Dissertations / Theses on the topic 'Cement- Silica'
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1
Brew, Daniel Robert Mitchell. "Impact of silica fume on cement performance." Thesis, University of Aberdeen, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369734.
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Organic ion exchanger resin beads are widely used in nuclear waste technology for pond water cleanup. They accumulate radioactive Cs and Sr in service. For disposal, the beads are encapsulated in cement but their stabilisation in cement has been difficult to achieve. The ion exchangers uptake calcium and inbibe water, as a result of which they swell, cracking the cement. Nuclear Electric had previously commissioned work on non-swelling formulations. These consist of mixtures of sulfate-resisting Portland cement, calcium hydroxide and silica fume. However, concerns have been expressed about cement durability in contact with brines. This thesis had as part of its objectives, (i) determination of the probable stability of the non-swelling matrix in MgSO4 brines and (ii) the corrosion potential of stainless steel in contact with the non-swelling cement. In addition, synthesis, characterisation work was performed on the reaction product of objective (i), M-S-H gel. Its alkali sorption capacity was determined as a function of both Mg/Si ratio and alkali concentration to assess its immobilisation potential.
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Forero, Duenas Carlos Antonio. "Characterisation of a silica-gel as a geotechnical cement." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301001.
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Björnström, Joakim. "Influence of nano-silica and organic admixtures on cement hydration : a mechanistic investigation /." [Go̊teborg], Sweden : Dept. of Chemistry, Göteborg University, 2005. http://www.loc.gov/catdir/toc/fy0801/2006411318.html.
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Björnström, Joakim. "Influence of nano-silica and norganic admixtures of cement hydration : a mechanistic investigation /." Göteborg : Göteborg University, Department of Chemistry, 2005. http://www.loc.gov/catdir/toc/fy0801/2006411318.html.
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Tank, Suresh Bhagwanji. "The use of condensed silica fume in Portland cement grouts." Thesis, University College London (University of London), 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307794.
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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
7
El-Khatib, Jamal M. "Durability related properties of PFA, slag and silica fume concrete." Thesis, University of Aberdeen, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315418.
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Concrete has the largest production of all man-made materials. Compared with other construction materials, it possesses many advantages including low cost, general availability of raw materials, low energy requirement and utilization under different environmental conditions. Therefore, concrete will continue to be the dominant construction material in the foreseeable future. However, durability of concrete and reinfored concrete structures are still of worldwide concern, so producing a good quality concrete which impedes the ingress of harmful substances into it is of paramount importance. Cement replacement materials have been introduced into concrete mixtures for the purpose of improving the durability performance. Hence, the aim of the present investigation is to study the durability of concrete with and without cement replacement materials under various initial curing conditions. In this thesis various concrete mixes with and without cement replacement materials were considered. The cement replacement materials were, pulverised fuel ash, condensed silica fume, and ground granulated blast furnace slag. Superplasticiser was added to the majority of the mixes considered and air entraining agent to some of the mixes. Various curing regimes were employed which comprised hot dry curing to simulate concrete in the hot arid areas in the world and curing at normal temperature. Curing involved air curing, membrane curing and moist curing for fourteen days followed by air curing. A number of tests were conducted at either one particular age or at various ages. These included tests on porosity and pore structure of pastes obtained by mercury intrusion porosimetry technique, water absorption which covers the water absorption of concrete obtained by shallow immersion and the water absorbed by capillary action when the concrete surface is in contact with water, sulphate resistance of concrete which is performed by immersing the concrete specimens in sulphate solution, and monitoring the change in length at various periods of immersion, chloride penetration profiles of concrete at various ages of exposure. In addition to these tests on durability related properties, tests on compressive strength were also performed. Throughout the study a correlation between pore structure and durability related properties is investigated. A comprehensive compilation of chloride penetration data is made and an empirical expression is derived for the prediction of long term diffusion coefficients. At the end of the investigation, limitations of the present study, conclusions and suggestions for future research are made.
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Thibodeaux, Kristin. "Alkali-silica reaction in oilwell cement slurries using hollow glass spheres." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/19288.
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Touma, Wissam Elias. "Alkali-silica reaction in Portland cement concrete : testing methods and mitigation alternatives /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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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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Di, Domenica Eleonora. "Recycling of end of life concrete fines (0 - 4 mm) into silica and cement." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8622/.
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The purpose of this work is to find a methodology in order to make possible the recycling of fines (0 - 4 mm) in the Construction and Demolition Waste (CDW) process.
At the moment this fraction is a not desired by-product: it has high contaminant content, it has to be separated from the coarse fraction, because of its high water absorption which can affect the properties of the concrete. In fact, in some countries the use of fines recycled aggregates is highly restricted or even banned.
This work is placed inside the European project C2CA (from Concrete to Cement and Clean Aggregates) and it has been held in the Faculty of Civil Engineering and Geosciences of the Technical University of Delft, in particular, in the laboratory of Resources And Recycling.
This research proposes some procedures in order to close the loop of the entire recycling process.
After the classification done by ADR (Advanced Dry Recovery) the two fractions "airknife" and "rotor" (that together constitute the fraction 0 - 4 mm) are inserted in a new machine that works at high temperatures.
The temperatures analysed in this research are 600 °C and 750 °C, cause at that temperature it is supposed that the cement bounds become very weak.
The final goal is "to clean" the coarse fraction (0,250 - 4 mm) from the cement still attached to the sand and try to concentrate the cement paste in the fraction 0 - 0,250 mm.
This new set-up is able to dry the material in very few seconds, divide it into two fractions (the coarse one and the fine one) thanks to the air and increase the amount of fines (0 - 0,250 mm) promoting the attrition between the particles through a vibration device.
The coarse fraction is then processed in a ball mill in order to improve the result and reach the final goal.
Thanks to the high temperature it is possible to markedly reduce the milling time.
The sand 0 - 2 mm, after being heated and milled is used to replace 100% of norm sand in mortar production.
The results are very promising: the mortar made with recycled sand reaches an early strength, in fact the increment with respect to the mortar made with norm sand is 20% after three days and 7% after seven days.
With this research it has been demonstrated that once the temperature is increased it is possible to obtain a clean coarse fraction (0,250 - 4 mm), free from cement paste that is concentrated in the fine fraction 0 - 0,250 mm.
The milling time and the drying time can be largely reduced.
The recycled sand shows better performance in terms of mechanical properties with respect to the natural one.
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Li, Zihui. "Acid Leaching Resistance and Alkali Silica Reaction (ASR) of Alkali-Activated Cement Free Binders." Thesis, Clarkson University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10640300.
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Recently, increased awareness of the significance of developing sustainable materials for construction has renewed the interest in exploring Alkali activated concrete (AAC), a concrete that contains no cement, but only industrial by-products such as fly ash and slag, as a low energy alternative to the conventional concrete. Although the feasibility of making alkali–activated concrete with acceptable strength and mechanical properties is well documented, the information regarding the long-term durability, including resistance to acid attack and alkali silica reaction (ASR), is far from comprehensive and there is a need to increase the understanding of these durability issues. In this dissertation, these durability issues are addressed, and improvements in this novel technology will increase acceptance in industry. This dissertation presents a comprehensive evaluation into the acid leaching resistance of Alkali-Activated Concrete (AAC) and Ordinary Portland Cement (OPC). The deterioration in AAC and OPC when exposed to different types of acid laden (organic and inorganic) environments are quantified by characterizing the strength degradation, mass change and visual appearances. The changes in microstructure development and chemical composition are examined and analyzed in order to determine the mechanism of deterioration. Additionally, the effect of the addition of nanoparticles on the mechanical properties and resistance to sulfuric leaching of Alkali Activated Slag concrete (AAS) are also explored in this study.
Furthermore, this dissertation summarizes the findings of an experimental evaluation of alkali silica reaction (ASR) in cement free alkali activated concrete (AAC). The susceptibility of AAC to deleterious ASR was evaluated in this study in accordance with relevant ASTM standards. This study also compares the resistance of AAC with ordinary portland cement concrete (OPC) while exposed to ASR under ASTM C 1293 and ASTM C1567 tests. In particular, the focus of this investigation is to assess the effectiveness of existing ASTM test methods in identifying the occurrence of ASR in alkali activated slag cement (AAS) concrete. In addition to that, influences of activator parameters including the effect of binder type, activator concentration, activator type and water content to the resistance of ASR in AAC were also evaluated. Finally, a scanning electron microscopic study coupled with EDX analyses was used to explain the mechanism of ASR occurrence in AAC and OPC.
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Al-Ghamdi, Hamed A. "Effect of curing and mix design parameters on durability of Portland cement and Portland cement-silica fume mortars in a hot-marine environment." Thesis, University of Aberdeen, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301075.
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This study was conducted to evaluate the effect of curing and mix design parameters, such as cement content and water to cementitious materials ratio, on the strength and durability characteristics of plain and silica fume cements exposed to a hot-marine environment. Specifically, the effect of curing and mix design parameters on chloride diffusion, shrinkage and carbonation of cement mortar specimens exposed to a hot-marine environment was evaluated. The results indicated that high water to cement ratio significantly influenced the durability performance of concrete through: (1) accelerating chloride diffusion and carbonation, (2) increasing the shrinkage and weight loss, and (3) reducing the compressive strength. Similarly, increasing the cement content increased the shrinkage for a given w/c ratio. However, the chloride diffusion and carbonation were minimized and strength was enhanced due to increasing cement content. The mix design parameters, namely, water-cement ratio and cement content significantly influenced the performance of both Type I and Type V cements, while the influence of these parameters on the performance of silica fume cements was insignificant. Although Type I cement mortars performed better than Type V cement mortars, the performance of silica fume cement was the best in terms of reduced chloride diffusion, carbonation and shrinkage, and enhanced strength. The beneficial effects of silica fume cements, were however, only evident in specimens subjected to good curing. Therefore, to extend the useful service-life of reinforced concrete structures exposed to hot-marine environments, the following mix design is recommended: (i) cement content should not be less than 350kg/m3; (ii) Type I cement with 10% silica fume; (iii) water to cementitious materials ratio of not more than 0.45; (iv) good curing.
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Winslow, Daniel F. "Effects of Iron and Grain Substrate on the Precipitation of Silica Cement in Quartz-Rich Rocks." Bowling Green State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1355966847.
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Luchini, Timothy John Franklin. "Development of High Strength Dicalcium Phosphate Anhydrous Cement with Nanosilica Sol." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1353010180.
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Oertel, Tina [Verfasser], and Josef [Akademischer Betreuer] Breu. "The Influence of Amorphous, Sub-Micrometer Silica Particles in Cement Pastes and Mortars with Very Low Water-to-Cement Ratios (Ultra-High Performance Concrete) / Tina Oertel. Betreuer: Josef Breu." Bayreuth : Universität Bayreuth, 2014. http://d-nb.info/1059910241/34.
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Joshua, Nilmini Sureka, University of Western Sydney, and Faculty of Science and Technology. "Novel phosphate bonding composites." THESIS_FST_XXX_Joshua_N.xml, 1997. http://handle.uws.edu.au:8081/1959.7/282.
