Softening deformation of iron ore in the form of sinter, pellet, and lump ore in the cohesive zone of an ironmaking blast furnace is an important phenomenon that has a significant effect on gas permeability and consequently blast furnace production efficiency. The macroscopic softening deformation behavior of the bed and the microscopic deformation behavior of the individual particles in the packed bed are investigated in this study using wax balls to simulate the fused layer behavior of the cohesive zone. The effects of softening temperature, load pressure, and bed composition (mono - single melting particles, including pure or blend particles vs binary ??? two different melting point particles) on softening deformation are examined. The principal findings of this study are: 1. At low softening temperatures, an increase in load pressure increases the deformation rate almost linearly. 2. At higher softening temperatures, an increase in load pressure dramatically increases the deformation rate, and after a certain time there is no more significant change in deformation rate. 3. The bed deformation rate of a mono bed is much greater than that of a binary one. 4. In a binary system, the softening deformation rate increases almost proportionally with the increase in the amount of lower melting point wax balls. 5. In a mono system with blend particles, the content of the lower melting point material has a more significant effect on overall bed deformation than the higher melting point one. 6. The macro softening deformation of the bed behaves the theory of creep deformation. 7. A mathematical model for predicting bed porosity change due to softening deformation based on creep deformation theory has been developed. 8. Increase in load pressure also reduces the peak contact face number of the distribution curves, and this is more prominent with higher porosity values. 9. The contribution of contact face number to bed porosity reduction is more pronounced in a mono system than in a binary system. 10. The porosity reduction in a binary bed is more due to the contact face area increase, presumably of the lower melting point particles. 11. The mono system has a single peak contact face number distribution pattern while the binary system exhibits a bimodal distribution pattern once the higher melting point material starts to deform. 12. In a binary system, an increase in deformation condition severity tends to reduce the contact face number of the higher melting point material without having to increase the contact face number of the lower melting point material accordingly to achieve a given porosity.

The influence of particle shape of coating pigments on theirpacking ability and on the flow properties of coating colourshas been investigated. The particle shapes considered werespherical, flaky and acicular (needle-shaped). In the case ofsuspensions containing monodisperse spherical polystyreneparticles, a concentration gradient appeared in the filter cakeforming during filtration under static conditions. Such agradient, monitoredby non-destructive magnetic resonanceimaging (MRI), is not accounted for in the traditionalfiltration theory used in coating technology. Good agreementwas found between a literature model describing filtrationthrough a compressible filter cake and the concentrationgradients measured by MRI. According to this model, the scaledconcentration gradient was the same at all times. For flaky (mainly kaolin) and acicular (aragonite)particles, a rapid method was evaluated to estimate a shapefactor of the pigment particle. Generalised mathematical modelsof oblate and prolate spheroids were applied to reduce thethree geometrical dimensions of the particle to two, the majoraxis and the minor axis. The shape factor, which is mass-based,was derived from a comparison between the results obtained bytwo different size-assessment instruments, viz. the Sedigraphand an instrument using light scattering. This yields a shapefactor distribution as a function of equivalent sphericalparticle size, but the results are uncertain for small particlediameters, below 0.2 µm. Good agreement was obtainedbetween the shape factor and a mass-based aspect ratio obtainedby image analysis, but the rapid method is generally moreaccurate for flaky than for acicular particles. Results obtained by capillary viscometry showed that therewas a relationship between the viscosity at high shear rates(&gt;105s-1) and the shape factor, but that it was notsufficient to use the median value of the shape factor toachieve proper information. A more complete evaluation requiresknowledge of the shape factor distribution, which is also givenin part by the method mentioned above. However, a large medianshape factor was related to a high high-shear viscosity.Non-Newtonian entrance pressure losses were sometimessignificant in capillary viscometry, indicating that it wasinappropriate to measure the shear viscosity with only onecapillary. Such effects were however relatively much morepronounced in slit die viscometry, especially in the case ofacicular particles, where the aspect ratio was a crucialparameter. The influence of the shape factor of kaolinparticles on the non-Newtonian entrance pressure losses over aslit die was surprisingly small. The high-shear viscosity ofcoating suspensions based on different pigments correlated withthe median pore size of the corresponding coating layer ratherthan with the porosity. <b>Keywords</b>: Aspect ratio, capillary viscometry, coatingcolour, filtration, particle packing, pigment, pore structure,rheology, shape factor, slit die viscometry, spheroid.

