Lors du forage des puits d'hydrocarbure, une pâte de ciment est coulée dans l'espace annulaire entre le cuvelage en acier et les formations géologiques traversées. Pompée à l'état liquide, cette pâte de ciment fait sa prise le long du puits sous différentes conditions de température et de pression. La gaine de ciment ainsi mise en place a pour principales fonctions de promouvoir l'étanchéité pour protéger le casing contre la corrosion, de fournir le support mécanique pour assurer la stabilité du puits et d'isoler les différents fluides dans les couches traversées. Au cours de sa vie dans le puits, depuis le forage à la complétion et de la production à l'abandon, la gaine de ciment est soumise à différentes sollicitations mécaniques et thermiques qui peuvent l'endommager et altérer ses principales fonctions. La réponse de la pâte de ciment soumis à ces sollicitations dépend non seulement des conditions d'hydratation mais aussi de l'histoire des chargements précédemment appliqués. La prédiction du comportement de la gaine de ciment doit donc se faire à l'aide d'une modélisation numérique qui nécessite une loi de comportement pour la pâte de ciment. Le but de cette thèse est d'établir une loi de comportement de la pâte de ciment en cours d'hydratation pendant le jeune-âge (les 144 premières heures). Pour ce faire, des essais calorimétriques, de mesures de vitesse des ondes et des essais œdométriques ont été réalisés sur une pâte de ciment pétrolier classe G (w/c = 0,44) en cours de prise. Les conditions d'hydratation explorées vont de 7 à 30°C pour les températures et de 0,3 à 45MPa pour les pressions. Les résultats expérimentaux ont montré que les déformations volumiques de la pâte de ciment dues à son hydratation (retrait macroscopique) sont considérablement influencées par la contrainte sous laquelle la pâte de ciment s'hydrate. Plus la contrainte d'hydratation est élevée, plus élevé est le retrait macroscopique à 144 heures. Inversement, les déformations irréversibles dues à un cycle de chargement mécanique à cet âge sont moins importantes pour les contraintes plus élevées. Les résultats ont également montrés qu'au cours de la prise du ciment, il existe un temps critique à partir duquel l'application des cycles de chargement mécanique crée des déformations résiduelles dans la pâte de ciment. Ce temps critique arrive à un degré d'hydratation relativement constant, compris entre 0,18 et 0,20. Le modèle « Boundary Nucleation and Growth » a été utilisé pour étudier la dépendance de ce temps critique à la pression et à la température. Pour la modélisation du retrait macroscopique et de la réponse contrainte – déformation de la pâte de ciment, un modèle élasto-plastique chemo-poro-mécanique couplé, prenant en compte la désaturation du milieu, a été développé. Ce modèle utilise une surface de charge fermée de type Cam-Clay et une loi plastique associée. La loi d'écrouissage dépend des déformations volumiques plastiques et du degré d'hydratation. Les paramètres du modèle ont été évalués pour simuler le retrait macroscopique de la pâte de ciment hydratée sous différentes contraintes et températures. A un degré d'hydratation donnée, le modèle permet également de simuler la réponse contrainte-déformation due à un chargement mécanique / When drilling oil & gas well, cement slurry is pumped between the casing and the rock formation. This cement slurry sets at different conditions of temperature and pressure. The role of this cement sheath is to provide zonal isolation of different fluid along the well, to protect the casing against corrosion and to provide mechanical support. During the life of the well, from drilling to completion, production and P&A (plug and abandonment), the cement sheath is submitted to various mechanical and thermal loading that can potentially damage its properties and alter its performance. The behavior of cement paste submitted to theses solicitations depends both on the hydration condition and the loadings previously applied on the cement paste. The prediction of cement sheath behavior should be done by numerical modeling, which needs a constitutive law for cement paste. The purpose of the present work is to establish a constitutive law of cement paste during its hydration at early age (first 144 hours). The approach is based on combined calorimetric, wave velocities and oedometric tests on an oil-well class G cement paste with water-to-cement ratio equals 0.44. The hydration conditions explored are 7 to 30°C for temperature and 0.3 to 45MPa for pressure. The experimental results showed that the volumetric strain due to cement hydration (macroscopic shrinkage) depends considerably on the hydration pressure. At 144 hours of hydration, the macroscopic shrinkage increases with the hydration pressure increase. But, the residual strain due to application of mechanical cycle at this age is less for cement hydrated under higher pressure. The experimental results revealed that during the hydration there is a critical time after which, the application of mechanical loading can potentially induce residual strain in cement paste. This time is reached at constant hydration degree between 0.18 and 0.20. The Boundary Nucleation and Growth model was used to model the pressure and temperature dependence of this critical time. A coupled elasto-plastic chemo-poro-mechanical model is developed to simulate the macroscopic shrinkage of cement paste hydrated at different conditions of temperature and pressure. A modified Cam-Clay type yield surface with associate flow rule is used. The hardening law depends both on the degree of hydration and on the plastic volumetric strain. At constant degree of hydration, the developed model permits to simulate the stress – strain behavior of cement paste due to the mechanical loading