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A cement material has been developed that has a controllable set time, compressive strength of about 50 MPa and shrinkage of under 2% when heated to 960 degrees centigrade. The main compound of this material has been shown to be the potassium analogue of struvite, in which potassium ion is substituted for the ammonium ion. The cement is formed by reacting a slurry made with potassium carbonate and monoammonium phosphate with magnesium oxide. Ihe amount and rate of addition of water to the mixture is controlled to determine the set time. It has been demonstrated that this cement may be used as a matrix in conjunction with cenospheres or cellulose fibres to form a low density composite material, and with silica powder to form a high strength composite. As well as optimising the cement mix for maximum strength and minimum shrinkage, a variety of properties of the K-cement were investigated. It was found that long term exposure of the cement to the atmosphere does not result in the formation of magnesium carbonate, but long term exposure to saline solutions can result in the formation of dypingite on the surface. No effect on strength was observed as a consequence of the age of the slurry or the cement, within 1-2 weeksDoctor of Philosophy (PhD)
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Barek, Jaroslav. "Vliv koloidního oxidu křemičitého na vybrané vlastnosti cementových past a malt." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240488.
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The presented diploma thesis deals with the potential use of colloidal silica in cement composites. Investigation is focused primarily on selected properties of cement pastes and mortars with colloidal silica content. Two selected types of colloidal silica (particles with average size of 14 nm) have been used as a cement addition and partial replacement of cement, respectively. The experimental program for cement pastes with colloidal silica included tests for isothermal calorimetry (the study of cement hydration) and thermal analysis (determining the portlandite content). Hardened cement pastes have been studied through measurements of compressive strength. The microstructure was examined by scanning electron microscopy. Hardened mortars with colloidal silica have been studied through measurements of compressive strength, flexural strength, modulus of elasticity and fracture mechanics parameters. Fracture mechanics tests show that 5 % and 20 % addition of colloidal silica can enhance after 28 days of curing fracture energy up to 18,4 % and 32,7 %, respectively. For the compressive strength enhancing effect of colloidal silica, it was found to be more pronounced in the early age, while rate of strength gain can be lower than the control in the later ages. Our investigations revealed that the silica sol will coagulate immediately when the cement is mixed into the water containing sol. The ionic composition of pore fluid significantly influences the stability of colloidal silica and lead to their aggregation. After additional tests it has been found that small addition of calcium hydroxide greatly improved the compressive strength of the resulting cement pastes with colloidal silica content. Addition of calcium hydroxide in conjunction with modified cement paste preparation can enhance compressive strength after 3 days of curing up to 64,4 % in comparison with the blank paste.
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De, Milito Jose Antonio. "Avaliação do desempenho de aglomerante a base de gesso com cimento portland de alto forno e silica ativa." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258270.
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Orientador: Gladis CamariniTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-09T18:12:28Z (GMT). No. of bitstreams: 1 DeMilito_JoseAntonio_D.pdf: 60807018 bytes, checksum: d77cec46bea9822138fd4024fad50842 (MD5) Previous issue date: 2007
Resumo
Resumo: O gesso é um aglomerante que tem sido muito empregado em revestimento de paredes. Apresenta um bom desempenho, é econômico e de fácil aplicação, mas limitado ao uso interno devido a sua sensibilidade à água. Algumas tentativas têm sido realizadas para melhorar a sua utilização em ambientes sujeitos à umidade. Neste sentido, pesquisas avançam na tentativa de empregar diferentes adições como resinas epóxi, polímeros, cimentos, escórias, impermeabilizantes, entre outros. O objetivo desta tese foi avaliar o desempenho das misturas de gesso com cimento Portland de Alto Forno e sílica ativa nos revestimentos internos e externos sujeitos à umidade. Para isso verificaram-se as propriedades macroscópicas das misturas por meio de ensaios físicos, químicos, físico-químicos e também a avaliação microestrutural utilizando a microscopia eletrônica de varredura. As misturas foram aplicadas em revestimentos de painéis de alvenaria de blocos de concreto e observados visualmente por um período de cinco anos. Além da observação visual foi verificada a resistência de aderência das misturas aplicadas internamente e externamente. Dos resultados obtidos observou-se uma possível coexistência entre o gesso e o cimento e que a adição de sílica ativa na mistura reduz a formação de etringita, principalmente nos revestimentos externos, sujeitos à umidade. A adição de cimento Portland melhora na abrasão e perda de massa, mesmo em idades mais avançadas. Assim, devido ao elevado custo de algumas adições, e as dificuldades de trabalhar com outros tipos de adição na obra, a adição de cimento Portland e sílica ativa ao gesso permitem uma melhoria de resistência, obtendo um revestimento de baixo custo e de fácil manuseio.
Abstract
Abstract: Plaster of Paris is a binding material being used in masonry as a plaster finish coat. Despite being economical, having good performance as and ease with wich it is applied in building, its use is limited to indoors. Some attempts has been made to improve its performance in external environment. In that sense, researches advance in the attempt at using several admixtures like epoxy resins, polymers, cements slags, waterproofing materials among other things. The objective of this thesis is to assess the performance of certain mixtures of rendering material containing plaster of Paris, slag cement and condensed silica fume when applied in the internal and external plaster finish coat. The macroscopic properties of the mixtures were analyzed through physical and chemical tests and also in SEM. Mixtures were applied on coatings of brick and mortar and visually inspected within five years. Bond strengths of the mixtures were measured, both in internal and external walls. Results showed compatibility between plaster of Paris and slag cement and that presence of condensed silica fume in the mixture reduced the formation of etringite, especially in the external coatings. The addition of Portland blastfurnace slag cement reduced the abrasion and the loss of mass, even in older ages. Therefore, due to the high cost of some admixtures, and the difficulty in working with other kinds of admixtures in the construction sites, the mentioned additions to the plaster rendering allow a mechanical strength improvement, thus resulting in low cost and good workability of the plaster finish coat.
Doutorado
Edificações
Doutor em Engenharia Civil
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Trindade, Guilherme Hoehr. "Influência da incorporação de cinza da casca do arroz e sílica ativa no cimento Portland frente à reação álcali-sílica : desenvolvimento de uma nova proposta de método para avaliação da RAS em materiais suplementares ao cimento Portland." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/131343.
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Alguns materiais, constituídos quase que exclusivamente por sílica, são empregados, de forma suplementar ao cimento Portland, por promoverem melhorias ao concreto, devido aos seus efeitos físicos e pozolânicos, além de atenderem a questões ambientais. No entanto, essa sílica pode gerar produtos indesejados na presença de álcalis, sendo este fenômeno conhecido como reação álcali sílica (RAS). Na presença de água, esses produtos são capazes de expandir no interior da massa de concreto, provocando fissuras internas e externas e, em casos mais graves, a degradação do elemento estrutural. Com a finalidade de evitar essa manifestação patológica, o presente trabalho propõe-se avaliar o potencial reativo frente à RAS da sílica ativa e dois tipos de cinzas da casca do arroz (CCA), uma comercial e outra residual. Nessa investigação foram adotados os teores de 5 a 50 %, utilizados como substituição parcial ao cimento Portland padrão. Os métodos de ensaio adotados nesta pesquisa foram o método acelerado em barras de argamassa segundo a NBR 15577 - 4/5, e dois novos métodos acelerados (cubos de pasta e prismas). O métodos acelerado em cubos de pasta avaliou a resistência à compressão, enquanto o método em prismas de pasta avaliou a variação dimensional. Os resultados obtidos em barras de argamassa apontaram que ambas as CCA investigadas, foram reativos frente à RAS. No entanto, o teor de 50 %, em ambas as CCA, se mostrou inócuo para essa reação. A sílica ativa foi considerada inócua em todos os teores avaliados. O aditivo superplastificante empregado não foi eficiente em reduzir a expansão provocada pela CCA. Os ensaios que avaliaram a expansão em prismas de pasta apresentaram uma ótima correlação positiva com o método normalizado em barras de argamassa. Nos prismas de pasta com 25 % de CCA industrial foram identificados os compostos franzinite, chessexite e thaumasite. Estes compostos apresentaram morfologia de acículas ora tortuosas ora delgadas e retilíneas compondo todas as amostras coletadas dessa pasta. A análise termogravimétrica apontou o alto poder adsorvente de água dessa pasta. Em conclusão, o ensaio em prismas de pastas a 48°C com 1,25 % de Na2Oeq demonstrou ser um método prático laboratorialmente e apresentou um grande potencial para avaliar os materiais suplementares ao cimento Portland frente a RAS, além de facilitar identificação dos produtos que provocaram expansão.Some materials, consisting almost exclusively for silica, are employed, supplementary form to Portland cement, for promoting improvements to concrete, due to their physical and pozzolanic effects and environmental issues. However, this silica may generate unwanted products in presence of alkalis. This phenomenon is known as alkali-silica reaction (ASR). In the presence of water, these products are able to expand inside concrete, generating internal and external cracks and, in severe cases, structural element degradation. In order to prevent this pathologic manifestation, the aim of the present study was to evaluate reactive potential in ASR of fume silica and two types of rice husk ash (RHA), a manufacturing and residual. Levels of 5 to 50 % were used as partial replacement to standard Portland cement. In the present study, accelerated method in mortar bars according to NBR 15577 - 4/5 and two new accelerated methods (pastes cubes and prisms) were used. Accelerated method in paste cubes evaluated compressive strength, while method in paste prims evaluated dimensional change. Results in mortar bars demonstrated, both RHA, were reactive to ASR. However, level of 50 %, both RHA, was innocuous to ASR. Fume silica was innocuous to ASR at all levels evaluated. Superplasticizer additive was not effective to reduce to expansion caused by RHA. In the cubes assay was possible to evaluate the reactive potential to ASR by analysis of variation coefficient. Results demonstrated a positive correlation between expansion in paste prism and standard method in mortar bars. In the paste prism with 25 % of RHA manufacturing were identified compounds of franzinite, chessexite and thaumasite. These compounds presented morphology of needles sometimes tortuous and sometimes thin and straight in all samples. Thermogravimetric analysis showed the high adsorbent power of water in this paste. In conclusion, paste prims assay at 48ºC with Na2Oeq 1.25 % demonstrated to be a practical laboratory method and presented a great potential to evaluate additional material to Portland cement in front of ARS, and this assay facilitates the identifications of products that cause expansion.
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Grande, Fernando Mazzeo. "Fabricação de tijolos modulares de solo-cimento por prensagem manual com e sem adição de sílica ativa." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18141/tde-07072003-160408/.
