AbstractAN IN-VITRO COMPARISON OF THE RETENTION OF PREFABRICATED PARALLEL-SIDED VENTED TITANIUM POSTS CEMENTED WITH THREE DIFFERENT DUAL-POLYMERIZABLE RESIN CEMENTSBy Maha M. El-Sayed, B.D.S., D.M.D.A Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science at Virginia Commonwealth University.Virginia Commonwealth University, 2003Thesis Director: David R. Burns, D.M.D. Associate Professor and Program DirectorGraduate ProsthodonticsDepartment of ProsthodonticsPurpose: The purpose of this in-vitro study was to compare the retentive strength of an autopolymerizing resin cement to three dual-polymerizable resin cements when used to cement paraposts without light activation and to relate diametral tensile stress and hardness as a measure of the degree of polymerization to the retentive strength of the different dual-polymerizable resin cements. Material and methods: 60 human extracted premolar teeth were endodontically-treated and randomly divided into 4 test groups (n=15). Parapost XP posts (size 5) were cemented using Panavia 21(control), Panavia F, RelyX Unicem and Linkmax resin cements. The latter three cements were dual-polymerizable and were not light-activated, and the control cement was autopolymerizable. Also, 140 resin cement samples were fabricated for diametral tensile stress and Knoop hardness testing. Each test had 70 samples, 10 of each of the following groups: Panavia 21, Panavia F light-activated, Panavia F autopolymerized, RelyX Unicem light-activated, RelyX Unicem autopolymerized, Linkmax light-activated, Linkmax autopolymerized. Post retention, diametral tensile stress and surface hardness tests were performed 1 week after sample fabrication or post cementation.Results: ANOVA and Tukey-Kramer statistical analysis revealed significant differences among the test groups for the three tests. Conclusions: Within the limitations of this in vitro study, tested dual-polymerization resin cements had similar or superior parapost retention to the control autopolymerizing resin cement without photoactivation. Dual-polymerizable resin cements had improved diametral tensile stress and surface hardness when light-activated than when autopolymerized. No correlation was observed between surface hardness and diametral tensile stress or between the tested physical properties of the resin cements and their retentive qualities

Neste trabalho avalia-se a confiabilidade de tubos circulares de concreto armado submetidos à compressão diametral utilizada no controle de qualidade da produção. O estudo envolve uma parte experimental e uma teórica. Na parte experimental foram ensaiados 32 tubos divididos em duas séries de 16 tubos de diâmetros nominais de 800 mm e 1200 mm. Cada série era formada por 12 tubos tipo ponta e bolsa (PB) e 4 tubos tipo ponta sem bolsa (PSB). Na parte teórica, os tubos foram analisados por um programa computacional baseado no método dos elementos finitos desenvolvido para pórticos planos considerando as não-linearidades física e geométrica. Na análise de confiabilidade, as funções de estado limite foram determinadas segundo o Método da Superfície de Resposta. Os resultados numéricos e experimentais da curva força versus deslocamento apresentaram boa concordância e indicaram que o tubo se comportou como um anel circular, uma vez que os tubos tipo PSB apresentaram forças últimas da ordem de 4% e 12% maiores que as obtidos para os tubos PB, respectivamente para os diâmetros nominais de 800 mm e 1200 mm. Entretanto, a presença da bolsa influenciou no valor da força de fissuração, sendo 6,4% e 33% maior para os tubos PB em relação aos tubos PSB para os diâmetros nominais de 800 mm e 1200 mm, respectivamente. A teoria de confiabilidade mostrou que a probabilidade de falha dos tubos de concreto para atender ao ensaio de compressão diametral foi fortemente influenciada pelo controle de qualidade dos materiais utilizados na fabricação dos tubos. Ainda, foi observado que os tubos analisados apresentaram índice de confiabilidade superior a 3,8, para atender ao ensaio de compressão diametral. Dentre as variabilidades mais influentes no cálculo do índice de confiabilidade, destacam-se a resistência à compressão do concreto, a espessura do tubo e a posição da armadura. / This work evaluates the reliability of circular reinforced concrete pipes subjected to diametrical compression considering the quality control of the production. The study includes experimental and theoretical parts. In the experimental part, 32 pipes divided in two series of 16 pipes according to the nominal diameter of 800 mm and 1200 mm were tested. Each series was composed by 12 spigot and pocket pipes (PB) and 4 ogee joint pipes (PSB). In the theoretical part, the pipes were analyzed using a computational program based on finite element method developed for frame structures considering physical and geometrical nonlinearities. In reliability analysis, the limit state functions were determined according to the Method of Response Surface. Numerical and experimental results of the loading versus displacement curves were well agreed and they indicated that the pipe behaves as a circular ring, once the PSB pipes presented maximum loads 4% and 12% higher than those obtained for PB pipes, respectively for nominal diameters of 800 mm and 1200 mm. However, the presence of pocket influenced the cracking loading, with 6.4% and 33% higher for PB pipes in relation to PSB pipes for the nominal diameters of 800 mm and 1200 mm, respectively. The reliability theory showed that the probability of failure of concrete pipes to meet the diametrical compression test was strongly influenced by the quality control of materials used in manufacturing the pipes. Also, it was observed that analyzed pipes presented reliability index greater than 3.8, to meet the diametrical compression test. Among the most influential variabi1ities in evaluating of reliability index, the concrete compressive strength, the pipe thickness and the position of the reinforcement in the pipe can be highlighted.

