In this dissertation, an experimental and numerical study of dense coarse solids-liquid flows has been performed. The experimental work mainly involved pressure drop measurements in a vertical flow loop. A limited number of measurements of solids velocity profiles were also obtained in the upward flow section of the flow loop. The numerical work involved simulations of coarse particles-in-water flows in vertical and horizontal pipes. The vertical flow simulations were performed using the commercial CFD software, ANSYS CFX-4.4, while ANSYS CFX-10 was used to simulate the flows in the horizontal pipes. The simulations were performed to investigate the applicability of current physically-based models to very dense coarse-particle flows.<p> In the experimental study, measurements of pressure drop and local solids velocity profiles were obtained. The experiments were conducted in a 53 mm diameter vertical flow loop using glass beads of 0.5 mm and 2.0 mm diameter solids for concentration up to 45%. The liquid phase was water. The measured pressure drop exhibited the expected dependence on bulk velocity and solids mean concentration. The wall shear stress was determined by subtracting the gravitational contribution from the measured pressure drop. For flow with the 0.5 mm particles at high bulk velocities, the values of the wall shear stress were essentially similar for each concentration in the upward flow sections but more variation, indicating the effect of concentration, was noted in the downward flow section. At lower bulk velocities, the wall shear stresses with the 0.5 mm glass beads-water flow showed a dependence on concentration in both test sections. This was attributed to an increase in the slip velocity. For the large particle (2.0 mm glass beads), similar observations were made but the effect of concentration was much less in the upward test section. In the downward test section, the wall shear stress for the flow of the 2.0 mm glass beads increased by almost a constant value for the bulk velocities investigated. The solids velocity profiles showed that the solids velocity gradient is large close to the wall. In addition, the solids velocity profiles indicated that the slip velocity increased at lower velocities due to increase in the bulk concentration in the upward flow section.<p> For the vertical flow simulations, different physical models based on the kinetic theory of granular flows were programmed and implemented in ANSYS CFX-4.4. These models, referred to as the kf-ef-ks-es, kf-ef-ks-es-Ts and kf-ef-ks-kfs models, were investigated by focusing on the closure laws for the solids-phase stress. The treatment of the granular temperature Ts depends on whether small- or large-scale fluctuating motion of the particles is considered. The models were implemented via user-Fortran routines. The predicted results were compared with available experimental results. The predicted solids-phase velocity profiles matched the measured data quite well close to the pipe wall but over-predicted it in the core region. The solids concentration, on the other hand, was significantly under-predicted for concentrations higher than 10%. Variations in the predictions of the phasic turbulent kinetic energy and the eddy viscosity were noted; the effect of solids concentration on them was mixed. A general conclusion drawn from the work is that a more accurate model is required for accurate and consistent prediction of coarse particle flows at high concentrations (less than 10%). In a related study, attention was given to wall boundary conditions again focusing on the effect of the solids-phase models at the wall. Comparison between numerical predictions, using some of the existing wall boundary condition models for the solids phase in particulate flows, with experimental results indicated that the physical understanding of the influence of the fluid and solids-phase on each other and their effect on frictional head loss is far from complete. The models investigated failed to reproduce the experimental results. At high solids concentration, it was apparent from the present study that the no-slip and free-slip wall boundary conditions are not appropriate for liquid-solid flows.<p> For the horizontal flow case, three-dimensional simulations were performed with a focus on the velocity and concentration distributions. Medium and coarse sand-in-water flows in three pipe diameters were considered to investigate the default solids stress models in ANSYS CFX-10. Simulations were performed for three cases by considering: 1) no additional solids-phase stress, i.e. no model for Ts; 2) a zero equation, and 3) an algebraic equilibrium model for the granular temperature. The model predictions were compared to experimental results. The effect of particle size, solids-phase concentration, and pipe diameter was explored using the algebraic equilibrium model. All the cases for the models considered exhibited the characteristic features of horizontal coarse particle slurry flows. The zero equation and the algebraic equilibrium model for the granular temperature produced similar results that were not significantly different from the prediction obtained when no solids-phase stress was considered. The comparison with experimental results was mixed. Locally, the measured solids-phase velocity distributions were over-predicted, whereas the solids concentration was reasonably reproduced in the core of all the pipes. The concentration at the bottom and top walls were over-, and under-predicted, respectively. This was attributed to the inappropriate phasic wall boundary condition models available.