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Neste trabalho, por meio de uma metodologia experimental foram analisados vários aspectos de tijolos modulares compostos por misturas binárias e ternárias de solo-cimento e solo cimento-sílica produzidos em prensa manual modelo SAHARA, com a finalidade de se obter parâmetros e diretrizes que visam um melhor desempenho do material. Realizaram-se ensaios em corpos-de-prova cilíndricos de maneira acessória no decorrer do trabalho, o que resultou no suporte para fundamentação de diversas avaliações sobre as composições de traços utilizados na fabricação dos tijolos. Foram executados painéis de parede com o objetivo de verificar o comportamento da alvenaria em relação à resistência à compressão e à deformabilidade das paredes, possibilitando correlações com os resultados dos ensaios de prismas, tijolos e argamassa de assentamento. As contribuições da pesquisa permitem relacionar a tecnologia da fabricação de tijolos de solo-cimento com o contexto de construção sustentável e o aproveitamento de resíduos industriais, além de sistematizar informações para a elaboração de um projeto tecnológico com os tijolos modularesIn this work, several aspects of modular bricks composed by binary and ternary mixtures of soil-cement and soil-cement-silica, produced by manual press model SAHARA, were analyzed by means of an experimental methodology, with the purpose of obtaining parameters and guidelines to aim a better performance of the material. During the work, tests in cylindrical samples were executed in an accessory way, what resulted in the support for theoretical basement of several evaluations about the compositions of proportions used in brick's production. Wall panels were constructed with the objective of verifying the masonrys behavior in relation to the compressive strength and walls strain, promoting correlation with the tests results in prisms, bricks and mortar. The researchs contributions allow to relate the technology of the production of soil-cement bricks with the context of sustainable construction and the use of industrial residues in the production of construction materials, besides systematizing information for the elaboration of a technological project with the modular bricks
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Janča, Martin. "Zlepšení dispergace křemičitého úletu ve vysokohodnotných betonech." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-295699.
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The goal of this work was to create a method for improving the dispersion of silica fumes for use in high performance concrete. Traditional methods used to design and manufacture high performance concrete emphasize the removal of coarse aggregates. Use of specially sorted fine aggregates at relatively low doses, the use of super-plasticizers and siliceous excrement. The low water content was achieved by using superplasticizer on a polycarboxylate basis. The standard ultrasound technology found in each laboratory was selected for the dispersion of silica fume. For experiments were we used dry silica fume powder and aqueous stabilized suspension. For comparison, were prepared different mixtures which showed the effects of the treatment prior to the use of silica fume.
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Kleib, Joelle. "Ecoconception des ciments : synthèse, hydratation et durabilité." Thesis, Ecole nationale supérieure Mines-Télécom Lille Douai, 2018. http://www.theses.fr/2018MTLD0009/document.
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Les ciments sulfoalumineux sont des liants hydrauliques qui, jusqu’aujourd’hui ne sont pas normalisés et ne possèdent donc pas une composition fixe. La teneur en ye’elimite – la phase principale de ce ciment- peut varier de 5 à 70 %. Or la composition du ciment sulfoalumineux (la composition du clinker ainsi que le pourcentage de gypse ajouté) est un paramètre critique qui contrôle sa réactivité, ses performances mécaniques, ainsi que sa durabilité. L’objectif principal de cette thèse est donc l’étude de l’influence de la composition des ciments sulfoalumineux sur leurs propriétés techniques, telles que les performances mécaniques et durabilité. Trois axes principaux ont été abordés. Tout d’abord une étude de l’influence de la composition du ciment sulfoalumineux (25-75 % en masse de ye’elimite) sur ses propriétés hydrauliques et mécaniques ainsi que sur la valeur limite en élément trace (Zn) a été menée. Dans ce but trois ciment sulfoalumineux (25, 50 et 75 % en masse de ye’elimite) ont été synthétisés. Ensuite l’effet de la variabilité de ce ciment sur sa durabilité dans l’eau pure et sulfatée a été investigué par rapport à un ciment sulfoalumineux commercial. Enfin, une étude des potentialités du ciment sulfoalumineux commercial à inhiber la réaction alcali silice dans les mortiers, lors de l’utilisation d’un granulat réactif (Silex), a été conduite. Il en résulte de cette étude qu’une augmentation de taux de ye’elimite dans le ciment sulfoalumineux engendre une augmentation des performances mécaniques. La valeur limite en Zn est de 0,3 % indépendamment de la composition du ciment sulfoalumineux. Par contre cette dernière influence la durabilité de ces ciments. Les résultats révèlent que même si la formulation contenant 75 % en ye’elimite confère les meilleures performances mécaniques, sa durabilité était la plus faible due à l’absence de stratlingite dans sa matrice cimentaire. Enfin, l’utilisation du ciment sulfoalumineux présente des bonnes potentialités à inhiber la réaction alcali siliceSulfoaluminate cements are hydraulic binders that, until today, are not standardized and therefore do not have a fixed composition. The content of ye'elimite - the main compound of this cement - can vary from 5 to 70 %. However, the composition of sulfoaluminate cement (clinker composition as well as the percentage of added gypsum) is a critical parameter that controls its reactivity, mechanical performance, as well as its durability. The main objective of this thesis is to study the influence of sulfoaluminate cements composition on their technical properties, such as mechanical performances and durability. Three main axes were discussed in this work. First, the influence of the sulfoaluminate cement composition (25-75 wt. % of ye'elimite) on its hydraulic and mechanical properties, as well as on the threshold limit of Zn, was studied. For this purpose three sulfoaluminate cements (25, 50 and 75 wt. % of ye'elimite) were synthesized. Then the effect of the variability of this cement on its durability in pure and sulphated water was investigated compared to a commercial sulfoaluminate cement. Finally, a study of the potentialities of commercial sulfoaluminate cement to inhibit the alkali silica reaction in mortars, when using a reactive aggregate (flint), was conducted. This study reveals that an increase in ye'elimite content in the sulfoaluminate cement increases the mechanical performance. The threshold limit of Zn is 0.3 % independently of the sulfoaluminate cement composition. Contrariwise, the sulfoaluminate cement composition influences the durability of these cements. Although the formulation containing 75 % of ye’elimite gives the best mechanical performances, its durability was lowest due to the absence of stratlingite in its cement matrix. Finally, the use of sulfoaluminate cement has good potential towards the inhibition of the alkali silica reaction
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Bradová, Lada. "Studium alkalicko křemičité reakce v hybridních systémech." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-414119.
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This study evaluates question of alkali–silica reaction (ASR) in hybrid system, which was designed in the bachelor's thesis, to meet the requirements of EN 197-1 and classified to the Blastfurnace CEM III/C cements. The durability of this system is a great unknown. For this reason, the same methods (ASTM C1260, ASTM C289 and ASTM C856) were used to observer the ASR effects as the ones used to observer the Portland cement based concrete. Supplementary methods include determination of compressive strengths according to EN 196-2 and scanning electron microscopy to observe the microstructure. Hybrid system results were compared to two different types of cements, CEM I and CEM III/B. From the results of the ASR evaluation assays, it was found that the hybrid system (CEM III/C-HB) and CEM III/B showed the lowest tendency to ASR. The results of the supplementary methods showed that CEM III/C-HB compressive strength increases after 14 days within NaOH by 43 % in comparison to 28 days strength. Based on those results, it is sure that the CEM III/C-HB shows little susceptibility to ASR.
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Černá, Eva. "Ověření vlivu složení betonů na životnost cementobetonových krytů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371844.
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Alcali – silica reaction often causes destruction of a concrete.constructions. In the theoretical part is described creation and causes of the ASR including assessment of individual components of concrete and their testing. The practical part is devoted to the results of some control tests of the concrete cover in the section 18 of the highway D1 (Měřín - Velké Meziříčí) and section D1-20 (Velké Meziříčí - Lhotka), the mechanical properties of the upper and the lower layer of the concrete cover and measuring the resistance of concrete against chemical deicing agents.
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Prokopec, Zdeněk. "Mechanické aktivace příměsí do betonů a ověření dopadů na fyzikálně-mechanické vlastnosti čerstvých a zatvrdlých betonů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225684.
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This work is devoted to describe the possibilities of mechanical activations of admixtures used in concrete. Then, the verification options of grind fly ash, both from brown and black coal, from the classical as well as fluidized combustion and examination their impact on physical and mechanical properties of concrete, especially on long-term development to old age 180 days. Further attention is paid to assessing the impact of the use of mechanically activated fly ash on hydration heat evolution and the associated volume changes in the age of 1 to 90 days. In this work are presented the results of basic technological tests on concretes using admixtures, especially fly ash.
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Bílek, Vlastimil. "Možnosti využití odpadních písků z výroby vodního skla ve stavebnictví." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-216992.
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Nowadays, the waste sands from the water glass production have no utilization and due to high alkali content are considered as a dangerous waste. So the aim of this thesis is to find and study some possibilities of their utilization in the building industry. First of all, some necessary analysis of these sands were performed and then some advantages and disadvantages of their application for production of materials based on portland cement and alkali activated materials were studied. Characteristics of fresh and hardened pastes, mortars and concretes containing these waste sands were determined. The most tested properties were their workability and their compressive and flexural strength. Close attention for the risks of alkali-silica reaction and for options of its suppressing by the mineral admixtures was paid.
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Munhoz, Flávio André da Cunha. "Efeito de adições ativas na mitigação das reações álcali-sílica e álcali-silicato." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-10012008-100734/.