Tratamento restaurador atraumático tornou-se uma opção real para o tratamento da cárie dentária em saúde pública no Brasil. O presente estudo teve como objetivo avaliar durabilidade, resistência e eficácia de 70 restaurações em 31 alunos (entre 6 a 12 anos de idade na Escola Municipal Rotary, RJ - Brasil). Depois de CPO-D e ceo-exame de acordo com critérios da OMS, todos os alunos com selecionados receberam TRA com VITRO MOLAR - DFL, juntamente com instruções de saúde bucal. Os critérios de exclusão foram a presença de cavidades muito profundas e exposição pulpar, casos em que os alunos foram encaminhados para o Postos de Saúde Municipal. In vitro avaliou-se a influência do tempo de entrada em serviço e do tipo de cobertura protetora utilizada na resistência coesiva do Cimento de Ionômero de Vidro utilizado, por meio de ensaios de tração diametral. Confeccionou-se para o teste de tração diametral 6 espécimes para cada variante, 72 no total, com dimensões de 4 mm de diâmetro por 8 mm de comprimento, divididos entre os grupos: grupo1 sem protetor (controle); grupo2 vaselina sólida; grupo3 verniz para unhas. Realizou-se ensaios mecânicos em uma máquina universal de ensaios EMIC DL 500 MF, após a confecção e estocagem individual dos espécimes em potes plásticos contendo 5 ml de água deionizada, que formaram os subgrupos descritos a seguir: a - 20 minutos; b - 2 horas; c - 24 horas; d - 7 dias. Os dados obtidos foram tratados por ANOVA e por Student Newman-Keuls (p<0,05). Ao se avaliar a influência dos diferentes protetores de superfície no CIV utilizado no presente trabalho observou-se que, os protetores de superfície tiveram influência no comportamento do material (p=0,000), com o verniz para unhas mostrando um desempenho superior ao da vaselina sólida. Quanto ao tempo, não foi possível verificar ruptura do material no prazo de 20 minutos, pois os corpos de prova sofriam deformação elástica catastrófica não sendo adequado para a finalidade desejada. Os tempos de 24 horas e sete dias foram semelhantes entre si e diferentes do tempo de duas horas. As restaurações foram clinicamente avaliadas depois de 6, 12, e 24 meses após sua alocação. No total 72 restaurações foram realizadas em 31 escolares. Depois de seis meses, 5 restaurações fraturaram e 3 perderam algum material. Após 12 meses, oito restaurações foram perdidas e apenas 1 fraturou. Na avaliação após 24 meses, mais 12 restaurações foram perdidas e 3 perderam material. Não foram registradas lesões cariosas secundarias após esse período, mesmo quando as restaurações foram parcialmente perdidas. Clinicamente conclui-se que quando a técnica do TRA é bem indicada e aplicada corretamente pode haver uma redução significativa no número de dentes perdidos por lesões de cárie nos indivíduos que participaram do nosso estudo. / Atraumatic restorative treatment (ART) has become a real option for caries treatment in public health in Brazil. The present study aimed to evaluate the durability, the resistance, and the effectiveness of ART restorations in vivo in 31 students (ages 6 to 12 yrs old at the Municipal Rotary School, RJ - Brazil). After DMF-T and dmf-t examination according to WHO criteria, all students with dental cavities received ART with VITRO MOLAR - DFL, along with oral health instruction. In vitro were evaluated the influence of time of entry into service and the type of protective covering used in the cohesive strength of the cement Glass Ionomer used by diametral tensile (TD).The glass iomer was manipulates according manufacture instructions and divided in three groups 1-without protector(control) G2-with solid vaseline and G3- nails varnish. Exclusion criteria were the presence of very deep cavities and exposed pulp exposition, in which cases the students were referred to the Municipality Health Care. For the traction tests, it was confectioned 6 specimens measuring 4 mm of diameter and 8 mm of lengths, individually storage in plastic tubs with 5ml of deodenized water. The mechanic trials were done in a universal machine EMIC DL 500 MF. Data were analyzed by ANOVA and Student Newman-Keuls (p<0,05). The influence of different protectors in the Glass Inomer,in the present work, it was observed that they had few influence in the material behavior, most f the time similar to the control group and the material suffer distortion when under a 20 minutes traction. The restorations were clinically observed after 6, 12, and 24 mos. In total, 72 restorations were made in 31 students. After 6 months, 5 restorations were fractured and 3 presented with some material lost. At 12 months, 8 more restorations were lost, only 1 was fractured, and 7 had lost some material. After 24 months, 12 more restorations were lost, 3 had lost some material. Although not all restorations could be evaluated until 24 months, no secondary caries was detected, even when the fillings were (partly) affected. This glass ionomer, when used in an ART setting, was successful in avoiding dental caries and its progression for at least one year, and therefore we recommend its use in areas with limited or no access to dental care.