Produktions- och optimeringspotentialen vid anaerob rötning av flytgödsel från nötkreatur granskades. Detta genom att, i laboratoriemiljö, undersöka förändringar i processtabilitet, gasproduktion och metanhalt vid tillsats av kycklinggödsel och pH-buffert med flytgödsel från nötkreatur som grundsubstrat. Tillsatsen av pH-buffert underlättade tillväxtfasen för mikroorganismerna, snabbare ökning i metanhalt och den totala metangasproduktionen ökade. Skillnaden var som störst under tillväxtfasen och avtog från stationärfas och framåt. Tillsats av kycklinggödsel har i detta fall inhiberat processen, möjligtvis på grund av ammoniakinhibering vid tillsats av det kväverika substratet som kycklinggödsel är. / Production potential and basis for optimization of anaerobic digestion with cattle manure was reviewed by examining process stability, gas production and methane content in a laboratory environment via addition of pH buffer and chicken manure with slurry from cattle manure as basic feedstock. Addition of pH buffer facilitated the growth of microorganisms by more rapid increase in methane content and greater quantities of produced methane gas. The effects were high during the growth stage but decreased, during and after, the stationary phase. Addition of chicken manure caused inhibition of the process, probably caused by ammonia inhibition from high nitrogen content in chicken manure.

<p>Produktions- och optimeringspotentialen vid anaerob rötning av flytgödsel från nötkreatur granskades. Detta genom att, i laboratoriemiljö, undersöka förändringar i processtabilitet, gasproduktion och metanhalt vid tillsats av kycklinggödsel och pH-buffert med flytgödsel från nötkreatur som grundsubstrat. Tillsatsen av pH-buffert underlättade tillväxtfasen för mikroorganismerna, snabbare ökning i metanhalt och den totala metangasproduktionen ökade. Skillnaden var som störst under tillväxtfasen och avtog från stationärfas och framåt. Tillsats av kycklinggödsel har i detta fall inhiberat processen, möjligtvis på grund av ammoniakinhibering vid tillsats av det kväverika substratet som kycklinggödsel är.</p> / <p>Production potential and basis for optimization of anaerobic digestion with cattle manure was reviewed by examining process stability, gas production and methane content in a laboratory environment via addition of pH buffer and chicken manure with slurry from cattle manure as basic feedstock. Addition of pH buffer facilitated the growth of microorganisms by more rapid increase in methane content and greater quantities of produced methane gas. The effects were high during the growth stage but decreased, during and after, the stationary phase. Addition of chicken manure caused inhibition of the process, probably caused by ammonia inhibition from high nitrogen content in chicken manure.</p>

No description available.

In der vorliegenden Arbeit wurden experimentelle Untersuchungen zu Material begrenzenden Einflüssen beim Multidrahtsägen von Silicium unter Verwendung gerader und strukturierter Drähte durchgeführt. Ziel dieser Arbeit war es, den Einfluss von dünnen und strukturierten Drähten auf den Drahtsägeprozess von Silicium und die erzeugten Waferqualitäten zu untersuchen. Zusätzlich galt es, Grenzen und Potentiale für den Einsatz dieser Drähte im Sägeprozess aufzuzeigen und ein Modell zu entwickeln, das den Materialabtrag in Silicium für strukturierte Drähte beschreibt. Die in dieser Arbeit verfolgten Lösungsansätze beinhalten im ersten Teil der Arbeit die Durchführung von Sägeexperimenten mit einer Eindrahtsäge. Es wurden dünne Drähte mit Durchmesser ≤ 100 µm und zwei unterschiedliche Siliciumcarbid (SiC) Korngrößenverteilungen untersucht. Zusätzlich wurden die Normalkräfte in Vorschubrichtung variiert. Im zweiten Teil der Arbeit werden Sägeexperimente mit einer Multidrahtsäge vorgestellt. Es wurden zwei unterschiedlich strukturierte Drähte mit variierten Drahtgeschwindigkeiten und Vorschüben im Vergleich zu geradem Draht untersucht. Der industrielle Einsatz dünner Drähte im Sägeprozess zur Reduzierung des Sägeverschnitts ist derzeit auf Durchmesser von 100 µm begrenzt. Die getesteten Drähte mit geringerem Durchmesser sind nicht wirtschaftlich einsetzbar, da sie