A busca por novas soluções técnicas que, de modo sustentável, diminuam o tempo de construção de obras de engenharia e as tornem mais econômicas, tem tomado, cada vez mais, as linhas de pesquisa do grupo de Engenharia Geotécnica da Universidade Federal do Rio Grande do Sul, onde já foram realizadas inúmeras pesquisas para estudar e compreender o comportamento de solos artificialmente cimentados. O cimento Portland é mundialmente utilizado no melhoramento da resistência e da deformabilidade dos solos, outrora impróprios para utilização. Para estudar a contribuição da cimentação para altas tensões de confinamento, foi construído um equipamento triaxial com capacidade de atingir 10 MPa de tensão confinante que permite o estudo do comportamento tensão-deformação-dilatância de solos artificialmente cimentados curados sob tensão. Juntamente, foi realizado um estudo um numa areia fina e uniforme, artificialmente cimentada, para três tempos de cura (3, 7 e 28 dias), da resistência à compressão simples (qu) e da resistência à compressão diametral (qt) em função da razão vazios/cimento (η/Civ). Os resultados mostraram que a resistência aumenta com a redução da relação vazios/cimento (η/Civ) e com o aumento do tempo de cura (t), sendo que a relação tração/compressão (qt/qu) é independente do tempo de cura e apresenta um valor médio de 0,15. Além dos resultados proferidos, outras misturas de solos granulares com diferentes tipos de cimento, variados tempos de cura, foram analisados e normalizados, obtendo-se uma curva única em que a resistência à compressão simples (qu) e a resistência à compressão diametral (qt) foram normalizadas e estão em função da relação vazios/cimento (η/Civ). Paralelamente pretendeu-se verificar qual o efeito do tipo de cura (sob tensão ou atmosférica) em misturas cimentadas com a realização de ensaios para tensões efetivas médias desde 250 kPa até 4000 kPa. Além disso, avaliou-se a variação do η/Civ e do tempo de cura para amostras curadas sob tensão. Os resultados mostram que, de um modo geral, com o aumento da tensão efetiva média, o tipo de cura não afeta os valores das tensões de desvio máximas. A parcela friccional tem uma predominância no comportamento tensão-deformação. O tipo de cura tem influência na definição da superfície de plastificação e da rigidez, verificando-se o aumento destas propriedades para amostras curadas sob tensão em relação a amostras curadas sob pressão atmosférica. Com base nos resultados obtidos nesta pesquisa, um modelo elasto-plástico com degradação da rigidez, que tem como parâmetros a resistência a compressão simples (qu), ângulo de atrito (ϕ’) e uma deformação equivalente (εs 0,7), foi proposto para simular o comportamento tensão-deformação de misturas de areias artificialmente cimentados em ensaios triaxiais, apresentando resultados satisfatórios. / The search for new technical solutions to reduce construction time of engineering works and to make them more cost-effective has been object of the research lines of the group of Geotechnical Engineering of Federal University do Rio Grande do Sul. Numerous studies have been conducted to analyse and understand the behaviour of artificially cemented. Portland cement is widely used for improving strength and deformability characteristics of soils. To study the contribution of cementation under high pressures, a 10 MPa confining pressure triaxial apparatus was built to study the stress-strain-dilatancy behaviour of artificially cemented soils cured under stress. In parallel a study was conducted on a artificially cemented uniform sand at three curing times (3, 7 and 28 days) to determine the unconfined compressive strength (qu) and splitting tensile strength (qt) according to voids/cement ratio (η/Civ) dosage methodology. The results showed that strength increases with the reduction of voids/cement ratio (η/Civ) and with the increasing of cure time (t). The tensile/compression ratio (qt/qu) is independent of curing time and presents a mean value of 0.15. In addition to these results, other granular soils mixtures with distinct types of cement and different curing times were analysed. A unique normalized curve was fit to unconfined compressive strength (qu) and splitting tensile strength (qt) against voids/cement ratio (η/Civ). At the same time, the effect of the curing type (under stress or atmospheric) was verified through triaxial compression tests with mean effective stresses ranging from 250 kPa to 4000 kPa. In addition, the variation of η/Civ and cure time was evaluated for samples cured under stress. The results show that, in general, by increasing the mean effective stress, the type of cure does not affect the values of the maximum deviatoric stress. The frictional portion is predominant in the stress-strain behavior. The type of cure affects the yielding surface and the stiffness of the samples. It was observed the increase in this properties for samples cured under stress compared to samples cured with atmospheric stress. Based on the outcomes of this study, with satisfactory results, an elastoplastic model with stiffness degradation (using unconfined compressive strength (qu), friction angle (’) and an equivalent strain (  s0.7)) was proposed to simulate the stress-strain behaviour of artificially cemented sands in triaxial tests.

