Yes / Real time measurement of melt rheology has been investigated as a Process Analytical Technology (PAT) to monitor hot melt extrusion of an Active Pharmaceutical Ingredient (API) in a polymer matrix. A developmental API was melt mixed with a commercial copolymer using a heated twin screw extruder at different API loadings and set temperatures. The extruder was equipped with an instrumented rheological slit die which incorporated three pressure transducers flush mounted to the die surface. Pressure drop measurements within the die at a range of extrusion throughputs were used to calculate rheological parameters such as shear viscosity and exit pressure, related to shear and elastic melt flow properties respectively. Results showed that the melt exhibited shear thinning behavior whereby viscosity decreased with increasing flow rate. Increase in drug loading and set extrusion temperature resulted in a reduction in melt viscosity. Shear viscosity and exit pressure measurements were found to be sensitive to API loading. These findings suggest that this technique could be used as a simple tool to measure material attributes in-line, to build better overall process understanding for hot melt extrusion.

Yes / The viscoelastic nature of polymeric formulations utilised in drug products imparts unique thermomechanical attributes during manufacturing and over the shelf life of the product. Nevertheless, it adds to the challenge of understanding the precise mechanistic behaviour of the product at the microscopic and macroscopic level during each step of the process. Current thermomechanical and rheological characterisation techniques are limited to assessing polymer performance to a single phase and are especially hindered when the polymers are undergoing thermomechanical transitions. Since pharmaceutical processing can occur at these transition conditions, this study successfully proposes a thermomechanical characterisation approach combining both mechanical and rheological data to construct a comprehensive profiling of polymeric materials spanning both glassy and rubbery phases. This approach has been used in this study to assess the mechanical and rheological behaviour of heterogenous polymer blends of hydroxypropyl cellulose (HPC) and hydroxypropyl methylcellulose (HPMC) over a shearing rate range of 0.1–100 s−1 and a temperature range of 30–200 °C. The results indicate that HPC and HPMC do not appear to interact when mixing and that their mixture exhibits the mechanistic properties of the two individual polymers in accordance with their ratio in the mixture. The ability to characterise the behaviour of the polymers and their mixtures before, throughout, and after the glassy to rubbery phase transition by application of the combined techniques provides a unique insight towards a quality-by-design approach to this and other polymer-based solid dosage forms, designed with the potential to accelerate their formulation process through obviating the need for multiple formulation trials.

Inkjet additive manufacturing is the next step toward ubiquitous manufacturing by enabling multi-material printing that can exhibit various mechanical, electronic, and thermal properties. These characteristics are realized in the careful formulation of the inks and their functional materials, but there are many constraints that need to be satisfied to allow optimal jetting performance and build quality when used in an inkjet 3-D printer. Previous research has addressed the desirable rheology characteristics to enable stable drop formation and how the metallic nanoparticles affect the viscosity of inks. The contending goals of increasing nanoparticle-loading to improve material deposition rates while trying to maintain optimal flow dynamics is the closely held trade secret in formulating these inkjet compositions. We use data from previous experiments and the CRC Handbook of Chemistry and Physics to train machine learning regression models to predict the relevant factors of inkjet printability at a standardized temperature of 25ºC: viscosity, surface tension, and density. These models were used to predict the rheological factors of the main components of a UV-curable inkjet ink formulation: UV-curable monomers and oligomers, photoinitiators, dispersants, and humectants. This paper compares the relative performance of five machine learning algorithms to assess the effectiveness of each approach for chemoinformatics regression tasks.

[pt] O estudo reológico de hidratos vem se tornando cada vez mais importante graças à constante expansão da indústria de óleo e gás, principalmente em águas ultra profundas. O processo de formação de hidratos é uma grande preocupação, principalmente porque, em muitos casos, leva ao bloqueio total dos dutos de produção, causando interrupção na produção, além de perda de tempo de dinheiro. Hidratos são compostos cristalinos formados por água e pequenas moléculas de gás, em condições termodinâmicas de alta pressão e baixa temperatura. A fim de estudar este fenômeno, por analogia, compostos químicos que facilitam esta formação, à pressão atmosférica, como ciclipentano (CP) e tetrahidrofurano (THF) são utilizados. No presente trabalho, emulsões compostas por CP, óleo Primol, água deionizada e Span 80 (agente estabilizador) foram utilizadas e analisadas no reômetro Physica MCR301. A partir de uma perturbação térmica, pôde-se caracterizar vários parâmetros que influenciam a formação dos hidratos, tais como: taxa de cisalhamento, temperatura de indução, fração volumétrica da água, taxa de resfriamento etc. Além disso, foram realizados testes que avaliam a habilidade de reconstrução dos hidrato com o tempo e a existência de uma tensão limite de escoamento, a partir de testes oscilatórios. / [en] The study of hydrates rheology is becoming increasingly important due to the constant expansion of the oil and natural gas industry to deeper water. The hydrate formation process is a big concern mainly because, in many cases, it ends up generating the blockage of pipelines, safety problems, and loss of time and money. Hydrates are crystals compounds formed by water and small gas molecules at typical thermodynamic conditions of high pressure and low temperature. In order to study the hydrates phenomenon by analogy, chemical compounds that facilitate their formation at atmospheric pressure are used, such as cyclopentane (CP) and tetrahydrofuran (THF). In this study, an emulsion formed from CP, Primol oil, deionized water, and Span 80 (as stabilizer agent) is employed. Initially, the results aim to characterize the several parameters that influence hydrate formation, such as: shear rate, induction temperature, water volume fraction, cooling rate etc. In another set of results, the ability of reconstruction of the CP hydrates and the existence of a yield strength are assessed.