zu geringe Standzeiten aufweisen und zu einer Slurryverarmung beitragen können. Es konnte eine Slurryverarmung des Schnittspalts in Silicium beobachtet werden, die um mehrere Zentimeter in den Schnittspalt ragt und dadurch den Drahtsägeprozess negativ beeinflusst, indem Sägeriefen entstehen. Die Verschleißuntersuchungen von Sägedrähten zeigen, dass eine lineare Abnahme der Drahtdurchmesserreduzierung in Abhängigkeit der akkumulierten Eingriffslänge in Silicium auftritt. Der Prozess der Durchmesserreduzierung wird maßgeblich durch die aufgebrachte Normalkraft, welche durch die Zugfestigkeit und Härte des Drahts beeinflusst wird, die Drahtgeschwindigkeit und die verwendete Korngrößenverteilung bestimmt. Es konnte durch Sägeversuche mit Drähten unterschiedlicher Hersteller gezeigt werden, dass das beobachtete Verschleißverhalten nicht einem Drahthersteller zuordenbar ist, sondern eine globalere Gültigkeit besitzt. Der industrielle Einsatz strukturierter Drähte wirkt sich positiv auf den Sägeprozess aus. Es konnten signifikant höhere Vorschübe bei ähnlichen Kräften im Vergleich zu geraden Drähten erreicht werden. Für einen Vorschub von 0,6 mm/min sind die Kraftwerte für strukturierten Draht A im Vergleich zu geradem Draht um 40% reduziert, für Draht B um 16%. Durch die Drahtstruktur wird ein größeres Slurryvolumen durch den Schnittspalt befördert, was zu einem homogeneren Materialabtrag entlang des Schnittspalts führt. Die erhöhten Vorschübe konnten sowohl für mono- wie auch für multikristallines Siliciummaterial erreicht werden. Zusätzlich wurden homogenere Waferdicken durch den Einsatz strukturierter Drähte beim Sägeprozess erzeugt. Auf Basis der Ergebnisse für strukturierte Drähte wurde ein theoretisches Modell für den Materialabtrag entwickelt, welches die in dieser Arbeit durchgeführten Experimente gut beschreibt. / In the present work experimental analyses were carried out to investigate the material limiting influences in the multi wire sawing process of silicon while using thin and structured wires. The purpose of the work was to investigate influences on the wire sawing process and the resulting wafer qualities caused by thin and structured wires. Additionally, the purpose was to define the limits and potentials of thin and structured wires in industrial wire sawing processes and to develop a model which describes the material removal in silicon for structured wires. Experiments with two different SiC particle size distributions in combination with wire diameters of ≤ 100 µm and varying normal forces in feed direction were carried out in the first part of this work with a single wire saw. Experiments with two differently structured wires and variation of the wire speed and feed rate are shown in the second part using a multi wire saw. The actual limit for industrial sawing applications to reduce kerf loss is reached for 100 µm thin wire diameters. The tested lower wire diameters are uneconomical due to shorter durability and to aggravate slurry depletion effects. Such a depletion effect of several centimeters length which is detrimental for the wire sawing process was observed at the end of a sawing channel. The results of the experiments showed that the steel wire diameter is reduced linearly with the accumulated sawn length of silicon. The material removal process of the steel wire is significantly influenced by the normal force in feed direction and the hardness of the wire. The experiments with wires of different suppliers showed no difference in the material removal process. Therefore the abrasive wear of wires has a more global validation. The results of the experiments using differently structured wires showed that significantly lower forces in feed direction occur for a given feed rate in comparison to straight wires. The forces are reduced up to 40% for structured wire A and up to 16% for wire B for a feed rate of 0,6 mm/min. A higher slurry volume is transported due to the structure of the wire which enables a more homogeneous material removal process along the cutting channel. Higher feed rates were reached for mono- and multi crystalline silicon material. Additionally, more homogeneous wafer thicknesses were cut using structured wires.