Made available in DSpace on 2016-08-31T13:33:38Z (GMT). No. of bitstreams: 1 CassadraNA_DISSERT.pdf: 6154828 bytes, checksum: 2ad89fa53878aa550ba1ccac38d663ba (MD5) Previous issue date: 2013-11-28 / The Brazil is a developing nation, where economic growth is directly proportional to the consumption of the various energy sources. Thus, the trend is that demand for energy will become greater than the supply, generating a great concern about the possible lack of energy. Given this reality, government policies direct efforts to diversify the country's energy matrix. However, generate more power is not enough: there is a need, in addition to the diversification of energy sources, save on use and eliminate waste. Within this context, the industrial sector is considered the highest energy consumption, where the main source is electricity consumed. In the specific case of the cement industry, electricity accounts for the second largest source of consumption and its use is practically all for the driving force, which in turn, has a high potential for energy efficiency. Thus, in order to analyze the energy performance of a cement industry by eliminating the waste of electricity, studies have been conducted and identified points of improvements in water supply system of a cement factory with a capacity of 10 million bags of cement per year. As part of the research and energy efficiency solutions, has deployed a new automation project, which provided the achievement of improvements in the operation, control, supervision and system measurements and their electrical parameters. These improvements were made possible due to the development and application of logical control for the level of general water tank and deployment of new technologies and to control the drive of centrifugal pumps. Results showed that the activation of the centrifugal pumps through frequency inverters is more efficient than the direct drive type match and / or soft-start. How to control the level of the general reservoir, it was evident that the Control type Proportional, Integral and Derivative maintains the level of the general constant reservoir and pump operation in continuous, without increasing power consumption. Thus, it has become the most suitable for achieving energy efficiency in the factory Water Supply System / O Brasil representa uma nação em desenvolvimento, onde seu crescimento econômico é diretamente proporcional ao consumo das diversas fontes de energia. Assim, a tendência é que a demanda por energia se torne maior que a oferta, gerando uma grande preocupação com a possível falta de energia. Diante dessa realidade, as políticas governamentais direcionam esforços para diversificar a matriz energética do país. No entanto, gerar mais energia não é suficiente: existe a necessidade de, além da diversificação das fontes de energia, economizar no uso e eliminar o desperdício. Dentro deste contexto, o setor industrial é considerado o de maior consumo de energia, onde a principal fonte consumida é a eletricidade. No caso específico da indústria cimenteira, a energia elétrica corresponde a segunda maior fonte de consumo e seu uso é praticamente todo destinado à força motriz, que por sua vez, apresenta alto potencial de eficiência energética. Assim, com o objetivo de analisar o desempenho energético de uma indústria de cimento através da eliminação do desperdício de energia elétrica, foram realizados estudos e identificados pontos de melhorias no Sistema de Abastecimento de Água de uma cimenteira com capacidade de 10 milhões de sacos de cimento por ano. Como parte da pesquisa e soluções de eficiência energética, foi implantado um novo projeto de automação, que proporcionou a realização de melhorias na operação, controle, supervisão e medições do sistema e suas respectivas grandezas elétricas. Essas melhorias foram possíveis, devido ao desenvolvimento e aplicação de lógicas de controle para o nível do reservatório de água geral e implantação de novas tecnologias e controle para o acionamento das bombas centrífugas. Os resultados comprovaram que o acionamento das bombas centrífugas através de inversores de frequência é mais eficiente que os acionamentos tipo partida direta e/ou soft-start. Quanto ao controle do nível do reservatório geral, ficou evidenciado que o Controle tipo Proporcional, Integral e Derivativo mantém o nível do reservatório geral constante e a operação da bomba em regime contínuo, sem aumentar o consumo de energia elétrica. Dessa forma, o mesmo tornou-se o mais indicado para obtenção de Eficiência Energética no Sistema de Abastecimento de Água da fábrica

