L'objectif de cette thèse est de développer un matériau cimentaire monolithe ayant une forte teneur en ettringite, capable de stocker et de déstocker de la chaleur, respectivement, par déshydratation endothermique et réhydratation exothermique. Une étude numérique et expérimentale du stockage de chaleur dans un réacteur thermochimique (prototype) contenant le matériau développé est aussi réalisée dans le cadre de cette étude. Pour atteindre ces objectifs, l'hydratation de différents liants ettringitiques a été suivie par DRX, ATG et MEB. Une simulation thermodynamique de l'hydratation a aussi été effectuée au moyen du logiciel GEMS (Gibbs Energy Minimization Sofware) afin d'optimiser la formulation du matériau. Le réseau poreux du matériau résultant a ensuite été amélioré par moussage chimique. Nous avons aussi étudié la durabilité et la stabilité du matériau ettringitique synthétisé (carbonatation, stabilité à la température, réversibilité du processus de stockage/déstockage sur plusieurs cycles). Pour prédire le comportement du système de stockage, un modèle bidimensionnel, prenant en compte les spécificités du matériau cimentaire, a été utilisé. Le bilan énergétique et massique dans le matériau poreux génère un système d'équations différentielles non-linéaires et couplées. La résolution numérique du système, effectuée en utilisant MatLab (r), est effectuée par discrétisation spatiale en utilisant la méthode des différences finies, et par intégration temporelle des variables d'état (température et pression de vapeur d'eau). La simulation du modèle, basée sur les propriétés mesurées du matériau en laboratoire, est ensuite utilisée comme outil de conception pour réaliser un premier prototype de réacteur thermochimique au laboratoire. Suite à ces essais, un prototype amélioré est ensuite élaboré et testé. Le résultat des essais de stockage et de déstockage de chaleur avec ces deux prototypes ont servi de validation du modèle numérique d'une part, et de preuve de concept du principe de stockage d'autre part. / The objective of this study is to develop an ettringite-based material with high energy storage density in low temperature conditions, allowing to charge and discharge heat by endothermic dehydration and exothermic rehydration, respectively; then to perform the numerical and experimental study of heat storage in a thermochemical reactor containing the produced material (prototype). To achieve these goals, the hydration of ettringite binders was followed by XRD, TGA and SEM. The thermodynamic simulation of the hydration was also performed using GEMS (Gibbs Energy Minimization Sofware). The porous network of the resulting material was improved by chemical foaming. Furthermore, the carbonation, thermal stability and reversibility tests were performed on the produced material. Physicochemical stability of the material over time was followed by XRD, TGA, SEM and IR. To predict the behavior of the storage system, a bidimensional model, taking account the specificities of the cementitious material, was developed. The heat and mass balance in the thermochemical reactor generates a system of non-linear and coupled differential equations. The numerical resolution was first made by spatial discretization using the finite difference method, then by temporal integration of variables (temperature and water vapor pressure) on MatLab (r). The model simulation, with material properties, was used as concept design to build the thermochemical reactor prototype in the laboratory (cylindrical adsorber). The result of heat storage tests with the prototype was used as proof of concept of the principle on the one hand, and a way to validate the numerical model.

abstract: How water behaves at interfaces is relevant to many scientific and technological applications; however, many subtle phenomena are unknown in aqueous solutions. In this work, interfacial structural transition in hydration shells of a polarizable solute at critical polarizabilities is discovered. The transition is manifested in maximum water response, the reorientation of the water dipoles at the interface, and an increase in the density of dangling OH bonds. This work also addresses the role of polarizability of the active site of proteins in biological catalytic reactions. For proteins, the hydration shell becomes very heterogeneous and involves a relatively large number of water molecules. The molecular dynamics simulations show that the polarizability, along with the atomic charge distribution, needs to be a part of the picture describing how enzymes work. Non Gaussian dynamics in time-resolved linear and nonlinear (correlation) 2D spectra are also analyzed. Additionally, a theoretical formalism is presented to show that when preferential orientations of water dipoles exist at the interface, electrophoretic charges can be produced without free charge carriers, i.e., neutral solutes can move in a constant electric field due to the divergence of polarization at the interface. Furthermore, the concept of interface susceptibility is introduced. It involves the fluctuations of the surface charge density caused by thermal motion and its correlation over the characteristic correlation length with the fluctuations of the solvent charge density. Solvation free energy and interface dielectric constant are formulated accordingly. Unlike previous approaches, the solvation free energy scales quite well in a broad range of ion sizes, namely in the range of 2-14 A° . Interface dielectric constant is defined such that the boundary conditions in the Laplace equation describing a micro- or mesoscopic interface are satisfied. The effective dielectric constant of interfacial water is found to be significantly lower than its bulk value. Molecular dynamics simulation results show that the interface dielectric constant for a TIP3P water model changes from nine to four when the effective solute radius is increased from 5 A° to 18 A° . The small value of the interface dielectric constant of water has potentially dramatic consequences for hydration. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2016

