 20 MPa em compressão diametral). Nos sistemas ligados com AH, observou-se grandes perdas em propriedades mecânicas antes da sinterização, as quais foram relacionadas ao aumento de densidade real dos precipitados do ligante e à perda de conexão entre as partículas da matriz. Em altas temperaturas, os precipitados de AH auxiliaram a sinterização e garantiram a obtenção de peças porosas quando se utilizou alumina grossa (PT: 44,3-47,7%).
Porous ceramics have a wide range of technological applications, such as thermal insulation in steelmaking furnaces, filter for high temperature fluids and as biomaterials. Obtaining these structures through the direct casting of aqueous suspensions is an interesting conformation method since pieces with complex geometries and large volumes can be produced. In this case, the consolidation usually occurs by the action of a hydraulic binder, which provides the minimum levels of mechanical strength in green samples. In refractory systems, the most used binders are calcium aluminate cement (CAC) and hydratable alumina (HA), due to the high refractoriness and competitive costs of these materials. Particularly, in porous alumina-based structures, they can provide distinct values of porosity and different types of microstructures. The purpose of the present work is to understand how CAC and HA interact with alumina. The effects of the binder content (from 10 up to 40% in volume) and the particle size of the matrix (fine and coarse) during initial heating up to 1500°C were studied. In general, larger volumes of binders provided green samples with less porosity but higher mechanical strength. Besides total porosity (TP), the microstructures generated from the transformations of crystalline or amorphous phases also influenced the mechanical results. In the case of CAC, the phases formed by in situ reactions improved the mechanical properties of the samples, despite the increase in porosity. In stoichiometric proportions, the crystals of calcium hexaluminate (CA6) formed after treatment at 1500°C inhibited the densification, favoring to maintain total porosity (36.7-46.5%), even with acceptable mechanical properties (above 20 MPa under diametric compression). In HA-bonded systems, before the sintering begins, a decrease in mechanical properties was noted and related to the increase in density of the precipitates and loss of connection between the matrix particles. At high temperature, the precipitates from HA aided the sintering and guaranteed porous samples in coarse alumina composition (TP: 44.3- 47.7%).

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Alireza, S., K. N. Fatemeh, and S. Hossein. "Improving thermo-mechanical properties of tabular alumina castables via using nano structured colloidal silica." Thesis, Sumy State University, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20571.

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Great attempts were made to reduce the amount of calcium aluminate cement (CAC) content in refractory castables to improve their hot strength. Using more than 2-3 wt% CAC may cause low melting phases formation in the refractory matrix leading to weak thermo-mechanical propereties of the castables. Colloidal Silica can affect the structure of refractory castables to achieve superior thermo mechanical properties. Replacing calcium aluminate cement (CAC) by colloidal silica as a water base binder, speeds up drying, reduces the amount of liquid phase at high temperatures and may lead to mullite formation, which will increase the hot strength of the refractory castables. In this research, the influence of colloidal silica addition on bulk density, apparent porosity and HMOR of a tabular alumina based refractory castable containing have been studied. The results showed that samples containing colloidal silica have higher hot strength compared to those containing only CAC as binder due to the better compaction, less liquid phase formation at high temperature. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20571

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Schmidt, Heinrich. "X-ray diffraction study of high temperature reaction products in the barium oxide-silica-alumina-ferric oxide system." Thesis, Pretoria : [s.n.], 2001. http://upetd.up.ac.za/thesis/available/etd-03072007-132505.

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Souza, Alexandre Luiz de. "Determinação simultânia de Cd/Pb em cimento usando TI como padrão interno e de Cr/Mn em alumina por espectrometria de absorção atômica com amostragem de suspensão." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-19102007-105035/.

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O objetivo desse trabalho foi o desenvolvimento de métodos analíticos para a determinação simultânea de Cd/Pb em cimento e Cr/Mn em alumina por espectrometria de absorção atômica com atomização eletrotérmica (SIMAAS) e amostragem de suspensão. Considerando os erros de amostragem de suspensão e as condições compromissadas impostas para a determinação simultânea, foi também objetivo do trabalho estudar a aplicação de padrão interno para corrigir erros sistemático e aleatório. A viabilidade de se usar o Tl como padrão interno foi explorada na determinação de Cd e Pb em cimento. O uso do padrão interno se baseou na hipótese de que o elemento Tl deveria adsorver quantitativamente sobre as partículas do material em suspensão. Foi feito o estudo térmico dos elementos Cd, Pb e Tl em soluções aquosas e suspensões, na presença e ausência de diferentes modificadores químicos. O melhor modificador químico (5 µg Pd + 3 µg Mg) foi escolhido com base nos gráficos de correlação. As melhores temperaturas de pirólise e atomização para a determinação simultânea de Cd e Pb foram 600°C e 2000°C, respectivamente. A preparação das amostras foi feita com suspensões contendo 30 µg L-1 de Tl em 0,1 % (v v-1) de HNO3 + 0,025 % (m v-1) de Triton X-100. A avaliação da exatidão foi feita com a determinação de Cd e Pb em cimento de construção civil e dentário com análise de solução e análise de materiais de referência de sedimento marinho (MESS1 e BCSS 1) e de rio (Buffalo River, IEAEA 356). Os resultados foram concordantes em um nível de confiança de 95% (teste t-student). Os limites de detecção (LD) obtidos foram 0,14 µg L-1 (1,4pg) para o Cd e de 1,2 µg L-1 (12 pg) para Pb. As massas características foram 1,2 pg e 25 pg para Cd e Pb, respectivamente. Na determinação simultânea de Cr e Mn em alumina não foi utilizado padrão interno. O estudo envolveu a obtenção de curvas de pirólise e atomização em presença de diferentes modificadores. Estudos de interferência mostraram que 100 mg L-1 de Al provocaram aumento nos sinais analíticos dos elementos que foi eliminado com o modificador químico NaOH (0,2 mol L-1) + HF (0,4 mol L-1) combinado com 350 µg de Nb. Nessa condição as temperaturas de pirólise e atomização foram 1400°C e 2400°C, respectivamente. As suspensões de alumina foram preparadas em 2 % (v v-1) HNO3. A avaliação da exatidão foi feita com a determinação de Cr e Mn em material de referência de alumina (Alumina Reduction Grade - 699) e os resultados foram concordantes em um nível de confiança de 95% (teste t-student). Os limites de detecção (LD), estimados a partir da variabilidade de 20 medidas consecutivas de uma solução contendo 2 % (v v-1) HNO3 foram 0,11 µg L-1 (2,2 pg) para Cr e 0,17 µg L-1 (3,5 pg) para o Mn. As massas características foram 10 pg e 1,3 pg para Cr e Mn, respectivamente.
The aim of this work was the development of analytical methods for the simultaneous determination of Cd/Pb in cement and Cr/Mn in alumina by electrothermal atomic absorption spectrometry (SIMAAS) and slurry sampling. Considering the errors of slurry sampling and the imposed compromissed conditions for the simultaneous determination, it was also the aiming of this work to study the application of internal standard for the sistematic and random errors correction. The viability of using Tl as internal standard was investigated for Cd and Pb determination in cement. The internal standard aplicability was based on the hypothesis of the element Tl would have to adsorver quantitatively on the particles of the material in suspension. The thermal behaviour of Cd, Pb and Tl in aqueous solutions and suspensions was obtained in presence and absence of different chemical modifiers. The best chemical modifier (5 mg Pd + 3 mg Mg) was chosen based on correlation graphs. The pyrolysis and atomization temperatures for the simultaneous determination of Pb were 600°C and 2000°C, respectively. The sample the preparation was made with 30 mg L-1 of Tl in 0,1% (v v-1) of HNO3 + 0.025% (m v-1 of Triton X-100. The evaluation of the accuracy was made with the determination of Cd and Pb in cement, microwave extraction in acid media and analysis of marine sediment reference materials (MESS1 and BCSS 1) and river sediment (Buffalo River, IEAEA 356). The results are concordant at 95% of confidence level using Studen\'s t-test. The detention limits (LD) was 0.14 µg L-1 (1.4 pg) for Cd and 1.2 µg L-1(12 pg) for Pb. The characteristic masses were 1.2 pg and 25 pg for Cd and Pb, respectively. The simultaneous determination of Cr and Mn in alumina was done without internal standard. Pyrolysis and atomization temperaturas were obtained in presence of different modifiers. Studies of interference shown that 100 mg L-1 of Al provoked increase in the analytical signals of Cr and Mn that was eliminated with the chemical modifier NaOH (0,2 mol L-1) + HF (0,4 mol L-1) combined with 350 mg of Nb as permanent chemical modifier. In this condition pyrolysis and atomization temperatures were 1400 °C and 2400 °C, respectively. The alumina suspensions were prepared in 2% (v v-1) HNO3. The evaluation of the accuracy was made with the determination of Cr and Mn in alumina reference material (Reduction Alumina Grating - 699) and the results were concordant at 95 % of the confidence level using Student\'s t-test. The detention limits (LD) were 0.11 µg L-1 (2.2 pg) for Cr and 0.17 µg L-1 (3.5 pg) for Mn. The characteristic masses were 10 and 1.3 pg for Cr and Mn, respectively.

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Fridrich, Jakub. "Cihelný recyklát jako surovina pro výrobu pálících pomůcek pro cihlářský průmysl." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401935.

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The focus of this thesis is the study of behavior of brick waste in the mixture with high alumina cement. The result of this research should be a draft of a composition and production process for material that could partly or fully substitute forging accessories in the brick production industry. The aim of this work is to verify the use of brick waste for such purpose. Usage of brick waste for refractories can help the current long-term effort for wasteless production processes.

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Carvalho, Renato Savi de. "Efeito de um agente primer e de ciclos térmicos para cocção de porcelana na resistência de união adesiva entre alumina e cimento resinoso." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/25/25131/tde-05112009-104837/.