Ce travail vise à mettre en relation les caractéristiques de la zone d’interphase « granulat-pâte de ciment » avec les caractéristiques de porosité, d’absorption d’eau, de dureté et de rugosité de calcaires poreux.La première partie de ce travail a consisté à étudier l’influence de la teneur en eau et de la dureté des granulats sur la résistance mécanique de mortiers. Les résultats montrent que, pour des calcaires poreux et absorbants, les mortiers fabriqués à partir de granulats à l’état sec sont plus résistants que ceux fabriqués à partir de granulats à l’état sursaturé. La deuxième partie de ce travail a consisté à étudier l’adhésion « roche-pâte de ciment ». Il a été constaté que la rugosité et l’état de saturation de la roche affectent significativement les résistances en traction et au cisaillement des composites.La dernière partie est consacrée à l’étude de la microstructure de la zone d'interphase par la technique d’analyse d’images. L’évolution de la porosité moyenne de la zone d'interphase est liée aux propriétés mécaniques des mortiers par la relation de Féret démontrant ainsi que la résistance à la compression dépend principalement de la mésoporosité de l’interphase. Le gradient de porosité est mis en relation avec le gradient de degré d’hydratation et le gradient de rapport E/C. Ces deux derniers sont calculés en appliquant le modèle de Powers. Les résultats obtenus montrent que pour des calcaires poreux et absorbants, la pâte de ciment et la zone d’interphase des mortiers de granulats secs et de granulats sursaturés ne sont pas équivalentes alors qu’initialement on visait le même rapport E/C. / The aim of this study was to relate the characteristics of interfacial transition zone (ITZ) "aggregate-cement paste" to the characteristics of porosity, water absorption, resistance and roughness of porous limestones.The first part of this work was to study the influence of moisture content and resistance of aggregates on the mechanical strength of mortars. The results show that, for porous and absorbent limestones, mortars made from dry aggregates are more resistant than those made from wet aggregates.The second part of this work was to study the ITZ of composites “rock-cement paste”. It was found that the surface roughness and the moisture content of rocks significantly affect the tensile and shear strengths of composites.The last part is devoted to the microstructure of ITZ by image analysis. The evolution of average porosity of ITZ is related to the mechanical properties of mortars by Féret’s law demonstrating that the compressive strength depends mainly on the mesoporosity of ITZ. The porosity gradient is related to the degree of hydration gradient and the W/C ratio gradient. These latter two are calculated by applying Powers’ model. The results show that for porous and absorbent limestones, the cement pastes and the ITZs of dry and wet aggregates mortars are not equivalent although initially we aimed to the same W/C ratio.

[pt] O objetivo do presente estudo consistiu na obtenção, caracterização mecânica e química das fibras de bucha vegetal (Luffa cylindrica) utilizadas, e o emprego das mesmas como possível reforço de compósitos cimentícios. Inicialmente, as fibras de bucha foram encaminhadas à prensa mecânica para perder o seu formato cilíndrico, propiciando uma moldagem mais facilitada, dos posteriores compósitos. A partir daí, foram submetidas a ensaio de tração direta, dividindo-se entre filamento e tecido, difração de raios-x (DRX), espectroscopia de infravermelho (IV), microscopia eletrônica de varredura (MEV) e análise em microscópio digital, com posterior análise em software digital. A matriz foi dosada, respeitando uma substituição parcial de 50 porcento de cimento, por materiais pozolânicos, como 40 porcento de metacaulinita e 10 porcento de cinza volante, com o objetivo de diminuir a quantidade de Hidróxido de Cálcio (HC), produto oriundo da hidratação do cimento. Também foi utilizado superplasticante na confecção da pasta, para melhorar a fluidez e assegurar que toda a área do molde fosse preenchida, além de prover o encharcamento uniforme da fibra. A caracterização química matriz se deu através do ensaio de termogravimetria (TGA), o qual foi capaz de corroborar a baixa presença de HC, propiciando a incorporação de fibras vegetais nessa matriz. As propriedades mecânicas foram avaliadas a partir de ensaio de flow tabe, de resistência à compressão e à flexão. O composto com a matriz supracitada foi confeccionado com as fibras de bucha vegetal nas direções do carregamento e posteriormente encaminhados ao ensaio de flexão de três pontos. Para agregar valor à discussão, foi fabricado um compósito sanduíche com a fibra de sisal (Agave sisalana) em conjunto com a fibra de bucha. Os compósitos cimentícios reforçados por fibra de bucha, e o compósito sanduíche apresentaram valores de resistência 33 porcento maiores, em relação