Lecithin wird unter anderem zur Steuerung der rheologischen Eigenschaften von Lebensmittelsuspensionen wie zum Beispiel Schokolade eingesetzt. In erster Linie findet dabei Sojalecithin Verwendung, wogegen die Wirkungen von Lecithinen aus Sonnenblumen oder Raps unzureichend dokumentiert sind. Anhand von Untersuchungen an Modellsuspensionen werden Wirkungsbeziehungen von Lecithin auf mikrostruktureller Ebene beleuchtet, um Ursachen für dessen Funktionalität in ölbasierten Suspensionen abzuleiten. Darüber hinaus erfolgt ein Vergleich der Wirkung von Soja-, Raps- und Sonnenblumenlecithin auf rheologische, sensorische und morphologische Eigenschaften von Schokolade. Rheologische Untersuchungen an Zucker/Öl- und Glaskugel/Öl-Suspensionen verdeutlichen den Einfluss der Suspensionsbestandteile auf die Wirkung von Lecithin in ölbasierten Suspensionen. Sedimentationsanalysen an Zucker/Öl-Suspensionen zeigen, dass die Reduktion der rheologischen Parameter mit der Senkung des Sedimentvolumens und einer verstärkt polydispersen Sedimentation einhergeht. Glaskugel/Öl-Suspensionen bilden im Vergleich zu Zucker/Öl-Suspensionen ein deutlich kompakteres Sediment, was auf geringer ausgeprägte Interaktionen zwischen den Glaspartikeln hindeutet und durch Untersuchungen mittels Rasterkraftmikroskop bestätigt wird. Die Anreicherung des Dispersionsmediums mit Lecithin führt zur Adsorption von grenzflächenaktiven Molekülen an der fest/flüssig-Grenzfläche und reduziert die adhäsiven Kräfte zwischen Zuckeroberflächen. In Zucker/Sojaöl-Suspensionen zeigen die Phospholipide Phosphatidsäure, Phosphatidylcholin und Phosphatidylethanolamin im Vergleich zu Sojalecithin eine geringer ausgeprägte Funktionalität bei kleinen Phospholipidkonzentrationen. Soja-, Raps- und Sonnenblumenlecithine besitzen in dunkler und in milchhaltiger Schokoladenmasse lediglich hinsichtlich ihrer Wirkung auf die Fließgrenze leichte Unterschiede. Die Präparate zeigen keine verallgemeinerbaren Wirkunterschiede auf die Fettkristallmorphologie und die Textur von gelagerter dunkler und milchhaltiger Schokolade. Des Weiteren lassen sensorische Untersuchungen keine signifikant ausgeprägte Präferenz für dunkle oder milchhaltige Schokolade erkennen, wenn die Probe mit Soja-, Raps- oder Sonnenblumenlecithin versetzt wird. Die Ergebnisse zeigen, dass die Reduktion der adhäsiven Kräfte zwischen Zuckerpartikeln eine Ursache für die Senkung der rheologischen Parameter und des Sedimentvolumens von Zucker/Öl-Suspensionen darstellt. Außerdem ist zu erkennen, dass bei geringen Phospholipidkonzentrationen synergetische Effekte zwischen unterschiedlichen grenzflächenaktiven Substanzen zu einem Anstieg der Funktionalität des eingesetzten Präparates führen können. Darüber hinaus ist festzustellen, dass Soja-, Raps- und Sonnenblumenlecithin die rheologischen, sensorischen und morphologischen Eigenschaften von Schokolade in gleichem Maß beeinflussen. / Lecithin is used in the food industry, for example to control the rheological properties of oil-based suspensions, such as chocolate. First and foremost, soybean lecithin is used, whereas the effects of possible alternatives, such as lecithin from sunflower or canola, are still insufficient documented. On the basis of model suspensions the effect of lecithin on the microstructural level will be investigated to derive causes of the functionality of the surfactant in oil-based suspensions. Additionally, a comparison is made regarding the effects of soybean lecithin, canola lecithin and sunflower lecithin on the rheological and morphological properties as well as on sensory characteristics of chocolate. Rheological studies illustrate the influence of the suspension components to the action of lecithin in oil-based suspensions. While, in sugar/oil-suspensions, lecithin reduces apparent viscosity and yield stress, the effect of the surfactant in glass sphere/oil-suspensions depends on the dispersion medium. Sedimentation analyses of sugar/oil-suspensions show that the reduction of the rheological parameters coincides with the reduction of the sediment volume and an increased polydisperse sedimentation. The sediment of glass sphere/oil-suspensions is more compact in comparison to sugar/oil-suspensions, indicating less pronounced interactions between glass spheres. Investigations using atomic force microscopy show the less pronounced interactions between glass spheres. While interactions (adhesive forces) are detectable between sugar surfaces dispersed in oil, no interactions can be determined between glass surfaces. The enrichment of the dispersion medium with lecithin results in the adsorption of the surfactants at the sugar surface and reduces the adhesive forces. In sugar/soybean oil