A sobrecarga hídrica (SH) é um achado comum em pacientes em diálise peritoneal (DP) e a inadequação do estado nutricional aumenta a morbimortalidade nesta população. A bioimpedância elétrica é um método rápido e não-invasivo para estimar os compartimentos corporais, incluindo a distribuição dos fluídos corporais nos espaços intra e extracelulares. O principal objetivo foi avaliar se a SH interfere em estado nutricional, composição corporal, gasto energético de repouso e um biomarcador de risco cardiovascular, em pacientes com Doença Renal Crônica tratados por DP. Caracterizou-se como um estudo observacional transversal, realizado no Hospital das Clínicas da FMRP-USP. Foram avaliados dados de composição corporal e estado hídrico por Bioimpedância Elétrica de Frequência Simples (BIA) e Bioimpedância Elétrica Multifrequência de Espectroscopia (BIS), a concentração sérica do peptídeo natriurético atrial (Nt pro - BNP) como biomarcador de risco cardiovascular, dados antropométricos, de consumo alimentar, gasto energético de repouso (GER), exames bioquímicos e dados clínicos de rotina dos pacientes. Trinta pacientes foram incluídos e classificados em normohidratados (NH) ou hiperhidratados (HH), pelo valor de sobrecarga hídrica de 1,1 L. Para análise estatística, o nível de significância foi pré-fixado em ?= 0,05. Os pacientes HH, em comparação aos NH, apresentaram além de maior sobrecarga hídrica (3,54 L ± 1,7 X 0,14 ± 0,6), maiores valores em água corporal total (ACT - 34,98 L ± 4,74 X 30,43 L ± 5,45), água extracelular (AEC - 17,91 L ± 2,87 X 13,84 L ± 2,30) e menores valores de ângulo de fase (4,02° ± 0,81 X 5,51° ± 0,77) na avalição por BIS; o Nt Pró - BNP mostrou-se maior nos HH (7686 pg/ml ± 8872 X 1334 pg/ml ± 1034). Não houve diferença significativa entre os grupos para dados antropométricos, nos demais exames bioquímicos, em aferições da força de preensão palmar, nas pontuações do MIS (Malnutrition Inflammation Score), nos dados de ingestão alimentar, e nem no GER. O grupo com sobrecarga hídrica mostrou, de fato, uma maior concentração de água em compartimento extracelular, possivelmente gerando aumento em Nt pro - BNP e menor ângulo de fase. Quando avaliado o grupo como um todo, os métodos (BIA e BIS) mediram os resultados igualmente somente no que se refere à resistência (p = 0,71). Sendo a ACT, água intracelular (AIC), AEC, massa livre de gordura (MLG), massa celular corporal (MCC) e ângulo de fase maiores na medições da BIA e somente massa gorda maior nas medições da BIS; correlações mostraram que os dados de massa livre de gordura e massa celular corporal foram os que mais se distanciaram, com coeficientes mais fracos, enquanto que as demais variáveis apresentaram forte correlação. Para o diagnóstico nutricional em vigência de sobrecarga líquida, deve-se considerar um conjunto de variáveis interpretadas de maneira complementar, possibilitando um diagnóstico nutricional mais detalhado. O uso rotineiro da BIS pode ajudar a refinar a avaliação do estado de hidratação e composição corporal destes pacientes em DP. / The fluid overload (FO) is a common finding in patients on peritoneal dialysis (PD) and the inadequacy of the nutritional status increases the morbidity and mortality in this population. The bioelectrical impedance is a quick and non-invasive method to estimate body compartments, including the distribution of body fluids in intra- and extracellular spaces. The main objective was to assess whether the FO affects body cell mass, nutritional status, resting energy expenditure and a biomarker of cardiovascular risk in patients with chronic kidney disease treated by PD. It is characterized as a cross-sectional observational study conducted at the Hospital of FMRP-USP. We evaluated data of body composition and water status by Simple Frequency Electric Bioimpedance (BIA) and Electric Multifrequency Spectroscopy Bioimpedance (BIS), the serum concentration of atrial natriuretic peptide (NT pro - BNP) as a biomarker of cardiovascular risk, anthropometric data, food intake, resting energy expenditure (REE), biochemical and clinical data from routine patient. Thirty patients were included and classified into normal hydration (NH) or hyper hydrated (HH) by fluid overload value of 1.1 L. For statistical analysis, the level of significance was pre-set at ? = 0.05. HH patients, compared to NH, presented in addition to increased fluid overload (3.54 L ± 1.7 X 0.14 ± 0.6), higher values in total body water (TBW - 34.98 L ± 4.74 ± 5.45 x 30.43 L), extracellular water (ECW - L 17.91 ± 2.87 X 13.84 ± 2.30 L) and smaller phase angle values (± 4.02 ° 0.81 X 5.51 ± 0.77 °) in a BIS appraisal; the Nt Pro - BNP was higher in HH (7686 pg / ml ± 8872 X 1334 pg / ml ± 1034). There was no significant difference between groups for anthropometric data, in other biochemical tests on measurements of grip strength, in scores of MIS (Malnutrition Inflammation Score), the food intake data, and not the REE. The group with fluid overload shows, in fact, a higher concentration of water in the extracellular compartment, possibly generating an increase in NT pro - BNP and lower phase angle. When evaluated the group as a whole, the methods (BIA and BIS) measure only the results also as regards the resistance (p = 0.71). And TBW, intracellular water, ECW, fat-free mass, body cell mass and larger phase angle measurements in the BIA and only greater fat mass in measurements of BIS; correlations show that free mass data of fat and body cell mass are the ones who are more distanced, with weaker coefficients, while the other variables are strongly correlated. For the nutritional diagnosis of fluid overload force, should be considered a set of variables interpreted in a complementary manner, enabling a more detailed nutritional diagnosis. The routine use of BIS can help refine the assessment of hydration status and body composition of these patients on PD.