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A reação álcali-agregado é uma manifestação patológica diretamente ligada à seleção dos materiais (cimento, agregados miúdo e graúdo, água e aditivos) que pode comprometer a durabilidade das estruturas de concreto, uma vez que a interação desses materiais e as condições ambientais é que vão conferir ao concreto determinadas propriedades ligadas à sua vida útil. A reação entre os hidróxidos alcalinos solubilizados na fase líquida dos poros dos concretos e alguns agregados reativos é lenta e resulta em um gel que, ao se acumular em vazios do concreto e na interface pasta-agregado, na presença de água, se expande, exercendo pressão interna no concreto. Ao exceder a resistência à tração do concreto, a pressão interna pode promover fissurações. A reação álcali-agregado requer a atuação conjunta de água, agregado reativo e álcalis. Sua prevenção pode ser feita a partir da eliminação de um dos fatores, ou seja, a partir do emprego de agregados inertes ou de cimentos com baixos teores de álcalis ou isolamento da umidade. Na impossibilidade de eliminar um dos fatores, medidas preventivas devem ser tomadas para o emprego de agregados reativos em obras de construção civil. Entre essas, destacam-se a utilização de cimentos com baixos teores de álcalis ou a de cimentos com adições ativas mitigadoras da reação álcali-agregado: escória de alto-forno, cinza volante, metacaulim e sílica ativa, que foi o objeto de pesquisa do presente trabalho. No programa experimental foram analisados dois tipos de agregado potencialmente reativos com os hidróxidos alcalinos: EDVDOWR e PLORQLWR_ JUDQtWLFR. O primeiro, proveniente de rocha ígnea, tem como constituintes deletérios vidro, clorofeíta, calcedônia (sílica criptocristalina), que dará origem à reação do tipo iOFDOL_VtOLFD. O agregado milonito granítico provém de rocha metamórfica, tem como constituintes deletérios quartzo microgranular, quartzo recristalizado, quartzo com extinção ondulante e quartzo e feldspato deformados, que dará origem ao tipo de reação iOFDOL_VLOLFDWR. Com o objetivo de avaliar a eficiência de adições ativas em mitigar as reações, os agregados foram combinados com 16 cimentos com adições ativas. Escória de alto-forno foi adicionada a 15%, 30%, 45% e 60% e cinza volante, a 10%, 15%, 25% e 35%, teores normalmente encontrados nos cimentos brasileiros. Metacaulim foi adicionada a 5%, 10%, 15% e 20%, e sílica ativa, a 5%, 10% e 15%, teores representativos da faixa normalmente adicionada diretamente a concretos. Todos os materiais utilizados foram caracterizados química, física e mineralogicamente, incluindo a análise petrográfica dos agregados. As barras de argamassa foram analisadas ao MEV, microscópio óptico de luz transmitida, realizaram-se ensaios de porosimetria por intrusão de mercúrio e análises térmicas para quantificar a teor de portlandita residual, e determinou-se o teor de álcalis dentro das barras após a realização dos ensaios para verificar a migração de íons de sódio. Os resultados indicam que a eficiência das adições ativas varia de acordo com a composição química e mineralógica das adições, da proporção desse material no cimento, e do grau de reatividade do agregado.The alkali-aggregate reaction is a pathologic manifestation that can induce the premature distress and loss in serviceability of concrete structures affected. It is directly associated to the selection of materials (cement, coarse and fine aggregates, water and additives), as the interaction between these materials and environmental condition will grant the concrete some of the properties related to its service life. The slow reaction between alkali hydroxides soluble in the liquid phase within concrete pores and reactive aggregates gives rise to a gel that piles up within concrete voids and the aggregate-paste interface. In presence of water, the gel expands and exerts internal pressure in the concrete. When the internal pressure exceeds the tensile strength, cracking may come up as result. The alkali-aggregate reaction requires the action of water, reactive aggregate and alkalis altogether. Prevention can be carried out by eliminating one of these factors, i.e. employing either inert aggregates or lowalkali cements, or keeping the concrete away from moisture. Otherwise, preventive measures must be taken when reactive aggregates are used in civil construction works, such as the use of low-alkali cements or composite cements bearing alkaliaggregate- reaction mitigating admixtures: blast-furnace slag, fly ash, metakaolin and silica fume, which are the object of the present research. The experimental work included the analysis of two potentially reactive aggregates to alkali hydroxides: basalt and granite milonite. The igneous basalt carries deleterious constituents such as glass, chloropheite (cryptocrystalline silica), that will give rise to the DONDOL_VLOLFD type reaction while the metamorphic granite milonite carries micro granular, recrystallized, undulate-extinction-bearing quartz and deformed feldspar grains, that give rise to DONDOL_VLOLFDWH type reaction. Aiming at evaluating how efficient in mitigating these reactions the active admixtures are, these aggregates were mixed with 16 composite cements. The contents of admixtures followed those usually found in Brazilian industrial cements for blast-furnace slag (15%, 30%, 45%, 60%) and fly ash (10%, 15%, 25%, 35%), and those generally added directly to concrete for metakaolin (5%, 10%, 15%, 20%) and silica fume (5%, 10%, 15%). All materials were characterized for their chemical composition, physical properties and mineralogy. Petrography was carried out on the aggregates. The mortar bars were analyzed at the scanning electronic and transmitted-light optical microscopes. Mercury-intrusion porosimetry and thermal analyses were carried out to quantify residual portlandite. The alkali content within the bars was determined in order to verify migration of Na+ ions. The results show that the efficiency of active admixtures varies according to their chemical and mineralogical composition and proportioning in cement, and to the aggregate reactivity.
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Moustachi, Om Elkhaïat. "Influence de la microstructure des mortiers de ciment portland armes de fibres sur leur comportement mecanique en flexion." Toulouse, INSA, 1986. http://www.theses.fr/1986ISAT0002.
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Analyse des modifications de la structure interne du mortier induites par l'introduction des fibres et determination de leur influence sur les proprietes mecaniques du mortier en flexion. Des fiches en paquets introduites dans le mortier se dispersent lors du malaxage en fibres individuelles espacees de quelques microns. Ces espaces, tres peu accessibles aux particules anhydres du ciment sont partiellement remplis par des hydrates. Ils rendent le mortier tres permeable aux fluides et influent directement sur son module d'elasticite en flexion qui diminue avec le pourcentage de fibres. L'effet d'armature des fibres se traduit par une augmentation de la resistance et de l'allongement a la rupture du mortier. De la fumee de silice dispersee a l'aide d'un fluidifiant reduit la porosite entre les fibres et augmente ainsi le module d'elasticite et sa resistance a la rupture
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Tixier, Raphaël. "Etude mineralogique et mecanique de la phase liante de graves routieres." Toulouse 3, 1987. http://www.theses.fr/1987TOU30133.
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Comparaison des caracteristiques mineralogiques et des proprietes mecaniques de melanges equiponderaux de fillers calcaires, dolomitiques ou quartzeux avec 5 liants : ciment portland, ciment alumineux, ciment au laitier, cendres volantes chaux eteinte et fumees de silice condensees chaux residuaire. Evocation d'un nouveau liant routier, par melange de cendres volantes, fumees de silice condensees et chaux (l'additivite des proprietes se realisant pour des proportions particulieres)
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Lázari, Larissa Mendes de [UNESP]. "Cimentos bioativos injetáveis funcionalizados com peptídeo osteogênico para reparação óssea." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/137991.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O desenvolvimento de biomateriais que promovam a reparação de tecidos lesionados tem sido objeto de intensa investigação. Em relação à reparação do tecido ósseo, as cerâmicas são materiais muito pesquisados em função de sua ampla possibilidade de uso, inclusive na confecção de pastas cimentícias moldáveis. A sílica mesoporosa apresenta elevada área de superfície específica (~1000 m2.g-1) e tamanho de poros usualmente em torno de 2-30 nm, atraindo atenção para aplicações como importantes carreadores de fármacos e proteínas. O peptídeo de crescimento osteogênico (OGP) é um tetradecapeptídeo endógeno, cuja forma ativa atua como agente anabólico e estimulador hematopoiético, promovendo a diferenciação osteoblástica. Desta forma, o objetivo deste trabalho foi desenvolver um cimento ósseo injetável, reabsorvível e bioativo, com sílica mesoporosa e peptídeo de crescimento osteogênico. O peptídeo foi sintetizado pelo método em fase sólida, purificado por Cromatografia Líquida (HPLC) e caracterizado por Espectrometria de Massas. O material mesoporoso foi sintetizado pela metodologia sol-gel e sua porosidade confirmada por Adsorção-dessorção de N2, Espalhamento de Raios X à Baixo Ângulo e Microscopia Eletrônica de Transmissão. Os cimentos foram preparados a partir de sulfato de cálcio (CaS), fosfato de cálcio (CaP) e aluminato de cálcio (CaAl), sem e com sílica mesoporosa, e analisados quanto suas características físico-químicas. Os experimentos in vitro foram realizados para avaliar o potencial citotóxico e genotóxico dos cimentos em cultura de células de ovário (CHO-K1) e análise da viabilidade celular e formação da matriz mineralizada em células pré-osteosblásticas (MC3T3-E1). O estudo in vivo foi realizado em defeitos ósseos críticos em calvária de ratos e analisado quanto à formação de tecido ósseo, por histomorfometria, e densidade do tecido neoformado, por imagens de raios X. As análises dos cimentos demostraram que a presença de partículas de sílica mesoporosa promoveu diferentes comportamentos físico-químicos quando comparados aos cimentos sem sílica, como maior razão líquido/pó e, consequentemente, maior porosidade e menor resistência mecânica à compressão. Os cimentos CaP e CaAl, sem e com sílica, mostraram bioatividade in vitro quando imersos em solução que simula o fluido corpóreo (Simulated Body Fluid - SBF). No estudo de liberação do peptídeo OGP, incorporado nas partículas de sílica mesoporosa pré-misturada aos cimentos, o cimento CaS apresentou maior velocidade de liberação em relação aos cimentos estudados, com 80% do conteúdo peptídico liberado em 24 horas. Em relação à viabilidade celular, os cimentos CaS, com e sem sílica, não foram citotóxicos, mas os cimentos CaP e CaAl, apresentaram citotoxicidade; todavia esse comportamento não comprometeu a proliferação celular e nos ensaios de avaliação da mutagenicidade, os cimentos não promoveram dano celular significante. Os testes envolvendo células MC3T3-E1 mostraram que a viabilidade celular e a capacidade de formação da matriz mineralizada foram independentes da presença do peptídeo OGP, sendo mais sensível à presença de sílica e ao tempo de tratamento com os meios condicionados. Os resultados do teste in vivo, com os cimentos CaP, com e sem sílica mesoporosa e peptídeo OGP, demostraram que esses se degradaram e promoveram maior formação óssea durante os primeiros 15 dias pós-cirúrgico, com aproximadamente 30% do defeito preenchido por tecido neoformado, assim como maior densidade nas margens dos defeitos quando comparados com o controle. No entanto, a presença do peptídeo OGP foi significante somente nos primeiros 30 dias pós-cirúrgico de análise e não houve diferença estatística com o cimento com sílica e sem peptídeo. Além do mais, não houve diferença entre os grupos experimentais e o controle nos períodos mais tardios de análise. De acordo com os resultados obtidos, conclui-se que, dentre os cimentos estudados, aqueles com partículas de sílica mesoporosa e peptídeo OGP são os mais promissores para o reparo do tecido ósseo, principalmente nos períodos iniciais de cicatrização, devido ao seu potencial osteogênico.
The development of biomaterials that promote repair of injured tissues has been the subject of intense research. Regarding the bone tissue repair, ceramics are one of the most researched biomaterials groups due to its wide possibility of use, including cement pastes with good moldability. The mesoporous silica has high specific surface area (~1000 m2.g-1) and pore size usually around 2-30 nm attracting attention for its applications as drugs and proteins carriers. The osteogenic growth peptide (OGP) is an endogenous tetradecapeptide, whose active form acts as an anabolic agent and hematopoietic stimulator, promoting osteoblast differentiation. Thus, the aim of this study was to develop an injectable bone cement, resorbable and bioactive, mesoporous silica and osteogenic growth peptide. The peptide was synthesized by the solid phase method, purified by High Performande Liquid Chromatography (HPLC) and characterized by Mass Spectrometry. The mesoporous materials were synthesized by sol-gel method and its porosity confirmed by Adsorption-desorption of N2, Small-angle X-ray Scattering and Transmission Electronic Microscopy. Cements were prepared from calcium sulfate (CaS), calcium phosphate (CaP) and calcium aluminate (CaAl), without and with mesoporous silica, and analyzed for its physicochemical characteristics. In vitro experiments were carried out to evaluate the cements cytotoxic and genotoxic potential in CHO-K1 hamster ovary cell line and analysis of the mineralized matrix formation in MC3T3-E1 osteosblastics cell line. The in vivo study was performed in critical defects in rat calvaria, and it has analized as formation of bone tissue by histomorphometry and density of newly formed tissue by X-ray images. The cements analysis have shown that the presence of mesoporous silica particles promoted different physico-chemical behavior when compared to those without silica, such as higher ratio Liquid/Powder, higher porosity and, hence, decreases the mechanical resistance. CaP and CaAl cements showed bioactivity in vitro when immersed in Simulated Body Fluid solution. Concerning OGP liberation, the CaS cement showed the fastest release in the OGP-mesoporous silica-loaded cement release studies, releasing 80% peptide loaded in 24 hours. Regarding cell viability, CaS cements with and without silica, were not cytotoxic, but the CaP and CaAl cement showed cytotoxicity; however this behavior did not affect cell proliferation. And in mutagenicity tests, the cements did not promote significant cell damage. The tests involving MC3T3-E1 cells showed that cell viability and mineralized matrix formation capacity is independent of the OGP peptide presence and it is more sensitive to the presence of silica and the treatment time with the conditioned culture media. The test in vivo, with CaP cements, with and without mesoporous silica and OGP, demonstrated that these cements have degraded and promoted increased bone formation during the first 15 postoperative days, with approximately 30% of the defect filled by newly formed tissue as well as higher density on the defects borders when compared to the control. However, the presence of OGP peptide was significant only during the first 30 days postoperative, but there was no statistical difference with silica cement and without this peptide. Furthermore, there was no difference between experimental groups and the control in the later study periods. According to the results, it is concluded that, among the cements studied, those with mesoporous silica particles and OGP peptide are the most promising for bone tissue repair, especially in the initial stages of healing due to its osteogenic potential.