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Coroas cerâmicas apoiadas sobre infra-estruturas de alumina densamente sinterizada configuram-se como excelentes opções para a reabilitação protética em casos de exigência estética, contudo, o aumento do conteúdo cristalino inviabiliza seu condicionamento por ácidos deixando a maneira ideal de cimentá-las ainda desconhecida. Coroas Procera AllCeram apresentam, em sua face interna, micro irregularidades interessantes ao embricamento e adesão resinosa, dispensando manobras de condicionamento. Objetivo: O objetivo deste trabalho foi avaliar a influência de elevadas temperaturas (500ºC à 950ºC) necessárias à cocção da porcelana de revestimento, na textura superficial da alumina, bem como o papel de um agente primer (Ivoclar Vivadent) na força de adesão entre alumina e cimento resinoso. Material e métodos: Sessenta (60) cilindros de alumina (3,5mm X 16mm) com rugosidade superficial idêntica à dos copings Procera foram divididos em quatro grupos (n=15). Grupo 1): Espécimes não submetidos a variação térmica, sendo G1a Sem aplicação do primer e G1b Com aplicação do primer e Grupo 2): Espécimes submetidos aos ciclos térmicos para cocção da porcelana feldspática, sendo G2a Sem aplicação do primer e G2b Com aplicação do primer. Sobre os cilindros aplicou-se porção do cimento resinoso químico MultiLink Ivoclar. Os espécimes foram levados a uma máquina de ensaios Universal para teste de cisalhamento a uma velocidade de 0.5mm/min e os dados submetidos à análise de variância a um critério e teste de comparações múltiplas de Tukey. Resultados: A força de adesão para cada um dos grupos foi: G1a = 2.468 MPa; G1b = 4.265 MPa; G2a = 2.339MPa e G2b = 4.185 MPa. Diferenças significantes foram observadas entre os grupos: G1a X G1b; G1a X G2b; G1b X G2a e G2a X G2b. Conclusões: Ciclos térmicos não produziram alterações na micro-estrutura superficial da alumina, tampouco comprometeram sua adesão ao cimento. O agente primer aumentou a força de união entre alumina e cimento resinoso. Fraturas coesivas do agente cimentante foram observadas apenas em alguns espécimes primer-tratados.
High-strength alumina based ceramic crowns are widely used in dentistry due to their favorable esthetic, however, the large amount of crystalline contents jeopardizes their acid etching property and the ideal luting remains unclear. Procera AllCeram restorations exhibits on their intaglio surface micro irregularities optimizing the bonding to resin, with no need for additional conditioning procedures. Purpose: The aim of the present study was to evaluate the influence of high thermal cycles (500ºC to 950ºC) needed to porcelain firing on alumina´s intaglio surface, as well as, the role of a primer agent (Ivoclar Vivadent) on shear bond strength between alumina and resin cement. Material and Methods: Sixty alumina cylinders (3,5mm X 16mm) with intaglio roughness of the Procera AllCeram copings were randomly divided into four groups (n=15). Group 1) Samples no submitted to thermal cycles variation, were G1a - no primer application and G1b - primer treated and Group 2: Samples submitted to thermal feldspathic porcelain firing cycles, were G2a - specimens no primer treated and G2b - primer treated specimens. Over the cylinders top a self-cure resin cement (Multilink Ivoclar) portion was applied. The specimens were loaded to failure in shear mode using a universal testing machine at a crosshead speed of 0,5mm/min. Data were analyzed with one-way analysis of variance and Tukey´s multiple comparison test. Results: The shear bond strength for each group was: G1a = 2.468 MPa; G1b = 4.265 MPa; G2a = 2.339 MPa e G2b = 4.185 MPa. Significant difference was found between the groups G1a X G1b; G1a X G2b; G1b X G2a e G2a X G2b. Conclusions: Thermal cycles did not change alumina´s surface micro structure, besides did not compromised it´s bonding strength to resin cement. Primer agent enhanced shear bond strength between alumina and resin cement. Luting agent´s cohesive fractures were observed only in some primer treated specimens.

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Souza, Alexandre Luiz de. "Estudo de métodos visando à análise direta de alumina, cimento e quartzo em ICP OES." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-13102011-085326/.

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O objetivo deste estudo foi avaliar parâmetros para o desenvolvimento de métodos visando à determinação elementar em alumina, cimento e quartzo por espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES) com amostragem de suspensão. Alguns elementos foram investigados como possíveis candidatos a padrões internos (PIs) Be, Dy, Gd, In, La, Sc, Y, Yb eTl. Amostras de material de referência certificado (CRM) de alumina (Alumina Reduction Grade 699), de cimento Portland (1889a Blended with Limestone e 1886a White Portland cement with low iron) do National Institute of Standard and Technology (NIST), e amostras de quartzo, cedidos pelo Departamento de Física da Universidade Federal de São Carlos (UFSCar), denominados T-4FI, T-2FI e T-4GR, foram utilizadas na otimização instrumental, no desenvolvimento e na avaliação da exatidão do método. Nanopartículas de sílica de alta pureza (Wacker HDK® T40), Wacker Chemie AG foram utilizadas no estudo de adsorção dos elementos e padrões internos como proposta de produção de material calibrante para a análise direta de sólidos. Para a escolha dos PIs foram construídos gráficos de correlação usando valores de potenciais de excitação, energias de ionização e temperaturas de fusão dos analitos e dos candidatos a PIs. Análise exploratória por agrupamentos hierárquicos (HCA) e análise dos componentes principais (PCA), também foram realizadas. A avaliação de desempenho do ICP OES foi feita em meio das suspensões das amostras a partir do estabelecimento de figuras de mérito como sensibilidade, robustez, seletividade e repetibilidade. Na otimização do foram considerados os parâmetros potência, vazão de nebulização e vazão de gás auxiliar. A determinação de Ca, Fe, Ga, Na, Si e Zn em alumina foi feita após dissolução em forno de micro-ondas com posterior precipitação do Al(III) com NH3. O uso de padrão interno foi essencial para a exatidão do método, com recuperações do CRM que variaram de 83 a 117%. Para a matriz cimento foram avaliados o efeito da concentração de ácido nítrico na extração dos analitos ( Al, Ca, Cr, Fe, K, Mg, Mn, Na, P, S, Si, Sr, Ti e Zn) e na adsorção dos elementos candidatos a PIs (Be, Sc, In, Dy). As determinações por suspensão e uso de padrão interno (exceto para Cr, S e Zn), com 0,5% v v-1 de HNO3, nebulizador Burgener e condições robustas do ICP geraram resultados com recuperações entre 68 e 119%. As determinações de Al, Ba, Cr, Fe, K, Li, Mg, Na, Sr e Ti em quartzo foram executadas com introdução de suspensão e ausência de padrão interno, usando condições do ICP similares àquelas adotadas na determinação elementar para matriz de cimento. Nesse caso as recuperações variaram de 90 a 107%. A adsorção dos analitos e padrões internos sobre as nanopartículas de sílica pode ser uma alternativa para a preparação de padrões de calibração quando se deseja realizar a introdução direta do material sólido em suspensão.
The aim of this study was to evaluate parameters for the development of methods for elements determination in alumina, cement and quartz by inductively coupled plasma optical emission spectrometry (ICP OES) with slurry sampling. Some elements were investigated as candidates for internal standards (ISs) Be, Dy, Gd, In, La, Sc, Y, Yb and Tl. Samples of certified reference material (CRM) of alumina (Alumina Reduction Grade - 699), Portland cement (blended with the 1889a and 1886a Limestone White Portland cement with low iron) from the National Institute of Standards and Technology (NIST), and quartz samples, suplied by the Department of Physics from Federal University of São Carlos (UFSCar), named T-4FI, T-2FI and T4GR were used to optimize instrumental, method development and accuracy evaluation of the method. Nanoparticles of high purity silica (Wacker HDK T40 ®), Wacker Chemie AG were used in the study adsorption of the analytes and internal standards as calibrating material for direct analysis of solids. Correlation graphs using excitation potentials, ionization energies and melting point temperatures were used for chosing the best ISs. Exploratory analysis using hierarchical cluster analysis (HCA) and principal component analysis (PCA) were also performed. Optimization of ICP OES was performed in aqueous and slurry samples to establishment figures of merit, such as sensitivity, robustness, selectivity and repeatability. In the optimization of ICP, power supply, nebulizer flow rate and auxiliary gas flow rate were considered. The determination of Ca, Fe, Ga, In, Si and Zn in alumina was made after decomposition in a microwave oven with subsequent precipitation of Al(III) with NH3 gas. The internal standard was essential to obtain the accuracy of the method, with recoveries of CRM analysis ranging from 83 to 117%. For the cement analysis was evaluated the effect of nitric acid concentration over analytes extraction (Al, Ca, Cr, Fe, K, Mg, Mn, Na, P, S, Si, Sr, Ti and Zn) and ISs candidate adsorption (Be, Sc, In and Dy). Determinations of the elements in cement slurry with the internal standard (except for Cr and Zn), with 0.5% v v-1 HNO3, nebulizer Burgener and robust conditions of ICP produced results with recoveries between 68 and 119%. The determinations of Al, Ba, Cr, Fe, K, Li, Mg, Na, Sr and Ti in quartz were performed with the slurry introduction and without of internal standard, using similar conditions of those adopted for cement matrix. In this case the recoveries ranged from 90 to 107% with addition and recovery test. The adsorption of the analytes and internal standards on silica nanoparticles could be an alternative for the preparation of calibration standards when considering performing the direct introduction of solid material.

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Solik, Jaroslav. "Možnosti využití slévárenských odprachů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-216871.

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This thesis explores the posibility of using of foundry filter ash for production of inorganic composite materials, that could be used primary in the construction industry. The thesis is divided into theoretical and experimental section, where theoretical section contain literature review of used materials and the experimental section summarizes the results of laboratory tests performed on tested mixture based on portland and alumina cement with various content of foundry filter ash. For comparison was also used another foundry waste - foundry sand. Prepared test bodies with dimension of 40 x 40x 160 mm was subjected to mechanical strength tests and the influence of amount of foundry waste on the strenght of the prepared mixtures was monitored. Next the thesis deals with possibilities of alkaline activation of foundry waste, where sodium water glass, sodium hydroxide and commercially supplied baucis L 160 component B were used as alkaline activator. These test mixtures were also subjected to mechanical strenght tests and the influence of amount of foundry waste on the strenght was observed too. The analysis of input materials were performed by XRF, TG – DTA – EGA and XRD powder diffraction methods. All strength tests were tested by testing equipment desttest 4310.

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Hywel-Evans, Paul Duncan. "The hydration of calcium sulpho aluminate cement." Thesis, Staffordshire University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320692.

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Payne, David Robert. "Mineralogical changes during the hydration and firing of refractory calcium aluminate cements." Thesis, University of Sheffield, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311975.

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Chavda, Mehul. "Phosphate-modified calcium aluminate cements." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/15402/.