This thesis presents how to establish a theoretical model to predict risk of thermal cracking in young concrete when cast on ground or an arbitrary construction. The crack risk in young concrete is determined in two steps: 1) calculation of temperature distribution within newly cast concrete and adjacent structure; 2) calculation of stresses caused by thermal and moisture (due to self-desiccation, if drying shrinkage not included) changes in the analyzed structure. If the stress reaches the tensile strength of the young concrete, one or several cracks will occur. The main focus of this work is how to establish a theoretical model denoted Equivalent Restraint Method model, ERM, and the correlation between ERM models and empirical experiences. A key factor in these kind of calculations is how to model the restraint from any adjacent construction part or adjoining restraining block of any type. The building of a road tunnel and a railway tunnel has been studied to collect temperature measurements and crack patterns from the first object, and temperature and thermal dilation measurements from the second object, respectively. These measurements and observed cracks were compared to the theoretical calculations to determine the level of agreement between empirical and theoretical results. Furthermore, this work describes how to obtain a set of fully tested material parameters at CompLAB (test laboratory at Luleå University of Technology, LTU) suitable to be incorporated into the calculation software used. It is of great importance that the obtained material parameters describe the thermal and mechanical properties of the young concrete accurately, in order to perform reliable crack risk calculations.  Therefore, analysis was performed that show how a variation in the evaluated laboratory tests will affect the obtained parameters and what effects it has on calculated thermal stresses.

Le processus de l’hydratation de ciment et la microstructure qui en résulte, dépendent de la formulation de la pâte et des conditions d’hydratation. Parmi différents facteurs, la température d’hydratation a un effet important sur la microstructure et les propriétés physiques et mécaniques des matériaux cimentaires. Ceci est particulièrement important pour l’étude du comportement des ciments pétroliers. En effet, dans un puits pétrolier, une gaine de ciment est coulée entre la roche réservoir et le cuvelage en acier pour assurer entre autre la stabilité et l’étanchéité du puits. En raison du gradient géothermique (environ 25°C par km), la gaine de ciment le long d'un puits est exposée à une température d'hydratation qui augmente avec la profondeur menant à une augmentation de perméabilité et une baisse de propriétés mécaniques le long du puits. L'objectif cette thèse est d'étudier l'effet de la température d'hydratation dans la gamme de 7°C à 90°C sur la microstructure d'une pâte de ciment (classe G) et d'établir le lien entre les modifications microstructurales et les propriétés élastiques du matériau. La caractérisation de la microstructure est faite en considérant une combinaison de plusieurs méthodes expérimentales, à savoir, la diffraction des rayons X & l’analyse Rietveld, l'analyse thermogravimétrique, porosimétrie par l'intrusion de mercure, l'évaluation de la porosité par lyophilisation ou par séchage à 11% HR, essais de sorption au Nitrogène et à la vapeur d'eau et finalement, la résonance magnétique nucléaire 1H. L’assemblage de masse des différentes phases de la microstructure a été évalué montrant une légère dépendance à la température d’hydratation. L’étude de la porosité a montré une augmentation de la porosité capillaire et une légère diminution de la porosité totale à 28 jours d’hydratation, ce qui résulte en une diminution de la porosité du gel de C-S-H en augmentant la température d'hydratation. Une méthode d'analyse a été proposée pour évaluer la densité saturée de C-S-H et sa composition chimique en termes des rapports molaires C/S et H/S pour un C-S-H sec et saturé. Les résultats montrent que la densité de C-S-H augmente avec la température d'hydratation expliquant ainsi l'augmentation observée de la porosité capillaire à températures élevées. Les rapports C/S et H/S diminuent avec l’augmentation de la température d’hydratation. La caractérisation de la microstructure a permis d’alimenter un modèle micromécanique destiné à prédire les propriétés élastiques de la pâte de ciment pour différentes températures d’hydratation. Des modèles d’homogénéisation auto-cohérents à deux et trois échelles ont montré que l’augmentation de la porosité capillaire ne suffit pas pour expliquer la baisse des propriétés mécaniques avec la température. En effet, l’augmentation de la densité de C-S-H avec la température d’hydratation annule l’effet de l’augmentation de la porosité capillaire sur les propriétés élastiques. La réduction des propriétés mécaniques pourrait être expliquée en considérant une distribution de porosité au sein de C-S-H sous forme de C-S-H basse densité LD et haute densité HD telle que proposée par Tennis et Jennings (2000). Cette possibilité est investiguée par une combinaison de techniques de porosimétrie : porosimétrie par l'intrusion de mercure, adsorption d'azote et désorption de vapeur d'eau et par un calcul inverse à l’aide de la modélisation micromécanique. Les résultats montrent que la porosité intrinsèque LD augmente légèrement tandis que la porosité intrinsèque HD diminue de manière significative avec l'augmentation de la température