Cerâmicas de alto conteúdo cristalino, como a zircônia policristalina tetragonal estabilizada por ítrio (Y-TZP), apresentam ótimas propriedades mecânicas quando comparadas às cerâmicas convencionais, sendo cada vez mais empregadas como materiais restauradores indiretos. Entretanto, seu sucesso também depende da formação de uma união confiável com os agentes de cimentação. Porém, o aumento do conteúdo cristalino modificou as características de adesão entre cerâmica e cimento resinoso, não existindo um protocolo de cimentação bem estabelecido na literatura. Portanto, este estudo teve como objetivo avaliar o efeito na resistência ao cisalhamento de diferentes tratamentos de superfície sobre a zircônia, utilizando dois cimentos resinosos, assim como avaliar as possíveis diferenças no modo das fraturas. Cento e vinte amostras retangulares de zircônia foram incluídas em resina acrílica e divididas em 12 grupos (n=10), de acordo com os tratamentos de superfície e os cimentos (Panavia F e Rely X U100). Para cada cimento, os grupos experimentais foram formados da seguinte maneira: RU e Pa - controle (sem nenhum tratamento de superfície); ApRU e ApPa (aplicação do Alloy Primer); MzRU e MzPa (aplicação do Metal/Zircônia Primer); JatRU e JatPa (jateamento com partículas de óxido de alumínio de 50µm); JatApRU e JatApPa (jateamento e aplicação de Alloy Primer); JatMzRU e JatMzPa (jateamento e aplicação do Metal/Zircônia Primer). Os corpos de prova foram armazenados em água destilada à temperatura de 37°C por 24 horas, antes do teste de cisalhamento em uma máquina de ensaio universal (EMIC). Os valores foram submetidos primeiro a ANOVA a um critério (resistência ao cisalhamento) e teste de Tukey (p 0,05), independente do tratamento e do sistema de cimentação. Em seguida, ANOVA a dois critérios (tratamento de superfície e sistema de cimentação) e o teste de Tukey foram aplicados para observar com maior precisão a interação entre cimento e tratamento de superfície. Os resultados apresentados foram: RU - 11,71a, ApRU - 21,49b,e, MzRU - 30,38c,d, JatRU - 34,40c, JatApRU - 30,66c,d, JatMzRU - 38,06c, Pa - 11,35a, ApPa - 11,98a, MzPa - 11,46a, JatPa - 33,50c, JatApPa - 23,14b,d,e, JatMzPa - 18,66a,e. Por meio dos resultados obtidos foi possível concluir que a resistência ao cisalhamento pode ser melhorada ao utilizar o jateamento com partículas de óxido de alumínio e, para o RelyX U100, somente a aplicação do Metal/Zircônia Primer resultou em valores de adesão comparavéis ao tratamento mecânico. O cimento RelyX U100 apresentou maior resistência de união quando comparado ao Panavia F. / High crystalline content ceramics, such as yttria stabilized tetragonal zirconia polycrystal (Y-TZP), show great mechanical properties when compared to conventional ceramics, being increasingly used as indirect restorative materials. However, its success also depends on the reliable bond formation with luting agents. Though, the high crystalline content modified the adhesiveness between ceramic and resin cement although there isnt any cementing protocol established in literature. Therefore, the purpose of this study was to evaluate the effect of the shear bond strength after different surface treatments on the zirconia, using two resin cements and to evaluate possible differences in fracture modes. One hundred and twenty rectangular samples of zirconia were embedded in acrylic resin and divided into 12 groups (n=10) according to the surface treatments and the cements (Panavia F and RelyX U100). For each cement, the experimental groups were formed as follow: RU and Pa - control (no surface treatment); ApRU and ApPa (application of Alloy Primer); MzRU e MzPa (application of Metal/Zirconia Primer); JatRU and JatPa (air abrasion with 50µm Al2O3 particles); JatApRU and JatApPa (air abrasion and application of Alloy Primer); JatMzRU and JatMzPa (air abrasion and application of Metal/Zirconia Primer). The specimens were stored in distilled water at 37°C for 24 hours prior to the shear bond strength test in a universal testing machine (EMIC). The data were first analyzed by one-way ANOVA (shear bond strength) and Tukey test (p<0.05), regardless of the treatment and the luting system. Then two-way ANOVA (surface treatment and luting system) and the Tukey test were applied in order to observe more accurately the interaction between cement and surface treatments.The results presented were: RU 11.71a, ApRU 21.49b,e, MzRU 30.38c,d, JatRU 34.40c, JatApRU 30.66c,d, JatMzRU 38.06c, Pa 11.35a, ApPa 11.98a, MzPa 11.46a, JatPa 33.50c, JatApPa 23.14b,d,e, JatMzPa 18.66a,e. Based on the results obtained, it was possible to conclude that the shear bond strength can be improved when air abrasion was used with aluminum-oxide particles and for the RelyX U100, only the application of Metal / Zirconia Primer resulted in adhesion values comparable to mechanical treatment. The RelyX U100 cement showed higher bond strength when compared to Panavia F.