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The effect of phosphate modification on CAC hydration is poorly understood, and the investigation in this thesis focuses on the sodium phosphate modification of a commercially available calcium aluminate cement, examining the following : (i) the effect of modification upon the fresh state properties, (ii) long-term phase evolution, (iii) binding phase characterisation, and (iv) trials of aluminium encapsulation. Formulations of CAC modified by sodium polyphosphate, sodium monophosphate and mixtures of these, in varying proportions, are investigated. ATR-FTIR and solution NMR are used to examine the chain length of phosphate ions in solution prior to mixing. Immediately after mixing the fresh state properties are investigated using isothermal calorimetry, to assess the effect of average phosphate chain length on the heat of hydration and thermal behaviour of pastes during the initial curing period. The phase assemblage over the long term is examined by XRD and TGA up to a period of 180 days, elucidating trends in hydration behaviour with phosphate modification. This focuses upon assessment of the degree of conversion, identifying phosphate modifications which prolong the presence of metastable CAC hydrates for up to 180 days and also formulations that prevent any conventional phases forming at all and hence avoid conversion. Promising formulations with no conventional CAC hydrate formations are studied up to a period of 1050 days to confirm the longer-term stability of the alternate hydrates being formed. Characterisation of these samples after hydrothermal treatment showed the formation of hydroxyapatite, boehmite and a zeolite type phase. The disordered binding phase of this system is further investigated using solid-state nuclear magnetic resonance (NMR) to probe the environments of the 31P and 27Al nuclei. Results from advanced REAPDOR NMR experiments, used to assess the interactions between these nuclei, are reported and confirm the presence of a disordered C-A-P-H type binding phase. i Results from trials of aluminium encapsulation are also reported, where corrosion is assessed by hydrogen evolution evaluation using mass spectroscopy and water displacement, differential scanning calorimetry, scanning electron microscopy, and mass loss measurements. Promising formulations with phosphate modification outperformed the neat CAC encapsulants in all experiments performed, considering both powder and plate aluminium. The series of formulations with polyphosphate to cement mass ratio of 0.4 are recommended for further investigation as waste encapsulants. It was determined from the results of this study that altering the average phosphate ion chain length in solution prior to mixing can be used as a tool to tune the fresh state properties, including the heat of hydration and setting time. The kinetics of long term hydration and phase assemblage development maybe affected with the addition of sodium monophosphate, and radically altered away from conventional CAC hydration and instead the formation of an x-ray amorphous binding phase. This binding phase, optimal formulations, is shown to be stable in to a minimum of 1050 days with elevated compressive strength. NMR spectroscopy is used to positively verify the binding phase to be a calcium aluminium phosphate hydrate phase. Optimised phosphate modified CAC formulations are shown to outperform other conventionally used cementitious encapsulants, including OPC, OPC/BFS and neat CAC.

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Morejón, Alonso Loreley. "Avaliação de cimentos ósseos de fosfato de cálcio com adições de aluminato e silicato de cálcio." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/32003.

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O aumento da longevidade da população mundial e dos acidentes com consequências traumáticas nas últimas décadas provocaram um incremento na demanda de materiais e tecnologias destinados à substituição de alguma função ou porção do organismo humano para assegurar a qualidade de vida do ser humano. Neste contexto, o desenvolvimento de novos biomateriais para a ortopedia e odontologia baseados nos fosfatos de cálcio é relevante, uma vez que estes apresentam composição química semelhante à fase mineral de ossos e dentes. Os cimentos de fosfatos de cálcio (CPC) possuem composição de fases cristalinas e resposta biológica similares às biocerâmicas de fosfato de cálcio utilizadas como material de implante por excelência devido à sua alta biocompatibilidade e excelente bioatividade; mas com a diferença de que estes podem ser facilmente moldados e adaptados ao local de implantação, injetados através de vias minimamente invasivas, ou misturados com diversos fármacos para obter uma ação terapêutica determinada e localizada no local de implantação. Em geral, tanto as biocerâmicas como os CPC apresentam baixas resistências mecânicas, pelo qual o objetivo principal deste trabalho foi a obtenção de novas formulações de CPC com propriedades mecânicas melhoradas mediante a adição de componentes de cimento Portland tradicional ou de cimento de aluminato de cálcio. Outras propriedades que se pretende melhorar com a adição de compostos portadores de silício são a bioatividade e osteogenicidade dos materiais resultantes, uma vez que os cimentos baseados em silicato de cálcio são altamente osteogênicos. Para isto, foi escolhido o sistema baseado em a-Ca3(PO4)2 e foram desenhadas diferentes formulações através da introdução de Ca3SiO5 (C3S) ou CaAl2O4 (CA), fases majoritárias dos cimentos Portland e cimentos de aluminato de cálcio que apresentam uma excelente resistência mecânica, além de ser biocompatíveis e bioativas. Do estudo realizado verificou-se que a adição de um 5% de C3S ao cimento baseado em a- Ca3(PO4)2 produz um incremento das propriedades mecânicas em longo prazo (14d) e melhora a bioatividade e citotoxicidade dos CPC tradicionais; no entanto, retarda a pega do cimento e a hidrólise do a-Ca3(PO4)2 e aumenta a o grau de degradação dos materiais. A introdução de SiO2 como modificação de esta formulação, embora diminuiu o pH resultante, retardou a pega do cimento provocando uma perda notável da resistência mecânica durante os primeiros estágios da reação. Por outro lado, a introdução de CA provocou uma diminuição da resistência à compressão dos cimentos, independente do teor adicionado, e não se observou a melhoria desta propriedade com o aumento do tempo. Contudo, a presença de CA permitiu a obtenção de materiais menos citotóxicos, e por consiguiente mais biocompatíves, assim como o aumento da bioatividade em relação aos CPC tradicionais.
The increased longevity of the world population and the growth of traumatic accidents in last decades, led to an increase in demand of materials and technologies for replacement of any portion or function of the human body to ensure the quality of human life. In this context, the development of new biomaterials for orthopedics and dentistry based on calcium phosphates is relevant, since they have similar chemical composition to the mineral phase of bones and teeth. The calcium phosphate cements (CPC) have composition of crystalline phases and biological response similar to calcium phosphate bioceramics used as implant material par excellence due to its high biocompatibility and excellent bioactivity; but with the difference that these can be easily shaped and adapted to the site, injected through minimally invasive means, or mixed with various drugs for a specific therapeutic action at the site of implantation. In general, both bioceramics such as CPC have low mechanical strength; whereby, the main objective of this study was to obtain new formulations of CPC with improved mechanical properties by adding components of traditional Portland cement or calcium aluminate cement. Other properties that are intended to improve with the addition of silicon compounds, are the bioactivity and osteogenic potential of the resulting materials, as it cements based on calcium silicate are highly osteogenic. For this, we chose a system based a-Ca3(PO4)2 and different formulations were designed by introducing Ca3SiO5 (C3S) or CaAl2O4 (CA), majority phases of Portland cement and calcium aluminate cements that have an excellent mechanical strength, and are biocompatible and bioactive. From the study it was found that the adittion of a 5% C3S to the a-Ca3(PO4)2 based cement, produces an increase in the mechanical properties in the long term (14d) and enhances bioactivity and cytotoxicity; however, enlarge the setting times and the degree of degradation ofaand hydrolysis of materials. The introduction of SiO2 as a modification of this formulation, resulted in a pH decreased, but in the increased of the setting times causing a noticeable loss of strength during the early stages of the reaction. Moreover, the introduction of CA reduced the compressive strength of cements, regardless of content added, and there was no improvement of this property with increasing time. However, the presence of CA allowed the production of materials less cytotoxic, and thereby to more biocompatible, as well as the increase in bioactivity relative to traditional CPC.

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Kraft, Lars. "Calcium Aluminate based Cement as Dental Restorative Materials." Doctoral thesis, Uppsala University, Department of Materials Science, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3070.

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This thesis presents the results from the development process of a ceramic dental filling material based on calcium aluminate cement. The main focus of the work concerns dimensional changes during setting, hardening and curing and the understanding of the factors controlling the dimensional stability of the system. A range of compositions for research purposes and the composition of Doxadent™ – a dental product launched on the Swedish market in October 2000 – were evaluated. Furthermore hardness characteristics, flexural strength, porosity and microstructure studies are presented. The studies of dimensional changes led to a thorough investigation of the measuring devices used and their relevance. A split pin expander technique, very simple in function, has been evaluated and improved. The technique is considered to be adequate for detecting dimensional stability in restrained samples, thus mimicking the case for real fillings in most tooth cavities. The dimensional changes in the calcium-aluminate based cement system are mainly controlled by the grain size, the exact composition and the compaction degree. The expansion of the calcium-aluminate cement system was in the early work decreased from several percent down to only tenths of a percent. Results show that Doxadent™ has less than 0.2% in linear expansion after 200 days of storage in water. However, long-term tests have been unable to verify whether expansion stops with time. Long-term in-vitro studies of dimensional changes also affect the test equipment used, which is why the long-term behavior of the dimensional stability has to be clinically evaluated. The material integrates excellently with the tooth structure, has hardness and thermal properties similar to those of enamel and dentine, and is also biocompatible during hardening. A patented process for the preparation of wet compacted specimens was also developed.

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Vávrová, Alžběta. "Příprava modifikovaných trikalciumaluminátových fází a studium jejich hydratačních procesů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401853.

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This diploma thesis deals with the preparation of modified tricalcium aluminate phases using sodium ions, and the study of their hydration processes and products. The X-ray diffraction analysis, isothermal calorimetry, laser diffraction, and scanning electron microscopy with energy dispersion analysis were used to solve this task. The preparation of modified tricalcium aluminate phases using high temperature methods has been described in the experimental section. Furthermore, the X-ray diffraction analysis was used to determine the purity of the prepared phases and the scanning electron microscopy with energy dispersion analysis was used to define the volume of sodium. Laser diffraction was used to measure a particle size distribution in the individual phases. Subsequently, hydration of the pure phases was performed in an isothermal calorimeter. It was followed by hydration of phases in the presence of different gypsum content and then in the presence of saturated portlandite solution. Hydration of some samples was stopped in order to better understand the hydration process. Hydration products were studied by X-ray diffraction analysis. The obtained results were compared with each other and the influence of sodium ions on both the structure of the prepared phases and the course of hydration and its products has been discussed. The effect of adding different volumes of gypsum and portlandite on the course of hydration of the individual phases was also compared.

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19

Morel, Bayram Murat. "Investigation Of The Effects Of Temperature On Physical And Mechanical Properties Of Monolithic Refractory Made With Pozzolanic Materials." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606700/index.pdf.

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In recent years, scientific studies are carried out to find new refractory material. Having good mechanical properties under very high temperatures, refractories are widely used in industries like iron, steel, glass, cement and pottery. Researches are focused on monolithic refractory making because of their superior properties comparing to conventional firebrick refractories. Providing a mono-block body, having no joints makes the monolithic refractories more durable at elevated temperatures. Easier production and installation are two main points that people are choosing monolithic refractories, thus an economy is made. In this study, for monolithic refractory production, high alumina cement was used as binding material. It is known that the increase in alumina (Al2O3) content increases the high temperature resistance, so that crushed firebrick, having 85% Al2O3 was used as aggregate. Pozzolanic materials, which are silica fume, fly ash, ground granulated firebrick and ground granulated blast furnace slag, were added to improve physical and mechanical properties of mortar. With the addition of steel fibres, change in compressive strength and flexural strength was observed.Superplasticizer was used to understand its behaviour under high temperatures. Portland cement containing mortars were also prepared to make comparison with high alumina cement containing specimens. Specimens were prepared in 5x5x5 cm and 4x4x16 cm prisms. They were cured for one day at curing room, then heated to 105°
C and then heated to 1100°
C. Weight, size and ultrasound velocity change, compressive strength and flexural strength tests were done to determine physical and mechanical properties of the monolithic refractories, before and after heating. Heated and non-heated specimens were pulverized for microstructural investigation with X-Ray diffraction (XRD) method. Using high alumina cement with 50 &ndash
60 % granulated blast furnace slag or granulated firebrick, by the weight of cement, and crushed firebrick as aggregate, a satisfactory monolithic refractory material was made. It was observed that, mechanical properties were decreased at the Portland cement used mortars after several times of heating and cooling cycles. Also, it was determined that the microstructure of the high alumina cement containing mortars did not deteriorate much at 1100°
C, as long as there was no change observed from the results.