aos corpos de prova moldados apenas com a matriz (sem reforço). / [en] The objective of this study was to obtain, mechanical and chemical fibre characterization of Loofah (Luffa cylindrica) used, and the use of same as possible reinforcement of cementitious composites. Initially, Loofah fibres were forwarded to the mechanical press for losing your cylindrical format, providing a more facilitated, molding of composite posterior. From there, were subjected to direct tensile test, dividing her time between filament and fabric, x-ray diffraction (XRD), infrared spectroscopy (IV), scanning electron microscopy (SEM) and microscope analysis Digital, with further analysis in digital software. The array was dosed, respecting a partial substitution of 50 per cent cement, Pozzolanic materials, such as 40 per cent metacaulinite and 10 per cent fly ash, with the goal of reducing the amount of calcium hydroxide (CH), native of cement hydration product. Superplasticizer was also used in the making of the folder, to improve the fluidity and ensure that the entire area of the mold were filled equally, in addition to providing the drenching fiber uniform. Chemical characterization through array of Thermogravimetry (TGA), which was able to corroborate the low presence of CH, resulting in the incorporation of vegetable fibers in this array. The mechanical properties were evaluated from flow tabe test, compression and flexural strenght. The compound with the above-mentioned matrix was made with Loofah fibres in the directions of loading and subsequently forwarded to the three-point flexural test. To add value to the discussion, made a sandwich composite with sisal fiber (Agave sisalana) in conjunction with the Loofah fiber. The cementitious composites reinforced by loofah fiber, and sandwich composite presented values of maximum 33 per cent larger in relation to specimens only molded array (no reinforcement), although it is not an improvement as significant as found in other synthetic or natural fibers, already studied and some in use by industry.

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

La carbonatation est une pathologie qui affecte les matériaux à base de ciment tels que les bétons et lesmortiers. Les zones carbonatées du matériau deviennent fragiles et perdent ainsi leur pouvoir deprotection des aciers contre la corrosion. Les produits de corrosion engendrent alors une dégradation dubéton pouvant aboutir à la ruine de la structure.Six types de bétons adjuvantés et deux pâtes de ciments ont été formulés grâce à une étude rhéologiqueafin d’étudier l’effet de la carbonatation accélérée et naturelle sur la durabilité des bétons et des pâtesde ciments à base de ressources algériennes. Pour ce faire, plusieurs méthodes d’investigation sontutilisées, aussi bien à l’échelle macroscopique que microscopique.En conclusion, le modèle rhéologique empirique développé peut être utilisé pour formuler des bétonsrésistants à la carbonatation. L’étude de la carbonatation démontre que le protocole accéléré, peut serévéler moins agressifs que la carbonatation naturelle, notamment pour des pâtes de ciment denses.Dans ce cas, la carbonatation accélérée de la surface tend à combler la microporosité superficielle dubéton, freinant ainsi la diffusion du dioxyde de carbone, contrairement à la carbonatation naturelle quiagit de manière plus diffuse sans totalement obstruer la porosité. Moins les bétons sont compacts, plusle protocole accéléré s’avère effectif. / The carbonation is a pathology which affects cement-based materials such as concretes and mortars.The carbonated skin of material becomes brittle and losses the protection of inner steels againstcorrosion. The corrosion products generate a degradation of the concrete which may lead to thecollapse of the structure.Six types of adjuvant concretes and two cement pastes have been designed by a rheological study inorder to study the effect of accelerated and natural carbonation on the sustainability of concretes andcement pastes based on algerian resources. For this purpose, several investigation methods were usedwith both macroscopic and microscopic scales.In conclusion, the empirical rheological model developed herein can be used to formulate concretesresistant to carbonation. The study of carbonation shows that the accelerated protocol may be lessaggressive than the natural one, especially for dense cement pastes. In this case, the acceleratedcarbonation of the surface tends to fill up the superficial microporosity of the concrete, slowing downthe production of carbon dioxide, contrary to the natural carbonation which acts more diffusely withoutcompletely obstructing the pores. The lesser compact is the concrete, the more effective is theaccelerated protocol.