Tratamento restaurador atraumático tornou-se uma opção real para o tratamento da cárie dentária em saúde pública no Brasil. O presente estudo teve como objetivo avaliar durabilidade, resistência e eficácia de 70 restaurações em 31 alunos (entre 6 a 12 anos de idade na Escola Municipal Rotary, RJ - Brasil). Depois de CPO-D e ceo-exame de acordo com critérios da OMS, todos os alunos com selecionados receberam TRA com VITRO MOLAR - DFL, juntamente com instruções de saúde bucal. Os critérios de exclusão foram a presença de cavidades muito profundas e exposição pulpar, casos em que os alunos foram encaminhados para o Postos de Saúde Municipal. In vitro avaliou-se a influência do tempo de entrada em serviço e do tipo de cobertura protetora utilizada na resistência coesiva do Cimento de Ionômero de Vidro utilizado, por meio de ensaios de tração diametral. Confeccionou-se para o teste de tração diametral 6 espécimes para cada variante, 72 no total, com dimensões de 4 mm de diâmetro por 8 mm de comprimento, divididos entre os grupos: grupo1 sem protetor (controle); grupo2 vaselina sólida; grupo3 verniz para unhas. Realizou-se ensaios mecânicos em uma máquina universal de ensaios EMIC DL 500 MF, após a confecção e estocagem individual dos espécimes em potes plásticos contendo 5 ml de água deionizada, que formaram os subgrupos descritos a seguir: a - 20 minutos; b - 2 horas; c - 24 horas; d - 7 dias. Os dados obtidos foram tratados por ANOVA e por Student Newman-Keuls (p<0,05). Ao se avaliar a influência dos diferentes protetores de superfície no CIV utilizado no presente trabalho observou-se que, os protetores de superfície tiveram influência no comportamento do material (p=0,000), com o verniz para unhas mostrando um desempenho superior ao da vaselina sólida. Quanto ao tempo, não foi possível verificar ruptura do material no prazo de 20 minutos, pois os corpos de prova sofriam deformação elástica catastrófica não sendo adequado para a finalidade desejada. Os tempos de 24 horas e sete dias foram semelhantes entre si e diferentes do tempo de duas horas. As restaurações foram clinicamente avaliadas depois de 6, 12, e 24 meses após sua alocação. No total 72 restaurações foram realizadas em 31 escolares. Depois de seis meses, 5 restaurações fraturaram e 3 perderam algum material. Após 12 meses, oito restaurações foram perdidas e apenas 1 fraturou. Na avaliação após 24 meses, mais 12 restaurações foram perdidas e 3 perderam material. Não foram registradas lesões cariosas secundarias após esse período, mesmo quando as restaurações foram parcialmente perdidas. Clinicamente conclui-se que quando a técnica do TRA é bem indicada e aplicada corretamente pode haver uma redução significativa no número de dentes perdidos por lesões de cárie nos indivíduos que participaram do nosso estudo. / Atraumatic restorative treatment (ART) has become a real option for caries treatment in public health in Brazil. The present study aimed to evaluate the durability, the resistance, and the effectiveness of ART restorations in vivo in 31 students (ages 6 to 12 yrs old at the Municipal Rotary School, RJ - Brazil). After DMF-T and dmf-t examination according to WHO criteria, all students with dental cavities received ART with VITRO MOLAR - DFL, along with oral health instruction. In vitro were evaluated the influence of time of entry into service and the type of protective covering used in the cohesive strength of the cement Glass Ionomer used by diametral tensile (TD).The glass iomer was manipulates according manufacture instructions and divided in three groups 1-without protector(control) G2-with solid vaseline and G3- nails varnish. Exclusion criteria were the presence of very deep cavities and exposed pulp exposition, in which cases the students were referred to the Municipality Health Care. For the traction tests, it was confectioned 6 specimens measuring 4 mm of diameter and 8 mm of lengths, individually storage in plastic tubs with 5ml of deodenized water. The mechanic trials were done in a universal machine EMIC DL 500 MF. Data were analyzed by ANOVA and Student Newman-Keuls (p<0,05). The influence of different protectors in the Glass Inomer,in the present work, it was observed that they had few influence in the material behavior, most f the time similar to the control group and the material suffer distortion when under a 20 minutes traction. The restorations