suspensions and at low phospholipid concentrations the results indicate a less pronounced functionality of the individual phospholipids, phosphatidylcholine, phosphatidylethanolamine and phosphatidic acid in comparison to soybean lecithin. In dark chocolate and milk chocolate soybean lecithin, canola lecithin and sunflower lecithin reduces apparent viscosity at low to medium shear rate in the same way. In contrast, small differences in terms of their effect on the yield stress are observed. The lecithins do not show differences regarding their impact on fat crystal morphology and texture of stored dark chocolate and milk chocolate. Furthermore, in sensory studies, no significant preference differences were detectable in case of dark chocolate or milk chocolate containing soybean lecithin, canola lecithin or sunflower lecithin. The results show that the reduction of the adhesive forces between sugar particles causes the reduction of rheological parameters and the sediment volume of sugar/oil-suspensions. Furthermore, at low phospholipid concentrations possible synergistic effects between different surfactants can lead to an increase of the functionality of suractants. Additionally it can be concluded that soybean lecithin, canola lecithin and sunflower lecithin affect the rheological and morphological properties as well as the sensory characteristics of chocolate in equal measure.

Telechelic associating polymer networks consist of polymer chains terminated by endgroups that have a different chemical composition than the polymer backbone. When dissolved in a solution, the endgroups cluster together to form aggregates. At low temperature, a strongly connected reversible network is formed and the system behaves like a gel. Telechelic networks are of interest since they are representative for biopolymer networks (e.g. F-actin) and are widely used in medical applications (e.g. hydrogels for tissue engineering, wound dressings) and consumer products (e.g. contact lenses, paint thickeners). In this thesis such systems are studied by means of a molecular dynamics/Monte Carlo simulation. At first, the system in rest is studied by means of graph theory. The changes in network topology upon cooling to the gel state, are characterized. Hereto an extensive study of the eigenvalue spectrum of the gel network is performed. As a result, an in-depth investigation of the eigenvalue spectra for spatial ER, scale-free, and small-world networks is carried out. Next, the gel under the application of a constant shear is studied, with a focus on shear banding and the changes in topology under shear. Finally, the relation between the gel transition and percolation is discussed.

New relative sea-level (RSL) observations dating from the late Pleistocene and early Holocene, during and after the collapse of the Cordilleran ice-sheet (CIS), are provided for two regions in southern coastal British Columbia. They record the glacial isostatic adjustment (GIA) response of the Earth to the changing surface load of the waning CIS. The data provide a new RSL curve for Sechelt, on the mainland coast north of Vancouver, and extend and revise a previously constructed curve for Barkley Sound on the west coast of Vancouver Island. The observations create a new profile of RSL curves oriented southwest-northeast across Vancouver Island and the Strait of Georgia. A previously-defined profile of RSL curves is oriented northwest-southeast profile along the east coast of Vancouver Island. The two profiles intersect in the central Strait of Georgia. The new RSL curves sample different parts of the Cascadia Subduction Zone (CSZ) and provide constraints on the history of the CIS. The Juan de Fuca plate subducts beneath the North American plate in roughly the same southwest to northeast direction as the RSL profile. GIA modelling of the RSL observations along this profile may indicate spatial variations related to the structure of the Cascadia Subduction Zone (CSZ). The CIS flowed roughly from northeast to southwest over the regions of interest. RSL observations along this path indicate how sea-level change differed with distance from the edge of the ice-sheet towards its centre. The CIS model of James et al. (2009b) is refined to fit observed sea levels while applying glacial geological constraints to regional ice sheet advance and retreat. Sea level in Barkley Sound dropped from greater than 27 m elevation before 15 cal kyr BP to -46 m below present around 12 cal kyr BP. At Sechelt, sea level closely follows the same trend as in the central Strait of Georgia, dropping from over 150 m before 14 cal kyr BP and falling past present levels after 12.4 cal kyr BP to a poorly constrained lowstand between 