FAPESP: 2012/21735-6
CAPES: 0224-13-8
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Bardella, Paulo Sergio. "Avaliação das propriedades fisicas e mecanicas de concretos produzidos com os cimentos Portland de alta resistencia inicial e de alto-forno aditivados com silica ativa curados termicamente." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257816.
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Orientador: Gladis CamariniDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: A durabilidade das estruturas de concreto depende da estrutura porosa e da impermeabilidade do concreto, uma vez que a entrada de água e de agentes deletérios iniciam os processos patológicos que diminuem a vida útil de uma estrutura de concreto. Dessa forma, o objetivo deste trabalho foi avaliar a resistência mecânica, permeabilidade, absorção e carbonatação natural de concretos submetidos a diferentes condições de cura. Os procedimentos de cura adotados são normalmente utilizadds em canteiros de obra e na produção de estruturas pré-moldadas de concreto: cura imersa até a idade de 7 dias, cura ambiente e cura térmica. A cura térmica foi realizada na temperatura de 60°C. Foram empregados concretos produzidos com cimento Portland de Alta Resistência Inicial (CP V ARI) e cimento Portland de Alto Forno (CP III) sem e com sílica ativa (em substituição ao cimento na proporção de 10% em massa) para cada um dos diferentes tipos de cura utilizados. Os resultados evidenciaram que o tipo de cura afeta o desempenho do concreto. A mudança do tipo de cura aplicada proporcionou variações nas propriedades mecânicas e na durabilidade dos concretos, principalmente no que diz respeito à sua estrutura porosa. Assim, um regime de cura adequado é essencial para garantir a resistência mecânica e a durabilidade dos concretos. A utilização de sílica ativa em substituição ao cimento melhorou o desempenho dos concretos, tanto para a resistência mecânica quanto para a durabilidade, independente do tipo de cura empregado
Abstract: The durability of concrete structures depends on porous structure and its impermeability. The entrance of water and deleterious agents begin the damage processes and reduce the life of the concretestructure. ln that way, the aim of this work was to evaluate the mechanical resistance, permeability, absorption and natural carbonation of concretes submitted to different curing procedures. The curing procedures adopted were usually used in civil construction and in the production of precast structures: moist curing until the age 6f 7 days, curing in air, and steam curing. The maximum temperature of steam curing was 60°C. All concretes were produced with High Early Strength Portland cement (CP V ARl) and Blastfurnace Portland cement (CP TIl) without and with silica fume (10% of replacement, by mass, of Portland cement) for each one of the different curing procedure used. The results showed that the curing procedure affects the concrete performance, providing variations in their mechanical properties and in their durability, mainly in porous structure. Therefore, the curing process used is essential to guarantee the mechanical resistance and the durability of the concretes. The use of silica fume improved the performance of the concretes, as for the mechanical resistance as for its durability, independent of the curing procedure used.
Mestrado
Edificações
Mestre em Engenharia Civil
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Rasool, Sava Tnar, and Omar Sharif. "Expansion of Sickla treatment plant : A study about the replacement of standard concrete to green concrete." Thesis, KTH, Betongbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278542.
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Stockholm Vatten has decided to close down the Bromma waste water treatment plantand manage the waste water from Bromma together with the waste water from the formerEolshällsverket to Henriksdal’s waste water treatment plant. Henriksdals wastewater treatment plant will be expanded for higher purification requirements and loads,estimated to be finished until 2040. This entails extensive renovations and additionsto the existing treatment plant in and on Henriksdalsberget, as well as a major expansionof the Sickla plant.The purpose of the study is to investigate an environmentally friendly alternative tothe standard concrete that will be used for the expansion of the Sickla plant. The largestenvironmental villain in concrete is the cement. The aim of this study has beento replace the cement with environmentally friendly additives in the largest possibleamount, thus reducing the negative impact of the cement on the environment.In the present study, a review was made of obtained data with exposure classes, then aliterature study was performed to gain knowledge in the area. With help from experts,two fictitious recipes for each exposure class have been calculated for the standardconcrete and the green concrete. In this way, a careful comparison between the concretetypes was made of the cement’s impact on global warming. Thereafter, a study wascarried out on existing EPDs, which were incorporated into the One Click LCA (2015)software. An LCA in the mentioned software was carried out, which enabled data to becompiled and a comparison of the climate impact between the four different fictitiousrecipes has been done.Compiled and compared data from LCA and analysis of EPDs show that 70% of thestructure with exposure class XD2 gets a 47% reduction in global warming when usinggreen concrete instead of standard concrete. Furthermore, the results show that theremaining 30% of the structure with exposure class XF3/XC4 gets a 20% reductionwhen using green concrete instead of standard concrete. The total reduction in globalwarming when using green concrete instead of standard concrete for the expansion ofSickla treatment plant was calculated to be 40%.Stockholm Vatten har beslutat att lägga ned Bromma reningsverk och leda avloppsvattnetfrån Bromma tillsammans med avloppsvattnet från det forna Eolshällsverkettill Henriksdals reningsverk. Henriksdals reningsverk ska byggas ut för högre reningskravoch belastningar beräknade till år 2040. Detta medför omfattande om- och tillbyggnationeri det befintliga reningsverket i och på Henriksdalsberget samt en storutbyggnad av Sicklaanläggningen.Syftet med detta arbete är att undersöka ett miljövänligare alternativ till standardbetongensom ska användas vid utbyggnaden av Sicklaanläggningen. Då den främsta”miljöboven” i betongen är cementet har målet med denna studie varit att ersätta cementetmed miljövänliga tillsatsmaterial i största möjliga mängd, i syfte att minskacementets negativa inverkan på miljön.I föreliggande arbete har en genomgång utförts på erhållna data med exponeringsklasser,därefter påbörjades en litteraturstudie i syfte att inhämta kunskaper inomområdet. Med hjälp av experter har två fiktiva recept för respektive exponeringsklassräknats fram för standardbetongen och den gröna betongen. Med denna metod genomfördesen noggrann jämförelse mellan de olika recepten avseende cementets inverkanpå den globala uppvärmningen. Därefter undersöktes existerande EPD:er, vilka infogadesin i programvaran One Click LCA (2015). En LCA i den nämnda programvaranutfördes, vilket möjliggjorde att data kunde sammanställas och en jämförelse av klimatpåverkanmellan de fyra olika fiktiva recepten kunde genomföras.Sammanställd och jämförd data från LCA och analys av EPD:er visar att 70% av konstruktionenmed exponeringsklass XD2 får en reducering på 47% på den globala uppvärmningenvid användning av grön betong istället för standardbetong. Vidare visarresultatet att resterande 30% av konstruktionen med exponeringsklass XF3/XC4 fåren reduktion på 20% vid användning av grön betong istället för standardbetong. Dentotala reduktionen på den globala uppvärmningen vid användning av grön betongistället för standardbetong för utbyggnaden av Sickla reningsverk beräknades till 40%.
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Ceferino, Gloria Esther Urrea. "Carbonatação acelerada: um estudo dos parâmetros, efeito da adição mineral, tipo de polpa celulósica e durabilidade em fibrocimento." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/74/74133/tde-14062017-092252/.