Made available in DSpace on 2015-03-26T13:36:43Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1071729 bytes, checksum: 589cee2281058f43c8a1df71161af722 (MD5) Previous issue date: 2012-02-16 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The goals of this work were to evaluate the influence of the use of pre-cooling and hydration on the longevity of coriander (Coriandrum sativum L.) leaves. In evaluating the use of pre-cooling were made bundles of leaves coriander 20-25 g. Immediately after the shape, the bundles were submerged for 10 min in a mixture at 5 °C with crushed ice and water (1:3 v/v), followed by storage at 20 and 5°C. The hydrocooling caused premature yellowing of the coriander leaves 72 and 96 h after the treatment, respectively, for storage at 20 and 5°C. It was concluded that the most appropriate treatment for post-harvest conservation of coriander bundles is the storage at 5 °C after harvest without pre-cooling. For to evaluation the effect of hydration of coriander leaves were used bundles 25-30 g, three times of submerged in water at 25°C (3, 6 and 9 h) and three percentages of weight loss before to immersion of the bundles in water (0.5 to 10%). The hydration was assessed in both storage temperatures. At first, the bundles were stored at 5°C and relative humidity (RH) of 80% after hydration, and the weight loss of 5 and 10% occurred at 5°C. At the second, the weight loss of 5 and 10% occurred at 25°C and the bundles were stored at 25°C and 54% RH. It was found that use of the hydration did not resulted in increase the longevity of coriander bundles, when the leaves were subsequently stored at 25°C. The hydration occasioned the appearance of dark spots on the leaves, yellowing and decay of leaves and branches, during storage at 25°C. The use of refrigeration at 5°C after hydration impeded the yellowing and branches of coriander bundles over the shelf life. The hydration for 3 h after harvest of coriander bundles can be used to increase in day the longevity of the same, if followed by storage at 5°C. / Os objetivos deste trabalho foram avaliar a influência do uso do pré-resfriamento da temperatura e da hidratação na longevidade de folhas de coentro Português (Coriandrum sativum L.). Na avaliação do uso do pré-resfriamento e do armazenamento refrigerado foram feitos maços de folhas de coentro de 20-25 g. Logo após o feitio, os maços foram imerso por 10 minutos em uma mistura a 5ºC de gelo moído e água (1:3 v/v), seguido de armazenamento a 20 e 5°C. O hidroresfriamento provocou o amarelecimento prematuro das folhas de coentro 96 horas após o tratamento para o armazenamento a 5°C. Concluiu-se que o tratamento mais indicado para conservação pós-colheita de maços de coentro é o armazenamento a 5°C após a colheita sem pré-resfriamento. Para avaliação do efeito da hidratação de folhas de coentro foram utilizados maços de 25-30 g, três tempos de imersão em água a 25°C (3, 6 e 9 horas) e três porcentagens de perda de massa fresca antes da imersão dos maços em água (0, 5 e 10%). A hidratação foi avaliada em duas temperaturas de armazenamento. Na primeira, os maços foram armazenados a 5°C e umidade relativa do ar de 80%, logo após a hidratação, e a perda de massa fresca de 5 e 10% obtida a 5 °C. Na segunda, a perda de massa fresca de 5 e 10% foi obtida a 25°C e os maços foram armazenados a 25°C e a 54% de umidade relativa. Verificou-se que uso da hidratação não resultou em aumento da longevidade de maços de coentro, quando estes foram posteriormente armazenadas a 25°C. A hidratação ocasionou o aparecimento de manchas escuras nas folhas, amarelecimento e apodrecimento do limbo e pecíolo, ao longo do armazenamento a 25°C. O uso da refrigeração a 5°C após o hidratação impediu o amarelecimento e apodrecimento dos maços de coentro ao longo da vida de prateleira. A hidratação, por 3 horas, após a colheita de maços de coentro pode ser utilizado para aumentar em dia a longevidade dos mesmos, se for seguida do armazenamento a 5°C.

Made available in DSpace on 2015-03-26T13:46:55Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1316996 bytes, checksum: b7801368db994b61ecaa104e7ec87528 (MD5) Previous issue date: 2010-12-03 / This study aimed to evaluate and compare the effects of isotonic and hypotonic electrolyte solutions containing different sources of energy administered via naso-esophageal probe of small-caliber streaming on clinical and laboratory parameters in healthy horses. Six adult females were used in two simultaneous 6x3 latin squares mixed model, using the splitplot and the treatments represent the plots and subplots evaluation times. Each experimental cycle, animals were switched to group, so that everyone went through all the treatments. The groups were divided as follows: electrolyte solution associated with hypotonic dextrose (SEDext), hypotonic electrolyte solution associated with maltodextrin (SEMalt) and isotonic electrolyte solution combined with calcium propionate (SEProp). The electrolyte solution was administered at a dose of 15 mL kg-1 h-1 for 12 hours in continuous flow via naso-esophageal probe, with restricted food and water. The clinical and laboratory evaluation was performed at times 0h (immediately before starting treatment), 6h (six hours of treatment), 12h (12 hours of treatment) and 24 hours (12 hours after treatment). The SEProp not increase blood glucose levels, determined the lowest plasma volume expansion, and cause bloating and abdominal discomfort. The SEDext increased intestinal motility, the rate and glucose plasma volume expansion, while SEMalt increased blood glucose, intestinal motility, and cause the greatest degree of plasma volume expansion. The values of serum electrolytes remained within reference to the species in all treatments. These results indicate great clinical importance in the administration of enteral solutions for use in horses. / O presente estudo objetivou avaliar e comparar os efeitos de soluções eletrolíticas isotônicas e hipotônicas contendo diferentes fontes de energia administradas via sonda nasoesofágica de pequeno calibre em fluxo contínuo, sobre parâmetros clínicos e laboratoriais em equinos hígidos. Foram utilizadas seis fêmeas adultas em dois quadrados latinos 6X3 simultâneos em modelo misto, utilizando-se o esquema de parcelas subdivididas sendo que os tratamentos representam as parcelas e os tempos de avaliação as subparcelas. A cada ciclo experimental, os animais foram trocados de grupo, de maneira que todos passaram por todos os tratamentos. Os grupos foram assim constituídos: solução eletrolítica hipotônica associada à dextrose (SEDext), solução eletrolítica hipotônica associada à maltodextrina (SEMalt) e solução eletrolítica isotônica associada ao propionato de cálcio (SEProp). A solução eletrolítica foi administrada na dose de 15 mL kg-1 h-1, durante 12 horas em fluxo contínuo via sonda naso-esofágica, com restrição de alimento e água. A avaliação clínica e laboratorial foi realizada nos tempos 0h (imediatamente antes do início do tratamento), 6h (seis horas de tratamento), 12h (12 horas de tratamento) e 24h (12 horas após o término do tratamento). O SEProp não aumentou a glicemia, determinou a menor expansão do volume plasmático, além de ocasionar distensão e desconforto abdominal. O SEDext aumentou a motilidade intestinal, a taxa glicêmica e a expansão do volume plasmático, enquanto o SEMalt aumentou a glicemia, a motilidade intestinal, além de ocasionar o maior grau de expansão do volume plasmático. Os valores dos eletrólitos séricos permaneceram na faixa de referência para a espécie em todos os tratamentos. Esses resultados sinalizam grande importância clínica na administração de soluções de uso enteral em equinos.