<p>The influence of particle shape of coating pigments on theirpacking ability and on the flow properties of coating colourshas been investigated. The particle shapes considered werespherical, flaky and acicular (needle-shaped). In the case ofsuspensions containing monodisperse spherical polystyreneparticles, a concentration gradient appeared in the filter cakeforming during filtration under static conditions. Such agradient, monitoredby non-destructive magnetic resonanceimaging (MRI), is not accounted for in the traditionalfiltration theory used in coating technology. Good agreementwas found between a literature model describing filtrationthrough a compressible filter cake and the concentrationgradients measured by MRI. According to this model, the scaledconcentration gradient was the same at all times.</p><p>For flaky (mainly kaolin) and acicular (aragonite)particles, a rapid method was evaluated to estimate a shapefactor of the pigment particle. Generalised mathematical modelsof oblate and prolate spheroids were applied to reduce thethree geometrical dimensions of the particle to two, the majoraxis and the minor axis. The shape factor, which is mass-based,was derived from a comparison between the results obtained bytwo different size-assessment instruments, viz. the Sedigraphand an instrument using light scattering. This yields a shapefactor distribution as a function of equivalent sphericalparticle size, but the results are uncertain for small particlediameters, below 0.2 µm. Good agreement was obtainedbetween the shape factor and a mass-based aspect ratio obtainedby image analysis, but the rapid method is generally moreaccurate for flaky than for acicular particles.</p><p>Results obtained by capillary viscometry showed that therewas a relationship between the viscosity at high shear rates(>10⁵s^-1) and the shape factor, but that it was notsufficient to use the median value of the shape factor toachieve proper information. A more complete evaluation requiresknowledge of the shape factor distribution, which is also givenin part by the method mentioned above. However, a large medianshape factor was related to a high high-shear viscosity.Non-Newtonian entrance pressure losses were sometimessignificant in capillary viscometry, indicating that it wasinappropriate to measure the shear viscosity with only onecapillary. Such effects were however relatively much morepronounced in slit die viscometry, especially in the case ofacicular particles, where the aspect ratio was a crucialparameter. The influence of the shape factor of kaolinparticles on the non-Newtonian entrance pressure losses over aslit die was surprisingly small. The high-shear viscosity ofcoating suspensions based on different pigments correlated withthe median pore size of the corresponding coating layer ratherthan with the porosity.</p><p><b>Keywords</b>: Aspect ratio, capillary viscometry, coatingcolour, filtration, particle packing, pigment, pore structure,rheology, shape factor, slit die viscometry, spheroid.</p>

Softening deformation of iron ore in the form of sinter, pellet, and lump ore in the cohesive zone of an ironmaking blast furnace is an important phenomenon that has a significant effect on gas permeability and consequently blast furnace production efficiency. The macroscopic softening deformation behavior of the bed and the microscopic deformation behavior of the individual particles in the packed bed are investigated in this study using wax balls to simulate the fused layer behavior of the cohesive zone. The effects of softening temperature, load pressure, and bed composition (mono - single melting particles, including pure or blend particles vs binary ??? two different melting point particles) on softening deformation are examined. The principal findings of this study are: 1. At low softening temperatures, an increase in load pressure increases the deformation rate almost linearly. 2. At higher softening temperatures, an increase in load pressure dramatically increases the deformation rate, and after a certain time there is no more significant change in deformation rate. 3. The bed deformation rate of a mono bed is much greater than that of a binary one. 4. In a binary system, the softening deformation rate increases almost proportionally with the increase in the amount of lower melting point wax balls. 5. In a mono system with blend particles, the content of the lower melting point material has a more significant effect on overall bed deformation than the higher melting point one. 6. The macro softening deformation of the bed behaves the theory of creep deformation. 7. A mathematical model for predicting bed porosity change due to softening deformation based on creep deformation theory has been developed. 8. Increase in load pressure also reduces the peak contact face number of the distribution curves, and this is more prominent with higher porosity values. 9. The contribution of contact face number to bed porosity reduction is more pronounced in a mono system than in a binary system. 10. The porosity reduction in a binary bed is more due to the contact face area increase, presumably of the lower melting point particles. 11. The mono system has a single peak contact face number distribution pattern while the binary system exhibits a bimodal distribution pattern once the higher melting point material starts to deform. 12. In a binary system, an increase in deformation condition severity tends to reduce the contact face number of the higher melting point material without having to increase the contact face number of the lower melting point material accordingly to achieve a given porosity.