d'hydratation. La diminution des propriétés élastiques des matériaux cimentaires avec l’augmentation de la température d'hydratation s’avère être due à l’action combinée de l'augmentation de la porosité capillaire et des changements de porosités intrinsèques à l’intérieure de C-S-H / The cement hydration process and the resulting microstructure are highly dependent on the cement formulation and the hydration conditions. Particularly, the hydration temperature has a significant influence on the cement paste microstructure and its mechanical properties. This is for instance important for understanding the behaviour and properties of oil-well cements which are used to form a cement sheath between the casing and the surrounding formation for stability and sealing purposes. This cement sheath is hydrated under a progressively increasing temperature along the depth of a well due to the geothermal gradient (about 25°C/km). It results generally in a decrease of the mechanical properties and an increase of permeability along the well. The aim of the present thesis is to investigate the effect of the hydration temperature in the range of 7°C to 90°C on the microstructure of a class G cement paste and to establish the link between these temperature dependent microstructure and the elastic properties of the material. The microstructure characterization is done by combining various experimental methods, including X-Ray diffraction associated with the Rietveld analysis, thermogravimetric analysis, mercury intrusion porosimetry, porosity evaluation by freeze-drying or drying at 11% RH, Nitrogen and water vapour sorption experiments and finally 1H nuclear magnetic resonance. The mass assemblage of microstructure phases at different curing temperatures has been evaluated and showed a slight dependence on the hydration temperature. The porosity evaluations show an increase of the capillary porosity and a slight decrease of the total porosity at 28 days, resulting in a decrease of the gel porosity by increasing the hydration temperature. An analysis method has been proposed to evaluate the C-S-H saturated density and chemical composition in terms of H/S and C/S molar ratios. The C-S-H bulk density is increasing with increasing hydration temperature which explains the observed increase of the capillary porosity for higher curing temperatures. The C/S ratio and H/S ratio for both solid and saturated C-S-H are decreasing with increasing curing temperature. The provided quantitative characterization of cement paste microstructure is used in a micromechanical modelling for evaluation of the elastic properties at various hydration temperatures. Two and three-scale self-consistent micromechanical models have shown that the increase of capillary porosity with increasing hydration temperature cannot fully explain the drop of elastic properties. This is mainly due to the increased elastic properties of C-S-H being denser at higher temperature that cancel the effect of increasing capillary porosity on the overall elastic properties. Another way to fully account for the decrease of the mechanical properties of cement paste is to consider the porosity distribution inside the C-S-H in the form of two distinguished C-S-H types, High Density (HD) and Low Density (LD) C-S-H, as proposed by Tennis and Jennings (2000). This possibility is probed by a combination of various porosity evaluations: Mercury intrusion porosimetry, nitrogen adsorption and water vapour desorption and by a back calculation using micromechanical modelling. The results show that the LD intrinsic porosity is slightly increasing while the HD intrinsic porosity decreases significantly with increasing hydration temperature. The decrease of the elastic properties of cement based materials with increasing hydration temperature is therefore a combined action of the increase of capillary porosity and the changes of intrinsic C-S-H porosities

The cement being used in the construction industry is the result of a chemical process<p>linked to the decarbonation of limestone conducted at high temperature and results in a<p>significant release of CO2. This thesis is part of the project EcoBéton (Green concrete) funded<p>by the French National Research Agency (ANR), with a purpose to show the feasibility of<p>high substitution of cement by mineral additions such as blast furnaces slag, fly ash and<p>limestone fillers. Generally for high percentages of replacements, the early age strength is<p>lower than Portland cement concrete. To cope with this problem, an optimisation method for<p>mix design of concrete using Bolomey’s law has been proposed. Following the encouraging<p>results obtained from mortar, a series of tests on concretes with different substitution<p>percentages were carried out to validate the optimisation method. To meet the requirements of<p>the construction industry related to performance of concrete at early age, which determine<p>their durability, a complete experimental study was carried out. Standard tests for the<p>characterization of the mechanical properties (compressive strength, tensile strength, and<p>setting) allowed to validate the choice of mix design on the basis of equivalent performance.<p>We focused on the hydration process to understand the evolution of the mechanical<p>properties. Setting time measurement by ultrasound device at different temperatures (10°C,<p>20°C and 30°C) showed that ground granulated blast furnace slag (GGBFS) and fly ash<p>delayed the setting process, while use of limestone filler may accelerate this process.