Made available in DSpace on 2015-05-08T15:00:05Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2912303 bytes, checksum: 1801a9b29f733961e785f9de516a1e30 (MD5) Previous issue date: 2010-03-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Oil well structures are built by placing a steel casing and by cementing the space (annulus) between the casing and rock formations throughout the geological layers of wellbores. The structural integrity of these systems resides on the cementing operation, which is designed to offer structural support as well as corrosion protection of the casing. It also promotes zonal isolation among rock formations throughout the wellbore, which not only helps to avoid losses in production, but also reduces potential environmental damage due to leakage of contaminated fluids. In order to achieve these objectives, a hydraulic seal between the casing and the cement and between the cement and the rock formations must be ensured, so that fluid channels in the cement sheath can be prevented. Although oil and gas companies have always been aspiring for perfect zonal isolation, the scope of existing zonal-isolation problems is enormous. Hence, a great number of researchers have been motivated to study and predict lost of zonal isolation, helping to reduce the magnitude of such complex problem. Most research focus on the improvement of the cement properties whereas least effort is given to interface related aspects. This is mostly given to the fact that such important zone is difficult to assess. Such difficulties are mainly associated to inherent anisotropies of Portland cement based materials. Interface related aspects of the cement hydration are strongly affected by the local chemistry of the components of the matrix. The effect of such complex microstructure on the engineering parameters must be carefully examined, so that evaluation of the structure integrity can be properly made via Non Destructive Testings. The aim of this work is to correlate the mechanical properties (destructive and non-destructive) with the microhardness of cement paste at early ages. The samples were cast using Early Strength Development Portland cement and three water to binder ratio (0.33, 0.44 and 0.55 by mass). Also, two sets of cement pastes were mixed with and without a ground redbrick waste pozzolan replacing cement (20% by mass). The test ages were 1, 3 and 7 days. The micro features of the early hydrated cement pastes were assessed by means of Scanning Electron Microscopy (Backscattered Electron Imaging Mode) and Vickers Microhardness. The data shows that the presence of the pozzolan affects the distribution of hydrated cement grains and the homogeneity of the cement matrix, yielding to different microfeatures, reflecting on the mechanical properties. The local chemistry prevails over the average properties of the cement paste, especially at the contact between steel and cement. / As estruturas de poços de petróleo são constituídas por tubulações metálicas revestidas com material cimentício as quais atravessam diversas formações geológicas. A integridade estrutural destes sistemas depende principalmente da integridade do material revestimento, que tem como funções oferecer suporte estrutural à tubulação metálica, além de protegê-la contra corrosão. Tal revestimento é ainda responsável por isolar as diferentes formações geológicas existentes ao longo do poço, objetivando não apenas evitar perdas na produção, mas também reduzir potenciais danos ambientais devidos a vazamentos de fluidos contaminantes. De modo a atingir estes objetivos, um perfeito isolamento hidráulico deve ser garantido tanto entre a tubulação metálica e o revestimento cimentício quanto entre este revestimento e as formações rochosas, de maneira que a migração de fluidos possa ser evitada. Embora as companhias de gás e petróleo venham buscando a obtenção de um perfeito isolamento hidráulico, a freqüência de ocorrência destes problemas é enorme em todo o mundo. Deste modo, grande número de pesquisas tem se voltado ao estudo e entendimento das causas associadas à quebra deste isolamento hidráulico, ajudando a reduzir a magnitude de tão complexo problema. A maioria destas pesquisas objetiva o aprimoramento das propriedades do revestimento propriamente dito, enquanto que um número bastante reduzido está associado a aspectos relacionados às interfaces destes sistemas. Tal particularidade deve-se em grande parte ao fato de que tão importante região possui grandes dificuldades de avaliação. Tais dificuldades estão associadas principalmente às anisotropias inerentes aos materiais à base de cimento Portland. Aspectos da interface relacionados à hidratação do cimento são fortemente afetados pela química local dos componentes da matriz cimentícia. O efeito desta complexa microestrutura nas propriedades de engenharia das estruturas deve ser cuidadosamente examinado, podendo a avaliação da de sua integridade ser apropriadamente efetuada mediante Testes Não Destrutivos. O objetivo deste trabalho é correlacionar propriedades mecânicas (obtidas mediante técnicas destrutivas e não-destrutivas) com a microdureza de pastas de cimento em pequenas idades. As amostras ensaiadas foram confeccionadas utilizando cimento Portland de Alta Resistência Inicial e três relações água/aglomerante (0.33, 0.44 e 0.55 em massa). Dois conjuntos de amostras foram preparados: com e sem substituição parcial do cimento (20% em massa) por pozolana constituída de resíduos de cerâmica vermelha moídos. As idades avaliadas foram 1, 3 e 7 dias. As características microestruturais e micromecânicas das pastas de cimento hidratadas foram acessadas mediante técnicas de Microscopia Eletrônica de Varredura (no modo retroespalhado) e Microdureza Vickers. Os resultados mostram que a presença da pozolana afeta a distribuição dos grãos de cimento hidratados e a homogeneidade da matriz cimentícia, modificando suas características microestruturais, refletindo nas propriedades mecânicas. A química local prevaleceu sobre as propriedades medias da pasta de cimento, especialmente no contato entre o cimento e a superfície metálica.