12 and 9 cal kyr BP. The initial crustal uplift rate near Sechelt was at least 85 mm/yr, comparable to that of the central Strait of Georgia. The sea-level observations are best fit with predictions employing an Earth model with a 60-km effective lithosphere thickness and asthenospheric viscosity and thickness of 4 × 1019 Pa s and 380 km, respectively. The transition zone and lower mantle viscosities are based on the VM2 Earth model (Peltier 2002). Sea level in Barkley Sound fell quickly (15-30 mm/yr), and observed sea level is best fit with the same asthenospheric viscosity, but with a thinner 30-km thick lithosphere, consistent with the regional tectonic structure. Revisions to the ice model are consistent with radiocarbon constraints on ice sheet history and provide good agreement with the observed sea-level history for the study regions as well as RSL histories previously described for the Strait of Georgia and southern Vancouver Island. / Graduate / 0372

In this investigation, SCCs were prepared by keeping the total mass of cementitious materials (cement and fly ash) constant at 500 kg/m3, in which 30, 40, 50, 60, and 70% of cement, by weight, was replaced by the high-lime and low-lime fly ash. For comparison, a control SCC mixture without any fly ash was also produced. The fresh properties of the SCCs were observed through, slump flow time and diameter, V-funnel flow time, L-box height ratio, U-box height difference, segregation ratio and the rheological parameters (relative yield stress and relative plastic viscosity). Relations between workability and rheological parameters were sought. Setting times and temperature rise of the SCC were also determined. The hardened properties included the compressive strength, split tensile strength, drying shrinkage and permeation properties (absorption, sorptivity and rapid chloride permeability tests) up to 360 days. The results obtained indicated that it is possible to produce SCC with a 70% of cement replacement by both types of fly ash. The use of high volumes of fly ash in SCC not only improved the workability and permeability properties but also made it possible to produce concretes between 33-40 MPa compressive strength at 28 days.

The objective of the research was to develop fundamental understanding of the process of deposition of complex mixtures by the inkjet method. The rheological properties and DOD drop formation dynamics of carbon black pigmented inkjet inks were investigated. It was found that the suspension microstructure responses to bulk motions, leading to shear rate and time dependent shear viscosity. However, DOD drop formation dynamics of highly pigmented inkjet ink and pure Newtonian fluid is similar even though shear rate up to 105 s-1 exists during inkjet jetting process. A proposed explanation for these observations is that the shearing time during DOD drop ejection is insufficient for changing and stabilizing the microstructure of the suspension. The effects of signal amplitude and jetting frequency on DOD drop formation dynamics of pure Newtonian fluids were investigated. A transition of DOD drop formation dynamics when the inkjet nozzle is switched from idle to jetting was identified. A qualitative investigation of DOD drop impaction and post-impaction behavior on inkjet paper and textiles was carried out. Dynamics of DOD drop accumulation and spreading on the substrates and final ink distribution show drastic differences between these two substrates.

Made available in DSpace on 2015-04-17T14:49:36Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2092428 bytes, checksum: 9f2660b1eca5b207292adc4d196cdd59 (MD5) Previous issue date: 2014-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The success of the food industry depends not only on sure foods are safety for consumers, but also the capacity to innovate and supply the market trends, like the demand for food products made from health benefits ingredients. In this way, this research aimed to develop and characterize a yogurt-like fermented beverage made from a mixture of goat s milk and water-soluble soy extract (WSSE), supplemented with inulin. To established the most suitable formulation, a Central Composite Design (CCD) in conjunction with Response Surface Methodology (RSM) was used, having as independent variables the concentrations of WSSE and inulin. The response variables were water holding capacity (WHC), syneresis index, pH, acidity, and rheological and sensory properties. By using that methodology was observed that increasing WSSE concentration was related to better results for rheological properties, WHC and syneresis index, whereas, a negative influence was observed on overall acceptability of the