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20

Kocián, Karel. "Příprava a průběh hydratace pojivového systému na bázi stroncium aluminátového cementu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2015. http://www.nusl.cz/ntk/nusl-217145.

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This diploma thesis deals with non-traditional binder, which is strontium aluminate, with his preparation and hydration. The behaviour of binary and ternary mixtures of strontium-calcium-barium aluminates was also studied. These aluminates were prepared by firing an equimolar mixture of aluminum oxide and the appropriate carbonate. Samples prepared this way, including their mixtures, were characterized by analytical methods such as X-ray diffraction analysis (XRD), thermal analysis with evolved gas analysis (TG-DTA and EGA), scanning electron microscopy (SEM), infrared spectroscopy (IR) and calorimetry, with the greatest importance for the study of the hydration process.

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21

Kirca, Onder. "Temperature Effect On Calcium Aluminate Cement Based Composite Binders." Phd thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607454/index.pdf.

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In calcium aluminate cement (CAC) systems the hydration process is different than portland cement (PC) systems. The hydration products of CAC are subjected to conversion depending on temperature, moisture, water-cement ratio, cement content, etc. Consequently, strength of CAC system can be seriously reduced. However, presence of other inorganic binders or additives may alter the hydration process and improve various properties of CAC based composites. The objective of this study is to investigate the temperature effect on the behaviour of CAC based composite binders. Throughout this research, several combinations of CAC-PC, CAC-gypsum, CAC-lime, CAC-ground granulated blast furnace slag (CAC-GGBFS) were studied. These CAC based composite binders were subjected to seven different curing regimes and their strength developments were investigated up to 210 days. In addition, the mechanism of strength development was examined by XRD analyses performed at 28 and 210 days. Finally, some empirical relationships between strength-time-curing temperatures were formulated. Experimental results revealed that the increase in ambient temperature resulted in an increase in the rate of conversion, thereby causing drastic strength reduction, particularly in pure CAC mix. It has been observed that inclusion of small amount of PC, lime, and gypsum in CAC did not induce conversion-free CAC binary systems, rather they resulted in faster conversion by enabling rapid formation of stable C3AH6 instead of metastable, high strength inducing CAH10 and C2AH8. On the other hand, in CAC-GGBFS mixes, the formation of stable straetlingite (C2ASH8) instead of calcium aluminate hydrates hindered the conversion reactions. Therefore, CAC-GGBFS mixes, where GGBFS ratio was over 40%, did not exhibit strength loss due to conversion reactions that occurred in pure CAC systems.

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22

Houghton, Sarah Justine. "Hydration and durability of calcium aluminate cements." Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/8639.

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23

Sindhunata. "A conceptual model of geopolymerisation /." Connect to thesis, 2006. http://repository.unimelb.edu.au/10187/1561.

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24

Sunnegårdh-Grönberg, Karin. "Calcium aluminate cement as dental restorative : Mechanical properties and clinical durability." Doctoral thesis, Umeå universitet, Tandhygienistprogrammet, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-270.

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In 1995, the Swedish government recommended the discontinuation of amalgam as restorative in paediatric dentistry. Because the mercury content in amalgam constitutes an environmental hazard, its use has declined. The use of resin composites is increasing, but the polymerisation shrinkage of the material is still undesirably high, and the handling of uncured resin can cause contact dermatitis. A new restorative material has recently been developed in Sweden as an alternative to amalgam and resin composite: a calcium aluminate cement (CAC). CAC has been marketed as a ceramic direct restorative for posterior restorations (class I, II) and for class V restorations. This thesis evaluates mechanical properties and clinical durability of the calcium aluminate cement when used for class II restorations. Hardness, in vitro wear, flexural strength, flexural modulus, and surface roughness were evaluated. A scanning electron replica method was used for evaluation of the interfacial adaptation to tooth structures in vivo. The durability was studied in a 2-year intra-individually clinical follow-up of class II restorations. Major results and conclusions from the studies are as follows: • The CAC was a relatively hard material, harder than resin-modified glass ionomer cement but within the range of resin composites. The CAC wore less than resin-modified glass ionomer cement but more than resin composite. • Flexural strength of CAC was in the same range as that of zinc phosphate cement and far below that of both resin composite and resin-modified glass ionomer cement. Flexural modulus of CAC was higher than both resin composite and resin-modified glass ionomer cement. The low flexural strength of CAC precludes its use in stress-bearing areas. • Surface roughness of CAC could be decreased by several polishing techniques. • For CAC restorations, interfacial adaptation was higher to dentin but lower to enamel compared with resin composite restorations. Fractures were found perpendicular to the boarders of all CAC restorations and may indicate expansion of the material. • After 2 years of clinical service, the class II CAC restorations showed an unacceptably high failure rate. Material fractures and tooth fractures were the main reasons for failure.

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Sunnegårdh-Grönberg, Karin. "Calcium aluminate cement as dental restorative : mechanical properties and clinical durability /." Umeå : Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-270.

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26

Swift, Paul David. "The development of calcium aluminate phosphate cement for radioactive waste encapsulation." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/5782/.

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Reactive metals such as aluminium metal make up a significant proportion of the UK’s legacy radioactive waste. Current treatment methods – encapsulation in PC-based cementitious systems – do not perform optimally when applied to reactive metals. Corrosion of encapsulated aluminium, caused by the availability of free-water and highly alkaline pore solution, results in expansive corrosion products and the generation of significant quantities of hydrogen gas, which compromises the long-term performance of waste packages. Calcium Aluminate Phosphate cements (CAP), formed from acid-base reaction between Calcium Aluminate Cements (CAC) and an acidic phosphate-based solution, were identified as alternative encapsulants that provide different internal chemistry i.e. pore solution of lower pH which may be advantageous when applied to the encapsulation of reactive metals. Various types of phosphates, monophosphates and polyphosphates, were assessed to identify suitable pre-cursor materials for producing a cementitious matrix when mixed with CAC, and a CAP formulation envelope suitable for the industry-defined processing and operational property requirements, was identified. The corrosion behaviour of aluminium encapsulated in the CAP system was characterised by a dormant period, during which the corrosion and gas generation rates were very low, and a significant increase after the dormant period. The phase evolution of the CAP system altered not only the physico-mechanical properties of the system in longer-term but was also responsible for the latent corrosion behaviour of aluminium encapsulated in the CAP system.

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27

Šot, František. "Výzkum vlastností materiálů pro použití ve vysokoteplotním solárním tepelně-akumulačním zásobníku." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-390284.

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The use of thermal storage energy, using phase change materials appears to be an effective way to store thermal energy storage with the benefits of the high amount of energy while maintaining isothermal nature of the process. PCM methods are used in latent thermal storage systems for heat pumps, as well as in solar engineering or for temperature control in spacecraft. The past decade has extended these principles for cooling and heating in the building. There are a number of PCM systems, which operate over a wide temperature range, are used in various applications. This document includes a brief overview of the development and analysis of available thermal storage working mainly on the principle of PCM.

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Torrens, Martí David. "Mezclas ternarias de cemento Portland, cemento de aluminato de calcio y sulfato cálcico : mecanismos de expansión." Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/134926.