Polymer extrusion is an energy intensive process whereby the simultaneous action of viscous shear and thermal conduction are used to convert solid polymer to a melt which can be formed into a shape. To optimise efficiency, a homogeneous melt is required with minimum consumption of process energy. In this work, in-process monitoring techniques have been used to characterise the thermal dynamics of the single screw extrusion process with real-time quantification of energy consumption. Thermocouple grid sensors were used to measure radial melt temperatures across the melt flow at the entrance to the extruder die. Moreover, an infrared sensor flush mounted at the end of the extruder barrel was used to measure non-invasive melt temperature profiles across the width of the screw channel in the metering section of the extruder screw. Both techniques were found to provide useful information concerning the thermal dynamics of the extrusion process; in particular this application of infrared thermometry could prove useful for industrial extrusion process monitoring applications. Extruder screw geometry and extrusion variables should ideally be tailored to suit the properties of individual polymers but in practise this is rarely achieved due the lack of understanding. Here, LDPE, LLDPE, three grades of HDPE, PS, PP and PET were extruded using three geometries of extruder screws at several set temperatures and screw rotation speeds. Extrusion data showed that polymer rheology had a significant effect on the thermal efficiency on the extrusion process. In particular, melt viscosity was found to have a significant effect on specific energy consumption and thermal homogeneity of the melt. Extruder screw geometry, set extrusion temperature and screw rotation speed were also found to have a direct effect on energy consumption and melt consistency. Single flighted extruder screws exhibited poorer temperature homogeneity and larger fluctuations than a barrier flighted screw with a spiral mixer. These results highlighted the importance of careful selection of processing conditions and extruder screw geometry on melt homogeneity and process efficiency. Extruder scale was found to have a significant influence on thermal characteristics due to changes in surface area of the screw, barrel and heaters which consequently affect the effectiveness of the melting process and extrusion process energy demand. In this thesis, the thermal and energy characteristics of two single screw extruders were compared to examine the effect of extruder scale and processing conditions on measured melt temperature and energy consumption. Extrusion thermal dynamics were shown to be highly dependent upon extruder scale whilst specific energy consumption compared more favourably, enabling prediction of a process window from lab to industrial scale within which energy efficiency can be optimised. Overall, this detailed experimental study has helped to improve understanding of the single screw extrusion process, in terms of thermal stability and energy consumption. It is hoped that the findings will allow those working in this field to make more informed decisions regarding set conditions, screw geometry and extruder scale, in order to improve the efficiency of the extrusion process. / Engineering and Physical Sciences Research Council