<p>Calorimetric studies over mortars and concretes made possible to calculate the activation<p>energy of the different mixtures and a decrease in heat of hydration of concretes with mineral<p>additions was observed which is beneficial for use in mega projects of concrete. Scanning<p>Electron Microscopy observations and thermal analysis have given enough information about<p>the hydration process. It was observed that the hydration products are similar for different<p>concrete mixtures, but the time of their appearance and quantity in the cement matrix varies<p>for each concrete mix.<p>Last part of the thesis was dedicated to the study of main types of shrinkage. First of all,<p>deformations measured were correlated to hydration, capillary depression and porosity<p>evolution. Results allowed concluding that the use of mineral additions has an actual effect on<p>the plastic shrinkage behaviour, but its impact is not proportional to the percentage of<p>additions. Substitution of cement by the additions seems to have a marked influence on the<p>kinetics of the shrinkage without any effect on its long term amplitude. The study of<p>restrained shrinkage under drying conditions by means of ring tests showed that concretes<p>with high percentage of slag addition seem more prone to cracking than the Portland cement<p>concretes. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Dans le cadre du stockage des déchets radioactifs en couches géologiques profondes (argilite du Callovo-Oxfordien), des bétons à faible alcalinité et à faible chaleur d'hydratation référencés "bas pH " ont été élaborés. L'utilisation de ces types de béton permet de limiter la dégradation des propriétés confinantes du matériau argileux type bentonite. Deux bétons bas pH à base de liants ternaires ont étudiés : un composé de ciment, fumée de silice et cendres volantes (TCV) et l'autre composé de ciment, fumée de silice et laitier moulu de haut fourneau (TL). L'objectif de l'étude est d'analyser le comportement de ces matériaux pour s'assurer : d'une mise en œuvre correcte à l'échelle industrielle, d'une bonne tenue chimique et mécanique dans le temps et d'un confinement performant. Le programme expérimental comprend la caractérisation physico-chimique et mécanique de ces matériaux à forte teneur en additions et est couplé à de la modélisation dans le but, in fine, de disposer d'outils permettant de prédire leur comportement au sein de l'ouvrage. Les résultats montrent qu'un cobroyage des constituants du liant permet d'améliorer la réactivité du liant et de s'assurer d'une bonne robustesse des formules de béton. La condition essentielle de l'obtention d'un pH de leur solution interstitielle de 11 est assurée dès 28 jours. Les bétons peuvent être considérés à faible chaleur d'hydratation du fait des échauffements rencontrés à court terme. A long terme, de hautes performances mécaniques, de faibles coefficients de perméabilité et de diffusion sont obtenus sur ces matériaux. Les modélisations de l'hydratation, de l'évolution de propriétés mécaniques, de l'endommagement, des déformations différées et des transferts hydriques ont été abordées. Le modèle d'hydratation utilisé a été adapté aux liants ternaires en prenant en compte les phénomènes de nucléation des additions sur l'hydratation du ciment. Pour les autres modèles, l'acquisition des mesures expérimentales a permis de fournir les données d'entrée pour leur utilisation et de vérifier leur validité sur des liants fortement dilués. Tous ces travaux permettent au final d'envisager sereinement la modélisation et la prédiction du comportement des structures réalisées en béton bas pH. / In the context of the radioactive wastes disposal in deep geological repository of clay, low-alkalinity and low heat of hydration concretes referenced "low pH " were designed. The degradation of the properties of the clay can be limited by using these types of concrete. Two types of low pH binder were chosen for this research: the first one is comprised of cement, silica fume and fly ash (TCV) and the other one is comprised of cement, silica fume and slag (TL). The objective of this research is to comprehend the behavior of these concrete in order to ensure the well-placing of the fresh concrete at an industrial scale and good mechanical performances, chemical stability and confining properties. The experimental program focuses on a physico-chemical and mechanical characterization of these recent materials with high pozzolanic addition content. The experimental data are then modeled for the purpose of having a tool that, in the end, is able to predict the behavior of the low pH concretes within the structure. The results show that grinding altogether the three constituents improves the reactivity of the binder and allows a good reproducibility of the low pH design. The most important criterion which is a pH of the interstitial solution below 11 is met at 28 days. The heat measurements at early age show that the low pH concretes are low heat of hydration concretes as well. In the long run, high mechanical performances, low permeabilities and diffusivities were obtained on these materials. The modeling of the hydration, evolution of mechanical properties, damage, creep and hydric transfers is also covered in this thesis. The model of hydration was adjusted to match the hydration of ternary binders by taking into account the effects of the additions such as the heterogeneous nucleation, on the hydration of the cement. As for the other models, the experimental results were used as data input to validate the models on binders with high replacement rates. Ultimately, this work allows us to contemplate serenely the modeling and the prediction of the behavior of structure made of low pH concretes.