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Portland cement is the most widely used building material. Is mainly composed of silicates, also has lesser proportion of aluminates and calcium sulfate. Its hydraulic nature generates in its hydration, the formation of new phases which provide properties (hardness, resistance...) very useful in the field of construction. Calcium aluminate cement is mainly composed of aluminate. Present a faster setting and resistance development higher than Portland cement. Its hydration provides different phases depending of the temperature. This fact provides conversion reactions with a volume decrease causing a resistance decrease. For generate a new properties or improve some of them, exist a wide range binders materials formed for one o few cements with diverse additions. The different combinations provide a variation in the hydrated phases produced which generate changes in the mechanical properties of binders materials. Ternary systems formed by CP/CAC/CS, have been used to produce mixtures with different setting and hardened properties than separately cements. However, within of building materials, the applications of these systems are limited at insides due to durability problems. This work studies the Portland cement rich zone within of ternary systems. Noting the hydrated phases formation, in special ettringite and relationship with dimensional variations which be produced. Generally is observed which an increase in the ettringite formation provides a higher dimensional variation. Ettringite formation is function of CP/CAC and CAC/CS ratios. The amount of aluminates and sulfates control the formation of this phase, if the sulfate present do not consumed all aluminates, these reacts with the ettringite to form monosulfoaluminate decreasing the expansion. In the contrary the amount of sulfate is high the ettringite formation higher and provides higher dimensional variation, that percentages up to 5% generates fissures. Also was verified that environmental of cured have influence in the dimensional variation. Samples with the same cement proportion and calcium sulfate have a different variation. When are cured at air be produced retraction, but when is cured under water be produced expansion. This fact may due at differences in the interlayer of the C‐S‐H, being more voluminous in the samples submerged per the inclusion of water molecules.
El cemento Portland es el material constructivo más usado. Está compuesto principalmente por silicatos, también tiene en menor proporción aluminatos y sulfato cálcico. Su naturaleza hidráulica, genera que en su hidratación se formen nuevas fases que proporcionan propiedades (endurecimiento, resistencia...) muy útiles en el campo de la construcción. El cemento de aluminato de calcio está compuesto principalmente por aluminatos. Presenta un fraguado más rápido y un desarrollo de resistencias mayores que un cemento Portland. Su hidratación proporciona diferentes fases dependiendo de la temperatura a la que ocurra. Este hecho produce ciertas reacciones de conversión con una disminución del volumen provocando una disminución de las resistencias. Con el fin de generar nuevas propiedades o mejorar alguna de ellas, existe un gran número de materiales compuestos formados por uno o varios cementos con diversas adiciones. Las diferentes combinaciones de materiales, producen una variación en la producción de las fases hidratadas que conllevan cambios en las propiedades mecánicas de los materiales compuestos. Los sistemas ternarios formados por CP/CAC/CS, se han venido usando para producir mezclas con propiedades de fraguado y endurecimiento diferentes a los que presentan los cementos constituyentes por separado. La demanda de este tipo de productos se ha visto incrementada, debido a la necesidad de una rápida puesta en servicio de ciertos sistemas constructivos. No obstante, dentro de los materiales de construcción sus aplicaciones, se han limitado a interiores debido a ciertos problemas de durabilidad. En este trabajo se estudia la zona rica en cemento Portland dentro de los sistemas ternarios. Observando la formación de fases hidratadas, en especial la etringita y relacionándolas con las variaciones dimensionales que se producen. De forma general se observa que un incremento en la formación de etringita produce una mayor variación dimensional. La formación de etringita es función de las relaciones CP/CAC y CAC/CS. El contenido de aluminatos y sulfatos rige la formación de esta fase, si los sulfatos presentes no consumen todos los aluminatos, estos reaccionan con la etringita para formar monosulfoaluminato disminuyendo la expansión. Pero si el contenido en sulfato es alto la formación de etringita aumenta provocando grandes variaciones dimensionales, que para porcentajes superiores al 5% provocan fisuras llegando a la destrucción de probetas si se sube en exceso. Así se comprobó que el medio de curado también influye en la variación dimensional que se produce. Muestras con las mismas proporciones de cementos y sulfato cálcico sufren variaciones diferentes. Cuando se curan al aire se produce retracción, pero cuando se curan bajo agua se produce expansión. Esto se puede deber a diferencias en la intercapa del gel C‐S‐H desarrollado, siendo más voluminoso en las muestras sumergidas por la inclusión de moléculas de agua.
El ciment Portland és el material constructiu més usat. Està compost principalment per silicats, també té en menor proporció aluminats i sulfat càlcic. La seva naturalesa hidràulica genera que a la seva hidratació es formin noves fases que proporcionen propietats (enduriment, resistència...) molt útils en el camp de la construcció. El ciment d’aluminat de calci es composa principalment per aluminats. Presenta un fraguat mes ràpid i un desenvolupament de resistències majors que el ciment Portland. La seva hidratació proporciona diferents fases depenent de la temperatura a la que es produeixi. Aquest fet produeix certes reaccions de conversió amb una disminució del volum provocant una disminució de les resistències. Amb la finalitat de generar noves propietats o millorar alguna d’elles, existeix un gran nombre de materials compostos formats per un o més ciments amb diversos afegits. Les diferents combinacions de materials produeixen una variació a la producció de fases hidratades que porten canvis a les propietats mecàniques dels materials compostos. Els sistemes ternaris formats per CP/CAC/CS , s’han utilitzat per a produir mescles amb propietats de fraguat i enduriment diferents als que presenten els ciments constituents per separat. La demanda d’aquest tipus de productes s’ha vist incrementada degut a la necessitat d’una ràpida posada en servei de certs sistemes constructius. No obstant, dins dels materials de construcció les seves aplicacions s’han limitat a interiors degut a certs problemes de durabilitat. En aquest treball s’estudia la zona rica en ciment Portland dins dels sistemes ternaris, observant la formació de fases hidratades, en especial la etringita i relacionant‐les amb les variacions dimensionals que es produeixen. De forma general s’observa que un increment en la formació d’etringita produeix una major variació dimensional. La formació d’etringita es funció de les relacions CP/CAC y CAC/CS. El contingut d’aluminats i sulfats regeix la formació d’aquesta fase: si els sulfats presents no consumeixen tots els aluminats, aquests reaccionen amb l’etringita per a formar monosulfoaluminat disminuint l’expansió. Però si el contingut de sulfat és alt la formació d’etringita augmenta provocant grans variacions dimensionals, que per a percentatges superiors al 5% provoquen fissures arribant a la destrucció de provetes si puja en excés. Així es va comprovar que el mitjà de crat també influeix en la variació dimensional que es produeix. Mostres amb les mateixes proporcions de ciments i sulfat càlcic pateixen variacions diferents. Quan es curen a l’aire es produeix retracció, però quan es curen sota l’aigua es produeix expansió. Això pot ser degut a diferències en l’intercapa del gel C‐S‐H desenvolupat, essent mes voluminosos a les mostres submergides per la inclusió de molècules d’aigua.

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Sio, Jeanette Dorol. "Influence of Pozzolanic Material in the Conversion and Corrosion Behaviour of Calcium Aluminate Cement." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12694.

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Calcium aluminate cement (CAC) is used as a protective lining to combat attack by microorganisms and their metabolic products on reinforced concrete sewer pipes. CAC corrosion behaviour is related to the conversion process of the aluminate hydrates. Full conversion can result to a 5-8 times increase in corrosion rate. Hence, understanding and controlling the rate and the processes that affect conversion is important in the effective use of CAC as a mitigation strategy against the attack of microorganisms. This study was focussed on the role of the pozzolanic material, i.e. fly ash, in suppressing the conversion of CAC. CAC mortars were prepared with constant water-cement ratio of 0.4 and with fly ash contents of 0%, 5%, and 25% weight. To assess the effectiveness of the fly ash, CAC mortars were cured at high temperatures (80-100oC) in water bath to accelerate conversion. Thermal analysis (TGA), X-Ray diffraction (XRD), and scanning electron microscopy (SEM) with integrated EDS and EBSD system were used to monitor the physical and mineralogical transformation of CAC during the conversion and leaching tests. Our study showed that pozzolanic materials have negative and positive impacts in CAC. Based on thickness loss, addition of fly ash improved the corrosion resistance of CAC. This can be attributed to the increased formation of the stratlingite (C2ASH8) that was found to be resistant to both organic and mineral acids. However, analysis based on weight loss and dissolved Al metal showed that addition of fly ash suppresses early corrosion but later corrosion is increased, which is attributed to greater formation of C3AH6 and greater porosity.

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30

Gosselin, Christophe. "Microstructural development of calcium aluminate cement based systems with and without supplementary cementitious materials /." Lausanne : EPFL, 2009. http://library.epfl.ch/theses/?nr=4443.

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Thèse Ecole polytechnique fédérale de Lausanne EPFL, no 4443 (2009), Faculté des sciences et techniques de l'ingénieur STI, Programme doctoral Sciences et Génie des matériaux, Institut des matériaux IMX (Laboratoire des matériaux de construction LMC). Dir.: Karen Scrivener.

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Alex, Jennifer. "Effect of sodium on the microstructure and properties of calcium aluminate cement bonded refractories." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/31583.

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Additions of 0.1 - 1.0 wt% Na on Al2O3-CaO and Al2O3-CaO-SiO2 model refractory castable systems were investigated with respect to the effect on formation characteristics, and mechanical properties of the consolidated refractory. In the Al2O3-CaO system, sodium is shown to form sodium β-alumina (NaβA) via the intermediate NaAlO2. Formation of NaβA disrupts the reaction path of calcia (CaO) with alumina (Al2O3), delaying crystallisation of calcium hexaluminate (CA6) from 1350 to 1500 °C. The linear expansion associated with NaβA is quantified and is shown to scale with the amount of dopant added: addition of 1 wt% Na leads to up to 47% additional expansion. The preferential formation of NaβA, rather than CA6, delays sintering and reduces the elastic modulus of systems with > 0.3 wt% additional Na as a consequence of a reduction of particle cohesion. With regards to the consolidated (i.e. heat treated) model castable, the system was able to tolerate addition of 0.3 wt% Na without a significant reduction in stiffness. Addition of 0.3 wt% Na had no negative effect on flexural strength of the formulation and up to ≤ 0.5 wt% Na does not affect creep resistance of the consolidated samples. NaβA formation was shown to result in enhanced internal friction, likely caused by Na+ ion hopping through the spinel-like planes of the NaβA. During long exposures to 1500 °C, sodium is lost from the samples as shown by quantification of NaβA and the internal friction peak associated with this phase. In the system Al2O3-CaO-SiO2 sodium leads to formation of nepheline (Nep, C2AS) and soda-anorthite (Na-An, Na-CAS2). Up to 1100 °C the system can tolerate the addition of 0.5 wt% Na with regards to elastic modulus and linear thermal expansion. At higher temperatures, the formation of a viscous phase leads to a significant deterioration of the creep resistance.

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Bürger, Camila Paes [UNESP]. "Cimento de Aluminato de Cálcio – Uso em defeitos ósseos induzidos em fêmures de coelhos (Oryctolagus cuniculus)." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/89022.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
O tratamento de não união e união retardada é um desafio constante na rotina do ortopedista veterinário. A dificuldade de se conseguir repouso adequado dos pacientes submetidos à osteossíntese, frequentemente, resulta em consolidações mal sucedidas. Com o objetivo de se avaliar o comportamento do cimento de aluminato de cálcio, foram induzidos defeitos ósseos de 3,57mm de diâmetro nos fêmures de 12 coelhos, sendo os do lado direito preenchidos com o referido biomaterial e os do esquerdo permaneceram vazios. Aos 15, 30 e 60 dias de pós-operatório, realizaram-se avaliações clínico-cirúrgicas, radiográficas e histológicas, a fim de se observar o potencial osteoindutor e osteocondutor do biomaterial no defeito ósseo, e se houve osteointegração. Os resultados evidenciaram que o cimento aluminoso, nesta formulação, não possui esses potenciais e nem poder de osteointegração, possivelmente por possuir porosidade reduzida
The treatment of non union and delayed union is a constant challenge for veterinary orthopedists. The difficulty in achieving adequate rest for patients which have undergone osteosynthesis results in unsuccessful bone consolidations. With the aim of evaluating the behavior of a calcium aluminate cement, bone defects of 3,57 mm of diameter were induced in femurs of 12 rabbits. The defects on the right side were filled with the biomaterial and the ones on the left side remained unfilled. The evaluation periods occurred at 15, 30 and 60 days after surgery. Clinical, surgical, radiographic and histological evaluations were performed in order to observe the osteoinductive and osteocondoctive potential of the biomaterial on the bone defects, as well to verify if there was osteointegration. The results showed that the aluminate cement does not have these potencial and nor cause osteointegration in the formulation used in this study

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Prates, Luiz Henrique Maykot. "Influencia do tratamento de superficie em uma liga de paladio-prata na resistencia de união de agentes cimentantes." [s.n.], 2000. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290112.