O presente trabalho discute comparativamente o comportamento mecânico de solos lateríticos e não lateríticos para uso em pavimentação. Para tanto foram ensaiados 3 pares de solos, sendo cada par constituído por solos de curvas granulométricas semelhantes, mesma classificação HRB e comportamentos distintos quanto à laterização. Foram realizados ensaios triaxiais convencionais do tipo CD saturado e não saturado sem controle de sucção e ensaios de compressão simples. A partir dos resultados dos ensaios foram modeladas as deformações elásticas em função das tensões de confinamento e determinadas as envoltórias de ruptura de Mohr-Coulomb. Concluiu-se que a maior resistência dos solos lateríticos está representada na componente coesão da envoltória de Mohr-Coulomb e que esta é mobilizada praticamente ao máximo desde o início em um ensaio triaxial. A diferença de resistência entre os ensaios saturados e não saturados também se mostrou na coesão, com a soma nesta da componente coesão aparente, fruto da sucção. O ângulo de atrito mostrou-se constante para as duas gêneses, tanto para a condição saturada como para a condição não saturada. Os solos lateríticos apresentam rigidez maior que os não lateríticos, tanto na condição saturada como na condição não saturada. Para os níveis de tensão de confinamento utilizados, a rigidez dos solos, de ambas as gêneses, na condição saturada, diminui com o aumento da tensão confinante. Também se observou que a ação da sucção existente nos ensaios não saturados proporciona, para ambas as gêneses, uma mudança da sensibilidade da rigidez ao aumento da tensão confinante. / The present paper discusses the mechanical behavior of lateritic and no-lateritic soils for use in pavement. To attain that goal, 3 pair soils were rehearsed, being each pair constituted by soils of similar granulometric curves, same HRB classification and different genesis. The experimental program was constituted of static triaxial compression test of the type saturated CD and of the type unsaturated without suction control and unconfined compression strength test. With the results of the tests, the elastic strains were modeled in function of the confinement stresses and the rupture paths of Mohr-Coulomb were determined. The analysis that the shear strength of the lateritic soils is greater than no-lateritic soil because of the cohesion. Since the begin it, the cohesion is mobilized practically to the maximum for both soils. The difference of shear strength between the saturated and unsaturated tests it is also cohesion, with the sum in that component of the cohesion apparent produced for suction. The angle of internal friction is constant for the two genesis as much for the saturated test as for the unsaturated test. The lateritic soils present greater stiffness than the no-lateritic soils, as much for saturated test as for unsaturated test. For the levels of confinement stresses used, in the saturated condition the stiffness of the soils decreases with the increase of the confinement stresses of both genesis. In addition, it was observed that the suction existent in the unsaturated testing produce a change of the sensibility of the soils stiffness to the increase of the confinement stress for both genesis.

A utilização do solo natural compactado com bentonita empregado em camadas impermeáveis para retenção de contaminantes é bastante usual para aterros sanitários. Neste trabalho são apresentados resultados de ensaios condutividade hidráulica e de resistência ao cisalhamento, realizados em equipamentos triaxiais. Além do solo natural, foram utilizadas misturas solo-bentonita nos teores de 2%, 4% e 6%. O solo arenoso ensaiado é encontrado na Planície Costeira Sul do Estado do Rio Grande do Sul. Os valores de condutividade hidráulica diminuiram tanto com o acréscimo do teor de bentonita, quanto com o aumento da tensão de confinamento. A condutividade hidráulica do solo apresentou uma redução de três ordens de grandeza quando este foi compactado com 6% de bentonita (de \'10 POT.-7\' para \'10 POT.-10\' m/s). Em relação a resistência ao cisalhamento do material, constatou-se que com o acréscimo do teor bentonita de 0 para 6%, a coesão efetiva aumentou (de 2,3 para 12,8 kPa) e o ângulo de atrito efetivo diminuiu (de 22,7º pra 14,0º). / Compacted soil-bentonite mixtures used as impermeable layers for retention of contaminants is quite usual in landfills. This paper presents the results of hydraulic conductivity and shear strength tests conducted in a triaxial apparatus. Natural soil, and soil-bentonite mixtures at 2%, 4% and 6% concentrations were tested. The sandy soil tested is found in the Southern Coastal Plain of Rio Grande do Sul. The hydraulic conductivity decreased with both the increase of bentonite content and increase of confining stress. Compared to natural soil, the hydraulic conductivity of compacted soil-bentonite mixtures at 6% content decreased by three orders of magnitude (from \'10 POT.-7\' to \'10 POT.-10\' m/s). Regarding the material shear strength, it was found that when the natural soil is compared to compacted soil-bentonite mixtures at 6% content, the effective cohesion increased (from 2.3 to 12.8 kPa) and the effective friction angle decreased (from 22. 7º to 14.0º).