Cada vez mais freqüente a utilização de técnicas tradicionais da engenharia geotécnica depara-se com obstáculos de caráter econômico e ambiental. A técnica do solo-cal torna-se atrativa quando o melhoramento das propriedades do solo do local constitui-se numa alternativa de projeto. A técnica de tratamento de solos com cal encontra aplicação, por exemplo, na construção de bases para pavimentos, na proteção de taludes em barragens de terra e como camada de suporte para fundações superficiais. Entretanto, ainda não existem metodologias de dosagem e projeto das misturas de solo-cal baseadas em critérios racionais como existe no caso do concreto, onde a relação água/cimento desempenha papel fundamental na obtenção da resistência desejada. Nesse sentido, este estudo tem por objetivo quantificar a influência da quantidade de cal, da porosidade e do teor de umidade de moldagem, sobre a resistência de um solo arenoso tratado com cal e rocha basáltica pulverizada, avaliar a adequação do uso das relações água/cal e vazios/cal na estimativa da sua resistência à compressão simples e comparar as variáveis envolvidas com amostras tratadas com cimento em iguais proporções. Para isso foram realizados ensaios de compressão simples e medidas de sucção matricial. Os resultados mostram que a resistência à compressão simples cresceu linearmente com o aumento da quantidade de cal e exponencialmente com a redução na porosidade da mistura compactada. Além disso, a variação do teor de umidade de moldagem não afetou consideravelmente a resistência à compressão simples em misturas compactadas numa mesma massa específica aparente seca. Verificou-se que, para o solo-cal no estado nãosaturado (estado em que normalmente se encontram os aterros compactados), a relação água/cal não é um bom parâmetro para estimativa da resistência à compressão simples. Ao contrário, a relação vazios/cal, assim como a relação vazios/cimento, definido pela razão entre a porosidade da mistura compactada e o teor volumétrico de aglomerante, ajustado por um expoente, demonstraram ser o parâmetro mais adequado na estimativa da resistência à compressão simples do solo-cal e do solo-cimento estudado. / Not rarely, the use of traditional techniques in geotechnical engineering faces obstacles of economical and environmental nature. The soil-lime technique becomes attractive when the improvement of the local soil is a project alternative. The treatment of soils with lime finds application, for instance, in the construction of pavement base layers, in slope protection of earth dams and as a support layer for shallow foundations. However, there are no dosage methodologies and design based on rational criteria as it exists in the case of concrete technology, where the water/cement ratio plays a fundamental role in the assessment of the target strength. In that sense, this study aims to quantify the influence of lime amount, the porosity and the moisture content on the strength of a sandy soil treated with lime and pulverized basaltic rock, as well as to evaluate the use of a water/lime ratio and a voids/lime ratio to assess its unconfined compression strength and to compare the evaluated variables with samples treated by cement in the same proportions. A number of unconfined compression tests and measures of matric suction were carried out. The results show that the unconfined compression strength increased linearly with the increase of the lime amount and exponentially with the reduction on the porosity of the compacted mixture. Besides, the change on the moisture content doesn’t remarkably affected the unconfined compression strength of mixtures compacted in the same dry density. It was verified that, for the soil-lime in the unsaturated state (state usually met in compacted fills), the water/lime ratio is not a good parameter for assessment of unconfined compression strength. In the other hand, the voids/lime ratio, as well as the voids/cement ratio, defined by the reason between the porosity of the compacted mixture and the volumetric binder content, adjusted by an exponent, demonstrated to be the most appropriate parameter in the estimate of unconfined compression strength of the studied soil-lime and soil-cement.