One of the most important boron minerals, colemanite is reacted with sulfuric acid to produce boric acid. During this reaction, gypsum (calcium sulfate dihydrate) is formed as a byproduct. In this study, the boric acid production was handled both in a batch and four continuously stirred slurry reactors (4-CFSSR&rsquo / s) in series system. In this reaction system there are at least three phases, one liquid and two solid phases (colemanite and gypsum). In a batch reactor all the phases have the same operating time (residence time), whereas in a continuous reactor all the phases may have different residence time distributions. The residence time of both the reactant and the product solids are very important because they affect the dissolution conversion of colemanite and the growth of gypsum crystals. The main aim of this study was to investigate the dynamic behavior of continuous flow stirred slurry reactors. By obtaining the residence time distribution of the solid and liquid components, the non-idealities in the reactors can be found. The experiments performed in the continuous flow stirred slurry reactors showed that the reactors to be used during the boric acid production experiments approached an ideal CSTR in the range of the stirring rate (500-750 rpm) studied. The steady state performance of the continuous flow stirred slurry reactors (CFSSR&rsquo / s) in series was also studied. During the studies, two colemanites having the same origin but different compositions and particle sizes were used. The boric acid production reaction consists of two simultaneous reactions, dissolution of colemanite and crystallization of gypsum. The dissolution of colemanite and the gypsum formation was followed from the boric acid and calcium ion concentrations, respectively. The effect of initial CaO/ SO42- molar ratio (1.00, 1.37 and 2.17) on the boric acid and calcium ion concentrations were searched. Also, at these initial molar ratios the colemanite feed rate was varied (5, 7.5, 10 and 15 g/min) to change the residence time of the slurry. Purity of the boric acid solution was examined in terms of the selected impurities, which were the magnesium and sulfate ion concentrations. The concentrations of them were compared at the initial molar ratios of 1.00 and 1.37 with varying colemanite feed rates. It was seen that at high initial CaO/ SO42- molar ratios the sulfate and magnesium ion concentrations decreased but the calcium ion concentration increased. The gypsum crystals formed in the reaction are in the shape of thin needles. These crystals, mixed with the insolubles coming from the mineral, are removed from the boric acid slurry by filtration. Filtration of gypsum crystals has an important role in boric acid production reaction because it affects the efficiency, purity and crystallization of boric acid. These crystals must grow to an appropriate size in the reactor. The growth process of gypsum crystals should be synchronized with the dissolution reaction. The effect of solid hold-up (0.04&ndash / 0.09), defined as the volume of solid to the total volume, on the residence time of gypsum crystals was investigated and the change of the residence time (17-60 min) on the growth of the gypsum was searched. The residence time at each reactor was kept constant in each experiment as the volumes of the reactors were equal. The growth of gypsum was examined by a laser diffraction particle size analyzer and the volume weighted mean diameters of the gypsum crystals were obtained. The views of the crystals were taken under a light microscope. It was observed that the high residence time had a positive effect on the growth of gypsum crystals. The crystals had volume weighted mean diameters of even 240 &micro / m. The gypsum crystal growth model was obtained by using the second order crystallization reaction rate equation. The residence time of the continuous reactors are used together with the gypsum growth model to simulate the continuous boric acid reactors with macrofluid and microfluid models. The selected residence times (20-240 min) were modeled for different number of CSTR&rsquo / s (1-8) and the PFR. The simulated models were, then verified with the experimental data. The experimentally found calcium ion concentrations checked with the concentrations found from the microfluid model. It was also calculated that the experimental data fitted the microfluid model with a deviation of 4-7%.