Ce travail de thèse est consacré à la caractérisation des propriétés mécaniques de l’interphase pâte de ciment-granulat au cours de l’hydratation et au cours de la dégradation chimique par lixiviation. La microstructure de l'interphase entre la pâte de ciment et les granulats est caractérisée par une porosité supérieure à celle de la pâte de ciment. Cette zone constitue un point de fragilité dans le béton et ses propriétés affectent fortement le comportement mécanique du béton à l’échelle macroscopique et à l’échelle de la structure. Dans ce travail, la résistance de l’interphase pâte de ciment-granulat est analysée expérimentalement à l'échelle locale. Des essais expérimentaux sont réalisés sur des composites constitués de granulats liés par une pâte de ciment portland préparée avec un rapport Eau/Ciment de 0,5. Des dispositifs expérimentaux dédiés ont été conçus et réalisés de manière à être adaptés à la taille et à la forme des échantillons. La forme des échantillons utilisés et les outils expérimentaux développés permettent de solliciter directement l’interphase. A différents stades de l'hydratation, des échantillons de pâte de ciment seule et des composites sont soumis à des essais de compression, de traction et de cisaillement direct. L’étude des propriétés mécaniques de l’interphase pâte de ciment-granulat révèle une faiblesse de cette zone en termes de propriétés mécaniques..Le protocole expérimental mis au point a permis d’étudier les effets du mécanisme de lixiviation du calcium au niveau de l’interphase sur les propriétés mécaniques du béton à l’échelle locale. Compte tenu du temps caractéristique long du phénomène de lixiviation, la mise en situation expérimentale au laboratoire est accélérée en remplaçant l’eau par une solution de nitrate d'ammonium. Afin de quantifier le développement et la cinétique de dégradation au niveau de la liaison cimentée, les fronts de lixiviation du béton sont caractérisés à différents degrés de dégradation en utilisant la phénolphtaléine comme traceur. Des essais mécaniques locaux (compression, traction et cisaillement) sont réalisés sur les composites et sur la pâte de ciment à différents temps de dégradation. L’étude de l’effet de la lixiviation à l’échelle locale montre le rôle important de l’interphase pâte de ciment-granulat lors du processus de dégradation chimique sur les propriétés mécaniques du composite. / In this work, we presents an experimental study to characterize the mechanical properties at the local scale of the cement paste-aggregate interface during hydration and during chemical degradation by leaching.It is generally accepted that the microstructure of the interface between the aggregates and the cement paste is characterized by a higher porosity than that of cement paste. This makes this zone a weak point in the concrete. The particular properties of this zone strongly influence the mechanical behavior of concrete. In this work, the mechanical properties of the cement paste-aggregate composite, are experimentally studied. The experimental tests are performed on composites at classical aggregate scale (one centimeter of section). These composite are composed by and Portland cement paste and aggregate. The cement paste is prepared with a water/cement ratio of 0.5. The shape of the prepared composites makes them convenient for direct tensile and shear tests. At different stages of hydration, we performed direct tensile and shear tests on the composites by means of specific devices. The same tests were carried out on the cement paste in order to compare with composites results. The shape of the prepared composites makes them convenient to characterize the cement paste-aggregate interface. At different stages of hydration, the composites are subjected to compression tests, direct tensile tests or shear tests. The study of the mechanical properties of the cement-aggregates interface revealed that the cement paste-aggregate interface is the weakest zone in the composite.An experimental protocol was developed to study the effects of calcium leaching mechanism at the cement paste-aggregate interface on the mechanical properties of the concrete. As the process of leaching with the deionised water occurs very slowly, the experimental study in the laboratory is accelerated by replacing the water by ammonium nitrate solution. To quantify the development and kinetics of degradation at the cemented bond, the concrete leaching fronts are characterized at different levels of degradation by using phenolphthalein. Local mechanical tests (compression, tensile and shear) are performed on composite and cement paste at different stages of degradation. The experimental results show that there is a leaching effect on the alteration of the mechanical properties at the cement paste-aggregate interface.