La fabrication additive (Impression 3D) consiste à fabriquer des objets couche par couche en utilisant un modèle 3D, un matériau approprié et une machine dédiée. Pour la construction, c’est un nouveau mode constructif qui se profile. Depuis 2010, la fabrication additive a fait un saut technique et médiatique dans ce secteur. Les projets d’impression 3D se sont multipliés et diversifiés avec les premières maisons construites entièrement au moyen de cette technologie (Winsun, D-Shape, Contour Crafting, Apis Cor…etc). Ce travail s’inscrit dans le cadre d’une thèse CIFRE démarrée en 2015 entre le laboratoire de génie civil de l’Ecole Centrale de Lille et l’entreprise Bouygues Construction. L’objectif de ce travail est d’étudier le potentiel de la fabrication additive pour la construction et plus précisément de proposer une formulation à matrice cimentaire qui sera mise en œuvre par impression 3D.La thèse est organisée en trois grandes parties.La première partie est consacrée à la définition de l’impression 3D et des matériaux cimentaires pour définir leurs interactions. La deuxième partie est dédiée à la formulation d’un matériau cimentaire imprimable. L’imprimabilité a été définie par trois indicateurs : l’extrudabilité, la buildabilté et l’adhérence. La troisième partie est destinée à la validation de la formulation proposée. Ce travail peut être considéré comme une première approche pour définir un protocole d’évaluation de l’imprimabilité des matériaux cimentaires à l’échelle du laboratoire ainsi qu’une première étape pour la conception d’une imprimante 3D destinée et adaptée à la construction. / Additive Manufacturing (3D printing) consists in building an object layer by layer following a 3D model. For this purpose an appropriate material, machine and model are needed. From Construction industry point of view, 3D printing is considered as a new building method. Since 2010, the use of 3D printing for construction has known a large evolution. More and more real construction projects are using this new technology. Some of these examples are Winsun in China, D-Shape in Italy, Contour Crafting in California or Apis Cor in Russia…etc.The work presented in this manuscript was conducted through an industrial PhD thesis (CIFRE) which was launched between “Ecole Centrale de Lille” and “Bouygues Construction” in 2015. The objective of this work was to study the potential of large scale 3D printing integration in the construction process and more precisely the development of a printable cement based mix design.The work is organized in three main parts.The first part was dedicated to 3D printing and cement based material as general concepts. Then their interactions were analyzed. The second part was devoted to the printable mix design. The printability was defined using three indicators: Extrudability, Buildability and layers adhesion. The third part was dedicated to check the printability of the proposed mix design. This work may be considered as a first approach to define a laboratory scale methodology for cement based materials printability testing. It is also a step to contribute to the development of construction 3D printers.

Les mousses cimentaires sont des matériaux solides poreux qui ont despropriétés isolantes intéressantes. Elles sont utilisées dans le domaine de laconstruction pour réduire la consommation énergétique des habitations. Cependant,lors de la prise cimentaire, certaines mousses se déstabilisent et s'effondrent. Laformulation de tels matériaux présente donc des difficultés techniques etscientifiques notamment du point de vue des interactions entre les nombreuxcomposés utilisés, organiques et minéraux. L’objectif de ce travail de thèse a doncété d’étudier spécifiquement les interactions entre la matière minérale et le tensioactifutilisé pour la mise en forme alvéolaire, afin de comprendre le rôle de l’agentmoussant dans les mécanismes de stabilisation des mousses. Pour ce faire, nousavons considéré un système réactif simplifié, mais proche de l’utilisation courante,composé d’un ciment classique, d'eau et d’un tensioactif dosable par spectroscopieUV-visible. Pour découpler les différents effets, nous avons étudié ce système à troiséchelles : la mousse cimentaire, le coulis non moussé et des films uniques. / Cement-based mineral foams are solid porous materials and presentvery interesting insulating properties. Such materials are used in the constructionsector in order to reduce the energy consumption of houses. However, theproduction of these materials can be difficult because of the kinetic competitionbetween foam stability and cement setting. Cement-based mineral foams areextremely complex materials because of the number of components and all theirinteractions. The objective of our study is to get insight into the interactions betweenmineral and organic compounds and to understand their role in the stabilizingmechanisms. Our strategy was to study a model system, sufficiently close the realone to be representative, and sufficiently simple to identify the contribution of thedifferent components. We used as a foaming agent a surfactant exhibiting acharacteristic peak in UV-visible spectroscopy in order to determine its function andposition in the complex system. We first worked on unfoamed slurries, then westudied thin liquid films and the foamed materials.