product. Inulin concentration, at the levels studied, showed a positive influence on apparent viscosity and overall acceptability of the beverages. By using the models obtained for response variables was elaborated a treatment containing the concentrations of WSSE and inulin that promoted the most suitable result. The fermented beverage elaborated was characterized for physicochemical and sensory properties and the refrigerated storage stability was analyzed during 28 days by evaluating microbiological, chemical and physical parameters. The results obtained from this treatment were compared with the results obtained from a control treatment made using goat s milk only and without inulin supplementation. The treatment containing WSSE and inulin showed better results for physical and chemical properties, showing better stability during refrigerated storage. However, control treatment showed a better overall acceptability, presenting aroma and taste more pleasant. Regarding to microbiological parameters, no significative differences were observed for these two treatments. / O sucesso da indústria de alimentos não depende apenas da certeza de que os alimentos são seguros para o consumo, mas também da habilidade para inovar e para atender as atuais tendências de mercado, como a demanda por alimentos elaborados a partir de ingredientes que, além de nutrir, trazem benefícios adicionais a saúde. Neste contexto, este trabalho objetivou desenvolver e caracterizar uma bebida fermentada tipo iogurte elaborada a partir de uma mistura composta por leite de cabra e extrato hidrossolúvel de soja (EHS), adicionada de inulina. Para a definição da formulação mais adequada foi utilizado um Delineamento Composto Central Rotacional (DCCR) em conjunto com a Metodologia de Superfície de Resposta (MSR), tendo como variáveis independentes as concentrações de EHS e inulina e como variáveis dependentes a capacidade de retenção de água, o índice de sinerese, pH, acidez e as propriedades reológicas e sensoriais. A partir desta metodologia, foi verificado que o aumento na concentração de EHS favoreceu a obtenção de melhores resultados para as propriedades reológicas, para a capacidade de retenção de água e para o índice de sinerese, no entanto, apresentou uma influência negativa sobre a aceitação sensorial do produto. A concentração de inulina, dentro dos níveis utilizados, influenciou de forma positiva sobre a viscosidade aparente e sobre a aceitação sensorial do produto. A partir dos modelos obtidos para as variáveis dependentes estudadas, foi elaborado um tratamento contendo as concentrações de EHS e inulina que forneceram os resultados mais satisfatórios. A bebida fermentada elaborada foi caracterizada quanto as propriedades físico-químicas e sensoriais e sua estabilidade foi avaliada durante um período de armazenamento refrigerado de 28 dias com relação a parâmetros microbiológicos, físicos e químicos. Os resultados obtidos a partir deste tratamento otimizado foram comparados com os resultados de um tratamento controle elaborado apenas com leite de cabra e sem a adição de inulina. O tratamento contendo EHS e inulina obteve melhores resultados com relação as propriedades físicas e químicas, apresentando melhor estabilidade durante o armazenamento. No entanto, o tratamento controle obteve uma melhor aceitação sensorial, apresentando sabor e aroma mais agradáveis. Com relação aos parâmetros microbiológicos, diferenças significativas não foram observadas entre estes dois tratamentos.

Étude du comportement d'ADN en solution et aux interfaces : actuellement, l'objectif de parvenir à une plus grande efficacité dans les processus de compaction de l'ADN, dans l'innovation des capteurs d'ADN et dans l'étude des changements dans les propriétés interfaciales générés entre les surfaces métalliques et les molécules d'ADN, est devenue un grand domaine d'intérêt en bioingénierie. Cette section de la thèse propose le couplage des techniques rhéométriques, électrochimiques et optiques afin d'effectuer une étude détaillée du comportement de molécules d'ADN en solution et aux interfaces, en fonction de la température, de la concentration en ADN et du potentiel électrique. Tout d'abord, le comportement rhéologique des solutions d'ADN, ainsi que la détection des concentrations critiques (C* et Ce), est discuté à partir d’expériences de rhéométrie en cisaillement permanent et harmonique. Après avoir étudié les propriétés des solutions d'ADN, des techniques électrochimiques et optiques ont été utilisés pour identifier les changements structurels aux interfaces Au/ADN et Pt/ADN, ainsi que pour décrire l'arrangement des chaînes d'ADN dans la double couche électrochimique pour les régimes dilué et semi-dilués. La