Full textAbstract:
O processo de cura de carbonatação acelerada em matrizes cimentícias reforçadas com fibras naturais é um avanço no caminho para a inovação dos materiais compósitos adequados para aplicação nas regiões em desenvolvimento. No entanto, estudos adicionais, sobre o mecanismo da carbonatação em compósitos cimentícios reforçados com fibras naturais, conhecimento para a escolha do tipo de fibra celulósica, os parâmetros da câmara de carbonatação, a idade para começar o processo de cura com carbonatação, a influência da adição mineral e quantificar as fases hidratadas do cimento antes e depois do ensaio de envelhecimento acelerado, e o teste de durabilidade são ainda necessários. O objetivo deste trabalho foi avaliar a definição de parâmetros opcionais para o processo de cura com carbonatação acelerada, identificar as principais fases hidratadas da matriz de cimento e a durabilidade do fibrocimento reforçado com polpa celulosica. As matérias-primas utilizadas para as formulações dos compósitos cimentícios usados nesta investigação incluem: cimento Portland, adição mineral (calcário ou sílica) e reforço de fibra natural (Eucalipto ou Pinus). Os compósitos cimentícios foram produzidas por um processo de sucção a vácuo da mistura e posterior prensagem em pequena escala em laboratório. As condições de cura foram conduzidas em vários conjuntos de amostras, que estudaram o efeito da concentração da carbonatação acelerada (0%, 20% e aproximadamente de 100% de CO2); o efeito de polpa celulósica (não branqueada e branqueada); o efeito da adição mineral (Calcário e Sílica) e, o efeito da durabilidade com o ensaio de envelhecimento acelerado (200 ciclos de imersão e secagem). Utilizou-se uma variedade de métodos de análise para avaliar a cinética de hidratação, as propriedades mecânicas e físicas e as implicações químicas nos compósitos; entre eles: difração de raios-X (DRX), análise termogravimétrica (TG e DTG), espectroscopia de infravermelho (FTIR), microscopia electrônica de varredura (MEV) e área superficial específica B.E.T. Nos compósitos sob concentrações perto do 100% de CO2, os resultados indicam que os compósitos reforçada com polpa branqueada apresentam nos ensaios de flexão valores médios estatisticamente significativos maiores do modulo de ruptura (MOR) e energia especifica ao redor do 24% comparados com os reforçados com polpa não branqueada. Nos compósitos sob concentrações 20% de CO2 os compósitos de sílica resultarem nos ensaios de flexão em valores médios estatisticamente significativos maiores no limite de proporcionalidade ao redor do 46% comparando com os compostos de calcário; O composto que utiliza sílica como adição mineral tem menor quantidade de hidróxido de cálcio (CH) em comparação com o composto com adição de calcário, com base no resíduo de CH detectado na análise de DRX: 3% e 11,5%, respectivamente. Após o envelhecimento acelerado, os compósitos com sílica sujeitos a dois regimes de cura diferentes (carbonatados e não carbonatados) não apresentam redução estatística do desempenho mecânico, com exceção da energia especifica; também há ausência de ettringite (AFt) no padrão XRD. Entretanto, os compósitos que foram sujeitos ao processo de carbonatação apresentam valores médios de MOR estatisticamente significativos mais elevados. Esta assim concluísse em este estudo que para compósitos cimentícios curados com carbonatação acelerada é indicado o uso de polpa branqueada com a sílica como adição mineral.Carbonation accelerated curing process on cementitious matrices reinforced with vegetal fiber is an advance on the way for innovative composite materials suitable for application in developing regions. However, further studies on the carbonation mechanism in natural fiber reinforced cement composite, knowledge about the choice of cellulose fiber, carbonation chamber parameters, the age at which to begin the carbonation curing, the influence of mineral addition and the amount of the main hydrated clinker phases before and after of accelerated aging cycles, and durability test are still needed. The aim of this work was to evaluate the definition of optional parameters for accelerated carbonation curing process, the main hydrated phases of the cement matrix and the durability of fiber-cement reinforced with cellulose pulp. The raw materials used for the cementitious composite mix designs used in this investigation include: Portland cement, filler (limestone or silica) and natural fiber reinforcement (eucalyptus or pines). The cementitious composites were produced by a slurry vacuum dewatering process followed by pressing in laboratory small scale. The curing conditions were conducted on various sets of samples which were studied the effect of accelerated carbonation concentration (0%, 20% and close of 100% of CO2); the effect of cellulosic pulp (unbleached or bleached); the filler effect (limestone and silica); and, the effect of accelerated ageing test (200 soak & dry cycles). A variety of analytical test methods were used to assess the hydration kinetics, the mechanical and the physical properties, and chemical implications in the composites; between them: (X-ray diffraction (XRD), thermogravimetric analysis (TG and DTG), Infrared spectrometer (FTIR), scanning electron microscopy (SEM) and B.E.T. surface area analyzer. On the samples subject to close 100% of CO2 the results indicate that the bleached pulp reinforcement composites show in flexural test average statistically significant higher values of modulus rupture and specific energy around 24 % relating with unbleached pulp. On the samples subject to 20% CO2 the silica composite resulted in flexural test average statistically significant higher values of Limit of proportionality around 46% comparing with the limestone composite; the composite with silica addition presents less amount of calcium hydroxide (CH) in comparison with the composite with limestone addition, based on the CH residue detected in the XRD analysis: 3% and 11.5% respectively. After accelerated aging, the silica composites subject to two different curing regimes (carbonated and uncarbonated) presents no statistical reduction of mechanical performance, also there is an absence of ettringite (AFt) at XRD pattern; nevertheless, the carbonated composites present a significantly higher average MOR values. Thus, it is concluded in this study that for cementitious composites cured with accelerated carbonation the use of bleached pulp with silica as mineral addition is indicated.
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Inada, Rafaela Nanami Handa. "Análise da alteração de cor promovida por materiais reparadores e cimentos endodônticos à base de silicato de cálcio com diferentes radiopacificadores /." Araraquara, 2018. http://hdl.handle.net/11449/153833.
Full textAbstract:
Orientador: Mário Tanomaru FilhoResumo: Materiais reparadores e cimentos endodônticos não devem promover alteração da coloração dental. Este estudo foi dividido em 3 publicações. Publicação 1 - avaliação da alteração cromática dentária promovida por cimentos de silicato tricálcico (TSC) associado com óxido de bismuto (TC-Bi), óxido de zircônio (TC-Zr), óxido de nióbio (TC-Nb) e Biodentine (BD). Publicação 2 - comparação dos efeitos cromáticos induzidos por cimentos TSC-Bi e silicato tricálcio com tungstato de cálcio (TSC-TC), MTA Angelus (MTA) e MTA HP Repair (MTAHP). Publicação 3 - avaliação das alterações cromáticas por cimentos endodônticos, AH Plus (AHP), MTA Fillapex (MTAF), Total Fill BC Sealer (TF) e NeoMTA Plus (NMTAP). Dentes bovinos (n=10) foram seccionados para obtenção de secções vestibulares e palatinos. Na face interna vestibular foram realizadas duas cavidades, uma na porção coronária e outra radicular, que foram preenchidas pelos materiais em estudo e com pasta triantibiótica como controle positivo (CP) e cavidades sem material como controle negativo (CN). A mensuração da alteração cromática (∆E) e luminosidade (L*) foram realizadas com espectrofotômetro, antes da inserção dos materiais (T0), imediatamente após a inserção (T1) e após 7 (T7), 15 (T15), 30 (T30), 60 (T60), 120 (T120) e 180 (T180) dias. Os dados foram avaliados por meio de teste de Análise de Variância de medidas repetidas a dois critérios e Post Hoc teste LSD-Fisher, ambos com nível de significância de 5%. Publicação 1 - na porção cor... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Repair materials and endodontic sealers should not promote tooth staining. This study was divided into 3 publications. Publication 1 - evaluation of dental discoloration of tricalcium silicate (TSC) cements associated with bismuth oxide (TC-Bi), zirconium oxide (TC-Zr), niobium oxide (TC-Nb) and Biodentine (BD). Publication 2 - comparison of the color effects induced by TSC-Bi cements and tricalcium silicate with calcium tungstate (TSC-TC), MTA Angelus (MTA) and MTA HP Repair (MTAHP). Publication 3 - evaluation of color changes by endodontic cements, AH Plus (AHP), MTA Fillapex (MTAF), Total Fill BC Sealer (TF) and NeoMTA Plus (NMTAP). Bovine teeth were sectioned to obtain vestibular and palatine sections. In the internal vestibular face, two cavities were performed, one in the coronary portion and the other one in the root, which were filled with the materials, and triantibiotic paste as the positive control (CP) and cavities with no filling as the negative control (CN). The measurement of the color change (ΔE) was performed with a spectrophotometer, before insertion of the materials (T0), immediately after insertion (T1) and after 7 (T7), 15 (T15), 30 (T30), 60 (T60), 120 (T120) and 180 (T180) days. The data were evaluated by Variance Analysis of repeated measurements at two criteria and Post Hoc LSD-Fisher test, both with a significance level of 5%. Publication 1 - in the coronary portion TSC and CP presented higher ΔE in T180 compared to T1 (p <0,05). Only TSC-Zr and TSC-... (Complete abstract click electronic access below)
Mestre
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Peterson, Vanessa Kate. "Diffraction investigations of cement clinker and tricalcium silicate using Rietveld analysis /." Electronic version, 2003. http://adt.lib.uts.edu.au/public/adt-NTSM20040830.173127/index.html.
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Thesis (Ph. D.)--University of Technology, Sydney, 2003."Submited for the degree of Doctor of Philosophy, University of Technology, Sydney, Dept. of Chemistry, Materials and Forensic Sciences, August 2003" Bibliographic references: leaves 224-232.
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Canham, Ian. "The control of alkali silica reaction using blended cements." Thesis, Aston University, 1987. http://publications.aston.ac.uk/9726/.
Full textAbstract:
It has been previously established that alkali silica reaction (ASR) in concrete may be controlled by blending Portland cement with suitable hydraulic or pozzolanic materials. The controlling mechanism has been attributed to the dilution of the cement's alkali content and reduced mobility of ions in concrete's pore solution. In this project an attempt has been made to identify the factors which influence the relative importance of each mechanism in the overall suppression of the reaction by the use of blended cements. The relationship between the pore solution alkalinity and ASR was explored by the use of expansive mortar bars submerged in alkaline solutions of varying concentration. This technique enabled the blended cement's control over expansion to be assessed at given `pore solution' alkali concentrations. It was established that the cement blend, the concentration and quantity of alkali present in the pore solution were the factors which determined the rate and extent of ASR. The release of alkalis into solution by Portland cements of various alkali content was studied by analysis of pore solution samples expressed from mature specimens. The specification for avoiding ASR by alkali limitation, both by alkali content of cement and the total quantity of alkali were considered. The effect on the pore solution alkalinity when a range of Portland cements were blended with various replacement materials was measured. It was found that the relationship between the type of replacement material, its alkali content and that of the cement were the factors which primarily determined the extent of the pore solution alkali dilution effect. It was confirmed that salts of alkali metals of the kinds found as common concrete contaminants were able to increase the pore solution hydroxyl ion concentration significantly. The increase was limited by the finite anion complexing ability of the cement.
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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.
Full textAbstract:
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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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.
Full textAbstract:
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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Gong, Tianxing. "Calcium phosphate silicate cement for risedronate drug delivery." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/51550.
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The effectiveness of bone cements in treating bone fracture is impaired by osteoporosis, which not only delays the osseointegration but also compromises the stability of implants. As a result, further fractures are not unusual after bone cement implantation in osteoporotic patients. This dissertation reports the investigation of the novel calcium phosphate silicate cement (CPSC) as a possible drug delivery system (DDS) for risedronate (RA) to treat osteoporosis and to restore bone fracture. Risedronate belongs to the family of bisphosphonate and, as the 3rd generation of bisphosphonate, can effectively suppress osteoclast activities and treat osteoporosis. In this work, the CPSC material properties were characterized as a function of RA content. High performance liquid chromatography was used to detect RA release profiles from cements and the Higuchi’s Law was employed to explain its release mechanisms. In vitro biocompatibility of RA-added CPSC (CPSC-R) was evaluated by MTT assays, flow cytometry, and real-time polymerase chain reaction. In the tibia implantation model from osteoporotic rabbits, biomarkers, X-rays, computed tomography, histology and PCR arrays were used to evaluate CPSC-R in vivo performance.
It has been found that RA greatly affected CPSC setting time and compressive strength in a concentration-dependent manner. It was also found that RA disrupted CPSC hydration and delayed calcium silicate hydrate gel formation. RA was progressively adsorbed onto the unreacted calcium silicate and formed calcium-RA complexes. RA release kinetics from cement was controlled by the implant degradation and was in a good agreement with the theoretical calculations. CPSC-R was biocompatible and improved osteoblast proliferation and differentiation. Biomarker studies showed that CPSC-R significantly reduced osteoclast activities as compared to the sham control (p < 0.05). The radiographic and histological examination demonstrated that CPSC-R improved osseointegration and bone formation, as compared to RA-free CPSC control group. Gene array studies indicated that CPSC-R implants could significantly up-regulate osteogenesis-related gene expressions as compared to the control groups.
In conclusion, this study indicates that CPSC is potentially a good Drug Delivery System of RA. The anti-osteoporotic effectiveness of this system could be beneficial in bone fracture treatments for patients who are suffering from osteoporosis.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Mendes, Aline Teixeira. "Propriedades físico-químicas de uma nova formulação de cimento biocerâmico." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/179694.