O concreto é o material de construção mais utilizado e nos últimos anos, estudos têm sido desenvolvidos em busca de materiais com desempenho mecânico e durabilidade superiores, com redução do consumo de cimento. Nesse contexto, tem-se o estudo do empacotamento de partículas associado à dosagem de concretos, produzindo estruturas mais densas e compactas, com melhor consumo energético. Basicamente, o empacotamento de partículas consiste em otimizar composições empregando partículas de diferentes tamanhos, promovendo o refinamento dos poros e, eventualmente, reduzindo o volume de pasta necessário para envolver as partículas da mistura. O empacotamento de partículas permite uma evolução nas propriedades do concreto, além de promover um benefício ambiental por meio da utilização de resíduos e subprodutos industriais, redução de emissões poluentes e economia de energia, mediante a redução do consumo de cimento na mistura. Diante disto, o presente trabalho tem por objetivo aplicar o conceito de empacotamento de partículas na otimização de traços de concretos convencionais e de alta resistência. Para isso, realizou-se inicialmente um estudo de dosagem, sendo determinados traços de referência pela metodologia tradicional. Aplicando o modelo de empacotamento de Alfred, foi determinado o coeficiente de distribuição de cada mistura e, então, os traços foram otimizados mantendo-se o mesmo coeficiente, sendo comparadas as propriedades dos concretos otimizados com propriedades das misturas de referência. Verificou-se que nas misturas otimizadas não foi possível obter a trabalhabilidade desejada, sendo necessário ajustar o teor de aditivo a fim de manter a mesma consistência. No estado endurecido, os concretos otimizados apresentaram desempenho físico e mecânico superior aos concretos dosados pela metodologia tradicional. Os ensaios não destrutivos apenas permitiram verificar a evolução com o tempo do módulo de elasticidade dinâmico e da porosidade, visto que a mudança da composição das misturas influencia diretamente no módulo e na velocidade de propagação da onda no material. Por fim, foi possível verificar a sustentabilidade dos concretos otimizados, que apresentaram índice de intensidade de ligante mais eficiente que os concretos de referência, reforçando a importância desse trabalho. / Concrete is the most widely used construction material and in recent years, studies have been developed in search of materials with higher mechanical performance and durability, with reduced cement consumption. In this sense, the study of particle packing associated to the mix design of concrete, producing denser and more compact structures, with better energy consumption, is being studied. Basically, particle packing consists of optimizing compositions employing particles of different sizes, promoting pore refinement and possibly reducing the volume of cement paste required to involve the particles in the mix. The particle packing allows an evolution in concrete\'s properties, besides promoting an environmental benefit using industrial wates and by-products, reduction of polluting emissions and energy saving, by reducing the consumption of cement in the mix. In this view, the present research aims to apply the concept of particle packing in the optimization of conventional and high strength concretes mix design. For this, a mix design study was carried out initially, being determined reference concretes mix design by the traditional methodology. Applying the Alfred\'s packing model, the distribution coefficient of each mix was determined and concretes mix design were optimized by keeping the same coefficient, and the properties of the optimized concretes were compared with the properties of the reference mixtures. It was verified that, in optimized mixtures, it was not possible to get the desired workability and it was required to fit the chemical admixture content in order to keep the same consistency. In the hardened state, the optimized concrete showed physical and mechanical performance higher than concretes designed by the traditional methodology. The non-destructive tests only allowed to verify the evolution of the dynamic elasticity modulus and the porosity with time, since the change of the composition of the mixtures directly influences the modulus and the wave propagation speed in the material. Finally, it was possible to verify the sustainability of the optimized concretes, which presented a binder intensity index more efficient than the reference concrete, reinforcing the importance of this research.