réponse obtenue par Spectroscopie d'Impédance Électrochimique (EIS), Modulation Interfaciale de la Capacitance (MIC) et Résonance des Plasmons de Surface (SPR) reflète un processus d'adsorption des molécules d'ADN sur les surfaces métalliques. Finalement, en utilisant des concentrations d’ADN dans le régime dilué, on a étudié la formation de nanoparticules de chitosane-ADN avec stœchiométrie définie pour le transfert de gènes.Le rôle de la dynamique micellaire et la rhéologie dans la libération contrôlée de médicaments: le transfert ciblé d'ingrédients actifs (vectorisation) est un grand défi pour la recherche thérapeutique. Ce procédé est utilisé pour contrôler le transfert des protéines, des gènes et des médicaments vers une cellule cible en l'associant à un vecteur. Les molécules pour la chimiothérapie sont souvent hydrophobes et ont besoin d’un vecteur pour être transférées. Dans cette section de la thèse, on cherche à comprendre les dynamiques d'échange collectives (fusion et fission) entre micelles de copolymères triblocs amphiphiles à l'équilibre et hors équilibre. Ensuite, on étudie les dynamiques d'échange collectives entre ces micelles, choisies comme vecteurs, et des liposomes, choisis comme cellules modèles. On utilise une technique de fluorescence avec un dérivé de pyrène hydrophobe pour suivre les processus de fusion et de fission. Après avoir caractérisé la structure des copolymères amphiphile et avoir étudié leur dynamique à l'équilibre et hors l'équilibre, nous proposons une technique de fluorescence qui permet de quantifier les dynamiques collectives de vectorisation entre les micelles et les liposomes. Les effets de la variation de la concentration de liposomes et de l’adsorption du chitosane sur la membrane du liposome et sur les micelles ont été étudiés. / Nowadays, the target for reaching a greater efficiency in DNA compaction processes, the innovation ofDNA sensors development and the study of changes in the interfacial properties generated between metalsurfaces and DNA molecules has become an area of great interest in bioengineering. This section of thethesis proposes the coupling of rheological, electrochemical and optical techniques to perform a detailedstudy of DNA molecules behavior in the bulk state of the solution and at the interface with two differentmetallic surfaces, as a function of parameters such as temperature, DNA concentration and electricpotential. Firstly, the rheological behavior of DNA/buffer solutions, as well as the evidence of the criticalconcentrations (C★ and Ce) is discussed from simple steady state and oscillatory dynamic shearexperiments. After studying DNA solutions properties, electrochemical and optical techniques are used toidentify structural changes in Au/DNA and Pt/DNA interfaces and to describe the arrangement of DNAchains in the electrochemical double-layer as a function of concentration and within each characteristicregime, i.e. dilute and semi-dilute regimes. The obtained response trough Electrochemical ImpedanceSpectroscospy (EIS), Modulation Interfacial of the Capacitance (MIC) and Surface Plasmon Resonance(SPR) techniques reflects an adsorption process of DNA molecules taking place onto the metal surfaces.Finally, by selecting DNA concentrations in the dilute regime, we studied the formation of chitosan-DNAnanoparticles with defined stoichiometry for gene transfer.The specific delivery of active ingredients, known as vectorization, has actually become a greatchallenge in therapeutic research. This process has been used to control the distribution of activeingredients such as proteins, genes for gene therapy and drugs, to a target by associating it with avector. Molecules for chemotherapy are frequently hydrophobic and require vectorization to betransported to the target cell. In this section of the thesis, we look up to understand the collectiveexchange dynamics (fusion and fission) between amphiphilic block copolymer micelles at the equilibriumand out of the equilibrium, and the exchange dynamics between these micelles (representing vectors)and the simplest model of cells (liposomes). We used a fluorescent technique with hydrophobic pyrenederivative to probe the fusion and fission of micelles at equilibrium. After characterizing amphiphilicblock copolymers structure and studying their dynamics in and out of equilibrium, we proposed a timescan fluorescence technique to quantify the collective vectorization dynamics between amphiphilic blockcopolymer micelles and liposomes. The effect of the variation of several parameters such as liposomeconcentration and a chitosan adsorption were investigated in order to control the vectorizationdynamics between these vectors and cells models.