Full textAbstract:
O sucesso do tratamento endodôntico a longo prazo depende do preparo químico mecânico e também da obturação dos sistemas de canais radiculares, que tem como objetivo prover o preenchimento de forma tridimensional com um material inerte. Um cimento endodôntico ideal deve ser biocompatível, ter tempo de presa adequado, estabilidade dimensional, união à dentina, baixa solubilidade, fácil manuseio e ser radiopaco. Para estabelecer um padrão nas pesquisas de materiais odontológicos algumas especificações são determinadas pela ISO e ANSI/ADA, onde são determinados os testes a serem realizados para cada tipo de material a ser avaliado. O objetivo desse estudo foi avaliar as propriedades físico-químicas de um novo cimento à base de silicato de cálcio tendo como fonte de comparação um cimento à base de resina epóxi. Para a avaliação do pH e liberação de cálcio, tubos de polietileno de 1mm de diâmetro interno e 10 mm de comprimento foram preenchidos com os cimentos e imersos em 10 ml de água deionizada. Após os períodos experimentais de 1, 24, 72 e 168 horas as amostras foram avaliadas quanto ao pH e a liberação de cálcio em um medidor de pH e espectrofotômetro colorimétrico respectivamente. Na análise da radiopacidade, solubilidade e tempo de presa foram confeccionados anéis com 10mm de diâmetro e 1mm de espessura do cimento; o valor da radiopacidade foi determinado de acordo com a densidade radiográfica (mm Al). Para a solubilidade os espécimes foram imersos em 50ml de água destilada por 7 dias, onde foi aferida a massa inicial (antes da imersão) e a final (após a imersão e desumidificação). A avaliação do tempo de presa foi realizada com agulhas Gilmore de 100g e 456,3g. O escoamento foi realizado com base na ISO 6876:2001. Os dados foram analisados por análise de variância e teste de Tukey (P<0,05). Os resultados encontrados nesse estudo, para valores de pH e Ca- foram significativamente maiores para o cimento Biosealer quando comparados ao AH Plus (P<0,05). Nos testes de escoamento, radiopacidade e tempo de presa o cimento biocerâmico demonstrou valores inferiores ao AH Plus (P<0,05). O Biosealer demonstrou uma alta solubilidade comparativamente ao AH Plus (P<0,05). É lícito concluir que, o cimento Biosealer demonstrou boas propriedades físico-químicas tais como; pH, liberação de cálcio, escoamento, radiopacidade e tempo de presa. Essa nova formulação de cimento endodôntico apresentou uma maior solubilidade do que a prevista na ISO 6876:2012.The success of long-term endodontic treatments depend on mechanical and chemical preparation, as well as on the root canal fillings, the purpose of which being providing filling in a three-dimensional fashion using inert material. The ideal endodontic cement must be biocompatible, have an appropriate setting time, dimensional stability, dentin bond strength, low solubility, be easy to manipulate and radiopaque. In order to set up a standard for research involving dental materials, some specifications are set forth by ISO and ANSI/ADA, in which the tests to be carried out for each material to be assessed are provided for. The goal of this study is to assess the physical and chemical properties of a new calcium silicate-based cement, to be compared with an epoxy resin-based cement. In order to assess calcium release and pH levels, polyethylene tubes with internal diameter of 1 mm and 10 mm in length have been filled with the cements and immersed in 10 ml of deionized water. After trial periods of 1, 24, 72 and 168 hours, the samples were assessed with regard to their calcium release and pH levels, using a colorimetric spectrophotometer and a pH mete, respectively. In order to assess radiopacity, solubility and setting time, rings with 10 mm in diameter and 1 mm in thickness were manufactured using the cements; the radiopacity levels were calculated in accordance with their radiographic density (mm Al). In order to assess solubility, the items were immersed in 50 ml of distilled water for seven days, with the initial mass (before immersion) and final mass (after immersion and dehumidification) being measured. The setting time assessment was carried out using Gilmore needles weighing 100 g and 456.3 g. Yield test was carried out based on ISO 6876:2001. The data obtained were analyzed through analysis of variance and Tukey test (P<0.05). The results found in this study with regard to pH e Ca- levels were significantly higher for the Biosealer cement, when compared with AH Plus (P<0.05). In the yield, radiopacity and setting time tests, the results for the bioceramic cement were lower when compared with AH Plus (P<0.05). The results for the Biosealer indicated higher solubility levels, when compared with AH Plus (P<0.05). It is conceivable to conclude that the Biosealer has shown good physical-chemical properties, such as pH, calcium release, yield, radiopacity and setting time. This new endodontic cement formulation has shown a higher solubility when compared with the level set forth in ISO 6876:2012.
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Jardine, Alexander Pompermayer. "Atividade antimicrobiana de cimentos que contêm silicato de cálcio em dentina infectada por biofilme muiti-espécies : um estudo em microcospia confocal à laser." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/151439.
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Este estudo teve como objetivo avaliar, em microscopia confocal à laser (CLSM), a ação antimicrobiana do Neo MTA Plus, do Biodentine e do MTA Angelus, utilizando um modelo de biofilme multi-espécies microcosmo, e descrever a morfologia dos microrganismos encontrados no biofilme, através da análise em microscópio eletrônico de varredura (MEV). Cinquenta e seis blocos de dentina, confeccionados a partir de raízes de dentes humanos, foram cortados em dimensões de 5 x 4 x 4 mm, limpos e esterilizados. Dois blocos foram utilizados para o controle do processo de esterilização. Os demais 54 foram fixados em placas de Hawley confeccionadas para 6 voluntários. Cada voluntário utilizou uma placa por 72 horas. Após esse período, os blocos foram mantidos em poços de cultura celular, contendo BHI, em estufa à 37ºC, por um período de 21 dias. Ao final do processo de maturação do biofilme, as amostras foram divididas aleatoriamente em 5 grupos, conforme os cimentos a serem testados e o método de análise: Neo MTA Plus (n=12), Biodentine (n=12), MTA Angelus (n=12), controle negativo (n=12) e grupo para análise em MEV (n=6). A seguir, os cimentos foram colocados em contato com o biofilme dos blocos dos grupos-teste e os conjuntos (bloco + cimento) ou os blocos do grupo controle e para análise em MEV foram recolocados em poços de cultura contendo BHI, onde permaneceram por 7 dias à 37ºC. A análise em CLSM foi realizada nos blocos de dentina e nos cimentos, separadamente. A analise em MEV foi realizada nas seis amostras do grupo correspondente. Todos os grupos apresentaram mais de 50% de bactérias viáveis. O Neo MTA Plus foi o único material a apresentar diferença significativa quando comparado ao grupo controle negativo (P=.0379). A análise em MEV mostrou um biofilme composto por bactérias de forma circular e de bastonetes, circundadas por matriz extra-celular. Em conclusão, todos os grupos apresentaram bactérias viáveis e o Neo MTA Plus teve a maior ação antimicrobiana.This study aimed to assess, by confocal laser scanning microscopy (CLSM), the antimicrobial effect of Neo MTA Plus, Biodentine and MTA Angelus, using a microcosmo biofilm model, and to describe the microrganisms morphology, by SEM. Fifty-six dentin blocks were made from human teeth roots, cut in a size 5 x 4 x 4 mm, cleaned and sterelized. Two blocks were used to sterelization control. The others 54 blocks were fixed in Hawley retainers made for 6 volunteers that used it for 72h. After this period, they were placed in wells with BHI for 21 days, at 37ºC. At the end of the biofilm growth, the samples were randomly divided in 5 groups: Neo MTA Plus (n=12), Biodentine (n=12), MTA Angelus (n=12), negative control (n=12), and SEM analysis (n=6). The cements were placed in contact with the blocks of the tested groups. All samples were replaced in wells with BHI by 7 days at 37ºC. CLSM analysis evaluated the dentin blocks and cements isolated. SEM observation were performed in the six samples of the respective group. All groups presented a level of viable bacteria higher than 50%. Neo MTA Plus was the only one that showed significant difference from the negative control group (P=.0379). SEM analysis showed a biofilm composed of spherical and rod-shaped bacteria surrounded by extracellular matrix. All groups presented viable bacteria and Neo MTA Plus had the highest antimicrobial effect.
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Scaffa, Polliana Mendes Cándia. "Efeito de diferentes tratamentos de superfície na resistência de união de um cimento resinoso à zircônia." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/25/25131/tde-01062009-150441/.
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As ceramicas a base de zirconia (Y-TZP) apresentam propriedades mecanicas superiores as das demais ceramicas odontologicas. Entretanto, o aumento do conteudo cristalino modificou suas caracteristicas de adesao a cimentos resinosos, tornando necessario o desenvolvimento de metodos mais efetivos de uniao a estes materiais. Este trabalho in vitro pretende, portanto, avaliar a influencia de diferentes tratamentos de superficie e de diferentes agentes de uniao na resistencia ao cisalhamento entre uma zirconia estabilizada por itrio e um agente cimentante autoadesivo (RelyX U100®/3M ESPE). Para tal, cilindros de PROCERA® Allzircon receberam como tratamento de superficie jateamento com oxido de aluminio (Al2O3 - 50 m) ou jateamento com o sistema Rocatec. Sobre a superficie tratada dos cilindros foram aplicados, de acordo com os diferentes grupos experimentais, o sistema adesivo Clearfil SE Bond® (Kuraray Co.), e os primers Metal Zirconia Primer (Ivoclar Vivadent) e Alloy Primer (Kuraray Co.) e, finalmente, o cimento resinoso adotado. Cada especime foi, entao, submetido ao teste de cisalhamento (0,05 mm/min), por meio da acao de uma alca de fio ortodontico passando o mais próximo possivel da interface adesiva. A analise de variancia a um criterios (ANOVA) e o teste de Tukey (p<0,05) mostraram que a realizacao do tratamento de superfície aumentou os valores de resistencia de uniao entre a ceramica e o cimento resinoso. O jateamento com o sistema Rocatec (15,33 MPa) apresentou valores significantemente maiores que o jateamento com Al2O3 (11,93 MPa). A aplicacao dos agentes de uniao resultou em uma maior resistencia adesiva, sendo que o sistema adesivo Clearfill SE Bond (17,07 MPa) teve um comportamento estatisticamente superior aos demais materiais. Entre os primers, o Metal Zirconia Primer (11,26 MPa) apresentou maior valor de resistencia de uniao que o Alloy Primer (10,01 MPa). Portanto, a associacao de um tratamento superficial com um agente de união e valida, ja que promoveu os maiores valores de resistencia adesiva.Yttrium-stabilized tetragonal zircon polycrystal (Y-TZP) ceramics show better mechanical properties than other dental ceramics. However, the high crystalline content modified their adhesiveness to resin cements, making it extremely necessary to develop a more effective adhesive strategy between them. This in vitro study intends to evaluate the influence of different surface treatments and different bond agents on the shear bond strength between a Y-TZP and self-adhesive resin cement. PROCERA® Allzircon cylinders (3.5 mm in diameter) received a surface airborne abrasion treatment with 50 m aluminum-oxide (Al2O3) particles or with the Rocatec system. According to the experimental groups, the adhesive system Clearfil SE Bond® (Kuraray Co.), and the primers Metal Zirconia Primer (Ivoclar Vivadent) and Alloy Primer (Kuraray Co.) were applied on the treated surface of the cylinders, before the application of the adopted resin cement (RelyX U100®/3M ESPE). Each specimen was submitted to the shear bond strength test (0.5 mm/min), by the action of an orthodontic stainless steel ligature wire (0.5 mm in diameter) loop, wrapped around the resin cement, as close as possible to the adhesive interface. One way-ANOVA and Tukey´s post hoc tests (p<0.05) revealed that surface treatment increased bond strength between the ceramic and the resin cement. Silica coating with the Rocatec system (15.33 MPa) showed significantly higher values than airborne abrasion with Al2O3 (11.93 MPa). Application of all bond agents improved shear bond strength: adhesive system Clearfil SE Bond (17.07 MPa) showed better performance than the other evaluated materials, and Metal Zirconia Primer (11.26 MPa) showed higher bond strength values than Alloy Primer (10.01 MPa). Therefore, the association of a surface treatment with a bond agent is suitable, once it resulted in higher values of adhesive strength.