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Orientador: Simonides Consani
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O propósito do estudo foi avaliar a influência de quatro tratamentos de superfície, efetuados em uma liga de paládio-prata, na resistência da união ao cisalhamento de três agentes cimentantes. Inicialmente, foram confeccionadas fundições em forma de disco (5 mm de diâmetro), com liga de paládio-prata, sendo os espécimes agrupados em pares, após limpeza manual e em ultra-som com água. Em seguida, os pares foram separados em quatro grupos de 30 cada, para realização de um dos seguintes tratamentos nas faces circulares opostas às correspondentes aos condutos de alimentação: 1 - bruto de fundição (controle); 2 aplicação de jato de óxido de alumínio malha 320; 3 - aplicação de jato de óxido de alumínio malha 60; e 4 - aplicação de jato de micro esferas de vidro malha 270. Após nova limpeza em ultra-som com água destilada, durante 5 minutos, os exemplares de cada grupo foram separados em três sub-grupos de 10 cada, sendo feita a fixação, através das faces tratadas, com um dos seguintes agentes cimentantes: A - cimento de fosfato de zinco; B - cimento de ionômero de vidro modificado por resina; e C - cimento resinoso. Dez espécimes de cada tratamento de superfície foram submetidos à análise da rugosidade média, sendo também feito Lo preparo de dois exemplares para observação com microscopia eletrônica de varredura. Após 24 horas de armazenagem em água destilada a 37°C, os pares fixados foram avaliados com ensaios de cisalhamento em máquina Instron (1 mm/min), até a ruptura das amostras. Os resultados foram submetidos à análise de variância e ao teste de Tukey (p < 0,05) e as médias obtidas (MPa) foram: Grupo 1 A: 1,77 (0,51); Grupo 1 B: 3,18 (1,42); Grupo 1 C: 1,63 (0,55); Grupo 2 A: 5,22 (0,88); Grupo 2 B: 11,90 (1,94); Grupo 2 C: 16,29 (3,94); Grupo 3 A: 4,03 (0,78); Grupo 3 B: 11,41 (2,69); Grupo 3 C: 14,15 (2,71); Grupo 4 A: 1,59 (0,44); Grupo 4 B: 2,24 (0,71); Grupo 4 C: 1,74 (0,51). As superfícies metálicas submetidas ao jato de óxido de alumínio (malhas 320 ou 60) proporcionaram maior resistência de união que a condição de bruto de fundição e que as superfícies submetidas ao jato de micro esferas de vidro malha 270. Nas superfícies tratadas com jato de óxido de alumínio, o cimento resinoso e o cimento de ionômero de vidro modificado por resina proporcionaram resistências de união estatisticamente superiores à do cimento de fosfato de zinco. Não houve relação entre a resistência de união dos agentes cimentantes e a rugosidade média das ligas metálicas
Abstract: The purpose of this study was to evaluate the influence of four metal surface treatments on the shear bond strength of three luting agents. Cast samples in a disk shape (5 mm in diameter) were made with palladium-silver alloy and grouped in pairs afier ultrasonic cleaning. The pairs were assigned into four groups of 30 each and submitted to the following treatments on the circular surfaces opposite to that of the sprue former: 1 - as cast (control); 2 - aluminum oxide blasting (320 mash); 3 - aluminum oxide blasting (60 mash); and 4 - glass beads blasting (270 mash). Afier new ultrasonic cleaning in distilled water, during 5 minutes, the samples of each group were assigned into three subgroups of 10 each, being made the cementing, by the treated surfaces, with the following luting agents: A - zinc phosphate cement; B - resin-modified glass ionomer cement; and C ¿ resin cement. Before luting, 10 specimens of each treatment had the surfaces measured for roughness and two samples were prepared to observation in scanning electronic microscope. Afier storing in distilled water at 37°C, during 24 hours, the cemented pairs were submitted to shear bond strength tests in an Instron machine (1 mm/min), until the failure. The results were analyzed by ANOVA and Tukey's test (p < 0,05) and the means (MPa) were: Group 1 A: 1.77 (0.51); Group 1 B: 3.18 (1.42); Group 1 C: 1.63 (0.55); Group 2 A: 5.22 (0.88); Group 2 B: 11.90 (1.94); Group 2 C: 16.29 (3.94); Group 3 A: 4.03 (0.78); Group 3 B: 11.41 (2.69); Group 3 C: 14.15 (2.71); _Group 4 A: 1.59 (0.44); Group 4 B: 2.24 (0.71); Group 4 C: 1.74 (0.51). The metallic surfaces submitted to the aluminum oxide blast treatment (320 or 60 mash) showed bond strengths significantly higher than those of surfaces as cast or submitted to glass beads blast (270 mash). On surfaces treated with aluminum oxide blast, the resin cement and the resin-modified glass ionomer cement showed bond strengths statistical/y superior to those of the zinc phosphate cement. There was not a relationship between the bond strengths of cementing agents and the roughness of metal/ic surfaces
Doutorado
Doutor em Materiais Dentários

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34

Hüller, Florian [Verfasser], Friedlinde [Akademischer Betreuer] Götz-Neunhoeffer, and Friedlinde [Gutachter] Götz-Neunhoeffer. "Hydration mechanisms of CA2 and alumina-rich calcium aluminate cements: Effects of mechanical activation, critical CA contents and crystallinity of AH3 / Florian Hüller ; Gutachter: Friedlinde Götz-Neunhoeffer ; Betreuer: Friedlinde Götz-Neunhoeffer." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1187523283/34.

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35

Costa, Eugenio Bastos da. "Aproveitamento de cinza pesada e lodo de anodização do alumínio para a produção do cimento sulfoaluminato de cálcio belítico." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/149248.

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A produção de cimento gera um impacto ambiental negativo, principalmente relacionado à emissão de dióxido de carbono (CO2). O clínquer do cimento sulfoaluminato de cálcio belítico (CSAB) possui um menor teor de óxido de cálcio e é produzido com uma reduzida temperatura de sinterização (aproximadamente 200ºC a menos em relação ao clínquer Portland), sendo considerado mais eco-amigável. Para a produção do cimento CSAB são necessárias matérias-primas ricas em alumínio e convencionalmente a bauxita é o minério utilizado para compor a farinha, o que mais onera a produção desse tipo de cimento. Soma-se ainda o fato que a geração de resíduos e subprodutos industriais torna-se inerente aos processos e o coprocessamento de resíduos vem sendo cada vez mais utilizado por razões ambientais e energéticas. Logo, fontes alternativas de alumina são fundamentais para a viabilização deste cimento e o aproveitamento de resíduos agregaria um valor econômico e sustentável ao produto final. De modo estequiométrico, a bauxita pode ser completamente substituída pelo lodo de anodização do alumínio (LAA), o qual também pode complementar o conteúdo de alumínio de outros resíduos, valorizando-os. O objetivo deste estudo foi avaliar a produção e as propriedades de clínqueres/cimentos CSAB a partir da substituição da bauxita por cinza pesada e LAA. Para a caracterização das matérias-primas, clínqueres e cimentos nos estados anidro e hidratado foram utilizadas as seguintes técnicas: fluorescência de raios X; microscopia eletrônica de varredura e espectrometria por energia dispersiva; termogravimentria; calorimetria; e difração de raios X com refinamento pelo método de Rietveld. A partir dos resultados obtidos, a substituição da bauxita foi limitada a nível parcial devido à elevada formação de belita e periclásio. Nos clínqueres produzidos, foi constatado que a presença da cinza pesada favorece a formação da estrutura cristalina ortorrômbica da fase ye’elimita. A presença dos resíduos altera a quantificação das fases, porém não compromete a estabilização das mesmas. A presença dos resíduos na composição dos cimentos afeta o período inicial de hidratação devido à redução do conteúdo de ye’elimita. Nos clínqueres produzidos com cinza pesada, ocorre a formação de até 12,6% da fase alita a 1250ºC, principal constituinte do clínquer Portland.
Cement production generates high negative environmental impact, mainly associated to CO2 emissions. Calcium sulfoaluminate belite cement clinker (CSAB) has lower content of calcium oxide, and sintering reduced temperature (about 200°C lower than that used for Portland clinker), being considered as eco-friendly binder. For its production high amount of alumina is required, however the scarcity and high cost of bauxite make these cements costly. Additionally, the generation of waste and by-products becomes a drawback in the industrial processes and the coprocessing of wastes in cement plants is increasing for environmental and energy savings reasons. Alternative sources of alumina would add an economic and sustainable value to the final product and previous work has shown that the aluminum anodizing sludge can replace bauxite in the production process. Other sources of wastes can also be a possibility to increase the production and reduce the raw materials costs of these cements. Thus, the objective of this study was the evaluation of novel CSAB cements produced with bauxite replacement by bottom ash and aluminum anodizing sludge. CSAB cements were produced in the laboratory from different amounts of sludge and ashes. The raw materials, clinkers/cements and hydration products were physicaly-chemicaly and mechanical characterized. Results showed that the mineralogy composition of CSAB clinker was strongly affected due to the addition of bottom ash. The amount of bottom ash waste replacing bauxite controls the belite and periclase formation. Also it influences the early age hydration due the reduced ye’elimite formation and important changes in the crystalline structures of this phase occurs in the clinkers. Clinkers prepared from these replacement, are able to form 12.6% of alite (main phase Portland clinker), not normally found in CSAB clinkers, being sintered at 1250°C.

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Sokolt, Stanislav. "Studium trvanlivosti hmot na bázi účelového vzniku ettringitu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-225887.

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This master thesis is focused on the binary and ternary systems with connective purposeful ettringite formation for fast hardening adhesive for ceramic tiles. It deals with the durability of these materials after exposure to the corrosive environment. It examines the physical and mechanical properties and mineralogy changes after exposure to corrosive environments. Within processing of this paper provides basic information concerning the connective concept of purposeful formation of ettringite.

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Almutairi, Jasi. "TIME DEPENDENT CHANGES IN MICRO-HARDNESS OF BIOACTIVE CEMENTS." Master's thesis, Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/309647.

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Oral Biology
M.S.
The objective of this study was to compare time dependent micro-hardness of several bioactive cement compositions as compared to that of non-bioactive cement, a conventional glass ionomer. Materials & Methods: Three bioactive materials Ceramir Crown & Bridge Cement (CCB), Mineral Trioxide Aggregate (MTA), Biodentine (BD)], and a glass ionomer cement, Fuji I luting cement (F1), were utilized in this study. Samples of the materials were prepared in a standard cylindrical mold 1.5 mm in height and 12.0 mm in diameter and stored in Phosphate-Buffered-Saline (PBS) at 37 degrees C. prior to testing to determine Vickers micro-hardness in a CSM micro-indentation testing device. Micro-hardness values were collected via 2 x 2 micro-indentation matrices on the exposed surfaces of the specimens. All materials were tested at 24 hours and 2 months and 11 + 1 month's incubation time. The bioactive materials displayed significant differences in Vickers hardness as a function of storage time as compared the Vickers hardness values over the similar timeframe for the control material, the glass ionomer material Fuji 1. The control glass ionomer cement did not displayed significant changes in Vickers hardness after prolonged liquid storage. The experimental bioactive materials both demonstrated long-term trends with significant increases (CCB) and decreases (Biodentine) in Vickers hardness after storage in the simulated body fluid (PBS). The mean Vickers hardness of the calcium aluminate/glass ionomer (CCB) material was significantly greater than the mean Vickers hardness values for the other three materials tested at all time-points evaluated. The conclusions of this study were as follows: Unlike conventional glass ionomer cement, both the calcium silicate and calcium aluminate/glass ionomer cement displayed significant changes in surface micro-hardness after prolonged storage in a simulated body fluid (PBS) that has been demonstrated to induce the formation of a surface bioactive layer. The calcium silicate cement had a significant reduction in surface micro-hardness over a period up to year; while the calcium aluminate/glass ionomer cement displayed a significant increase in surface micro-hardness over that same time period. The formation of and changes in the bioactive surface layers formed on these materials may account for changes in the micro-hardness of these bioactive materials.
Temple University--Theses

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Shatat, Fayez. "The effect of resin based coatings on fluoride release of glass ionomer cement, an in vitro study." University of the Western Cape, 2018. http://hdl.handle.net/11394/6399.