were clinically observed after 6, 12, and 24 mos. In total, 72 restorations were made in 31 students. After 6 months, 5 restorations were fractured and 3 presented with some material lost. At 12 months, 8 more restorations were lost, only 1 was fractured, and 7 had lost some material. After 24 months, 12 more restorations were lost, 3 had lost some material. Although not all restorations could be evaluated until 24 months, no secondary caries was detected, even when the fillings were (partly) affected. This glass ionomer, when used in an ART setting, was successful in avoiding dental caries and its progression for at least one year, and therefore we recommend its use in areas with limited or no access to dental care.

Neste trabalho avalia-se a confiabilidade de tubos circulares de concreto armado submetidos à compressão diametral utilizada no controle de qualidade da produção. O estudo envolve uma parte experimental e uma teórica. Na parte experimental foram ensaiados 32 tubos divididos em duas séries de 16 tubos de diâmetros nominais de 800 mm e 1200 mm. Cada série era formada por 12 tubos tipo ponta e bolsa (PB) e 4 tubos tipo ponta sem bolsa (PSB). Na parte teórica, os tubos foram analisados por um programa computacional baseado no método dos elementos finitos desenvolvido para pórticos planos considerando as não-linearidades física e geométrica. Na análise de confiabilidade, as funções de estado limite foram determinadas segundo o Método da Superfície de Resposta. Os resultados numéricos e experimentais da curva força versus deslocamento apresentaram boa concordância e indicaram que o tubo se comportou como um anel circular, uma vez que os tubos tipo PSB apresentaram forças últimas da ordem de 4% e 12% maiores que as obtidos para os tubos PB, respectivamente para os diâmetros nominais de 800 mm e 1200 mm. Entretanto, a presença da bolsa influenciou no valor da força de fissuração, sendo 6,4% e 33% maior para os tubos PB em relação aos tubos PSB para os diâmetros nominais de 800 mm e 1200 mm, respectivamente. A teoria de confiabilidade mostrou que a probabilidade de falha dos tubos de concreto para atender ao ensaio de compressão diametral foi fortemente influenciada pelo controle de qualidade dos materiais utilizados na fabricação dos tubos. Ainda, foi observado que os tubos analisados apresentaram índice de confiabilidade superior a 3,8, para atender ao ensaio de compressão diametral. Dentre as variabilidades mais influentes no cálculo do índice de confiabilidade, destacam-se a resistência à compressão do concreto, a espessura do tubo e a posição da armadura. / This work evaluates the reliability of circular reinforced concrete pipes subjected to diametrical compression considering the quality control of the production. The study includes experimental and theoretical parts. In the experimental part, 32 pipes divided in two series of 16 pipes according to the nominal diameter of 800 mm and 1200 mm were tested. Each series was composed by 12 spigot and pocket pipes (PB) and 4 ogee joint pipes (PSB). In the theoretical part, the pipes were analyzed using a computational program based on finite element method developed for frame structures considering physical and geometrical nonlinearities. In reliability analysis, the limit state functions were determined according to the Method of Response Surface. Numerical and experimental results of the loading versus displacement curves were well agreed and they indicated that the pipe behaves as a circular ring, once the PSB pipes presented maximum loads 4% and 12% higher than those obtained for PB pipes, respectively for nominal diameters of 800 mm and 1200 mm. However, the presence of pocket influenced the cracking loading, with 6.4% and 33% higher for PB pipes in relation to PSB pipes for the nominal diameters of 800 mm and 1200 mm, respectively. The reliability theory showed that the probability of failure of concrete pipes to meet the diametrical compression test was strongly influenced by the quality control of materials used in manufacturing the pipes. Also, it was observed that analyzed pipes presented reliability index greater than 3.8, to meet the diametrical compression test. Among the most influential variabi1ities in evaluating of reliability index, the concrete compressive strength, the pipe thickness and the position of the reinforcement in the pipe can be highlighted.