Neste trabalho se buscou criar uma base tecnológica para síntese digital e visualização virtual de microestruturas de materiais policristalinos monofásicos, visando disponibilizar software e metodologias de baixo custo aos pesquisadores da área ou de áreas correlatas. Para isso foram levantados e testados métodos, sistemas, bibliotecas e algoritmos computacionais pertinentes ao problema em questão. A técnica de síntese escolhida adotou uma simulação física de empacotamento de partículas seguida por tesselação espacial baseada no diagrama Voronoi. Para testar a abordagem uma amostra de um material real foi reconstituída digitalmente. O modelo reproduziu com grande precisão a distribuição de tamanhos de grão, o número de faces por grão e o número de vizinhos imediatos da referência. Na frente de visualização virtual buscou-se definir um modelo capaz de lidar com grandes quantidades de dados e baseado em princípios cognitivos sólidos, que permitisse maior extração de conhecimento de modelos microestruturais. A técnica de visualização em múltiplas escalas foi considerada a mais apropriada aos modelos cujos objetos e detalhes abrangem diversas escalas espaciais, permitindo ao computador lidar com vastas quantidades de dados ao alternar entre qualidade e quantidade no processo de geração de imagens. Técnicas de visualização tradicionais também foram testadas e a técnica de corte se mostrou fundamental, principalmente para a exploração direta do interior do modelo, mas também para a extração de dados voltados a análise microestrutural estereológica. / The main goal of this work is to create a technological foundation for digital synthesis and virtual visualization of single-phase polycrystalline materials microstrutures, aiming to offer low cost software and methodologies to materials science researchers and alike. Several methods, applications, libraries and algorithms were tested and the most appropriate were selected for further exploration. The chosen microstructural synthesis technique uses newtonian particle packing simulation, followed by a Voronoi-based tesselation. This simple approach were put to test using a real material sample. The sample were digitally built and meaningfull parameters like grain size distribution, edges per face and mean number of neighbours were replicated with acceptable precision. Regarding visualization, the most relevant issue was the specification of a computationally scalable method based on proven cognitive principles, capable to deal with a huge amount of information and to support efficient knowledge extraction from microstructural models. The multiscale approach has proved to be the most suited for models that spans several scales in space, allowing computers to store and display large quantities of data and to manage the tradeoff between quality and quantity in the rendering process. Traditional visualization techniques were tested as well and section visualization has proved to be paramount for internal model visualization, as it is for stereological microstructural analysis.

Strain localization, the phenomenon of large shear deformation within thin zones of intensive shearing, commonly occurs both in-situ and in the laboratory tests on soils specimens. The intriguing mechanism of strain localization and how it will affect the general behavior of soil specimens have been investigated by many researchers. Some of the efforts have focused on finding the links between material properties (void space, fabric tensor) and mechanical behavior (stress, strain, volumetric strain). In the last ten years, several extensive studies have been conducted at Georgia Tech to investigate the mechanism of strain localization and link the microstructural properties with the engineering behavior of Ottawa sands. These studies have included 2-D and 3-D characterization of soil microstructures under either triaxial or biaxial shearing conditions. To extend and complement these previous studies, the current study focuses particularly on 3-D reconstruction, analysis and modeling of specimens of Ottawa sand subject to triaxial or biaxial loading. The 3-D microstructure of biaxial specimens was reconstructed using an optical microscopy based montage and serial sectioning technique. Based on the reconstructed 3-D digital volumes, a series of 2-D and 3-D characterizations and analyses, including local void ratio distributions, extent of shear bands, influence of soil fabrics and packing signature effects, were conducted. In addition to the image analysis based reconstruction and characterization, the 3-D discrete element method (DEM) code, PFC3D, was used to explore both biaxial and triaxial shear related soil behaviors at the global and particulate scale. Void ratio distributions, coordination numbers, particle rotations and displacements, contact normal distributions and normal contact forces as well as global stress and strain responses were investigated and analyzed to help understand the mechanism of strain localization. The microstructures of the numerical specimens were also characterized in the same way as the physical specimens and similar strain localization patterns were identified. Combined with the previous related studies, the current study provides new insights into the strain localization phenomenon of Ottawa sands subject to triaxial and biaxial loading. In addition, the reconstructed digital specimens were subject to a series of dissection studies which revealed exciting new insights into "microstructure signatures" which exist at both meso and micro scales within the real and simulated specimens.