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Magister Scientiae Dentium - MSc(Dent) (Paediatric Dentistry)
The use of glass ionomer cement (GIC) restorative materials assists in the prevention of dental caries due to its long-term fluoride release. However, poor physical strength is one of the main drawbacks of GIC. A surface coating is recommended to improve the physical strength and is considered necessary during the overlapping stages of setting reactions of GIC restorative materials. The development of resin based coatings has improved the properties of the material but the effect on fluoride release needs investigation.

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Wang, Jia. "Hydration mechanism of cements based on low-CO2 clinkers containing belite, ye’elimite and calcium alumino-ferrite." Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10169/document.

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L’objectif de ce travail a été d’apporter une meilleure compréhension des mécanismes réactionnels de l’hydratation de ciments appartenant à la famille de ciment BCSAF afin de développer des schémas réactionnels simplifiés permettant d’optimiser les ciments à base d’un clinker BCSAF et d’autres constituants pour des applications spécifiques. Les ciments étudiés ont été réalisés à partir d’un clinker contenant 52% de belite, 33% de ye’elimite and 14% de ferrite et diverses quantités d’anhydrite et de calcaire. A partir de l’étude détaillée de l’hydratation d’un ciment contenant 95% de clinker et 5% d’anhydrite, il a été démontré que le mécanisme de l’hydratation est constitué de deux périodes successives : le début de l’hydratation est contrôlé par l’hydratation de la ye’elimite réagissant avec l’anhydrite, tandis que la suite de l’hydratation est contrôlée par les hydratations de la belite et de la ferrite qui réagissent avec certains des hydrates formés lors de la première période. La vitesse de nucléation de la strätlingite contrôle le début de l’hydratation de la belite. Le principal paramètre qui contrôle cette dernière est la concentration en sulfate de la phase aqueuse qui doit être très faible. Ainsi C-S-H n’est pas formé au début de l’hydratation de la belite certainement à cause de l’inhibition de sa nucléation par de trop fortes quantités d’aluminate en solution. Par conséquence, c’est indirectement la concentration en sulfate de la solution qui contrôle le début de l’hydratation de la belite and ainsi les réactions conduisant à sa réduction à travers la précipitation de phase notamment lors de l’hydratation de la ye’elimite pour former de l’ettringite. Ainsi d’une façon générale, la strätlingite commence à nucléer quand la ye’elimite a complètement réagi. D’autre part, une synergie entre les hydratations de la belite et de la ferrite permet de former des hydrogrenats et des C-S-H à des temps longs au détriment de la strätlingite formée auparavant. Un mécanisme d’hydratation similaire a été trouvé pour les ciments contenant des quantités plus importantes d’anhydrite à l’exception de ceux qui contiennent une quantité d’anhydrite supérieure que la quantité théorique permettant de faire réagir toute la ye’elimite en ettringite. Toutefois pour le premier type de ciments, une augmentation de la quantité d’anhydrite allonge à la fois le temps d’apparition de la seconde période et la durée des différentes étapes de cette dernière. Donc l’hydratation est globalement plus lente. Pour le second type de ciment, contenant de fortes quantités d’anhydrite, le mécanisme d’hydratation est assez différent car l’hydratation de la belite commence dès le début de l’hydratation et conduit à la formation, soit d’ettringite contenant Si, soit de C-S-H. L’effet de 15% de calcaire a également été étudié pour le ciment contenant 95% de clinker et 5% d’anhydrite. Les résultats ont montré que le calcaire ne change pas la première période de l’hydratation mettant en jeu principalement la ye’elimite et l’anhydrite. Par contre la seconde période, durant laquelle la belite et la ferrite s’hydratent, est fortement retardée à son début. Ceci peut être dû à un retard de la nucléation de la strätlingite à cause de concentrations en sulfate de la solution restant plus longtemps élevées par le fait que l’ettringite est stabilisée en présence de carbonate par la formation de phases AFm carbonatées qui inhibent la formation de monosulfoaluminate de calcium hydraté. Pour finir, des perspectives sont données notamment afin de réduire la durée de la première période de l’hydratation et ainsi permettre un démarrage plus rapide de l’hydratation de la belite et de la ferrite
The objective of this work was to better understand the hydration mechanisms of cements belonging to the family of BCSAF cement in order to develop simple mechanistic models which can help us to optimise mixtures of BCSAF clinker and other compounds for specific applications. The studied cements were made from a clinker containing 52% of belite, 33% of ye’elimite and 14% of a ferrite phase and various amounts of anhydrite and limestone. From the Detailed investigation of the hydration of cement containing 95% of clinker and 5% of anhydrite, it has been demonstrated that the mechanism of hydration has two main successive periods of hydration: the beginning of hydration is controlled by ye’elimite and anhydrite, while the remaining of hydration is governed by belite and the ferrite phase that react with some of the hydrates formed during the first period. It is C2ASH8 nucleation rate that governs the beginning of the hydration of belite. The main parameter that governs the nucleation rate of strätlingite is [SO4]2- that has to be low. C-S-H does not form as the initial hydrate for belite hydration due to the inhibition effect of high aluminate concentration on C-S-H nucleation. As a consequence, this is indirectly the sulphate concentration that controls the beginning of belite hydration and thus the reactions leading to its reduction, mainly the hydration of ye’elimite to form ettringite. Globally it is once ye’elimite has been completely reacted that strätlingite may nucleate. A synergy between the reactions of belite and ferrite is found to accelerate the formation of later hydrate, hydrogarnet and C-S-H at the expense of strätlingite.A similar mechanism of hydration has been found for cements having higher anhydrite contents at the exception of cements that have more anhydrite than the theoretical anhydrite content to consume all ye’elimite to form ettringite. For the former cements, more anhydrite can strongly delay the second period of the hydration where both belite and ferrite react. In the later cases, the mechanism of hydration is quite different as belite does start to react till the beginning of hydration certainly forming either a Si containing ettringite or C-S-H. The influence of 15% of limestone was investigated on the cement containing 95% of clinker and 5% of anhydrite. The results showed that limestone did not change the first period involving anhydrite and ye’elimite, but strongly delayed the beginning of the second period where both belite and ferrite hydrate. This may be due to a delayed nucleation of strätlingite induced by a longer period having higher [SO4]2- as ettringite is stabilised by the precipitation of carbonated AFm at the expense of calcium monosulfoaluminate hydrate, thanks to the carbonate ions brought by limestone. Finally some perspectives are given in order to reduce the duration of the first period and then to enable the hydration of both belite and ferrite more rapidly

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Silva, Ligia Luzia Buarque e. "Estudo comparativo da adaptação marginal entre copings metalicos, In-Ceram alumina e e.max Press, antes e apos a cimentação." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287813.

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Orientador: Alexandre Brait Landulpho
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Esse estudo avaliou a adaptação marginal entre copings metálicos, In-Ceram e e.max Press, antes e após cimentação em preparos sobre dentes bovinos, utilizando dois tipos de cimento resinosos. Noventa incisivos bovinos foram fixados em resina acrílica ativada quimicamente e as porções coronárias foram preparadas para coroa total, com expulsividade de 8o e término cervical em ombro. Trinta copings foram confeccionados para cada tipo de material, onde foram adaptados sobre os preparos com carga estática de 9 Kgf por 1 minuto e a discrepância marginal foi medida com microscópio de mensuração (STM). Em seguida, 15 amostras para cada tipo de coping foram cimentadas sobre os dentes com agente resinoso convencional, e mais 15 amostras para cada coping foram cimentadas com agente autoadesivo com uma carga estática de 9 Kgf por 7 minutos e novamente a discrepância marginal foi medida. Os resultados mostraram que antes da cimentação, houve diferenças significativas (p<0,05) no desajuste marginal entre os sistemas, sendo que o e.max Press apresentou maior desajuste. Após a cimentação os copings de metal e In-Ceram não apresentaram diferenças significativas (p>0,05) entre os cimentos. O sistema e.max Press apresentou um maior desajuste (p<0,05) quando cimentado com agente resinoso convencional. Quando os sistemas foram cimentados com agente resinoso convencional, o menor desajuste foi encontrado no metal (p<0,05), sendo que não houve diferenças significativas (p>0,05) entre os outros dois sistemas. Quando cimentados com o agente autoadesivo, não apresentaram diferenças significativas (p>0,05)
Abstract: This study evaluated the marginal adaptation of metal copings, In-Ceram and Press, before and after cementation in preparations on bovine teeth using two types of resin cement. Ninety bovine incisors were embedded in resin and the coronal portions of the teeth were prepared to receive complete crowns with 8o of tapering and right shoulder. Thirty crowns were fabricated for each coping. The crowns were then seated on the teeth with 9 Kgf static loads for 1 minute and the marginal discrepancy was mensured using a microscopic (STM). Afterwards, the copings were removed and fifteen samples of each coping were luted on the teeth with resin cement, and fifteen with self-adhesive resin cement applied 9 Kgf static loads for 7 minutes and the marginal discrepancy was mensured again. The results showed that before to cementation, there were significant differences (p <0.05) in the marginal fit between the systems, and the e. max Press show higher discrepancy. After cementing the metal copings and In-Ceram showed no significant differences (p>0.05) between the cements. The system e.max Press showed a significant discrepancy higher (p <0.05) when cemented with conventional resin. When the systems were cemented with resin conventional, the lowest discrepancy was found in the metal (p <0.05), with no significant differences (p> 0.05) between the other two systems. When cemented with the self agent adhesive, no significant differences (p> 0.05)
Doutorado
Protese Dental
Doutor em Clínica Odontológica

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Nehring, Jörg [Verfasser], Friedlinde [Akademischer Betreuer] Götz-Neunhoeffer, and Friedlinde [Gutachter] Götz-Neunhoeffer. "Acceleration of ordinary Portland cement based systems by calcium aluminate cement: New insights into the hydration kinetics of C3S / Jörg Nehring ; Gutachter: Friedlinde Götz-Neunhoeffer ; Betreuer: Friedlinde Götz-Neunhoeffer." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2021. http://d-nb.info/1225557917/34.

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42

Silva, Ligia Luzia Buarque e. "Estudo comparativo da adaptação entre copings metalicos e de alumina, no sistema In-Ceram, antes e apos cimentação." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287835.