[pt] Esta pesquisa apresenta um estudo experimental do comportamento de corpos de prova de concreto armado com fibras metálicas comprimidos diametralmente e os submetidos à tração direta. Foram analisados 72 corpos de prova no LEM-DEC da PUC-Rio, sendo 54 cilíndricos variando-se o diâmetro e o consumo de fibras para o ensaio de compressão diametral e 18 variando-se o consumo de fibras para o ensaio de tração direta. Os 54 corpos de prova foram divididos em três grupos de acordo com a resistência à compressão (20, 30 e 50 MPa), cada grupo com 18 corpos de prova com consumo de fibras (20 kg/metro cúbico, 40 kg/metro cúbico e 60 kg/metro cúbico) e diâmetros distintos (5 cm, 10 cm e 15 cm). Foram avaliados a resistência de tração, energia de deformação e efeito escala. Os resultados obtidos permitem analisar a influência do consumo de fibras e do diâmetro do corpo de prova. A resistência à tração varia linearmente com o consumo e o diâmetro do corpo de prova, verificando-se que a resistência do corpo de prova com diâmetro de 15 cm é 42 por cento menor que o de 5 cm. A energia de deformação não apresentou acréscimo significativo com o aumento do consumo de fibras de 40 kg/metro cúbico para 60 kg/metro cúbico. A análise do efeito escala mostra um decréscimo da resistência à tração com incremento da dimensão do corpo de prova, e os resultados se assemelham aos estudos realizados por Carpinteri (1995), mesmo com consumos de fibras distintos. Os 18 corpos de prova submetidos à tração direta têm a mesma dimensão, diferindo em resistência (20, 30 e 50 MPa) e consumo (20 kg/metro cúbico, 40 kg/metro cúbico e 60 kg/metro cúbico). Nesses foi avaliada a energia de deformação plástica e elástica. A região plástica não fica delineada para o consumo de 20 kg/metro cúbico apresentando um comportamento similar ao concreto convencional. / [en] This research presents an experimental study on the behavior of reinforced concrete specimens with steel fibers submitted to the splitting test and to direct tension. A total of 72 specimens were tested in the LEM-DEC PUC-Rio; 54 specimens with three different diameters and fiber consume for the diametral compression test and 18 with variations of fiber volume fraction for the direct tension test. The 54 specimens were divided into three groups according to their compressive strength (20, 30 and 50 MPa), each group having 18 specimens with variations of fiber volume fraction (20 kg / cubic meter, 40 kg / cubic meter and 60 kg / cubic meter and diameter (5 cm, 10 cm and 15 cm). The purpose was to investigate the tensile stress, the fracture energy and the size effect. The results allowed the analysis of the influence of the fibers and specimen diameter on each variable before mentioned. The tensile stress varies linearly with fiber volume fraction and diameter, and the resistance of the specimens with 15 cm in diameter is 42 per cent less than the resistance of the 5 cm specimen. The fracture energy was not increased significantly with the increase of fiber content from 40 kg fibers / cubic meter to 60 kg / cubic meter. The size effect analysis shows that tensile strength decreases as the diameter increases. These results are similar to those of studies conducted by Carpinteri (1995), even with different values of fiber consume. The 18 specimens submitted to direct tension had the same diameter, varying in resistance (20, 30 and 50 MPa) and fiber volume fraction (20 kg / cubic meter, 40 kg / cubic meter and 60 kg /cubic meter). Here the plastic and elastic deformations were evaluated. The plastic region is not clearly defined for the fiber fraction of 20 kg / cubic meter presenting a behavior similar to the conventional concrete.