La microcirculation sanguine est un système constitué de réseaux complexesde vaisseaux sanguins de diamètres micrométriques. C’est le lieu privilégié deséchanges de gaz et de nutriments entre le sang et les tissus.Les écoulements dans ces réseaux sont gouvernés par les propriétés des constituantsdu sang c’est-à-dire des cellules en suspension dans du plasma et plus particulièrementdes globules rouges qui sont les cellules majoritaires dans le sang.Selon les conditions de l’écoulement, les globules rouges, qui sont des particulesdéformables, peuvent présenter différents types de formes et de dynamiques quiinfluencent la rhéologie de la suspension. Les interactions hydrodynamiques entreglobules rouges et avec les parois dans les vaisseaux confinés influencent égalementles écoulements à travers des phénomènes de diffusion mais aussi de structurationdes globules au sein de la suspension. Il a notamment été montré que des couchesde plasma dépourvues de globules rouges près des parois des vaisseaux sanguins induisentune diminution de la viscosité effective de la suspension lorsqu’on diminuele diamètre du vaisseau. Par ailleurs, des structurations en file ont également étéobservées dans la microcirculation sanguine avec des conséquences probables surla rhéologie. Au cours de ces travaux de thèse, nous avons investigué les propriétésrhéologiques de suspensions de globules rouges en micro-écoulement grâce à uneméthode de rhéométrie microfluidique. Nous avons focalisé notre attention sur larelation entre la rhéologie et la structuration de la suspension dans un canal, liéeau confinement ainsi qu’aux régimes dynamiques des globules en écoulement.Dans certains cas pathologiques comme la drépanocytose où les propriétés desglobules rouges peuvent être modifiées, les écoulements dans la microcirculationpeuvent être perturbés et conduire à des crises vaso-occlusives dont les mécanismesphysiques restent mal compris. Nous avons exploré la dynamique de formationd’occlusions et leurs évolutions dans des réseaux de canaux micrométriques modèlesavec des suspensions de globules rouges dont les propriétés ont été modifiées,révélant ainsi une dynamique complexe où l’adhésion et des effets d’obstructionsinterviennent. / Blood microcirculation consists in blood flowing in complex microvessel networks.Gas and nutrient exchanges between blood and tissues occur in these networks.Microcirculatory blood flows are governed by the properties of blood components,mainly red blood cells suspended in plasma. Red blood cells are deformableparticles which can exibit different shapes and motion dynamics that influence therheology. Hydrodynamic interactions between red blood cells and with walls of theconfined channels lead to diffusion and structuration in the suspension that alsoaffects the rheology. Plasma cell-free layers near walls observed in the microcirculationinduce a decrease of the effective viscosity with decreasing vessel diameter.Other types of structuration like layering of red blood cells have been observed inthe microcirculation with possible rheological consequences. In the present work,we investigated the rheology of confined red blood cell suspensions and focusedon the link between rheology and structuration of the suspension thanks to amicrofluidic viscosimeter.The sickle cell disease which modifies the properties of red blood cells leadsto flow disorders with the formation of occlusions in the narrow capillaries ofthe microcirculation. We explored the formation and the evolution of occlusionsin simplified networks of microchannels when properties of red blood cells aremodified, revealing complex dynamics where adhesion and jamming effect occur.

La technologie du béton progresse très rapidement, principalement en ce qui concerne l'amélioration de ses propriétés mécaniques. Au cours des dernières années, de grands efforts ont été faits pour améliorer l'apparence de la surface du béton. L'amélioration de la surface du béton améliore non seulement l'aspect esthétique du béton, mais protège également le béton contre les agressions provenant de l'environnement. La surface du béton brut présente généralement de nombreux défauts de surface. Ces défauts sont visibles à l'œil nu par des variations de couleur ou de texture. Selon la littérature, l'ensemble de tous ces défauts est dû à la composition initiale du béton, aux formes de remplissage et enfin, aux conditions de conservation après démoulage. Au travers de ma thèse j'ai travaillé sur l'influence de la composition des matériaux cimentaires sur l'aspect final de la surface une fois durcie, et notamment en analysant le rapport E/C. Les essais ont tous été effectués sur de ciment CEM I. Pour la partie expérimentale, nous avons fabriqué des pâtes de ciment et des mortiers avec différents rapports E/C dans des moules métalliques de 4x4x16 $cm^3$. Nous avons utilisé un spectre colorimètre pour mesurer l'intensité de la lumière réfléchie en termes de luminance et un microscope numérique pour mesurer la rugosité des surfaces en termes de surface développée. A partir de nos résultats, nous avons observé que l'augmentation du rapport E/C engendre l'éclaircissement des surfaces et une diminution de la rugosité de la surface des matériaux cimentaires. Nous avons également effectué des essais rhéologiques sur des pâtes et des mortiers frais. Pour les pâtes, un rhéomètre rotatif de l'IRC (Institut de Recherche en Constructibilité) -ESTP Paris a été utilisé, tandis que