A deformabilidade é uma propriedade fundamental em projetos geotécnicos. A constatação de que as deformações em várias obras de engenharia se situam na faixa de pequenas e muito pequenas deformações e as limitações das técnicas de ensaio em medir tal nível de deformações levaram ao desenvolvimento de técnicas com base em solicitações dinâmicas, dentre as quais, as de coluna ressonante e bender elements. Particularmente, o emprego da técnica de bender elements tem crescido devido à simplicidade de execução dos ensaios, e determinação do módulo de cisalhamento máximo dos solos. Diversos estudos acerca das propriedades deformacionais dos solos determinadas por este método têm sido conduzidos em solos saturados ou secos, não obstante, estudos desta natureza em solos não saturados ainda são relativamente escassos. Esta pesquisa investigou a influência de algumas variáveis, como a sucção e a tensão confinante sobre a deformabilidade de um solo laterítico não saturado típico do interior do Estado de São Paulo, empregando bender elements, coluna ressonante e compressão triaxial com instrumentação interna. Além disso, buscando uma caracterização mais completa deste solo, ensaios de compressão triaxial foram realizados para quantificar sua resistência ao cisalhamento. Os resultados destes ensaios sugeriram a ocorrência de encruamento em solo indeformado, e uma envoltória planar de resistência foi usada para representar a resistência ao cisalhamento da amostra compactada. Já no que se refere à deformabilidade, os resultados indicaram que a redução do teor de umidade de compactação, o aumento do confinamento isotrópico ou da sucção são responsáveis por um solo menos deformável. Dados dos ensaios com bender elements foram bem representados por uma função potencial quando o módulo de cisalhamento máximo e a sucção foram normalizados pela tensão confinante líquida. Para o solo compactado não saturado, também ensaiado em coluna ressonante, dados obtidos por ambas as técnicas foram comparados, notando-se velocidades de ondas de cisalhamento um pouco superiores para os ensaios com bender elements, que foram atribuídas às mais altas frequências nestes ensaios. / Stiffness is a fundamental property in geotechnical design. The fact that strains are in the smallto- very small strain range in several engineering works and the limitations of testing techniques in measuring such level of strains led to the development of dynamic techniques, such as resonant column and bender elements. Specifically, the bender elements technique has been increasingly used due to the simplicity in performing tests and computing the maximum shear modulus of the soil. Several studies have been carried out to assess stiffness properties of dry or saturated soils via bender elements, however, studies of this nature are still relatively scarce in unsaturated soils. This research investigated the influence of some variables, like suction and confining stress, on the stiffness of a lateritic unsaturated soil, typical of São Paulo State, via bender elements, resonant column and triaxial compression tests with local gauges. Furthermore, aiming at a more complete characterization of this soil, triaxial compression tests were performed in order to quantify its shear strength. Results from these tests suggested the occurrence of strain hardening on undisturbed specimens, and a planar shear strength envelope was used to represent the compacted sample data. Regarding soil stiffness, results indicated that it increases with a reduction in the compaction moisture content or an increase in isotropic confining stress or suction. Data from bender elements tests were nicely represented by a power function when maximum shear modulus and suction were normalized by the net confining stress. Results of unsaturated compacted soil obtained from bender elements and resonant column tests were compared and slightly larger shear wave velocities were noticed in bender elements tests, which were attributed to the larger testing frequencies used in these tests.

A compactação de aterros pode gerar comportamento anisotrópico, a depender do teor de umidade de compactação, entre outros fatores. O principal objetivo deste estudo foi investigar alguns aspectos relacionados à anisotropia inerente induzida pela compactação de um solo laterítico. Após realizar a caracterização mineralógica, geotécnica e microestrutural deste solo, estudou-se a resistência ao cisalhamento, condutividade hidráulica, compressibilidade e deformabilidade. O solo estudado foi classificado como laterítico arenoso (LA\') e apresentou agregação relativa da ordem de 12%. A metodologia desenvolvida no intuito de corrigir o aumento na massa específica seca das camadas inferiores, causado pelo processo de compactação, mostrou-se eficaz. A partir da curva de compactação foram consideradas amostras representativas das três condições de umidade de compactação: ramo seco, umidade ótima e ramo úmido. Corpos de prova foram talhados paralelamente e ortogonalmente às camadas de compactação. Os ensaios de porosimetria revelaram um comportamento bimodal na distribuição do tamanho de poros e também que o teor de umidade de compactação não interferiu no tamanho dos microporos. Para o solo compactado no ramo seco e na umidade ótima, a resistência ao cisalhamento correspondente à direção ortogonal se mostrou superior àquela correspondente à direção paralela às camadas de compactação. Por outro lado, a resistência ao cisalhamento no ramo úmido mostrou-se praticamente independente da direção de talhagem dos corpos de prova. Este comportamento se deve à maior capacidade do solo, em um dado teor de umidade, em absorver a energia aplicada e distribuí-la na direção paralela e ortogonal. Com relação às propriedades elásticas do material, observou-se que o aumento do teor de umidade de compactação contribui para redução da anisotropia de deformabilidade. Dentre as propriedades investigadas, a anisotropia de condutividade hidráulica das amostras correspondente ao ramo úmido foi a mais pronunciada, exibindo fluxo oito vezes maior na direção vertical que na horizontal. Finalmente, as discussões e análises presentadas nesta pesquisa mostraram que o grau de anisotropia depende diretamente do teor de umidade de compactação e que diminui com incremento das tensões aplicadas no solo. / Compacted embankments can have anisotropic behavior, depending on several factors, including the compaction water content. The aim of this study was to investigate some aspects regarding the inherent anisotropy of a lateritic soil, caused by the compaction process. After performing the geotechnical, mineralogical and microstructural characterization, properties of shear strength, hydraulic conductivity, compressibility and deformability were investigated. This soil this soil was classified as lateritic sand. The grainsize distribution curve indicates 12% the fine particle aggregation. The methodology developed in order to correct the increase in dry density of the lower layers, generated by the compression process, was effective. From the compaction curve, representative samples corresponding to the three compaction water content conditions, representing the dry side, the optimal water content and the wet side were considered. Specimens were trimmed parallel and orthogonally to the compaction layers. The porosimetry tests showed a bimodal behavior in the pore size distribution and also that the compaction water content did not influence the size of the micropores. For the compacted soil sample corresponding to the dry side and optimum water content, the shear strength corresponding to the orthogonal direction was higher than that corresponding to the parallel direction to the compaction layers. However, they were almost equal for both the orthogonal and the parallel directions to the compaction layers. This behavior is due to the higher capacity of the soil at a given moisture content, to absorb the energy applied and distribute it in parallel and orthogonal direction. The analysis the values of maximum shear modulus of the material showed that increasing compaction water content reduces the anisotropy degree. Among the investigated properties, the hydraulic conductivity anisotropy of the samples corresponding to the wet branch was the most pronounced, showing permeability eight times higher in the vertical direction than that in the horizontal direction. Finally, the discussions and analyzes presented in this study showed that the degree of anisotropy directly depends on the compaction water content and decreases with increase confining stress applied to the soil specimens.