In real life, immediately after joint replacement, the artificial joint is actually bathed in blood (and clotted blood) instead of synovial fluid. Blood contains large molecules and cells of size ~ 5 to 20 μm suspended in plasma and considered to be a non-Newtonian (pseudoplastic) fluid with density of 1060 Kg/m³ and viscosity ~ 0.01 Pas at shear rates of 3000 s⁻¹ (as obtained in this work). The effect of these properties on friction and lubrication is not fully understood and, so far to our knowledge, hardly any studies have been carried out regarding friction of metal-on-metal bearings with various clearances in the presence of lubricants such as blood or a fluid containing macromolecules such as hyaluronic acid (HA) which is a major component of synovial fluid increasing its viscosity and lubricating properties. In this work, therefore, we have investigated the frictional behaviour of a group of Smith and Nephew Birmingham Hip Resurfacing implants with a nominal diameter of 50mm and diametral clearances in the range ~ 80 μm to 300 μm, in the presence of blood (clotted and whole blood), a combination of bovine serum (BS) with hyaluronic acid (HA) and carboxymethyl cellulose (CMC, as gelling agent) adjusted to a range of viscosities (~0.001-0.2 Pas), and bovine serum with CMC adjusted to a similar range of viscosities. These results suggested that reduced clearance bearings have the potential to generate high friction especially in the presence of blood which is indeed the in vivo lubricant in the early weeks after implantation. Friction factors in higher clearance bearings were found to be lower than those of the lower clearance bearings using blood as the lubricant. Similar trends, i.e. increase in friction factor with reduction in diametral clearance, were found to be also the case using a combination of BS+CMC or BS+HA+CMC as lubricants having viscosities in the range 0.1-0.2 and 0.03-0.14 Pas, respectively. On the other hand, all the lubricants with lower viscosities in the range 0.001-0.0013 and 0.001-0.013 Pas for both BS+CMC and BS+HA+CMC, respectively, showed the opposite effect, i.e. caused an increase in friction factor with increase in diametral clearance. Another six large diameter (50mm nominal) BHR deflected prostheses with various clearances (~ 50-280μm after cup deflection) were friction tested in vitro in the presence of blood and clotted blood to study the effect of cup deflection on friction. It was found that the biological lubricants caused higher friction factors at the lower diametral clearances for blood and clotted blood as clearance decreased from 280μm to 50μm (after deflection). The result of this investigation has suggested strongly that the optimum clearance for the 50 mm diameter MOM BHR implants to be ≥150μm and <235μm when blood lubricant used, so as to avoid high frictions (i.e. avoid friction factors >0.2) and be able to accommodate a mixed lubrication mode and hence lower the risk of micro- or even macro-motion specially immediately after hip implantation. These suggested optimum clearances will also allow for low friction (i.e. friction factors of <0.2-0.07) and reasonable lubrication (dominantly mixed regime) for the likely cup deflection occurring as a result of press-fit fixation.

Esta dissertação apresenta os resultados de uma pesquisa cujo objetivo principal é avaliar o comportamento mecânico de misturas de solo-cimento e fosfogesso e cimento destinadas à construção de bases rodoviárias. O solo-cimento é um material de uso consolidado em pavimentação. Na composição das misturas de solo-cimento foram utilizados dois diferentes solos pertencentes a um mesmo grupo segundo as classificações HBR e USCS, mas considerados, respectivamente, de comportamento laterítico, segundo a classificação MCT. O fosfogesso é um resíduo sólido na produção de adubos, constituindo-se em um elemento agressivo ao meio ambiente devido a sua natureza ácida e por conter elementos radioativos e metais pesados. Por ser instável frente a ação da água, este material deverá ser estabilizado com cimento para uso em pavimentos. As amostras destas misturas foram submetidas a ensaios de compressão simples, compressão diametral e triaxiais cíclicos. Nos ensaios de compressão simples e compressão diametral, metade dos corpos de prova foi submetida a imersão prévia em água por quatro horas antes dos ensaios e a outra metade foi ensaiada sem imersão. Os corpos de prova com teores de 4, 7 e 10% foram compactados na energia normal de ensaio de Proctor e curados por 3, 7 e 28 dias. Para as misturas de fosfogesso e cimento foram utilizados apenas os teores de 7 e 10%. Observou-se que valores crescentes de tempo de cura e teor de cimento conduziram a maiores valores de resistência e rigidez. Ensaios realizados após imersão em água apresentaram valores de resistência à compressão diametral menores do que os obtidos sem imersão. Os resultados dos ensaios triaxiais cíclicos mostram o efeito predominante da tensão desvio no valor do módulo de resiliência quando comparado com o efeito da tensão de confinamento. Concluiu-se também que as misturas compostas de solo de comportamento laterítico apresentam melhor desempenho que as ) misturas compostas com solos de comportamento não laterítico. Comparando-se o desempenho mecânico das misturas de solo-cimento com o das misturas de fosfogesso e cimento, estas últimas apresentam resistência e rigidez