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Coz, Fernández Alberto. "Comportamiento ambiental de lodos de fundición estabilizados/solidificados." Doctoral thesis, Universidad de Cantabria, 2001. http://hdl.handle.net/10803/10686.
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El objetivo de esta tesis ha sido el tratamiento de un residuo (lodo de fundición) procedente del lavado húmedo de los gases del horno fusor. Para ello, se ha evaluado la peligrosidad del residuo y, posteriormente, se han estudiado diferentes tratamientos previos al vertido y se ha realizado su evaluación ambiental. El lodo de fundición es un residuo ecotóxico, debido principalmente a la alta concentración de cinc y a la carga orgánica (fenoles) del mismo, pudiéndose establecer relaciones matemáticas entre la ecotoxicidad y la concentración de cinc y fenoles, tanto en el residuo original como en los productos finales. Entre las diferentes tecnologías de tratamiento, destacan los procesos de estabilización/solidificación con cal o cemento como agente aglomerante, por su elevado interés en residuos de carácter tóxico mixto: orgánico e inorgánico. Se ha llevado a cabo un estudio exhaustivo de los diferentes aditivos utilizados en dichos procesos y se han desarrollado diferentes formulaciones cal o cemento y aditivos/residuo con el fin de cumplir los parámetros ambientales, concluyéndose con la relación existente entre formulación y evaluación ambiental y obteniendo una patente de invención.The aim of this work has been the study of the treatment of foundry sludge coming from after wet cleaning of gases of the furnace in foundry activities. Previously, the hazardous of the waste material has been evaluated. Later, different treatments have been studied and the environmental evaluation have been conducted. Foundry sludge is an ecotoxical waste due to inorganic (basically zinc) and organic (phenols) pollutants, being able to establish mathematical relationships between the ecotoxicity and the concentration of zinc and phenols, both in waste and end-products. Among the different technologies for the treatment, stabilisation/solidification processes with lime or cement as binders are very interesting technologies for waste of mixed character (organic and inorganic). An exhaustive study of different additives used in these processes has been carried out and different formulations have been developed in order to inertise the waste materials, concluding with the relationships between formulation and environmental evaluation and obtaining a patent.
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Stundebeck, Curtis J. "Durability of ternary blended cements in bridge applications." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5082.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on November 6, 2007) Includes bibliographical references.
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Jeffers, Jonathan. "In silico simulation of long term cement mantle failure in total hip replacement." Thesis, University of Southampton, 2005. https://eprints.soton.ac.uk/388231/.
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Andrade, Aline Silva. "Biocompatibilidade e bioatividade de cimentos à base de silicato tricálcico : estudo in vitro e in vivo /." Araraquara, 2016. http://hdl.handle.net/11449/138911.
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Orientador: Mario Tanomaru FilhoBanca: Gisele Faria
Banca: Marco Antônio Húngaro Duarte
Resumo: Cimentos à base de silicato tricálcico são desenvolvidos como alternativa ao Mineral Trióxido Agregado (MTA). O objetivo do estudo foi avaliar a biocompatibilidade e bioatividade do cimento experimental silicato tricálcico com 20% de óxido de zircônio (ZrO2) (STC) e MTA Plus (MTAP). Capítulo1- Células humanas de osteoblastos (Saos-2) foram utilizadas para análise da viabilidade celular por meio dos ensaios de MTT e Vermelho Neutro (NR), da bioatividade pela atividade da enzima fosfatase alcalina (ALP) e da presença de área mineralizada pela coloração de Vermelho de Alizarina (ARS). Os dados obtidos para MTT, NR e ALP foram analisados por ANOVA e Bonferroni, e ARS, por ANOVA e Tukey (p ≤ 0,05). Nos ensaios de viabilidade celular, os materiais não foram citotóxicos. Maior atividade de ALP ocorreu aos 7 dias para todos materiais avaliados. Área mineralizada foi observada em todos os grupos, sendo menor para o grupo STC. Concluiu-se que o cimento experimental silicato tricálcico com 20% de óxido de zircônio e MTA Plus apresentam citocompatibilidade e potencial bioativo. Capítulo 2- A reação inflamatória induzida pelo STC e MTAP foi investigada em subcutâneo de ratos. Tubos de polietileno foram preenchidos com STC (n= 20) e MTAP (n= 20) e implantados no subcutâneo dorsal de quarenta ratos. No grupo controle (GC; n= 20), tubos vazios foram implantados. Após 7, 15, 30 e 60 dias, os tubos de polietileno com o tecido conjuntivo circundante foram fixados e embebidos em parafina. O núme... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Tricalcium silicate- based cements have been developed as an alternative to Mineral Trióxido Agregado (MTA). The aim of the study was to evaluate biocompatibility and bioactivity of the tricalcium silicate cement replaced with 20% zirconium oxide (STC) e MTA Plus (MTAP). Chaper 1- Human osteoblastic cells (Saos-2) were exposed to test materials and assessed for viability, MTT and Neutral Red (NR) assay, and bioactivity for ALP activity assay and alizarin red staining (ARS). Unexposed cells acted as the control group. Statistical analysis was performed using ANOVA and the Bonferroni post- test (P < 0.05) to MTT, NR and ALP, and ANOVA and Tukey post- test (P ≤ 0.05) to ARS. MTT and NR results, all tested cements were non-cytotoxic. The highest ALP activity occurred at the 7th days. Mineralized area was observed in all materials, STC group showed lower mineralized area. Experimental tricalcium silicate with 20% zirconium oxide and MTA Plus have present biocompatibility and bioactive potential. Chapter 2- The inflammatory reaction induced by tricalcium silicate cement replaced with 20% zirconium oxide (STC) e MTA Plus (MTAP) was evaluated in rat subcutaneous tissues. A polyethylene tube filled with STC (n= 20) and MTAP (n= 20) was placed into the dorsal subcutaneous of forty rats; in the control group (GC; n= 20), empty tubes were implanted. After 7, 15, 30 and 60 days, the polyethylene tubes surrounded by connective tissue were embedded in paraffin. The number of inflammatory ce... (Complete abstract click electronic access below)
Mestre
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Veleba, Ondřej. "Studium vlivu složení na mechanické vlastnosti vysokohodnotného betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2008. http://www.nusl.cz/ntk/nusl-216217.
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This work is devoted to study the influence of the composition on mechanical properties of high performance concret based on portland cement. 29 samples of high performance concrete (HPC) warying in composition were prepared. The constituents used for HPC preparation were: cement Aalborg White, silica fume, finelly ground blast furnace slag, finelly ground silica, calcinated bauxite and polycarboxylate based superplasticizer. The mechanical parameters (flexural and compressive strength) of the samples were observed after 7 and 28 days of moist curing. Compressive strength values after 28 days were in the range of 92 to 194 MPa and the flexural strength values were in the range of 7 to 23 MPa (without using of fiber reinforcement). The graphs showing mechanical parameters depending on the mixture composition were constructed and consequently evaluated.
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Nguyen, Dan-Tam. "Microindentation Creep of Calcium-Silicate-Hydrate and Secondary Hydrated Cement Systems." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31519.
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The nanostructure, physical properties and mechanical performance of C-S-H, 1.4 nm tobermorite, jennite, and ettringite were studied. C-S-H of variable stoichiometries was examined as a model system in comparison with that produced in the hydration of Portland cement. The current Master’s thesis is comprised of four research papers designed to improve the current understanding of the nanostructure and engineering properties of C-S-H systems and modified C-S-H systems. Many of the controversial issues in cement science were identified and were addressed in a comprehensive research study, which examined the key features of the C-S-H systems at the nano-structure level. In Chapter 4, each paper presented new evidence for a number of mechanical aspects of C-S-H materials. Numerous advanced analytical tools were used in order to verify the observations made in each section. The major achievements of the current work are mentioned briefly as follows:
1. It was determined that microindentation is a useful method for determining the creep behavior of C-S-H of various stoichiometries, 1.4 tobermorite, jennite, and ettringite.
2. Microindentation parameters i.e. creep modulus, indentation modulus and indentation hardness are porosity dependent.
3. Microindentation creep measurements on C-S-H (C/S = 0.80 and 1.20) demonstrated that creep modulus, indentation modulus, and indentation hardness are all dependent on mass-loss from the 11%RH condition.
4. Evidence was presented that the nanostructural role of interlayer water in C-S-H has a significant influence on the creep process.
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Zhou, Shuxin. "Synthesis and characterization of calcium phosphate silicate bio-cements." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46355.
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Calcium phosphate silicate cement (CPSC) describes a family of materials in which the powder component is composed of the mixture of hydraulic calcium silicates and calcium phosphates. CPSC was developed and characterized in this work with the broad goal to address, and possibly overcome, the disadvantages of calcium silicate and calcium phosphate cements used in medical and dental fields. The main objective of this work was to synthesize and characterize CPSC, focusing particularly on the hydration process of CPSC. The cements consisting of various amounts of triclacium silicate (C₃S) and calcium phosphate monobasic (CPM), were synthesized by the sol-gel process, followed by heat treatment at 1550ºC and planetary ball-milling. It has been determined that after mixing with water, C₃S hydrates to calcium silicate hydrates (C-S-H) and calcium hydroxide (CH); within 10 min CPM reacts with CH to form dicalcium phosphate dihydrate (DCPD), which further reacts with CH and precipitates hydroxyapatite (HAP). It is proposed that the phosphate ions incorporate into C-S-H to form another type of hydrates C-S-P-H. The morphology of the hydrates depends on the process of hydration and the composition of CPSC. At the early stages of hydration, the hydration products form “almond-shaped” particles that serve as a nucleation site for the hydrates. The hydrates take tubular shape and form bundles clustered along the radial direction of the tubes. CPM influences the hydration kinetics of C₃S by increasing the duration of the hydration acceleration period rather than increasing the hydration rate, especially for the higher content of CPM in CPSC. CPM also increases the porosity of CPSC and reduces the content of CH, thought to be the “weak link” in the set CPSC. As a compromise between the two effects, the optimal content of CPM appears to exist at about 10 wt% of CPM in CPSC. After immersion in simulated body fluid, HAP forms on the surface of CPSC indicating that CPSC is bioactive in vitro. Cytotoxicity assay and cell adhesion assay against human gingival fibroblast indicated that the biocompatibility of CPSC is significantly enhanced.