La sûreté du stockage des déchets radioactifs repose en grande partie sur la capacité de confinement du conteneur et de l’ouvrage qui lui sont dédiés. Dans le cas des déchets radioactifs de Faible et Moyenne Activité à Vie Courte (FMA-VC), cette propriété de confinement, assurée par des matrices solides à base de matériaux cimentaires, est mesurée sur la base d’un essai de diffusion naturelle, consistant à faire traverser un traceur, de type radioactif, dans un échantillon représentatif, duquel on retire, a posteriori, un coefficient de diffusion. L’évolution de ces matériaux et les améliorations apportées à la fabrication de nouvelles enveloppes de confinement induisent des durées d’essai pouvant atteindre plusieurs années.L’objectif premier de ce travail consiste en la détermination du coefficient de diffusion effectif d’une espèce de référence, qui sera dans notre cas l’eau tritiée, dans un intervalle de temps réduit. L’approche théorique repose sur la compréhension du phénomène de transport d’espèces ioniques en solution soumises à un champ électrique. Sur les bases d’un protocole expérimental clairement établi et de la définition du facteur de formation, caractéristique topologique intrinsèque du réseau poreux, il a été possible de déterminer le coefficient de diffusion effectif de l’eau tritiée d’une gamme de bétons et de mortier d’intérêt, et cela en seulement quelques heures.Dans un second temps, la comparaison de l’essai de migration sous champ électrique constant, développé dans ce travail, avec l’essai classique de diffusion naturelle à l’eau tritiée a mis en exergue deux points cruciaux. La non-prise en compte de la décroissance radioactive du tritium dans l’interprétation de l’essai de diffusion naturelle à l’eau tritiée amène une sous-estimation non-négligeable de la valeur du coefficient de diffusion. La conservation, lors de leur phase de maturation, des matériaux d’essais dans des conditions inadaptées, induit des mesures selon la technique de migration sous champ électrique constant disparates et non répétables.Dans un dernier temps, la validation complète de la technique électrocinétique, sujet initial de ce travail, repose sur la vérification des hypothèses théoriques énoncées au préalable. Le facteur de formation, et a fortiori le coefficient de diffusion effectif, est une grandeur indépendante de la force ionique de la solution porale du matériau considéré, cela pour une gamme de solution courante dans le domaine des matériaux cimentaires. Le facteur de formation s’avère aussi indépendant de l’amplitude du champ électrique appliqué, aussi pour une gamme et des durées d’essai adaptées aux conditions de mesures définies dans le protocole. Enfin, lorsque les valeurs de coefficients de diffusion effectifs obtenues en migration et diffusion naturelle à l’eau tritiée sont comparées sur plusieurs formulations maîtrisées de matériaux cimentaires / The safety and the reliability of a radioactive waste repository rely essentially on the confinement ability of the waste package and the storing structure. In the case of the low-level and intermediate level short-lived radioactive waste, the confinement property, relying on solid matrices made of cement-based materials, is assessed through a natural diffusion test, using a radioactive tracer, from which an effective diffusion coefficient is deduced. The evolution of the materials and more particularly the enhancement of the confinement properties of cement-based materials lead to test duration from a couple of months to a couple of years.The main objective of the present work involves the determination of the effective diffusion coefficient of reference chemical species, in our case the tritiated water, within a shorter time. The theoretical foundation is based on the description of ionic species mass transfer under the effects of an electrical field. With the definitions of a precise experimental protocol and of a formation factor, considered as an intrinsic topological feature of the porous network, it is possible to determine the effective diffusion coefficient of tritiated water for various types of concretes and mortars, and this within a few hours only.The comparison between the developed accelerated test, based on the application of a constant electrical field, and the normed natural diffusion test, using tritiated water, underlined two critical issues. First, omitting the impact of the radioactive decay of tritium during a natural diffusion test, leads to a non-negligible underestimation of the effective diffusion coefficient. Second, maintaining samples in high relative humidity conditions after casting is essential in order to avoid contrasted and unrelated results when performing the electrokinetic tests.Eventually, the validation of the electrokinetics technique, main objective of this work, rests on the assessment of the theoretical hypothesis previously formulated. The formation factor, as well as the effective diffusion coefficient, does not depend on the ionic strength of the material pore solution, this being validated for solutions of different composition encompassing the cement materials pore solution diversity. The formation factor also does not vary when the amplitude of the applied electrical field varies, provided both the test duration and the electrical field amplitude are kept within acceptable boundaries. Finally, the comparison between the values of the effective diffusion coefficient obtained with both the constant field migration test and the natural diffusion techniques, for perfectly conditioned and prepared materials, leads us to invalidate the assumption that the effects of the double electrical layer are negligible