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / No Brasil, a produÃÃo anual declarada de resÃduos pneumÃticos à da ordem de 40 milhÃes de unidades, estimando um descarte de pelo menos 25 milhÃes de pneus por ano. Segundo estatÃstica da AssociaÃÃo Nacional da IndÃstria de PneumÃticos, 100 milhÃes de pneus inservÃveis estÃo espalhados pelo paÃs em aterros, terrenos baldios, rios e lagos, causando enormes problemas de ordem ambiental. Com a resoluÃÃo 258 do Conselho Nacional do Meio Ambiente, CONAMA, a reciclagem de pneus inservÃveis passou a ser obrigatÃria em 2005, sendo a proporÃÃo desta reciclagem de 120%, ou seja, a cada 4 pneus produzidos ou importados, 5 tem que ser reciclados, contribuindo, assim, para a eliminaÃÃo do passivo ambiental existente. A presente dissertaÃÃo trata de uma anÃlise quÃmica e reolÃgica de ligantes asfÃlticos modificados com borracha de pneu, com o intuito de melhorar o desempenho dos ligantes, quando aplicados nos revestimentos asfÃlticos, bem como minimizar o problema ambiental. Para modificar o ligante asfÃltico foi utilizado o processo Ãmido, sendo verificado o comportamento de diferentes teores de Ãleo aromÃtico (2,5; 4,5 e 6,0%) e a granulometria da borracha de pneu moÃdo (BPM 3) passando na peneira de N 80 (0,180mm) com teor de 20% em peso (p/p). Para efeito de comparaÃÃo foi analisada uma amostra comercial de asfalto-borracha. O estudo das amostras produzidas em laboratÃrio e comercial foi realizado em um reÃmetro de cisalhamento dinÃmico (DSR) e a caracterizaÃÃo quÃmica em um espectrÃmetro na regiÃo do infravermelho (FTIR). O Ãleo aromÃtico influenciou nas propriedades quÃmicas e reolÃgicas do ligante modificado em laboratÃrio, tendo em vista que os espectros na regiÃo do infravermelho apresentaram o aparecimento de novas bandas. A viscosidade diminui com a presenÃa do Ãleo e melhorou a trabalhabilidade do material. A regiÃo de viscoelasticidade linear foi maior para a amostra que continha 4,5 e 6,0% de Ãleo aromÃtico. Nas curvas mestras foi observado que a borracha pode diminuir trincamentos por fadiga em temperaturas intermediÃrias e proporcionaram um comportamento elÃstico superior ao das amostras de ligante asfÃltico puro, bem como a formaÃÃo de um platà que indica uma rede polimÃrica no ligante modificado. Os ligantes modificados produzidos em laboratÃrio apresentaram desempenhos superiores com relaÃÃo à amostra comercial e ligante asfÃltico puro. Pode-se atribuir as diferenÃas Ãs caracterÃsticas como teor de borracha, tipo de ligante asfÃltico puro e diluente utilizado durante a modificaÃÃo do LAB / In Brazil, the annual production of waste tires is in the order of 40 million units, with an estimated tire disposal of at least 25 million units per year. According to statistics of the National Association of Tire Industry, 100 million of useless tires are spread around the country in landfills, vacant land, rivers and lakes, causing enormous environment damage. The recycling of scrap tires has become mandatory since 2005 according to the resolution 258 of the National Council on the Environment (NCE) and the recycling rate must be of 120%, i.e., for every 4 tires produced or imported, 5 have to be recycled, thus contributing to the elimination of existing scrap tires. This dissertation deals with the chemical and rheological analysis of asphalt binder modified with rubber tires in order to improve the performance, when applied to the asphalt coating, and minimize the environmental problem. The wet process was used to modify the binder. It was verified the effect of different levels of aromatic oil (2.5, 4.5 and 6.0%) and the particle size of the incorporated rubber through the sieve passing 80 (0.180mm) containing 20% by weight (w/w). For comparison purposes, it was considered a commercial sample of rubber asphalt. The rheological study of samples produced in laboratory and commercially available was conducted in a dynamic shear rheometer (DSR) and the chemical analysis was performed in an infrared spectrometer with Fourier Transform Infra Red (FTIR). The aromatic oil influenced the chemical and rheological properties of the modified binder produced in the laboratory, since the spectra in the infrared showed the appearance of new bands. Viscosity decreased with the presence of oil and the workability of the material was improved. The region of linear viscoelasticity was higher for the sample that contained 4.5 and 6.0% aromatic oil. The master curves showed that rubber can reduce fatigue in intermediate temperatures and provide a greater elastic response for the modified samples. It was observed a plateau in the  master curves which indicates the formation of a polymer network in the modified binder. The modified binder produced in the laboratory showed a greater performance with respect to the commercial sample and the pure asphalt binder. The differences in the rheological behavior of the samples can be attributed to the rubber content, type of asphalt binder and rubber used during the modification process