As propriedades do solo cotidianamente podem não ser adequadas às características e às necessidades de projeto. É apresentada, como alternativa, a técnica de reforço com inclusão de elementos fibrosos à matriz de solo cimentado e não cimentado. Ainda, embora comuns, o comportamento do solo frente a solicitações cíclicas não é completamente conhecido. Nesse sentido, o estudo do comportamento de hidratação e da resposta cisalhante cíclica de um resíduo de mineração cimentado reforçado com fibras é objetivado. Para tanto, medidas de retração química, medidas de rigidez ao longo da hidratação e ensaios simple shear monotônicos e cíclicos foram realizados com resíduo de mineração cimentado e não cimentado, reforçado com fibras e não reforçado. O resíduo, oriundo da mineração de ouro, um silte arenoso com traços de argila, foi cimentado com diferentes teores de cimento Portland, entre 0% e 10% em relação à massa de solo seco, e reforçado com 0% e 0,5%, em relação à massa de sólidos secos, de fibras de polipropileno de 50mm de comprimento e 0,1mm de espessura, equivalentes a um índice aspecto de 500. Os resultados demonstraram que as fibras não afetaram o processo de hidratação das misturas de resíduo de mineração cimentadas, que apresentam tendência de atenuação logarítmica da retração química com o tempo. Quanto maiores as relações água/cimento, maior o nível de retração química. A inclusão de fibras a misturas de resíduo de mineração cimentadas, da mesma forma, não afetou a evolução dos valores de rigidez inicial, que crescem com tendência logarítmica em função do tempo e aumentam com o acréscimo do nível de cimentação. Sob condições monotônicas de cisalhamento, a adição de fibras conferiu ao material cimentado e não cimentado comportamento de endurecimento. Sob condições cíclicas de deformação cisalhante controlada, as fibras não afetaram a resposta cisalhante das amostras não cimentadas e provocaram aumento dos valores da tensão cisalhante das amostras cimentadas após sucessivos ciclos de esforços. Sob condições cíclicas de tensão cisalhante controlada, a adição de fibras às misturas não cimentadas proporcionou o aumento da resistência aos ciclos de esforços e às misturas cimentadas provocou aumento dos níveis de deformação cisalhante. A concordância das mesmas envoltórias de resistência tanto às trajetórias de tensões dos ensaios monotonônicos quanto às trajetórias dos ensaios cíclicos sob diferentes condições de carregamento possibilitou a obtenção dos mesmos parâmetros de resistência das misturas analisadas sob diferentes condições de carregamento. / The soil properties commonly may not suit the project characteristics and requirements. It is presented, as alternative, the improvement technique of fibrous elements inclusion to the cemented and uncemented soil matrix. Moreover, although common, the behaviour of soil under cyclic loads is not completely known. In this sense, the study of the hydration behaviour and the cyclic shear response of fibre reinforced cemented mine tailings is the main objective of this research. Therefore, chemical shrinkage measurements, stiffness measurements during hydration and monotonic and cyclic simple shear tests were conducted on fibre reinforced and unreinforced cemented and uncemented mine tailings. The tailings, produced from gold mining, are classified as a sandy silt with traces of clay and were cemented with different amounts of Portland cement, ranging from 0% to 10% by dry weigh of soil, and reinforced with 0% and 0.5% by dry weigh of solids of polypropylene fibers 50mm long and 0.1mm thick, equivalent to an aspect ratio of 500. The results showed fibres did not affect the hydration process of cemented mine tailings mixtures, which presents logarithmic attenuation of chemical shrinkage over time. The greater the water / cement ratio, the higher the level of chemical shrinkage. The inclusion of fibers to cemented mine tailings, likewise, did not affect the evolution of initial stiffness values, that raise logarithmic over time and increase with the increase of the cementation level. Under monotonic shear conditions, the addition of fibers confers hardening behaviour to the uncemented and cemented materials. Under shear strain controlled cyclic conditions, fibres did not affect the shear response of uncemented samples and increased shear stress values of cemented samples after successive load cycles. Under shear stress controlled cyclic conditions, the fibres addition to the uncemented mixtures increased the resistance to load cycles and to the cemented mixtures increased levels of shearing strain. The agreement of the same strength envelopes to both monotonic and cyclic stress paths, under different cyclic loading conditions, allows the use of the same strength parameters of mixtures analyzed under different loading conditions.