pour les mortiers, le rhéomètre de CERIB (à Épernon) a été privilégié. Par nos résultats, nous avons observé que l'augmentation de l'eau dans la composition des matériaux cimentaires engendre considérablement la diminution du seuil de cisaillement et de la viscosité. Les modèles mathématiques pour décrire l'écoulement de matériaux cimentaires utilisés étaient les modèles classiques (Bingham, Herschel Bulkley et Casson) et modifiés par Papanastasiou. A partir de la régression numérique, nous avons observé que la loi de Herschel Bulkley et tous les autres modèles modifiés sont bien adaptés pour décrire le comportement des pâtes de ciment. Pour les mortiers, les modèles Bingham, Herschel Bulkley et tous les modèles modifiés sont bien adaptés pour les mortiers fluides. Enfin, la loi de Bingham-Papanastasiou a été choisie pour modéliser l'écoulement des pâtes de ciment via COMSOL multiphysics. Les résultats numériques sont comparés avec ceux d’expérimentation / This thesis deals with the study of the influence of the water variations in the concrete-formwork interface. The proposed approach is intended to analyze two aspects. • The role of the concrete mixing formulation, and the casting procedures on the finished mortar surface. • The movement of water in concrete formwork interface. Firstly, we search to confirm the phenomenological results on the relationship between the luminance of the concrete surface and its roughness, this last being governed by the local W/C ratio in the formwork interface. This relationship will be established for compositions of modern concrete. After, we will examine the role of operational factors on the granular segregation on the mortar surface and their consequences on the bleeding of the specimens, on the water movements as well as on the color of the surface. Parameters : Formulation parameters : granular composition, G/S, S/G, W/C ratio and admixtures Parameters of implementation: Temperature and relative humidity, vibration, waiting time, type of formwork, release agents. Maturation parameters: temperature, relative humidity, form release deadline and carbonation

La micro extrusion (ou DIW) est une technique de fabrication additive basée sur le dépôt continu de filaments couche par couche. Utilisée pour l'impression de structures poreuses, le DIW de céramiques denses et résistantes reste un défi. L'avantage du DIW réside dans sa capacité à produire des composites, offrant la possibilité de combiner la mise en forme complexe à un contrôle microstructural et fonctionnel précis de matériaux bioinspirés par exemple.Notre travail se concentre sur l'utilisation de gels de boehmite, un précurseur d'Al2O3, en tant que matrice céramique pour obtenir différentes microstructures. Des légers changements dans la composition des gels conduisent à des microstructures et donc à des propriétés différentes. En combinant la polyvalence microstructurale de ces gels avec une maîtrise rhéologique, on peut imprimer des composites avec des propriétés mécaniques améliorées.L'impression de céramiques denses et résistantes passe par la compréhension des propriétés rhéologiques qui définissent une encre imprimable. Le vieillissement de la boehmite est idéal pour corréler les critères géométriques avec la rhéologie pour fournir un critère universel pour l'imprimabilité. Aussi, l'écoulement à l'intérieur des buses de DIW peut aligner des plaquettes d'alumine pendant l'impression. Ceci fournit à l'objet imprimé une ténacité à la rupture accrue dans la direction souhaitée, avec la possibilité de dévier la propagation de la fracture. Un objet peut ainsi être conçu avec précision, en alternant des couches denses et des couches tenaces pour combiner la complexité de la forme avec l'adaptation du comportement mécanique / Direct Ink Writing is an additive manufacturing technique based on continuous layer-by-layer filament deposition. Mostly used to print porous structures, DIW of dense and strong ceramic objects remains an open challenge. However, the advantage of DIW resides in its ability to print multimaterial objects, offering the possibility to combine complex shaping to precise microstructural and functional control, from bioinspired materials, to novel composite structures.Our work focuses on using boehmite gels for DIW, an Al2O3 precursor, as a ceramic matrix to obtain different microstructures. Very small changes to the gels composition lead to completely different microstructures and hence, functional properties. By combining the microstructural versatility of boehmite gels with an understanding of rheology, we are able to print micro and macrocomposites with enhanced mechanical properties. Printing dense and strong ceramic objects starts with understanding the rheological properties that define a printable ink. Boehmite suspensions were ideal to correlate geometrical criteria with rheology and surface tension effects to provide a universal figure of merit for printability. We take advantage of the flow behavior inside DIW nozzles to align alumina platelets during printing. This provides the printed object with increased fracture toughness in the desired direction, with the ability to deviate the fracture propagation perpendicularly to the printing direction. A single object can thus be precisely designed, alternating between dense, strong layers, and directionally tough, fracture deviating layers, to combine the complexity of the shape with the tailoring of mechanical behavior