significativamente menores. Entretanto, o desempenho das misturas de fosfogesso e cimento, principalmente no tocante à deformabilidade, é comparável ao de materiais empregados em pavimentação, como algumas bases estabilizadas granulometricamente de uso corrente. / This work presents the results of a research whose main objective is to evaluate the mechanical behavior of soil-cement and phosphogypsum and cement mixtures for the construction of road bases. The soil-cement is a traditional useful material in pavement construction. The in composition of the soil-cement mixtures were used. Two different soils with same HRB and USCS classifications, but considered, respectively, of lateritic and non-Iateritic behavior, according to the MCT classification. The phosphogypsum is a solid by-product of the fertilizers production, it\'s an aggressive element to the environment due to its acid nature and for containing radioactive elements and heavy metals. For being unstable in the presence of water, this material should be stabilized with cement for use in pavements. The samples of these mixtures were submitted to tests of unconfined compressive strength, diametral compression and cyclic triaxial loading test. In the tests of unconfined compressive strength and diametral compression, half of the specimens were submitted previous immersion in water for four hours before the test and the other half was tested without immersion. The specimens with cement content of 4, 7 and 10% were compacted using the normal energy of Proctor test and cured during 3, 7 and 28 days. For the phosphogypsum and cement mixtures were just used cement content of 7 and 10%. It was observed that higher values of time of cure and cement content led to higher strength and stiffness values. Tests performed after immersion in water presented strength values for the unconfined compressive and diametral compression strength than those obtained without immersion. The results of the cyclic triaxial loading test show the predominant effect of the deviateric stress in the value of the resilience modulus when compared with the effect of the confinement tension. It was also concluded that the mixtures composed with lateritic behavior soil presented better performance than mixtures composed with non lateritic behavior soil.Comparing the mechanical performance of the soil-cement mixtures with the one of the phosphogypsum and cement mixtures, the last one presents strength and stiffness signiflcantly lower. However, the performance of the phosphogypsum and cement mixtures, mainly concerning the deformability, is comparable to the performance of materials employed in paving, as some soil stabilized bases.

Esta dissertação apresenta os resultados de uma pesquisa cujo objetivo principal é avaliar o comportamento mecânico de misturas de solo-cimento e fosfogesso e cimento destinadas à construção de bases rodoviárias. O solo-cimento é um material de uso consolidado em pavimentação. Na composição das misturas de solo-cimento foram utilizados dois diferentes solos pertencentes a um mesmo grupo segundo as classificações HBR e USCS, mas considerados, respectivamente, de comportamento laterítico, segundo a classificação MCT. O fosfogesso é um resíduo sólido na produção de adubos, constituindo-se em um elemento agressivo ao meio ambiente devido a sua natureza ácida e por conter elementos radioativos e metais pesados. Por ser instável frente a ação da água, este material deverá ser estabilizado com cimento para uso em pavimentos. As amostras destas misturas foram submetidas a ensaios de compressão simples, compressão diametral e triaxiais cíclicos. Nos ensaios de compressão simples e compressão diametral, metade dos corpos de prova foi submetida a imersão prévia em água por quatro horas antes dos ensaios e a outra metade foi ensaiada sem imersão. Os corpos de prova com teores de 4, 7 e 10% foram compactados na energia normal de ensaio de Proctor e curados por 3, 7 e 28 dias. Para as misturas de fosfogesso e cimento foram utilizados apenas os teores de 7 e 10%. Observou-se que valores crescentes de tempo de cura e teor de cimento conduziram a maiores valores de resistência e rigidez. Ensaios realizados após imersão em água apresentaram valores de resistência à compressão diametral menores do que os obtidos sem imersão. Os resultados dos ensaios triaxiais cíclicos mostram o efeito predominante da tensão desvio no valor do módulo de resiliência quando comparado com o efeito da tensão de confinamento. Concluiu-se também que as misturas compostas de solo de comportamento laterítico apresentam melhor desempenho que as ) misturas compostas com solos de comportamento não laterítico. Comparando-se o desempenho mecânico das misturas de solo-cimento com o das misturas de fosfogesso e cimento, estas últimas apresentam resistência e rigidez significativamente menores. Entretanto, o desempenho das misturas de fosfogesso e cimento, principalmente no tocante à deformabilidade, é comparável ao de materiais empregados em pavimentação, como algumas bases estabilizadas granulometricamente de uso corrente. / This work presents the results of a research whose main objective is to evaluate the mechanical behavior of soil-cement and phosphogypsum and cement mixtures for the construction of road bases. The soil-cement is a traditional useful material in pavement construction. The in composition of the soil-cement mixtures