Le béton est le matériau le plus utilisé dans le monde. Son succès vient de son accessibilité et ses performances mécaniques, surtout lorsqu'il est renforcé par de l'acier. Dans le béton, l'acier doux est naturellement protégé par la formation d'une couche d'oxyde protectrice. Ceci est possible avec l'alcalinité du béton résultant de l'hydratation du ciment Portland.Cependant, la fabrication du ciment Portland est responsable de 5 à 7% des émissions anthropiques mondiales de CO2. Le développement du ciment Belite-Ye'elimite-Ferrite (BYF) comme liant alternatif est une solution prometteuse avec une diminution de 20 à 30% des émissions de CO2 par rapport à la production de ciment Portland. Les propriétés sont en cours d'évaluation et la possibilité d'utiliser l’acier doux en renfort sans corroder en fait partie.Cette thèse traite de la corrosion de l'acier incorporé dans des matériaux à base de ciment BYF sous différents angles. Tout d'abord, une étude d'hydratation détaillée a été effectuée pour comprendre l'évolution de l'électrolyte, c'est-à-dire de la solution interstitielle et de l'assemblage de phases. Ensuite, la passivation des barres d'armature d'acier ordinaire intégrées dans des mortiers renforcés a été étudiée. De plus, des analyses ont été effectuées avec des échantillons d'acier immergés dans des extraits aqueux de pâtes de ciment équivalentes pour caractériser la structure et l'épaisseur du film passif. Enfin, l'impact des chlorures initiaux sur la corrosion des mortiers renforcés a été évalué.L'hydratation a été caractérisée par plusieurs techniques, au jeune âge et pendant un an, avec des techniques telles que la calorimétrie isotherme, la spectroscopie d'émission optique par plasma à couplage inductif, la thermogravimétrie, la diffraction des rayons X et la porosimétrie par intrusion au mercure. L'évolution de l'acier dans les mortiers a été évaluée avec des techniques électrochimiques. L'applicabilité des techniques non destructives courantes (potentiel de demi-cellule, résistance à la polarisation linéaire, et l'impédance électrochimique) a été validée par des mesures de polarisation potentiodynamique large et une inspection visuelle. Le film passif formé dans des extraits aqueux des mortiers a été caractérisé par des techniques électrochimiques couplées aux mesures de spectroscopie de photoélectrons aux rayons X. Une fois que la passivation établi, l'impact des chlorures initiaux sur les mortiers renforcés a été évalué.Pour le BYF, le processus d'hydratation et les assemblages de phases hydratées sont différents du ciment Portland, mais la solution interstitielle est finalement très basique après un jour (pH de 13). La principale différence est le pH qui est inférieur (10.6) avant la prise. Les mesures ont montré que l'acier se passive avec le même niveau de protection qu’avec le ciment Portland. La différence est le temps nécessaire pour atteindre le meilleur niveau de protection (28 jours avec le ciment BYF au lieu de 7 jours avec le ciment Portland). Les échantillons d’acier immergés dans des extraits aqueux de ciment Portland et BYF après 28 jours d’hydratation ont présenté une épaisseur et une composition similaires, indiquant que le milieu BYF est aussi protecteur que celui de Portland. L'acier passive dans les mortiers BYF (E/C = 0.5) contenant 0.4% de chlorures par masse de ciment, ce qui ne remet pas en question, pour ce nouveau ciment, la limite imposée par la norme européenne EN-206 aux bétons armés. / Concrete is the most widely used material in the world. The success lies on its affordability and mechanical performance, especially when reinforced with steel. Once embedded in the concrete, mild steel is naturally protected by the formation of a protecting oxide layer. This is possible thanks to the alkalinity of the concrete which results from the hydration of the Portland cement.However, Portland cement manufacturing is responsible of about 5 to 7% of the global anthropogenic CO2 emissions. The development of Belite-Ye’elimite-Ferrite (BYF) cement as alternative binder is a promising solution with a decrease of 20 to 30% in CO2 emissions compared to Portland production. The properties are being evaluated and the possibility of using mild steel reinforcement without corroding is part of it.This thesis approaches the corrosion of steel embedded in BYF cement based materials from various angles. First, a detailed hydration study was performed to understand the evolution of the “electrolyte”, i.e. of the pore solution and of the phase assemblage. Second, the passivation of ordinary steel rebar embedded in reinforced mortars was investigated. In addition, analyzes were carried out with steel samples immersed in aqueous extracts of equivalent cement pastes to characterize the structure and the thickness of the passive film. Finally, the impact of the initial chlorides on corrosion of reinforced mortars was evaluated.The hydration was characterized by several techniques, at early-age and then over one year, with techniques such as isothermal calorimetry, inductively coupled plasma optical emission spectroscopy, thermogravimetry, X-ray diffraction and mercury intrusion porosimetry. The evolution of steel embedded in mortars was evaluated with several electrochemical techniques. The applicability of current non-destructive techniques (half-cell potential readings, linear polarization resistance and electrochemical impedance spectroscopy) has been validated by large potentiodynamic polarizations and visual inspection. The passive film formed in aqueous extracts of the mortars was characterized with electrochemical techniques coupled to X-ray photoelectron spectroscopy measurements. Once the passivation understood, the impact of the initial chlorides on the reinforced mortars was evaluated.For the BYF, the hydration process and the hydrated phase assemblages are different from Portland cement, but the interstitial solution is finally very basic after one day (pH of 13). The main difference is the pH that is lower (10.6) before setting. The measurements showed that steel was effectively passivated in BYF mortars with the same level of protection as with Portland cement. The difference between the BYF and Portland cement is the time required that to reach the greatest level of protection (28 days instead of 7 days), probably because of initial lower pH value. The steel immersed in Portland and BYF aqueous extracts obtained after 28 days of hydration exhibited similar thickness and composition of protective layer, indicating that BYF media was as protective as Portland ones. Steel passivates in BYF mortars (W/C = 0.5) containing 0.4% chlorides by cement mass which is in agreement with the limit imposed by the European Standard EN-206 to reinforced Portland concretes.