Neste trabalho são apresentados resultados de ensaios triaxiais convencionais, de compressão confinada e triaxiais com controle de tensão, realizados em amostras saturadas e com controle de sucção, em corpos de prova indeformados coletados ao longo de um perfil típico de solo da cidade de São Carlos - SP. A partir dos dados obtidos, faz-se um estudo do comportamento de deformação e resistência do solo, em condições não saturadas, ao longo de todo perfil amostrado. Para o solo residual de arenito realiza-se também um estudo das suas principais características de elastoplasticidade, para a condição saturada e para o caso dos ensaios realizados com controle de sucção. Mostra-se que as superfícies de plastificação obtidas para o solo podem ser ajustadas de modo razoável pela superfície de escoamento do Cam-Clay modificado, utilizada nos modelos de Alonso et al. (1990) e Balmaceda et al. (1992). Para esta superfície, o uso de uma lei de fluxo associada conduziu a resultados satisfatórios. Um modelo constitutivo é proposto para representação do comportamento do solo em condições não saturadas. Uma nova superfície de plastificação e uma nova lei de fluxo (não associada) são propostas para o solo, conseguindo-se uma melhor previsão dos pontos de escoamento situados à esquerda da projeção da linha de estados críticos e diminuindo-se os valores dos desvios angulares dos vetores de incrementos de deformação plástica. No modelo constitutivo proposto neste trabalho, a superfície de escoamento LC do solo é obtida levando-se em consideração não somente os valores da pressão de pré-adensamento, mas também os valores de &#947(s). Os modelos constitutivos proposto e de Balmaceda et al. (1992) são utilizados na simulação dos ensaios de laboratório, obtendo-se bons resultados. Com o uso dos parâmetros adotados para a simulação dos ensaios de laboratório são realizadas previsões do comportamento de estruturas de fundação em campo, obtendo-se resultados satisfatórios. / This thesis deals with the application of elasto-plastic concepts to a typical non saturated soil from São Carlos - SP. The soil profile analysed is composed at is upper part of a sandy soil of coluvium origin and of a residual soil from sandstone at depths larger than 8 m. The water level is at a depth of about 10 m. The experimental work included compression triaxial tests following different stress paths and confined compression tests performed both on saturated and on unsaturated specimens. In the case of the residual soil of sandstone, its main elastoplastic characteristics are studied. It is shown that yield points can be fairly fitted by the yield surface proposed by of Alonso et al. (1990) and Balmaceda et al. (1992), which are an extension of modified Cam-Clay yield surface. In this case, an associated flow law also gave reasonable results in reproducing experimental data. In order to get a better adjustment between experimental and theoretical results, a new constitutive model is proposed using a new yield surface and a non associated flow law. It is shown that this new yield surface can better adjust experimental yield points, mainly those located at left of the critical state line (C.S.L.) and the new flow rule leaded to lower deviation of incremental plastic strain vectors. In the proposed model, the yield surface LC is obtained considering both &#947(s) and po experimental values. The proposed and Balmaceda et al. (1992) models were utilised to predict the laboratory soil behaviour, showing good results. The parameters already used to reproduce laboratory tests were also used to model foundation structures built in the soil studied and a fair agreement between experimental and predict results was obtained.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-05-18T14:18:46Z No. of bitstreams: 1 sergioluizmotajunior.pdf: 65970440 bytes, checksum: b08afa740679beb93b85550945b417d2 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-01T18:47:10Z (GMT) No. of bitstreams: 1 sergioluizmotajunior.pdf: 65970440 bytes, checksum: b08afa740679beb93b85550945b417d2 (MD5) / Made available in DSpace on 2016-07-01T18:47:10Z (GMT). No. of bitstreams: 1 sergioluizmotajunior.pdf: 65970440 bytes, checksum: b08afa740679beb93b85550945b417d2 (MD5) Previous issue date: 2012-02-14 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O objetivo do presente estudo foi o desenvolvimento de uma nova ponteira para ser acoplada aos aparelhos fotopolimerizadores utilizados para colagem de bráquetes e acessórios ortodônticos, e teste da efetividade da mesma em ensaio mecânico in vitro. A ponteira é espelhada na superfície interna e baseia-se em conceitos físicos de refração e reflexão de luz. Apresenta como principal vantagem, a redução do tempo clínico necessário para o procedimento de colagem, reduzindo, dessa forma, a possibilidade de contaminação durante o processo. Através do ensaio de resistência mecânica ao cisalhamento e da determinação do Indice Remanescênte de Adesivo (IRA), testou-se a ponteira em uma amostra composta por 120 corpos de prova, sendo a mesma dividida em 2 grupos. No grupo 1 foi utilizado aparelho fotopolimerizador de fonte de luz halógena e no grupo 2 foi utilizado fonte de LED. Cada grupo foi subdividido. Nos subgrupos H1 e L1 utilizou-se a ponteira convencional dos respectivos instrumentos. Nos subgrupos H2 e L2 a colagem foi feita utilizando-se a ponteira desenvolvida. Os valores dos testes de cisalhamento e IRA para os subgrupos foram comparados entre si. Os resultados mostraram que não houve diferença estatisticamente significante, tanto para os ensaios de resistência ao cisalhamento (p>0,05), quanto para o IRA (p>0,05) entre os subgrupos. Conclui-se que 1 - os testes de ensaios mecânicos, assim como a análise do IRA mostraram que a nova ponteira desenvolvida, cumpriu os requisitos necessários à colagem dos acessórios ortodônticos; 2 – o tempo de colagem foi reduzido pela metade, sendo necessária uma só incidência. / The porpose of the present study was the development of a new device to be coupled to light-curing units for bonding orthodontic brackets and accessories and test of its efficacy in “in vitro” mechanical trial. The inner surface of the device is mirrored and is based on physical concepts of light refraction and reflection. The main advantage of such device is the reduced clinical time needed for bonding and the lesser possibility of contamination during the process. 