were used. Two different soils with same HRB and USCS classifications, but considered, respectively, of lateritic and non-Iateritic behavior, according to the MCT classification. The phosphogypsum is a solid by-product of the fertilizers production, it\'s an aggressive element to the environment due to its acid nature and for containing radioactive elements and heavy metals. For being unstable in the presence of water, this material should be stabilized with cement for use in pavements. The samples of these mixtures were submitted to tests of unconfined compressive strength, diametral compression and cyclic triaxial loading test. In the tests of unconfined compressive strength and diametral compression, half of the specimens were submitted previous immersion in water for four hours before the test and the other half was tested without immersion. The specimens with cement content of 4, 7 and 10% were compacted using the normal energy of Proctor test and cured during 3, 7 and 28 days. For the phosphogypsum and cement mixtures were just used cement content of 7 and 10%. It was observed that higher values of time of cure and cement content led to higher strength and stiffness values. Tests performed after immersion in water presented strength values for the unconfined compressive and diametral compression strength than those obtained without immersion. The results of the cyclic triaxial loading test show the predominant effect of the deviateric stress in the value of the resilience modulus when compared with the effect of the confinement tension. It was also concluded that the mixtures composed with lateritic behavior soil presented better performance than mixtures composed with non lateritic behavior soil.Comparing the mechanical performance of the soil-cement mixtures with the one of the phosphogypsum and cement mixtures, the last one presents strength and stiffness signiflcantly lower. However, the performance of the phosphogypsum and cement mixtures, mainly concerning the deformability, is comparable to the performance of materials employed in paving, as some soil stabilized bases.

In real life, immediately after joint replacement, the artificial joint is actually bathed in blood (and clotted blood) instead of synovial fluid. Blood contains large molecules and cells of size ~ 5 to 20 2m suspended in plasma and considered to be a non-Newtonian (pseudoplastic) fluid with density of 1060 Kg/m3 and viscosity ~ 0.01 Pas at shear rates of 3000 s-1 (as obtained in this work). The effect of these properties on friction and lubrication is not fully understood and, so far to our knowledge, hardly any studies have been carried out regarding friction of metal-on-metal bearings with various clearances in the presence of lubricants such as blood or a fluid containing macromolecules such as hyaluronic acid (HA) which is a major component of synovial fluid increasing its viscosity and lubricating properties. In this work, therefore, we have investigated the frictional behaviour of a group of Smith and Nephew Birmingham Hip Resurfacing implants with a nominal diameter of 50mm and diametral clearances in the range ~ 80 2m to 300 2m, in the presence of blood (clotted and whole blood), a combination of bovine serum (BS) with hyaluronic acid (HA) and carboxymethyl cellulose (CMC, as gelling agent) adjusted to a range of viscosities (~0.001-0.2 Pas), and bovine serum with CMC adjusted to a similar range of viscosities. These results suggested that reduced clearance bearings have the potential to generate high friction especially in the presence of blood which is indeed the in vivo lubricant in the early weeks after implantation. Friction factors in higher clearance bearings were found to be lower than those of the lower clearance bearings using blood as the lubricant. Similar trends, i.e. increase in friction factor with reduction in diametral clearance, were found to be also the case using a combination of BS+CMC or BS+HA+CMC as lubricants having viscosities in the range 0.1-0.2 and 0.03-0.14 Pas, respectively. On the other hand, all the lubricants with lower viscosities in the range 0.001-0.0013 and 0.001-0.013 Pas for both BS+CMC and BS+HA+CMC, respectively, showed the opposite effect, i.e. caused an increase in friction factor with increase in diametral clearance. Another six large diameter (50mm nominal) BHR deflected prostheses with various clearances (~ 50-2802m after cup deflection) were friction tested in vitro in the presence of blood and clotted blood to study the effect of cup deflection on friction. It was found that the biological lubricants caused higher friction factors at the lower diametral clearances for blood and clotted blood as clearance decreased from 2802m to 502m (after deflection). The result of this investigation has suggested strongly that the optimum clearance for the 50 mm diameter MOM BHR implants to be ¿1502m and <2352m when blood lubricant used, so as to avoid high frictions (i.e. avoid friction factors >0.2) and be able to accommodate a mixed lubrication mode and hence lower the risk of micro- or even macro-motion specially immediately after hip implantation. These suggested optimum clearances will also allow for low friction (i.e. friction factors of <0.2-0.07) and reasonable lubrication (dominantly mixed regime) for the likely cup deflection occurring as a result of press-fit fixation. / Smith & Nephew Orthopaedics Ltd.