The importance of studying the behaviour and properties of concrete can be highlighted by considering the fact that concrete is the most used man-made material in the world. The very first step in making concrete is its mix design and deciding the type and amount of constitutes used in the production of concrete which should fulfil the requirements of the final product. Mix design models are commonly used for the purpose of proportioning concrete ingredients while anticipating the properties of the final product.  The current document deals with the commonly used principals in mix design models namely particle packing theory and excess water/paste layer theories. The conducted studies includes an investigation on accuracy of particle packing models (Toufar, 4C, CPM) and also tries to address the issue with measurement of specific surface area of particles as an essential input to water/paste layer theories.  It has been observed that the particle packing models can predict the packing density with acceptable margin. However, it should be mentioned that the particle packing models by themselves are not mix design models but should be rather used as a part of a mix design. In addition, it was found that the accuracy of calculating the specific surface area of particles based on their size distribution curve can be further improved by assuming angular platonic solids as uniform shape of aggregate instead of traditional approach of assuming spheres for aggregates’ shape.

Neste trabalho se buscou criar uma base tecnológica para síntese digital e visualização virtual de microestruturas de materiais policristalinos monofásicos, visando disponibilizar software e metodologias de baixo custo aos pesquisadores da área ou de áreas correlatas. Para isso foram levantados e testados métodos, sistemas, bibliotecas e algoritmos computacionais pertinentes ao problema em questão. A técnica de síntese escolhida adotou uma simulação física de empacotamento de partículas seguida por tesselação espacial baseada no diagrama Voronoi. Para testar a abordagem uma amostra de um material real foi reconstituída digitalmente. O modelo reproduziu com grande precisão a distribuição de tamanhos de grão, o número de faces por grão e o número de vizinhos imediatos da referência. Na frente de visualização virtual buscou-se definir um modelo capaz de lidar com grandes quantidades de dados e baseado em princípios cognitivos sólidos, que permitisse maior extração de conhecimento de modelos microestruturais. A técnica de visualização em múltiplas escalas foi considerada a mais apropriada aos modelos cujos objetos e detalhes abrangem diversas escalas espaciais, permitindo ao computador lidar com vastas quantidades de dados ao alternar entre qualidade e quantidade no processo de geração de imagens. Técnicas de visualização tradicionais também foram testadas e a técnica de corte se mostrou fundamental, principalmente para a exploração direta do interior do modelo, mas também para a extração de dados voltados a análise microestrutural estereológica. / The main goal of this work is to create a technological foundation for digital synthesis and virtual visualization of single-phase polycrystalline materials microstrutures, aiming to offer low cost software and methodologies to materials science researchers and alike. Several methods, applications, libraries and algorithms were tested and the most appropriate were selected for further exploration. The chosen microstructural synthesis technique uses newtonian particle packing simulation, followed by a Voronoi-based tesselation. This simple approach were put to test using a real material sample. The sample were digitally built and meaningfull parameters like grain size distribution, edges per face and mean number of neighbours were replicated with acceptable precision. Regarding visualization, the most relevant issue was the specification of a computationally scalable method based on proven cognitive principles, capable to deal with a huge amount of information and to support efficient knowledge extraction from microstructural models. The multiscale approach has proved to be the most suited for models that spans several scales in space, allowing computers to store and display large quantities of data and to manage the tradeoff between quality and quantity in the rendering process. Traditional visualization techniques were tested as well and section visualization has proved to be paramount for internal model visualization, as it is for stereological microstructural analysis.