La sélection des matériaux utilisés dans les moteurs aéronautiques est un enjeu majeur pour assurer la sécurité des passagers, optimiser les performances de l’avion et maîtriser les coûts. Dans les parties les plus chaudes des moteurs (i.e. chambre de combustion et turbine), les pièces sont généralement constituées de superalliages à base nickel en raison de leurs excellentes propriétés mécaniques à haute température. Vulnérables aux phénomènes de corrosion et d’oxydation à haute température, les superalliages doivent la plupart du temps être revêtus afin de prolonger leur durée de vie (ingénierie de surface). La composition chimique et l’architecture des revêtements sont alors adaptées en fonction du régime de température et des phénomènes de dégradation rencontrés (i.e. corrosion à chaud, oxydation et/ou érosion). En vue de répondre aux nouvelles réglementations environnementales, de nouvelles voies de synthèse et de fonctionnalisation sont à l’étude comme alternatives aux procédés industriels actuels. Dans le cadre du projet Européen « PARTICOAT », le LaSIE a démontré la faisabilité d’élaborer des systèmes barrières thermiques complets (couche de diffusion + barrière thermique) en une seule étape à partir de barbotines (« slurries ») à base aqueuse contenant des microparticules d’Al. Dans cette étude, l’ajout de Cr comme dopant a été étudié. L’addition de Cr a permis d’abaisser l’activité de l’Al lors de l’étape d’aluminisation et de limiter les réactions exothermiques entre Al et substrat à base de nickel. L’optimisation des ratios entre Al et Cr a permis d’obtenir différentes microstructures de revêtement. Diverses architectures de dépôts ont également pu être testées grâce à la souplesse d’élaboration des revêtements par barbotines. L’influence de l’atmosphère (Ar, air) et celle des conditions de traitement thermique ont également été étudiées. Enfin, la durabilité des revêtements développés au cours de la thèse a été évaluée au cours d’essais de corrosion à chaud et d’oxydation. / The selection of materials is of utmost importance in gas turbine engines to ensure the security of the passengers, optimize the performances of the aircraft and be cost efficient. In the hottest region of the engines (i.e. combustion chamber and turbine), the components are usually made of nickel-based superalloys. These materials can resist to high mechanical loads at high temperature but are vulnerable to aggressive environments. Therefore, nickel-based superalloys are usually coated to increase their durability in the engine (surface engineering). The chemical composition and the coating architecture are carefully adjusted depending on the temperature regime and the mechanisms of degradation encountered (hot corrosion, oxidation and/or erosion). New synthesis routes and functionalization are currently developed as alternative solutions to industrial processes. As a promising alternative approach, different studies were carried out in the LaSIE laboratory under the European project “PARTICOAT” and confirmed the possibility to elaborate complete thermal barrier systems (diffusion coating + thermal barrier coating) from Al-containing water-based slurries. In this work, the role of Cr as a doping agent was investigated. The addition of Cr decreased the thermodynamic activity of Al upon aluminizing and limited the exothermic reactions usually reported between Al and nickel-based materials. Different architectures of coatings were obtained thanks to the flexibility and the adaptability of the slurry coating process. The gas composition (Ar, air) and the heat treatment conditions were also investigated. Finally, the high temperature resistance of the slurry coatings developed during this work was evaluated under hot corrosion and oxidation conditions.

Le phosphore est un élément crucial pour la vie sur Terre, de par son implication dans les processus bioénergétiques, le stockage et le traitement de l'information génétique. C'est également l'un des nutriments limitants en agriculture, aux côtés de l'azote et du potassium. Depuis la révolution verte au milieu du 20ième siècle, le monde agricole est dépendant des engrais phosphorés à bas coûts, fabriqués à partir d'une ressource fossile et nécessaires à l'amélioration des rendements des cultures à même de répondre aux besoins en nourriture d'une population en forte croissance. Cependant cette ressource, la roche phosphatée, s'épuise progressivement. De plus, son utilisation est très peu efficiente : moins de 20% du phosphore extrait se retrouve effectivement dans la nourriture consommée. L'une des raisons de cette faible efficience est la spécialisation de régions entières dans des productions agricoles spécifiques. Ainsi, les régions spécialisées dans les cultures à hauts rendements ont besoin de grandes quantités d'engrais minéraux alors que les régions d'élevage intensif ont des excédents de lisier sans terres agricoles suffisamment grandes et proches pour servir de zones d'épandage. L'épandage excessif de lisier en Bretagne est la cause première d'eutrophisation des cours d'eau. Le phosphore contenu dans le lisier porcin pourrait être recyclé sous forme de struvite (MgNH4PO4,6H2O), un engrais phosphaté à dissolution lente, très concentré et facilement transportable vers les régions de cultures végétales nécessitant une fertilisation phosphatée importante. Le phosphore du lisier porcin étant initialement présent sous une forme minérale