120 bodies of proof were used for testing the shear bond strength of brackets bonded with the device. The Adhesive Remnant Index (ARI) was also determined. The sample was divided into 2 groups. In group 1 a halogen light-curing unit was used and in group 2 a led lightcuring unit was used. Each group was then subdivided. In subgroups H1 and L1, a conventional light guide rod was used. In subgroups H2 and L2 bonding was performed with the mirrored device coupled to the tip of the guide light rod. The values obtained for the shear bond strength and the ARI in the subgroups were compared. Results showed that there was no statistically significant difference for the shear strength (p>0,05) and the ARI (p>0,05) between the subgroups. Conclusions are that 1 - The tests of mechanical trials and the ARI analysis showed that the new device fulfilled the requisites for bonding orthodontic accessories; 2 - time for bonding was reduced to half, being necessary only one light exposure.

Orientadores: Fernanda Miori Pascon, Regina Maria Puppin Rontani / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-20T05:29:10Z (GMT). No. of bitstreams: 1 Iwamoto_AlexsandraShizue_M.pdf: 5068520 bytes, checksum: 5edcd14cf180873ed3b9ce319f696504 (MD5) Previous issue date: 2012 / Resumo: O objetivo do estudo foi avaliar in vitro a influência de diferentes materiais obturadores e agentes de limpeza na resistência da união de pinos de fibra de vidro à dentina radicular e na qualidade da interface adesiva. 156 raízes de dentes bovinos decíduos foram selecionadas, preparadas endodonticamente e distribuídas em 4 grupos de acordo com os materiais obturadores (39 dentes): 1- Controle (sem material); 2- Pasta Calen® + óxido de zinco (OZ); 3- Pasta Vitapex®; 4- Pasta Calcipex II®. Após 7 dias, as raízes foram desobturadas e subdivididas de acordo com os agentes de limpeza (13 dentes): A - Controle (sem limpeza); B - Etanol a 70%; C - Tergenform®. A cimentação do pino foi realizada com cimento resinoso RelyXMR ARC após condicionamento com ácido fosfórico a 35 % e aplicação do sistema adesivo Adper Single BondTM 2. Os espécimes foram armazenados por 7 dias, seccionados e preparados para avaliação da resistência da união (n=10) e análise da interface por meio da infiltração por nitrato de prata (n=3). O teste push-out foi conduzido na máquina de ensaio universal EMIC com velocidade 0,5mm/min. Os dados obtidos em Kgf foram convertidos em MPa e submetidos à ANOVA dois fatores (materiais obturadores x agentes de limpeza) e ao teste Tukey (p<0,05). Amostras representativas dos grupos foram observadas em Microscopia Eletrônica de Varredura (MEV) após a realização do teste push-out para ilustrar a fratura ocorrida. Para avaliação qualitativa da interface adesiva entre dentina/cimento e cimento/pino, as áreas infiltradas pela solução de nitrato de prata foram observadas em MEV e mensuradas por um único examinador previamente calibrado (nível de coincidência intra-examinador=98%), calculadas em porcentagem e submetidas ao teste Kruskal-Wallis (p<0,05) e à análise descritiva. Para os resultados da resistência da união, verificou-se que houve interação entre os fatores de estudo (p=0.0043). A pasta Calen®+OZ e limpeza com etanol apresentou o maior valor de resistência da união, diferindo estatisticamente do grupo sem limpeza. Valores intermediários foram encontrados para a limpeza com Tergenform®. As pastas Vitapex® e Calcipex® não apresentaram diferenças entre os agentes de limpeza e menores valores de resistência da união foram para o grupo controle (sem material obturador) e limpeza com Tergenform®, diferindo dos outros agentes de limpeza. Observou-se que não houve diferença entre os grupos para a infiltração de prata nas interfaces adesivas entre cimento e dentina radicular, que variou de 20,63% a 56,62%. Dessa forma, pode-se concluir que: (1) os materiais obturadores e os agentes de limpeza interferiram na resistência da união de pinos de fibra de vidro e dentina radicular; (2) ao realizar a obturação do canal radicular com pasta Calen®+OZ o melhor agente de limpeza foi o etanol a 70%; (3) para as pastas Vitapex® e Calcipex II® não há necessidade de agentes de limpeza; e (4) todos os grupos sofreram infiltração na interface de união entre cimento/dentina radicular, independente dos materiais obturadores e agentes de limpeza estudados / Abstract: The aim of this in vitro study was to evaluate the post-cement-dentin adhesive interface quality and the effect of different filling materials and cleaning agents on the bond strength of glass fiber posts to primary root dentin. This study included 156 roots of bovine primary teeth which were endodontically treated and assigned to four groups (39 teeth each group) according to filling materials: 1 - control (no material); 2 - Calen® paste + zinc oxide (ZO); 3 - Vitapex® paste; and 4 - Calcipex II® paste. After seven days, the filling materials were removed and the roots for each