Les minéraux argileux gonflants tels que les smectites sont omniprésents à la surface de la Terre et possèdent d'importantes capacités d'hydratation et d'absorption/rétention de contaminants. Ainsi, ces dernières exercent une influence clé sur les transferts d'éléments dans les environnements de surface. Ces propriétés sont particulièrement importantes quand les smectites sont utilisées comme barrières ouvragées ou géologiques pour les installations de contrôle des déchets. Les molécules d'eau dans l'interfoliaire représentent plus de 80% de l'eau en contact avec les smectites, dans des conditions non saturées. La caractérisation de l'organisation et de la dynamique de l'eau dans les smectites est donc essentielle pour prédire la mobilité des contaminants, dont le principal vecteur est l'eau. Dans ce cadre général, les présents travaux décrivent, dans un premier temps, la structuration interfoliaire eau/cations dans des conditions saturées, jusqu'alors méconnue. Puis, dans un second temps, nous avons examiné l'influence des paramètres structuraux (tels que la quantité et l'emplacement des charges, la composition chimique et plus particulièrement la présence de groupements fluors/hydroxyles) sur les propriétés d'hydratation des smectites. Une série d'échantillons couvrant toute la gamme de composition des smectites a donc été synthétisée et caractérisée structurellement. Une attention particulière a été accordée à la détermination du montant (isothermes vapeur d'eau de sorption) et la distribution (de diffraction des rayons X) de l'eau dans l'espace interfoliaire. La modélisation moléculaire a permis d'aller plus loin dans la compréhension de l'origine des comportements contrastés observés expérimentalement, et de déterminer l'influence des différents paramètres cristallochimiques sur l'hydratation de la smectite. Cette étape est essentielle pour la prédiction de la réactivité des smectites dans l'environnement sur la base d'un nombre limité de paramètres cristallochimiques. / Swelling clay minerals such as smectites are ubiquitous at the Earth surface and possess major hydration ability and contaminant uptake/retention capacity. As a consequence smectites exert a pivotal influence on elemental transfers in surficial environments. These properties are especially relevant also when smectites are used as sealant in engineered or geological barriers for waste disposal facilities. As interlayer H2O molecules account for more than 80% of smectite water in undersaturated conditions, characterization of H2O organization and dynamics in smectites interlayers is essential to determining the geometrical and dynamical properties of clay barriers for waste disposal and to predicting the mobility of contaminant whose principal vector is water. Within this general framework, the present works describe, in a first time, the structuration of interlayer water/cations in saturated conditions. Then, in a second time, review the influence of structural parameters such as the amount and location of layer charge deficit and the chemical composition (and more especially the presence of structural fluorine/hydroxyl) on smectite hydration properties. A set of samples covering the whole compositional range of swelling phyllosilicates has thus been synthesized and characterized chemically and structurally. Special attention was paid to determining the amount (water vapor sorption isotherms) and the distribution (X-ray diffraction) of interlayer water. Molecular modeling allowed unraveling the origin of the contrasting behaviors observed experimentally and to determine the influence of the different crystal-chemical parameters on smectite hydration. This step is essential for the prediction of smectite reactivity in the environment from a limited number of crystal-chemical parameters. Molecular modeling allowed unraveling the origin of the contrasting behaviors observed experimentally and to determine the influence of the different crystal-chemical parameters on smectite hydration. This step is essential for the prediction of smectite reactivity in the environment from a limited number of crystal-chemical parameters.

A presente Tese tem por objetivo estudar alguns aspectos das interações água-detergente que são importantes para o entendimento das propriedades fisico-químicas da própria micela. além das interações que ocorrem na pseudo-fase micelar. Estas interações foram estudadas utilizando-se duas técnicas: RMN de 1H, para avaliar o efeito de micelas aquosas iônicas, zwitteriônicas e não-iônicas sobre a estrutura da água; e o estudo cinético da hidrólise espontânea de um éster do ácido carbônico, para determinar a reatividade cinética desta água além de, possivelmente, esclarecer alguns aspectos da questão da penetração da água na micela. Foi determinado o efeito da concentração do detergente e a presença de deutério no solvente sobre os deslocamentos químicos dos prótons da água. Foi usada a seguinte série de detergentes: dodecilsulfato de sódio (SOS, aniônico), dodecilbenzenossulfonato de sódio (SDBS, aniônico), perfluoroctanoato de sódio (SPFO, aniônico), cloreto de cetiltrimetilamônio (CTACl, catiônico), éter octilfenil(9,5)polioxietilênico (TX-100) e dodecildimetilamônio-3-propanossulfonato (DDAPS, zwitteriônico). O deslocamento químico dos prótons da água. depende linearmente da concentração de detergente e os coeficientes angulares das retas são sinsíveis à concentração de deutério no solvente. A partir destas correlações foram calculados os fatores de fracionamneto deutério/prótio,&#966; cujas magnitudes dão uma idéia