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Orientador: Alexandre Brait Landulpho
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Este estudo analisou comparativamente a adaptação marginal antes e após a cimentação de copings metálicos e de alumina, no sistema In-Ceram, em preparos sobre dentes bovinos, utilizando dois tipos de cimento. Sessenta incisivos bovinos foram fixados em resina acrílica ativada quimicamente e as porções coronárias foram preparadas para coroa total, utilizando pontas diamantadas tronco cÃ'nica no 4103 com paredes axiais com expulsividade de 8o e término cervical em ombro. Trinta coroas foram confeccionadas para cada tipo de coping. Após, os copings foram adaptados sobre os preparos com carga estÃ¡tica de 9 Kgf por 1 minuto e a discrepância marginal foi medida com microscópio de mensuração (STM). Em seguida, os copings foram removidos e 15 amostras de cada tipo de coping foram cimentados sobre os dentes com cimento de fosfato de zinco (SS White, Petrópolis, RJ. Brasil) e 15 com cimento resinoso (Rely X ARC 3M/ESPE Divisão Dental â?¿ Brasil), aplicou-se uma carga estática de 9 Kgf por 7 minutos e novamente a discrepância marginal foi medida. Os resultados foram submetidos à Análise de Variância e ao Teste de Tukey (5%) e indicaram que os dois tipos de copings apresentaram desajuste cervical após a cimentação estatisticamente superior ao desajuste cervical antes da cimentação, para os dois cimentos. O sistema In-Ceram apresentou valores de desajuste cervical estatisticamente superior quando cimentados com cimento resinoso. Nenhuma diferença estatástica foi observada entre os dois tipos de copings quando cimentados com cimento de fosfato de zinco
Abstract: The purpose of this study was to evaluate the marginal fit before and after cementation of metal and aluminium oxide In-Ceram copings, on bovine teeth preparation using two kinds of cement. Sixty bovine incisors were embedded in resin and the coronal portions of the teeth were prepared to receive complete crowns usin a 4103 diamond bur under refrigeration with 8o of tapering and right shoulder. Thirty crowns were fabricated for each coping. The crowns were then seated on the teeth with 9 Kgf static loads for 1 minute and the marginal discrepancy was mensured using a microscopic (STM). Afterwards, the copings were removed and fifteen samples of each coping were luted on the teeth with zinc phosphate (SS White/Esp, PetrÃ³polis, RJ. Brasil) and resin cement (Rely X ARC 3M/ESPE DivisÃ£o Dental â?¿ Brasil), applied 9 Kgf static loads for 7 minutes and the marginal discrepancy was mensured again. Data were submitted to analysis of variance and TukeyÂ's test (5%); results showed that the two copings had cervical fits after cementation statistically higher than those before cementation, concerning both cements. The In-Ceram system showed statistically higher values for the cervical fits when resin cement was used. No statistically significant difference was found between the copings concerning cements with zinc phosphate
Mestrado
Protese Dental
Mestre em Clínica Odontológica

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Konradsson, Katarina. "Influence of a dental ceramic and a calcium aluminate cement on dental biofilm formation and gingival inflammatory response." Doctoral thesis, Umeå : Umeå University, Faculty of Medicine, Odontology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1069.

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Bürger, Camila Paes. "Cimento de Aluminato de Cálcio - Uso em defeitos ósseos induzidos em fêmures de coelhos (Oryctolagus cuniculus) /." Jaboticabal : [s.n.], 2010. http://hdl.handle.net/11449/89022.

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Resumo: O tratamento de não união e união retardada é um desafio constante na rotina do ortopedista veterinário. A dificuldade de se conseguir repouso adequado dos pacientes submetidos à osteossíntese, frequentemente, resulta em consolidações mal sucedidas. Com o objetivo de se avaliar o comportamento do cimento de aluminato de cálcio, foram induzidos defeitos ósseos de 3,57mm de diâmetro nos fêmures de 12 coelhos, sendo os do lado direito preenchidos com o referido biomaterial e os do esquerdo permaneceram vazios. Aos 15, 30 e 60 dias de pós-operatório, realizaram-se avaliações clínico-cirúrgicas, radiográficas e histológicas, a fim de se observar o potencial osteoindutor e osteocondutor do biomaterial no defeito ósseo, e se houve osteointegração. Os resultados evidenciaram que o cimento aluminoso, nesta formulação, não possui esses potenciais e nem poder de osteointegração, possivelmente por possuir porosidade reduzida
Abstract: The treatment of non union and delayed union is a constant challenge for veterinary orthopedists. The difficulty in achieving adequate rest for patients which have undergone osteosynthesis results in unsuccessful bone consolidations. With the aim of evaluating the behavior of a calcium aluminate cement, bone defects of 3,57 mm of diameter were induced in femurs of 12 rabbits. The defects on the right side were filled with the biomaterial and the ones on the left side remained unfilled. The evaluation periods occurred at 15, 30 and 60 days after surgery. Clinical, surgical, radiographic and histological evaluations were performed in order to observe the osteoinductive and osteocondoctive potential of the biomaterial on the bone defects, as well to verify if there was osteointegration. The results showed that the aluminate cement does not have these potencial and nor cause osteointegration in the formulation used in this study
Orientador: Cíntia Lucia Maniscalco
Coorientadora: Paola Castro Moraes
Banca: Julio Carlos Canola
Banca: Gustavo Garkalns de Souza Oliveira
Mestre

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Ng, Geok Bee Serina [Verfasser], Johann Peter [Akademischer Betreuer] Plank, and Peter [Akademischer Betreuer] Müller-Buschbaum. "Interactions of Polycarboxylate based Superplasticizers with Montmorillonite Clay in Portland Cement and with Calcium Aluminate Cement / Geok Bee Serina Ng. Gutachter: Peter Müller-Buschbaum ; Johann Peter Plank. Betreuer: Johann Peter Plank." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/103128026X/34.

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Rashid, Shahwana. "On the hydration of calcium aluminate cements : new insights from synchrotron radiation experiments real time." Thesis, University of London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264219.

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Másilko, Jiří. "Syntéza vysokopevnostních kompozitů na bázi anorganického cementu a polymeru." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-233354.

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The subject of the doctoral thesis is the study of moisture resistance of macro-defect-free (MDF) composites based on calcium-aluminate cement and polyvinylalcohol used as polymer. MDF cements are perspective materials providing unique properties relative to traditional cement pastes with great potential to incoming constructional utilization. But it is known that MDF cements exhibit sensitivity to water, with swelling and reduction of strength. Therefore the work is aimed in monitoring of an organic polymer effect on the moisture resistance of MDF materials and phase changes. The effects of three different organotitanate cross-linking agents on the properties were investigated. The organotitanate-modified MDF cement samples exhibited improved moisture resistance as compared to the standard samples when exposed to 100 % relative humidity or water at laboratory conditions. The influence of composition at different curing on the properties of model MDF cement samples was observed. The characterization of MDF samples was based especially on test of flexural strength, XRD, DTA/TGA and EGA, EDS and scanning electron microscopy analyses.

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Valdivia, Juan Rommel Medina. "Resistência de união de um cimento resinoso a diferentes superfícies de alumina densamente sinterizada." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/25/25131/tde-26052010-082846/.

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O propósito deste estudo foi avaliar a resistência adesiva ao cisalhamento de um cimento resinoso à alumina densamente sinterizada testando o tratamento superficial feito pelo fabricante. O cimento utilizado foi o Multilink (Ivoclar Vivadent) e a alumina foi a Procera®Alumina (Nobel Biocare) constituída por 99,9 % de óxido de alumínio densamente sinterizado. Trinta e dois cilindros de alumina foram confeccionados pela Nobel Biocare, onde um dos extremos deste cilindro recebeu o tratamento superficial e o outro não. Para a aplicação do cimento resinoso sobre os cilindros de alumina, utilizou-se uma matriz de Teflon com um orifício central de 3,5mm de diâmetro por 3,0mm de profundidade. Foram determinados 4 grupos experimentais: Grupo 1 superfície sem tratamento; Grupo 2 superfície sem tratamento e com aplicação de adesivo; Grupo 3 - superfície com o tratamento realizado pelo fabricante; Grupo 4 superfície com tratamento realizado pelo fabricante e com adesivo. Após a aplicação do cimento nos 4 grupos, os espécimes foram armazenados em água deionizada a 37ºC durante 24h, sendo, em seguida, montados em uma máquina universal de ensaios para realização dos testes de resistência ao cisalhamento. Os resultados foram submetidos à análise de variância a dois critérios e ao teste de Tukey para comparação entre os grupos. A superfície tratada (grupo 3) apresentou valores significativamente maiores que todos os outros grupos. A presença do adesivo diminuiu a resistência adesiva quando aplicado na superfície tratada, mas não deu diferença significante quando aplicado na superfície sem tratamento.
The aim of this study was to investigate the shear bond strength between a resin cement and densely sintered alumina treated by the fabricant. The resin cement used was the Multilink (Ivoclar Vivadent) and the alumina the Procera®Alumina (Nobel Biocare) made with 99,9% of densely sintered aluminum oxide. Thirty two alumina cylinders were made by Nobel Biocare, and in one of the extremes was applied a own`s fabricant surface treatment. For the application of the cement, a Teflon matrix with a central hole (diameter of 3,5 mm and a height of 3,0 mm) was used. Four groups were created: Group 1 surface without treatment; Group 2 - surface without treatment and with adhesive; Group 3 surface with the own`s fabricant treatment; Group 4 - surface with the own`s fabricant treatment with adhesive. After the cement application, the specimens were stored in water at 37º C for 24 hours. Then the samples were placed in a universal testing machine for making the shear strength test. Statistical analysis was performed with two-way analysis of variance (ANOVA), and paired comparisons between groups were done with Tukey`s multiple comparison. Higher significant values were detected for Group 3 when compared with all the other groups. The adhesive decreased the shear bond strength when laid on the treated surface, and there were no difference when laid on the untreated surface.

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Repka, Martin. "MDF kompozity AC-PVAl se zvýšenou odolností proti vlhkosti." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-216599.

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Polymerem impregnované cementové materiály představují zajímavou a perspektivní alternativu klasických portlandských cementových past. Hlavním zástupcem těchto materiálů jsou macrodefect-free (MDF) kompozity, složené z anorganického pojiva a organického polymeru. I přes řadu vynikajících mechanických vlastností je plné zavedení MDF kompozitů na trh omezené především z důvodu jejich relativně nízké odolnosti vůči vlhkosti. Jednou z možností jak zvýšit odolnost výsledného MDF vůči vlhkosti je „in situ“ síťování polymeru. V této práci byla připravena počáteční série MDF kompozitů na bázi hlinitanového cementu a polyvinylalkoholu se třemi typy organo-titanátových síťovacích činidel (Tyzory). Efekt modifikace MDF kompozitů byl hodnocen na základě zkoušek pevnosti v tahu za ohybu po uložení materiálů v různých vlhkostních podmínkách.

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Pekárková, Jana. "Ověření termodynamické stability ettringitu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240041.

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The thesis deals with possibilities of FBC fly ash utilization for composite cements. It focuses on thermodynamic stability of ettringite, which is produced during composite cements hydration. Specific tasks are dedicated to observation of influence of outdoor environment and influence of calciumhydrosilicate environment to stability of ettringite.

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Dissertations / Theses on the topic 'Alumina cement'

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