L’optimisation des performances énergétiques du bâtiment et la réduction des émissions de CO2 générées par le secteur de la construction sont devenus des enjeux majeurs. Il s’agit non seulement de réduire considérablement les consommations d’énergie liées au chauffage et à la climatisation durant la période de fonctionnement des bâtiments mais aussi de choisir des matériaux à faible impact carbone en privilégiant l’utilisation de ressources renouvelables et locales. Ces dernières années ont vu naître un intérêt croissant pour les bétons de chanvre. Ces agromatériaux associent un granulat végétal issu de la tige du chanvre avec un liant minéral. Il en résulte un matériau isolant qui présente une certaine efficacité à réguler les variations de température et d’humidité. Considérés comme multifonctionnels, les bétons de chanvre constituent une alternative écologique aux enveloppes traditionnelles. Face aux matériaux à isolation répartie comme le béton cellulaire ou la brique dont l’impact carbone est élevé, les bétons de chanvre présentent l’inconvénient d’être peu résistants mécaniquement et sont de ce fait associés à une structure porteuse. Ce travail de thèse s’inscrit dans une démarche visant d’une part à diversifier la ressource végétale utilisée pour la confection des agromatériaux de construction en développant un béton innovant incorporant les balles de riz de Camargue et d’autre part à étudier certains procédés dans l’optique d’améliorer les performances mécaniques de ces matériaux après les premiers mois de cure. Le premier objectif a consisté à caractériser la balle de riz naturelle préalablement à son association avec un liant à base de chaux. Les caractéristiques propres au granulat de balles de riz se sont traduites par la fabrication d’un agrobéton moins dosé en eau et de densité apparente plus élevée que celle du béton de chanvre (en restant inférieure à 800 kg.m-3). La conductivité thermique du béton à base de balles de riz s’est montrée similaire à celle du béton de chanvre pour un ratio massique « liant/granulat (L/G) » identique. En revanche, les performances mécaniques en compression se sont révélées plus faibles pour le béton à base de balles de riz après 1 mois de cure à 20°C et 50%HR.Le second axe de travail s’est porté sur le suivi temporel des caractéristiques mécaniques et du durcissement du liant jusqu’à 10 mois de conservation soit à 20°C et 50%HR soit en conditions extérieures. Les bétons de chanvre se sont caractérisés par un gain de résistance en compression plus favorable que celui observé sur les bétons de balles de riz malgré une cinétique de durcissement du liant équivalente. Cette conservation naturelle a été comparée à une cure en carbonatation accélérée (CO2). Les résultats ont montré que ce procédé a permis d’obtenir une résistance en compression 2 mois après la fabrication des éprouvettes équivalente à celle obtenue après 10 mois de conservation à l’extérieur. Considérant que la résistance mécanique du béton à base de balles de riz est limitée par la liaison mécanique liant/particule, ce travail s’est porté également sur l’effet d’un traitement des particules à l’eau de chaux saturée. S’il s’est montré inefficace pour le béton de chanvre, il a permis d’améliorer la résistance en compression des bétons à base de balles de riz.Enfin, cette étude a traité de l’effet d’une cure humide (95%HR) et d’une élévation de température (50°C) sur le durcissement du liant et l’acquisition des résistances mécaniques à court terme. L’étude a été préalablement menée sur des mortiers de chaux. Les résultats ont montré que ce type de cure permet une très forte augmentation de la résistance mécanique du liant après 28 jours par un effet cinétique sur les réactions d’hydratation. Toutefois, ces conditions de cure ont entrainé une perturbation de la zone de transition entre le liant et la particule et par conséquent une dégradation des propriétés mécaniques des agrobétons. / The improvement of building energy efficiency and the reduction of CO2 emissions from the construction industry have become a major issue over the last years. We need to cut the energy consumption linked to heating and cooling of buildings during their operating period but also to choose materials with low carbon footprint using renewable and local resources.Hemp concretes are more and more used in green construction. These bio-based building materials consist of hemp-derived aggregates mixed with mineral binders and water. These concretes have attractive insulating properties and present some effectiveness in buffering variations of temperature and humidity in buildings. Considered as a multifunctional material, hemp concrete can offer an eco-friendly alternative to traditional building envelopes but have the disadvantage of being very low strength. Unlike cellular concrete or clay bricks, hemp concretes cannot be used as load-bearing materials but for infilling walls with a wood timber frame. The aim of this thesis work is, on the one hand, to diversify plant aggregates used for the manufacturing of bio-based concretes by developing an innovative material based on local rice husk from the Camargue area and on the other hand to investigate some processes in order to increase mechanical strength of these materials after the first months of curing. The first objective of this work was to characterize rice husks prior to incorporating them in a lime-based mix. Intrinsic features of rice husks led to the manufacturing of a new bio-based concrete designed with a lower water content and a higher apparent density than hemp concrete (by remaining below 800 kg.m-3). Thermal conductivity of rice husk concrete was comparable to that of hemp concrete for a given « binder on aggregates (B/A) » mass ratio. Nevertheless, mechanical performances in compression have proved lower for the rice husk concrete after one month of hardening at 20°C and 50%RH. The second line of the work dealt with the evolution of mechanical properties and binder hardening over time. Specimens were cured during 10 months either at 20°C and 50%RH or exposed outdoors. Hemp concrete exhibited a higher compressive strength gain over time than that achieved for rice husk concrete despite a same hardening kinetics. This curing under natural carbonation was compared to an accelerated one (CO2 curing). Accelerated carbonation provided the opportunity to obtain the same compressive after 2 months than that reached after the outdoor exposure during 10 months. Considering that compressive strength of rice husk concrete is restricted by the bonding strength between the binder and the aggregates, this work also focused on the effect of a lime-water treatment of plant aggregates. This latter was not efficient for hemp concrete but increased compressive strength of rice husk concrete. Finally, the effect of a moist curing (95%RH) and elevated temperature (50°C) on binder hardening and strength development of bio-based concretes was investigated. This aspect was also studied on lime-based mortars. The results showed that this type of curing led to a strong increase of mechanical strength for the binder after 28 days due to kinetic effects on hydration reactions. Nevertheless, these curing conditions were detrimental to the transition zone between the binder and the plant aggregates and consequently counterproductive for the mechanical performances of bio-based concretes.