O uso do cimento nas dosagens de materiais cimentícios sempre foi uma preocupação na construção civil por questões de custo. Com o surgimento das discussões sobre sustentabilidade, as preocupações passam a ocorrer também com relação aos impactos ambientais gerados em sua produção, principalmente as emissões de 2. Apesar de grandes esforços industriais para a redução destas emissões, as estratégias adotadas não têm sido eficientes para atingir patamares de redução suficientes. Neste cenário, a substituição de parte do cimento por finos inertes, conhecidos como fíleres, provenientes de matérias-primas abundantes e baratas, podem proporcionar ganhos econômicos e ambientais, já que estes materiais apresentam menor impacto de produção por não necessitarem serem submetidos a processos térmicos. Além disso, a adição de fíleres na matriz cimentícia pode contribuir para o aumento da eficiência dos ligantes, pois possibilita o melhor empacotamento de partículas, com diminuição de vazios, que contribui para a redução do teor de água na mistura o que significa possibilidade de desempenho mecânico satisfatório com menos clínquer. O presente trabalho teve como objetivo avaliar o potencial de substituição de parte do cimento por fíleres de quartzo em pastas cimentícias, visando reduzir o consumo de clínquer. Foram avaliados os comportamentos reológicos e mecânicos de dosagens de pastas e argamassas de clínquer-fíler, verificando o desempenho dos materiais produzidos. Para estudo das pastas foram feitas caracterizações das matérias-primas, ensaios de reologia para determinar o teor ótimo de dispersante, e ensaios de resistência à compressão para teores de água fixos, variando os fíleres com três composições granulométricas distintas. Para avaliação das argamassas, foram realizados ensaios de resistência à compressão e determinados os módulos de elasticidade. A análise dos resultados foi feita por meio de comparativos entre os comportamentos reológicos e mecânicos das misturas, além do cálculo do indicador de eficiência Binder Intensity (BI), que é uma relação entre o consumo de cimento e a resistência mecânica. Os materiais produzidos com fíleres atingiram comportamentos reológicos próximos ao material convencional, mas com teores de água reduzidos, contribuindo para o alcance de boas resistências mecânicas com menor consumo de cimento, e módulos de elasticidade equivalentes. Os resultados obtidos nos II experimentos realizados comprovam os ganhos de eficiência alcançados com a adição de fíleres de quartzo em materiais cimentícios e a viabilidade para aplicação na construção civil. / The use of cement in cementitious materials dosages has always been a concern in civil construction for costs issues. With the emergence of sustainability discussions, also arise concerns about environmental impacts generated in its production, mainly 2 emissions. Although the large industrials efforts to reduce these emissions, the strategies adopted havent been efficient to achieve sufficient reduction levels. In this scenario, partial replacement of cement by inert fines, denominated fillers, from abundant and cheap raw materials, can provide environmental and economic gains, since these materials produce lower environmental impact as they dont need to be submitted to thermal processes. Beyond that, the fillers addition in cementitious matrix can contribute to the increase of binders efficiency, as it allows the particles packaging, with the decreasing of voids, which contributes to the reduction of water content in the mixture which means possibility of satisfactory mechanical performance with less clinker content. Thus, this study aims to evaluate the potential of cement replacement by quartz fíller in cement mixtures, in order to reduce clinkers consumption. Were evaluated the rheological and mechanical behavior of pastes and mortars dosages made of clinker-filler, and was verified the performance of the materials produced. To the paste study, were made raw materials characterizations, rheology tests to determine the optimum dispersant content, and compressive strength tests for fixed water contents, varying three fillers with different particle sizes. For mortars evaluation, were performed compressive strength tests and was determined the elastic modulus. The analysis of the results were made though comparisons between mixtures rheological and mechanical behaviors, besides the calculation of the efficiency index Binder Intensity (BI), which is a relation between cement consumption and the mechanical strength. The materials produced with fillers reached a rhealogical behavior close to the conventional materials behavior, but with reduced water contents, contributing to the achievement of good mechanical resistance with lower cement consumption, and equivalentmodulus of elasticity. The results obtained in the experiments performed demonstrate the efficiency gains achieved with the addition of quartz fillers in cementitious materials and the feasibility for application in the civil construction industry.