quantitativa do efeito do detergente sobre a estrutura da água. Para averiguar a origem micelar do fracionamento observado, foram determinados também os fatores de fracionamento para compostos modelos. Estes são constituídos de cadeias carbônicas curtas que não formam agregados mas que possuem os mesmos grupos hidrofílicos dos detergentes. Foram usados os seguintes compostos como modelos: butilsulfato de sódio (modelo para SDS), p-tolouenossulfonato de sódio (modelo para SDBS), perfluorobutirato de sódio (modelo para SPFO) e brometo de butiltrimetilamônio (modelo para CTACl). Os resultados obtidos mostram que estes compostos perturbam pouco a estrutura água e são diminuidores da sua estrutura. Os detergentes, com a excessão de DDAPS e TX-100, claramente aumentam a estrutura da água devido a efeitos eletrorrestritivos. Interações inter e intramoleculares entre os íons do DDAPS resultam numa neutralização interna das cargas e explicam o seu pequeno efeito (aumento) sobre a estrutura do solvente. Nao é fácil oferecer uma explicação simples para a diminuição da estrutura da água na presença de TX-100, pois existe a interferência de fatores cujos efeitos sobre o fracionamento não podem ainda ser avaliados. Entre estes destacamos o enrolamento das cadeias oxietilênicas do detergente. a presença de água fisicamente presa entre estas cadeias e o fato de que a distruibição das moléculas de água entre as unidades de oxietileno não é homogênea. Foram determinadas as constantes de velocidade, os parâmetros de ativação e o efeito isotópico cinético do solvente para a hidrólise independente do pH de carbonato de bis(2,4-dinitrofenila) , na presença de SDS, CTABr, CTACl, TX-100 de cetildimetilamônio-3-propanossulfonato (HDAPS) . O efeito micelar foi analisado em termos da transferência do éster do seio aquoso para água micelar, e do efeito salino acoplado a fatores eletrostáticos das micelas iônicas. Como modelo para o efeito da transferência do meio, a reação foi estudada em misturas de água e acetonitrila. O efeito salino foi avaliado estudando a reação em presença de alguns dos compostos-modelo acima mencionados. Houve mudanças marcantes na entropia e na entalpia de ativação da reação somente em presença de grandes quantidades de acetonitrila no solvente (fração molar de 0,55 a 0,90). O efeito salino foi pequeno. Todos os detergentes, especialmente o SDS, diminuiram velocidade da reação devido a fatores entálpicos desfavoráveis. Para ter uma idéia do sítio da solubilização do éster nas micelas usadas, estudamos o efeito de acetato e decanoato de p-nitrofenila (compostos usados como modelo para CDNF), sobre os deslocamentos químicos dos grupos de cada detergente. Os resultados mostram que o sítio de solubilização destes ésteres não está predominantemente na região da superfície da micela. Os ésteres movimentam-se rapidamente (em relação à escala do tempo da RMN), em todo volume da micela. Efetuamos um cálculo simples mostrando que a penetração da água até os primeiros dois grupos metilênicos pode dar origem a um volume hidratado da micela de mais de 50%. Uma consideração dos parâmetros de ativação, dos resultados de RMN de 1H e do significado do cálculo do volume micelar efetuado, nos levou a concluir que nossos dados cinéticos podem ser explicados sem a necessidade de assumir uma micela extensivamente hidratada, como por exemplo aquela proposta pelo modelo de aglomeração poros (porous cluster model). / Study of micelle-water interactions is relevant to the physical chemistry of the micelle itself, and for a better understanding of the interactions occuring therein. In the present thesis two aspects of these interactions were studied: the effect of the organized assembly on the structure of water at the micellar interface, and on the kinetic reactivity of water as probed by examining the pH-independent (spontaneous) hydrolysis of a carbonate ester. The effect of the following surfactants on the structure of water was studied: sodium dodecylsulphate (SDS, anionic) sodium dodecylbenzene sulphonate (SDBS, anionic), sodium perfluorooctanoate (SPFO, anionic), cetyltrimethylammonium chloride (CTACl, cationic), polyoxyethylene (9.5) octylphenyl ether (TX-100, nonionic), dodecyldimethylammonio-3-propane sulphonate (DDAPS, zwitterionic). The dependence of the chemical shift of the water protons on the surfactant concentration, and on the deuterium content of the solvent was used to calculate the deuterium/protium fractionation factor, &#966;. The magnitude of the latter (relative to unity, the fractionation factor for bulk water) gives a quantitative idea of the solvent structure perturbation by the micellar pseudophase. In order to ascertain that the observed D/H fractionation is micelle-induced, the fractionation factors for model compounds were also determined. These were short-chain, i.e., non-aggregating compounds bearing the same head-groups as the surfactants. The following model compounds were used: sodium butylsulphate (model for SDS), sodium p-toluenesulphonate (model for SDBS), sodium perfluorobutyrate (model for SPFO) and butyltrimethylammonium bromide (model for CTACl). The following conclusions were drawn from the determined fractionation factors: whereas the short-chain compounds perturb the structure of water only slightly, and are usually water structure breakers, the presence of the micelles clearly enhances the structure of the solvent. Exceptions are zwitterionic DDAPS (marginal structure enhancement) and nonionic TX-100 (water structure decrease). The behavior of the zwitterionic surfactant was explained based