O progresso científico e tecnológico das últimas décadas registra um avanço significativo no processo de obtenção da cal, porém, há uma lacuna de conhecimento de base referente à sua ação quando empregada em conjunto com o cimento Portland. O uso da cal nas argamassas mistas de acabamento tem sido associado positivamente apenas à plasticidade no estado fresco e à sua deformabilidade no estado endurecido. Maiores informações são necessárias sobre a ação da cal na evolução das propriedades da argamassa no estado fresco, vinculadas à hidratação do cimento. Este conhecimento é importante para o desenvolvimento de formulações que atendam ao desempenho desejado em diferentes aplicações. O entendimento do mecanismo de hidratação do cimento em presença da cal constitui uma plataforma para estudos de adições minerais ativas ao clínquer, com adição de cal hidratada como fonte externa de cálcio, na produção de novos materiais cimentícios sustentáveis. O estudo em pasta realizado teve como foco a interação cimento-cal visando identificar os fenômenos químicos e físicos relevantes que se sucedem à adição de água ao sistema. Foram caracterizadas as idades iniciais de hidratação do cimento por meio de ensaios de calorimetria de condução, termogravimetria (TG/DTG) e difratometria de raios X em material no estado fluido e em regime consecutivo de coleta de dados. Os experimentos envolveram as proporções 1:1 e 1:2 de cimento Portland tipo CP II E com cales hidratadas tipos CH I e CH III de natureza cálcica e dolomítica, respectivamente. A cal CH I incorpora à mistura elevado teor de hidróxido de cálcio com imediata saturação do meio por íons hidroxila e íons cálcio; a cal CH III incorpora também, em maior quantidade, filler carbonático. Por efeito químico, devido à presença da cal, há alteração da velocidade de hidratação, mas com formação dos produtos de reação característicos da hidratação do cimento. Por efeito físico, o filler carbonático e a fração insolúvel do hidróxido de cálcio da cal, presente no meio saturado, atuam como nucleador para precipitação de fases hidratadas. O efeito combinado desses fenômenos promoveu aceleração da hidratação do cimento Portland, principalmente no período de indução, quando prevalecem as reações de formação de etringita e de aluminatos de cálcio hidratados. / In the last decades, scientific and technological progress has shown a significant advance in the process of obtaining lime; however, there is gap knowledge with relation to its action when employed together with Portland cement. The use of lime in finishing mix mortars has only been positively associated to the fresh state plasticity and ability to deformation in the hardened state. It is necessary to collect data about the role of lime in the gradual development of the properties of mortars in the fresh state, linked to cement hydration. Such knowledge is important to develop formulas which can meet the required performance in different uses. The current demand of sustainable materials has favored the addition of minerals to the composition of Portland cement, and hydrated lime as an extern source of calcium, is a feasible alternative to the composition of byproducts and mixtures to be used as alternative binders. This research focused the cement-lime interaction aiming at identifying relevant chemical and physical phenomena which succeed the addition of water to the system. The paste study characterized the early ages of hydration by means of isothermal calorimetric, thermogravimetric, X-ray diffraction in material in the fluid state analysis collecting data in a consecutive basis. The experiments were carried out by using two proportions of Portland cement type CP II E with hydrated lime types CH I and CH III, calcic and dolomitc, respectively. By adding lime CH I to the cement-water system, calcium hydroxide is abundantly incorporated, with immediate saturation by means of hydroxide ions and calcium ions. The addition of lime CH III, also incorporates, in greater amount, finely ground limestone. Due to chemical effect because of the presence of lime, there is alteration in speed of hydration, forming products characteristics to the cement hydration process. Due to physical effect, the filler and the lime insoluble fraction of calcium hydroxide, present in the saturated environment, work as facilitators to the precipitation of the hydrated phases. The combined effect of these two phenomena accelerated hydration of Portland cement, mainly in the induction period, when ettringite and hydrated calcium aluminates formation reactions prevail. The advancement made in terms of knowledge permits to broaden comprehension on the behavior of mixtures in early stages, when hardening and consolidation processes are applied to mortars and help rheologic studies which involve their application. The understanding of the hydration mechanism in the presence of lime sets a base to study additions of active minerals to the clinker and produce new sustainable cementious compounds.