material subdivided into 3 groups (13 teeth) according to cleaning agents: A - No cleaning (control); B - 70% ethanol; and C - Tergenform®. Glass fiber posts were luted using dual polymerized resin cement (RelyXMR ARC) after 35% acid etching, rinsing and application of the adhesive system (Adper Single BondTM 2). The specimens were stored for 7 days, sectioned and prepared for push-out bond strength test (n=10) and interface analysis by silver nitrate leakage (n=3). A push-out test was performed using a universal test machine (EMIC) at a crosshead speed of 0.5 mm/min. Data obtained in Kgf were converted into MPa and submitted to two-way ANOVA (filling materials x cleaning agents) and Tukey tests (p<0.05). After the push-out test, representative samples of the groups were submitted to scanning electron microscopy (SEM) to illustrate the failure modes. The adhesive interface between dentin/cement and cement/post were also analyzed by SEM. The leakage (expressed in percentage) was measured by a single examiner previously calibrated (intra-examiner coincidence level = 98%) using a silver nitrate solution. Data obtained for leakage were submitted to the Kruskal-Wallis test (p<0.05) and descriptive analysis. Interaction was observed between filling materials and cleaning agents, concerning bond strength values (p=0.0043). Calen® paste+ZO with 70% ethanol showed the highest values, significantly different from the groups using no cleaning agents. Vitapex® and Calcipex® showed no significant difference between cleaning agents. The lowest bond strength values were found for the control with Tergenform®. No statistical difference was observed between groups concerning silver leakage (20.63% to 56.62%) in the adhesive interface between cement and dentin. In conclusion, filling materials and cleaning agents influenced the bond strength, but not the adhesive interface between intracanal posts and root dentin; as a cleaning agent, 70% ethanol responded better to Calen® paste+ZO; cleaning agents are not required for Vitapex® and Calcipex®; all groups showed leakage in the adhesion interface between cement resin/dentin root, regardless of the filling materials and cleaning agents studied / Mestrado / Odontopediatria / Mestre em Odontologia

Le béton auto-plaçant renforcé de fibres (BAPF) est l’un des récents développements dans le monde de la technologie du béton combinant les performances de l’auto-consolidation avec la ductilité post-pic et les nombreux avantages face à la fissuration grâce à la présence des fibres dans le béton. L’utilisation de BAPF accroît l’efficacité économique globale de la phase de construction en réduisant la main d’oeuvre, ou la consommation d’énergie requise, en accélérant la vitesse de construction, la réduction ou l’élimination de ferraillage conventionnel et à la simplification des détails et placement du ferraillage. Le BAPF a gagné en popularité dans ses utilisations durant les dernières années telles dans les tabliers de ponts, les poutrelles et les poutres. En dépit de preuve d’amélioration de synergie entre la technologie d’auto-placement et l’ajout de fibres dans le BAPF, il est obligatoire de déterminer les propriétés convenables de ce matériau pour trouver les caractéristiques inappropriées dans le béton à l’état frais et durci. A cet égard, les défauts, tels l’agglomération de fibres, la ségrégation et la performance d’écoulement et le placement incorrects à cause de propriétés rhéologiques inappropriées à l’état frais, entraînent une réduction dans la résistance évaluée. L’objectif principal de cette étude est d’évaluer les propriétés du béton auto-plaçant (BAP), des mélanges intégrant différentes teneurs en granulats et du BAPF (avec insertion de différents types et teneurs de fibres). Ceci peut aider au développement de BAPF avec une rhéologie adaptée et une performance mécanique adéquate incluant une résistance d’adhésion et de cisaillement convenable pour des applications structurelles. Dans le but d’évaluer l’effet des fibres sur les propriétés rhéologiques de BAP à l’état frais, des mélanges intégrant quatre types de fibres avec différents élancement (L/D) seront étudiés. Ces fibres incluent des crochets d’acier (STH 55/30), du fil d’acier tréfilé (STN 65/13), de la macro-fibre synthétique de propylène (PP 56/38) et de l’alcool polyvinylique (PVA 60/12) avec différentes teneurs volumiques (0.25%, 0.5%) ajoutées au BPA de référence. Tous les mélanges ont un rapport w/b fixé à 0,42 et la teneur en granulats grossiers est respectivement de 29, 32 et 35% par volume de béton. Les caractéristiques de béton frais ont été évaluées en considérant l’affaissement, l'évaluation du temps d’écoulement (V-funnel), l'amplitude à l'écoulement du BAP (J-Ring), le tassement de surface et le rhéomètre ConTec. Les propriétés du béton durci, en particulier la résistance à la compression, la résistance à la traction par fendage, la résistance à la flexion, et le module élastique ont été évaluées. L’effet des types de fibres, des teneurs en fibres et en granulats sur la résistance à la rupture et la robustesse du BAP au cisaillement des mélanges optimisés, incluant le BAP de référence, le SCCAGG (32% and 35%), le FRSCC ST-H (0.25% and 0.5%), le FRSCCPP (0.25% and 0.5%), le PVA (0.25% and 0.5%) et le ST-N (0.25% and 0.5%) ont été testés en utilisant l’essai de cisaillement direct pour évaluer la résistance en cisaillement et la résistance résiduelle du béton. Les résultats des essais prennent en considération la capacité portante en cisaillement de l’élément structurel fabriqué à partir de BAPF. Les résultats des essais montrent que l’ajout de fibres était beaucoup plus efficace que l’accroissement de