solide, il est nécessaire de le dissoudre avant de le précipiter en struvite. Parce-que la dissolution par acidification chimique est trop chère et implique un mauvais bilan environnemental, le procédé développé lors de cette thèse utilise l'acidogénèse, un procédé biologique au cours duquel la matière organique est convertie en acides organiques en absence d'oxygène, acidifiant naturellement le lisier porcin. Différents déchets organiques ont été testés en tant que co-substrats dans du lisier porcin brut ou digéré, provoquant une fermentation de type lactique lorsque le co-substrat possédait une forte teneur en glucides facilement biodégradables, et une fermentation avec de nombreux acides organiques produits lorsque la teneur en glucides facilement biodégradables était faible. Il a pu être démontré que la fermentation lactique était le fait de bactéries appartenant au genre Lactobacillus, alors que divers Clostridiales dominaient lors des autres fermentations avec la production d'acétate, propionate, butyrate et valérate. Un réacteur en semi continu alimenté d'un mélange de lisier brut de petit pois et de carottes a permis la dissolution de 50% du phosphore total soit 750 mg-P/L. Après centrifugation, 3.4 g d'hydroxyde de magnésium par litre de surnageant a été ajouté afin d'élever le pH à 8 et ainsi précipiter la struvite. 99% du phosphore dissous a alors été abattu. Le solide obtenu contenait 70% de struvite, un léger excès de phosphore et de magnésium, ainsi que de la matière organique. L'acidogénèse permet l'hydrolyse de la matière organique complexe et la formation d'acides organiques. De ce fait, ce procédé de recyclage du phosphore contenu dans le lisier porcin pourrait être implémenté dans les nombreuses unités de méthanisation présentes en Bretagne et qui traitent des effluents animaux ainsi que des déchets organiques d'origine agricole, industrielle et municipale. La struvite obtenue pourrait être vendue dans les régions ayant besoin de fertilisation phosphatée alors que la matière organique du digestat pourrait être maintenue en Bretagne. Un tel procédé réduirait significativement l'eutrophisation due à l'épandage excessif du lisier tout en diminuant les besoins en fertilisants minéraux fossiles grâce à une source alternative aux performances fertilisantes équivalentes. / Phosphorus is a crucial nutrient for life, implicated in cellular bioenergetics as well as storage and processing of genetic information. It is also one of the limiting nutrients in agriculture with nitrogen and potassium. Since the green revolution in the middle of the 20th century, agriculture has relied on increasing amounts of cheap mineral P-fertilizers produced from a fossil resource to improve crop yields and sustain population growth. However, the resource is depleting and its use efficiency is poor: less than 20% of extracted P is actually consumed in food. One of the reasons for this is the specialization of entire regions into on type of agricultural production or another. Thus, regions focusing on high yield crops require large applications of fossil mineral fertilizers while intensive livestock breeding areas cannot find an output for their P-rich manure due to the distance with crop fields in need of P fertilization. Over application of animal manure in Brittany is the main cause of eutrophication in the region. Phosphorus could be recovered from pig manure as struvite, a concentrated, slow-release mineral fertilizer easily transported to crop-oriented regions in need of P fertilization. P in pig slurry is mostly under a solid inorganic form, requiring dissolution prior to precipitation as struvite. Because chemical acidification is too expensive and harmful to the environment, the process developed in this PhD relied on acidogenesis, a biological process in which organic matter is converted to organic acids under anaerobic conditions, thus naturally acidifying the swine slurry. Various organic wastes were tested as organic co-substrates on raw and digested pig slurry, leading to lactic acid fermentation when the co-substrate had a high content in easily biodegradable carbohydrates and a fermentation with diverse organic acids produced at low content in easily biodegradable carbohydrates. Lactobacillus was the genus responsible for lactic acid fermentation and various Clostridiales dominated otherwise, producing acetate, propionate, butyrate and valerate. A reactor was operated with semi-continuous feeding of raw swine slurry and carrot/pea, leading to the dissolution of 50% total-phosphorus or 750 mg-P/L. After centrifugation, struvite was precipitated in the supernatant by adding magnesium hydroxide to increase the pH to 8. 99% of dissolved P precipitated. The solid recovered contained 70% of struvite, a slight excess of P and Mg as well as organic matter. Because hydrolysis of organic matter and production of organic acids occurs during acidogenesis, the process could be implemented in the many anaerobic digestion units installed in Brittany treating animal manure and agricultural, industrial and municipal organic waste. The struvite recovered could be sold to regions in need while the digestate impoverished in P and rich in organic matter could be kept locally. Such process would reduce eutrophication due to over application of pig manure and also reduce the reliance on fossil P fertilizer by offering an alternative source with equivalent fertilizing performances.