on the negligible electrostrictive effect of the micelle due to inter and intramolecular interactions between the head-ions. A simple rationale for the case of TX-100 is not easy because of can complicate such interpretation: the followino factors that coiling of the oxyethylene chains, physical trapping of water between the chains, noneven distribution of the water molecules along the oxyethylene chains. Rate constants, activation parameters, solvent kinetic isotope effect were determined for the pH-independent hydrolysis of 2,4-dintrophenyl carbonate in the presence of SDS, CTABr, CTACl. TX-100 and cetyldimethylammonio-3-propane sulphonate (HDAPS). The micellar effect was analyzed in terms of a transfer Effect, a salt and an electrostatic effect. The first refers to the transfer of the ester form bulk water to \"micellar\" water, and was mimicked by studying the reaction in water-acetonitrile mixtures. Salt effect was evaluated by conducting the hydrolysis in the presence some of the above mentioned short-chain compounds. For the reaction in aqueous acetonitrile the entropy and enthalpy of activation showed sizable changes only at high mole fraction (0.55 to 0.90) of the organic solvent. Salt effect was negligible. The tested detergents, specially SDS, slow the reaction rate due to unfavorable enthalpy. The solubilization site of the ester in the micelles was assesed by 1H NMR. using p-nitrophenyl acetate and decanoate as models. This study showed that the ester in the micelles is not localized at, or very near, to the micelle/water interface, but is rapidly moving (on the NMR time-scale) all over the micellar volume. Analysis of the obtained activation parameters, coupled with the 1H NMR data, and with the result of simple geometric calculation led us to conclude that deep water penetration in the micelle (e.g ., according to the porous cluster model) is not essential to rationalize our data.

Made available in DSpace on 2014-10-09T12:36:01Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:48Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2015-03-26T13:47:05Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2371628 bytes, checksum: 9631d9a8b7d00f653756914084d81d42 (MD5) Previous issue date: 2012-03-16 / The following study has the goal of evaluate the effects of electrolytic hypotonic solution which is associated to sucrose, dextrose or maltdextrin that are administrated through enteral application nasoesophageal with small-caliber and continuous flux on horses clinical parameters. It was used six adult female, mixed on two latin square 6x3 simultaneous in mix models, it was also used the subdivided parcels scheme and the treatments represent the parcel and the time of sub parcel evaluation. On each experimental cycle, the animals were group rearranged so all of them were submitted to all treatments. The animals were also leaded to an adaptation period in the stall and alimentation. The groups were distributed as follows: SEDext electrolytic hypotonic solution associated dextrose. SEMalt electrolytic hypotonic solution associated with maltodextrin and SESaca - electrolytic hypotonic solution associated with sucrose. The electrolytic solutions doses were administrated in 15mL-1kg-1h-1, for a period of 12 hours. The clinical and laboratorial evaluation was performed at times 0h (immediately starting treatment), 6h (six hours of treatment), 12h (12 hours of treatment) and 24 hours (12 hours after treatment). O SESaca has expanded the plasmatic volume, increased the intestine motility, however the glycemic rate has not increased. O SEDext has increased the glycemic rate, the intestine motility, and expanded the plasmatic volume, whiles the SEMalt, expanded the plasmatic volume, was also the electrolytic solution that increased the most the glycemic rate to the animals. There was not change to the serum electrolyte, remaining between the physiologic limits to the species. These results demonstrate the efficiency in the clinic to administer enteral electrolyte solutions for use in horses. / O presente estudo tem como objetivo avaliar os efeitos de soluções eletrolíticas hipotônicas associadas à sacarose, dextrose ou maltodextrina administradas via enteral por sonda nasoesofágica de pequeno calibre em fluxo contínuo sobre parâmetros clínicos e laboratoriais em equinos. Foram utilizadas seis fêmeas adultas, mestiças 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 às subparcelas. A cada ciclo experimental, os animais foram trocados de grupo, de maneira que todos passaram por todos os tratamentos. Os animais passaram por um período de adaptação as baias e a alimentação. Os grupos foram assim constituídos: SEDext - solução eletrolítica hipotônica associada a dextrose, SEMalt - solução eletrolítica hipotônica associada à maltodextrina e SESaca - solução eletrolítica hipotônica associada a sacarose. As soluções eletrolíticas foram administradas na dose de 15 mL-1 kg-1 h-1, durante 12 horas. 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 SESaca expandiu o volume plasmático, aumentou a motilidade intestinal, porém, não aumentou a taxa glicêmica. O SEDext aumentou a taxa glicêmica, a motilidade intestinal e expandiu o volume plasmático, enquanto o SEMalt, além de expandir o volume plasmático, foi a solução eletrolítica que mais aumentou a taxa glicêmica dos animais. Não houve alteração nos valores dos eletrólitos séricos, permanecendo dentro dos limites fisiológicos para espécie. Esses resultados evidenciam a eficiência na clínica ao administrar soluções eletrolíticas de uso enteral em equinos.