la teneur en agrégats sur la résistance au cisaillement du BAP. L’amélioration de la contrainte au cisaillement à la rupture comparée au mélange de référence est plus grande avec 16.3% pour l’ajout de fibre de type STN 0.5%, 15.8% pour l’ajout de fibre de type STH 0.5%, 14.92% pour l’ajout de fibre de type PP 0.5% et 7.73% pour l’ajout de fibre de type PVA 0.5%. De plus, l’ajout de fibres améliore le comportement post-pic en cisaillement du BPA en comparaison à l’augmentation de la teneur en granulats. L’augmentation de la teneur en fibres de 0.25% à 0.5%, par volume de béton, a amélioré la résistance et la ténacité au cisaillement, le comportement en flexion peu importe le type de fibres. Cette amélioration a été la plus élevée dans le cas du STH 0.5% et la plus basse pour des valeurs de PVA0.5%. La réponse de la résistance à l’adhésion des barres d’armatures localisées à différentes hauteurs de l’élément de mur (effet top-bar) a été étudiée pour des mélanges optimisés; le BPA de référence, les mélanges ST-H 0.5, et PP 0.5 ont été testés à travers l’essai d’arrachement direct des barres coulées dans le large élément de mur. Utilisation de fibres de propylène et de fibres à crochets d’acier au BPA a légèrement augmenté le facteur de modification à l’adhérence (effet top-bar) de 1 dans le cas du BPA jusque 1,1 et 1,2 pour les fibres de propylène et de crochets d’acier respectivement. Les éléments de mur fabriqués à partir du mélange de BPA de référence a montré la distribution de résistance la plus uniforme avec moins de 5% de réduction de sa résistance à l’adhérence sur la hauteur. Ces pertes de résistance à l’adhérence pour les éléments de mur coulés avec du BPA intégrant les de fibres de propylène et de fibres à crochets d’acier sont respectivement de 10% et 20%. / Abstract : Fiber reinforced self-consolidating concrete (FR-SCC) is one of the recent developments in the world of concrete technology which combines the self-consolidating performance with the post-peak ductility and multiple cracking advantages due to presence of fiber reinforcement in concrete. The use of FR-SCC increases the overall economic efficiency of the construction process by reducing the workforce, or energy consumption required, increasing speed of construction, reduction or elimination of the conventional reinforcement and to the simplification of reinforcement detailing and placement. The FR-SCC has gained increasing popularity applications in the last few years such as bridge decks, girders and beams. Despite the improvement evidence of synergy between self-consolidating technology and fiber addition in the FR-SCC, finding adequate properties of this material is mandatory to find any improper characteristics in the fresh and hardened states. In this regards, defects, such as fiber clustering, segregation and improper flow performance and placement due to improper rheological properties in the fresh state, which leads to reduction in strength, are evaluated. The main objective of this study is to evaluate some rheological and mechanical properties of self-consolidating concrete (SCC) mixtures with different aggregate contents and FR-SCC (incorporating different fiber types and contents). This can help to develop of FR-SCC with adapted rheology and proper mechanical performance including bond strength and shear strength for structural application. In order to evaluate the effect of fibers on rheological properties of SCC in the fresh state, mixtures incorporating four types of fibers with different aspect ratio (L/D) were investigated. The fibers included steel hooked (STH 55/30), steel drawn wire needles (STN 65/13), synthetic macro-fiber propylene (PP 56/38) and polyvinyl alcohol (PVA 60/12) with variety of volume content (0.25%, 0.5%) added to the SCC reference. All mixtures has a fixed w/b ratio of 0.42 and different coarse aggregate contents of 29, 32 and 35%, by volume of concrete. The fresh concrete characteristics were evaluated by considering the slump flow, V-funnel, J-Ring, surface settlement and ConTec rheometer. The hardened properties, mainly compressive strength, splitting tensile strength, flexural strength, flexural toughness, and modulus of elasticity were evaluated. The effect of fiber type, fiber content, and coarse aggregate content on ultimate shear load and shear toughness of the optimized mixtures. The mixtures including SCC reference, SCC with aggregate volume of 32% and 35% (SCCAGG 32% and SCCAGG 35%), SCC incorporating ST-H fibers with the dosages of 0.25% and 0.5% (FRSCC ST-H 0.25% and FRSCC ST-H 0.5%), SCC incorporating PP fibers with the dosages of 0.25% and 0.5% (FRSCC PP 0.25% and FRSCC PP 0.5%), SCC incorporating PVA fibers with the dosages of 0.25% and 0.5% (FRSCC PVA 0.25% and FRSCC PVA 0.5%) and SCC incorporating ST-N fibers with the dosages of 0.25% and 0.5% (FRSCC ST-N 0.25% and FRSCC ST-N 0.5%) were tested using the direct shear push-off test to evaluate shear strength and residual shear strength of the concrete. These test results could be used in the shear load carrying capacity of the structural element made by FRSCC. The test results show that adding fiber was much more effective than increasing aggregate content on the shear strength behaviour of SCC. The ultimate shear stress improvement of the mixtures incorporating fiber compared to the SCC reference mixture were 16.3% for STN 0.5%, 15.8% for STH 0.5%, 14.92% for PP 0.5%, and 7.73% for PVA 0.5% mixture. Moreover, adding fibers improved the post-peak shear behaviour of SCC compared to addition of aggregate content. Increasing the fiber content from 0.25% to 0.5%, by volume of concrete, improved shear strength, shear toughness and flexural