Revestimentos de argamassa, embora largamente utilizados, ainda e cada vez mais, geram interesse, tanto por parte do meio acadêmico quanto pelas empresas construtoras. Este fato se deve pela, sempre presente, necessidade de melhoria da tecnologia, visando, principalmente, maior conhecimento dos elementos constituintes do sistema de revestimento e, também, devido ao grande número de manifestações patológicas ocorridas neste tipo de revestimento, em especial o descolamento. Neste contexto, este trabalho teve como objetivo avaliar a influência da camada de preparo da base, o chapisco, quanto a sua forma de aplicação e composição, na resistência de aderência de revestimentos de argamassa aplicados sobre substrato de concreto de baixa porosidade. Para isso, foram moldadas placas de concreto com dimensões de (35x25x5)cm e resistência, aos 28 dias de, aproximadamente, 30MPa, que receberam argamassa de chapisco e posteriormente foram revestidos com argamassa de revestimento. Afim de isolar o efeito do chapisco, nesta pesquisa, o substrato de concreto e a argamassa de revestimento foram mantidos fixos, sendo, então, o chapisco o único elemento variável do sistema. Em relação ao chapisco variou-se sua forma de aplicação (manual e mecanizada), sua composição, onde foi analisada a mudança de granulometria (uma contínua e bem graduada e uma descontínua e mal graduada), a introdução de sílica ativa e de aditivo retentor de água. O substrato de concreto teve cura submersa em água e cal, durante 28 dias, e a argamassa de chapisco e a argamassa de revestimento foram curadas à temperatura de 23±2°C e umidade relativa do ar de 60±10% por 3 e 28 dias, respectivamente. Após 59 dias do início da moldagem, o conjunto “substrato+chapisco+argamassa de revestimento” foi submetido aos ensaios de resistência de aderência à tração e ao cisalhamento. A partir dos resultados obtidos é possível afirmar que quanto a forma de aplicação, a aplicação mecanizada utilizada, de recipiente acoplado, a canequinha, não gerou resultados satisfatórios, uma vez que para as características da argamassa de chapisco utilizada, sendo está de alta relação água/cimento, a aplicação resultou em uma camada desuniforme, mostrando que aplicação manual, mesmo rústica, para chapiscos ainda é a melhor escolha. Quanto a composição do chapisco, os melhores resultados obtidos para a resistência de aderência foram obtidos com chapiscos confeccionados com areia de granulometria contínua e bem graduada. A introdução da sílica no chapisco mostrou uma tendência de melhora para a resistência de aderência à tração e uma melhoria significativa, comprovada por análise estatística, na resistência ao cisalhamento e a introdução de aditivo retentor de água, promoveu uma melhora significativa na resistência de aderência à tração e uma tendência de melhora na resistência de aderência ao cisalhamento. / Although widely used, mortar wall coverings still generate interest by both academia and construction companies. This fact is caused by the ever-present need for improved technology, having as principal objective the more refined knowledge about the constituents of the coating system and also the large number of pathologies occurring in this type of siding, in particular its detachment. In this context, this study had the objective of analizing the influence of the application form and composition of slurry mortar on the bonding strength of coatings applied over concrete substrate. For this, concrete plates of 35x25x5cm were molded, with compressive strength at 28 days of, approximately, 30MPa. After that, the plates were coated with coating mortar and slurry mortar. In order to isolate the effect of slurry mortar in this research, the concrete substrate and mortar coating were kept fixed, and the slurry mortar is the only variable element of the system. It was varied the form of application (manual and mechanized), the composition, where were analyzed the change of sand granulometry (a continuous and well-graded, a discontinuous and bad-graded), the introduction of silica and water retaining additive. The concrete substrate was curing in water and lime for 28 days, and mortar coating and slurry mortar were cured at 23±2°C and relative humidity of 60±10%, for 3 and 28 days, respectively. After 59 days from the start of the molding of concrete plates, the "substrate+slurry mortar+mortar coating" samples were subjected to tests of tensile bond strength and shear. From the results obtained, were is can be said that the mechanized application form used did not generate satisfactory results, possibly due to high water/cement ratio of the slurry mortar used, resulting in an uneven layer, showing that manual application, even rustic, for slurry mortar is still the best choice. For the composition of slurry mortar, the best results for bond strength were obtained with slurry mortars made with well-graded sand with a continuous granulometric. The introduction of silica in the slurry mortar showed a tendency to increase the tensile bond strength and a significant increase, proven by statistical analysis, in shear bond strength. The introduction of water retaining additive, a significant improvement in tensile bond strength and a tendency to increase the shear bond strength.