toughness behaviour regardless of the fiber types. This enhancement was highest in the case of STH 0.5% and lowest values for PVA0.5%. The bond strength response of rebars located at different heights of the wall element (top-bar effect) investigated for optimized mixtures, including SCC reference, ST-H 0.5, and PP 0.5 mixtures was tested through direct pull-out test of rebars cast in the large wall elements. Adding propylene and steel hooked fibers to SCC is found to slightly increase the bond modification factor (top-bar effect) from 1 in the case of SCC up to 1.1 and 1.2 for propylene and steel hooked fibers, respectively. The wall elements made with SCC reference mixture showed the most uniform bond strength distribution and had less than 5% reduction of bond strength along the height. These bond strength losses for wall element cast with SCC incorporating 0.5 % of steel hooked fiber and that of propylen fiber with the same volume are 10% and 20%, respectively.

KBS-3 and very deep borehole (VDH) concepts are two major types of long-term geologicaldisposal methods for high-level radioactive waste (HLW) isolating from the biosphere. TheKBS-3V concept for isolating the HLW at the depth of 400-500 m, is the officially proposedoption in Sweden and has been the subject of considerable research in the past few decades,while the VDH concept was considered as an option in the 1950s but later became discouragedbecause of insufficient experience in drilling technology. The greatest merit of the VDHconcept is that the almost stagnant groundwater in the deep boreholes prevents the transport ofthe possible release of radionuclides into the rock or up to the ground level. Since variousdisadvantages of the KBS-3V concept were found in previous research, the superiority of VDHconcept attracted the researchers to continue studying it into the late 1980s.The geological repositories of both of KBS-3V and VDH types primarily consist of a naturalbarrier (host rock) and of an engineering barrier (also known as a buffer/backfill barrier).According to the principle of IAEA and national relative research organizations, thebuffer/backfill material should have low permeability and good expandability, as well assuitable physical and sealing properties.The thesis concerns the VDH concept and is focused on the construction and performance ofthose parts of the sealed repository that are not affected by high temperature or gamma radiation.In the lower part of a VDH repository, the clay packages containing HLW will be exposed tohigh temperature (100-150 􀄇 ) in the borehole and to highly saline groundwater. In theinstallation phase of HLW, the groundwater will be pumped out and replaced by medium-softsmectite clay mud in which the HLW packages are installed vertically. During the hydrationand maturation of the clay components, the microstructural reorganization, water transport,migration of clay particles and redistribution of the density of the components take place. Thematuration determines the transient evolution of the clay seals and influences the rheologicaland soil mechanical behavior in the installation phase. The maturation of clay system alsodetermines their ultimate sealing potential of VDH repositories.This study presents the work carried out for investigating the maturation of the buffer-backfillclay in the HLW deep borehole. Initially in the study three types of clays, the Namontmorillonite,magnesium-rich and illite-smectite mixed layer clays, were examined for estimating their performance as the barrier candidate material. This is mainly presented in theliterature review. The experimental study was conducted on montmorillonite GMZ clays andI/S mixed-layer Holmehus clay. The expandability and permeability tests were carried out forinterpretation of the recorded swelling development and assessment of the effect of the salineconditions, with the goal of deriving a relationship between swelling pressure and hydraulicconductivity for different dry densities. The maturation tests of initially fully-saturatedHolmehus clay and partly saturated GMZ clay were performed. During the tests, the shearstrength mobilised by the relative movement of densified mud and migrated dense clay -contained in a perforated central tube - were determined. According to the results of shearstrength tests, the maximum operation time or the number of clay packages to be placed in asingle operation was evaluated, whilst the suitable saturation degree of the dense clay wasdiscussed as well.A model of the maturation of initially water-saturated clay seals based on Darcy’s law wasworked out and the evolution of the clay components in a lab-scale borehole using Holmehusclay were performed and compared with the experimental recordings. Good agreementsbetween the physical behaviors of the theoretical simulations and the measurements wasachieved by which the validity of the model was verified. Using the results, the hydration andsoil migration in the entire maturation process were presented in diagram. The model was alsoused for preliminary evaluation of the maturation products in real boreholes by assuming thesame Holmehus clay as used in the tests. Two constellation of borehole and dense clay withdifferent diameters, 80 cm borehole /60 cm clay and 80cm/50cm, were assumed. The resultsrespecting dry density and hydraulic conductivity of the ultimate maturation products, and thedegree of homogeneous of the buffer and backfill clay system in the assumed boreholes, arepresented and discussed. The options of different mineral types and initial physical propertiesof the candidate buffer clays provide a reference for engineering barrier design of HLW disposalin VDH.