A temática ambiental começou a ser discutida de forma mais ampla há cerca de 50 anos. Na última década, porém, este debate se intensificou e se estendeu por todos os segmentos sociais e setores produtivos, em maior ou menor intensidade. Um dos setores que vem se deparando fortemente com essa questão é produção de carne suína. A atividade é de fundamental importância para as economias brasileira e gaúcha, destacando-se o grande volume negociado com mercados internacionais. Por outro lado, ela exerce grande pressão ambiental, dado seu alto potencial poluidor, o que se agravou devido ao aumento da produção e à intensificação da atividade ocorrida nos últimos anos. Outra característica marcante da atual cadeia produtiva de carne suína, especialmente no sul do país, é o sistema de integração entre indústria e produtor rural, onde a coordenação da cadeia fica por conta da empresa integradora, o que tem contribuído para o aumento da produtividade. Dentro desse contexto é que se desenvolveu este trabalho, cujo objetivo é analisar se as ações adotadas por produtores de suínos (terminação), que atuam em sistema de integração com a Eleva Alimentos, minimizam os impactos ambientais decorrentes da suinocultura. O estudo foi realizado em duas etapas. A primeira, de caráter exploratório, teve a finalidade de obter melhor entendimento sobre o assunto. A segunda etapa, de caráter descritivo, foi conduzida de acordo com a estratégia de estudo de caso. Foram realizadas observações diretas em 53 granjas de suínos em terminação, todas de produtores integrados à Eleva Alimentos, destacada agroindústria do mercado de carnes do Brasil. Foi também feita uma entrevista com o responsável pela área de Meio Ambiente, a fim de identificar o posicionamento da empresa frente aos desafios da sustentabilidade. Os resultados mostraram que a empresa vem estimulando seus integrados a adotar algumas inovações, principalmente no sentido de racionalização dos recursos nas granjas. Entretanto, muitos investimentos ainda podem ser feitos, especialmente para tratamento e disposição adequada dos dejetos. Foi possível concluir também que existem caminhos para que a atividade seja, de fato, mais sustentável. Para isso, muitas ações ainda precisam ser realizadas, tanto pelo setor público quanto privado. / The debate about environmental questions has begun, in a broader way, about 50 years ago. However, during the last decade, this discussion became intensive in all the social classes and productive sectors, in a bigger or smaller intensity. One of the sectors that have been strongly put on pressure is the pork production. The activity is extremely important for both brazilian and south brazilian economies, where the more than 50% of the production is trade with international markets. On the other hand, the activity has high polluting potential, what got worse because of the growth and the intensiveness of the production occurred the last years. Another characteristic of the modern swine production, especially in South Brazil, is the integration systems established between rural producers and industries. In this kind of relationship chain coordination is s responsibility of the industry. This factor contributed still more for the productivity growth. So, the present study aims for analyze if techniques adopted by swine producers (termination) that operate in a integration system with “Eleva Alimentos” minimize the environmental impacts caused by swine production. The study has two parts. The first, which goal was get a better understanding about the subject, has exploratory character. The second one has descriptive character and has been conducted using the case study strategy. Direct observations have been done in 53 farms of “Eleva Alimentos” integrated producers. An interview with the company environmental manager also has been done to identify the behavior of the organization facing the challenges of sustainability. Rresults show that the company stimulates the producers to adopt some innovations, specially to rationalize natural resources. Nevertheless lots of investments must be done, mainly to deal with slurry. It was possible as well to assure there are ways to make the swine production a more sustainable activity actually. However, a lot of new practices must be adopted, as much public policies as in the private sector.