Das chemisch-mechanische Planarisieren (CMP) in der Halbleiterindustrie ist ein Prozess mit sehr vielen Einflussgrößen, wobei das Polierergebnis unter anderem von den Eigenschaften der Wechselwirkungskomponenten Wafer, Poliersuspension und Polierpad abhängig ist. Bei der Entwicklung neuer Schaltkreisentwürfe werden die strukturellen Abhängigkeiten der Topografie nach dem CMP häufig im Verlauf von zeit- und kostenintensiven Lernzyklen aufgedeckt und angepasst. Um Dauer und Kosten für die Entwicklung neuer Schaltkreise zu reduzieren, sollte im Rahmen eines BMBF-Projektes ein umfassendes Gesamtmodell, welches den Polierprozess ausführlich beschreibt, entwickelt werden. Für die Umsetzung dieses Vorhabens ist ein umfassendes qualitatives und quantitatives Verständnis der mechanisch-hydrodynamischen und physikalisch-chemischen Mechanismen zu erarbeiten, welche den Materialabtrag und die Planarisierung beim CMP bestimmen. Ziel der vorliegenden Arbeit war es zum einen, mittels direkter Kraftmessung am AFM die Wechselwirkungskräfte zwischen den Festkörperoberflächen von Schleifpartikel und Wafer sowie zwischen den Schleifpartikeln untereinander in CMP-relevanten Flüssigkeiten und ihre Bedeutung für das CMP zu untersuchen. Um die Wechselwirkungskräfte am AFM bestimmen zu können, war zuvor die Entwicklung einer geeigneten Versuchsanordnung nötig. Zur Absicherung der Ergebnisse aus den Kraftmessungen wurde eine Methode erarbeitet, um die zwischenpartikulären Wechselwirkungen mittels rheologischer Untersuchungen indirekt bestimmen zu können. Des Weiteren fanden rheologische Messungen zur Untersuchung der Fließeigenschaften der Poliersuspensionen statt, wobei außerdem der Einfluss anwendungsrelevanter hydrodynamischer Kräfte auf die Stabilität der Poliersuspension zu überprüfen war. Als Poliersuspensionen kamen kommerziell verfügbare Slurries sowie eine Modellslurry zum Einsatz. Neben Systemen mit dispergierten Silica-Partikeln wurde auch eine Slurry mit Ceria-Partikeln als disperse Phase betrachtet. Die kontinuierliche Phase einer Poliersuspension ist ein Mehrkomponentensystem und enthält unterschiedlichste Additive. Untersucht wurde der Einfluss von pH-Wert und Elektrolytkonzentration auf die Wechselwirkungskräfte, das Fließverhalten sowie den Materialabtrag.

<p><b>Part I: Micromechanics of dense suspensions</b></p><p>Particulate suspensions are ubiquitous in the industry & nature. Fresh concrete, uncured solid rocket fuel, & biomass slurries are typical industrial applications, while milk & blood are examples of naturally occurring suspensions. These suspensions exhibit many non-Newtonian properties like rate-dependent rheology & normal stresses. Other than volume fraction, particle material, inter-particle interactions determine the rheological behavior of suspension. The average inter-particle gaps between the neighboring particles decrease significantly as the suspension volume fraction approaches the maximum packing fraction in dense suspensions. So, in this regime, the short-ranged non-contact interactions are important. In addition, the particles come into contact due to asperities on their surfaces. The surface asperities are present even in the case of so-called smooth particles, as particles in real suspensions are not perfectly smooth. Hence, contact forces become one of the essential factors to determine the rheology of suspensions.</p><p> </p><p>Part I of this thesis investigates the effects of microscopic inter-particle interactions on the rheological properties of dense suspensions of non-Brownian particles by employing discrete particle simulations. We show that increasing the roughness size results in a rise in the viscosity & normal stress difference in the suspensions. Furthermore, we observe that the jamming volume fraction decreases with the particle roughness. Consequently, for suspensions close to jamming, increasing the asperity size reduces the critical shear rate for shear thickening (ST) transition, resulting in an early onset of discontinuous ST (DST, a sudden jump in the suspension viscosity) in terms of volume fraction, & enhances the strength of the ST effect. These findings are in excellent agreement with the recent experimental measurements & provide a deeper understanding of the experimental findings. Finally, we propose a constitutive model to quantify the effect of the roughness size on the rheology of dense ST suspensions to span the entire phase-plane. Thus, the constitutive model and the experimentally validated numerical framework proposed can guide experiments, where the particle surface roughness is tuned for manipulating the dense suspension rheology according to different applications. </p><p> </p><p>A typical dense non-Brownian particulate suspension exhibits shear thinning (decreasing viscosity) at a low shear rate followed by a Newtonian plateau (constant viscosity) at an intermediate shear rate values which transition to ST (increasing viscosity) beyond a critical shear rate value and finally, undergoes a second shear-thinning transition at an extremely high shear rate values. This part unifies & quantitatively reproduces all the disparate rate-dependent regimes & the corresponding transitions for a dense non-Brownian suspension with increasing shear rate. The inclusion of traditional hydrodynamic interactions, attractive/repulsive DLVO (Derjaguin and Landau, Verwey and Overbeek), contact interactions, & constant friction reproduce the initial thinning as well as the ST transition. However, to quantitatively capture the intermediate Newtonian plateau and the second thinning, an additional interaction of non-DLVO origin & a decreasing coefficient of friction, respectively, are essential; thus, providing the first explanation for the presence these regimes. Expressions utilized for various interactions and friction are determined from experimental measurements, resulting in an excellent quantitative agreement with previous experiments. </p><p><br></p><p><b>Part II: Motion in a stratified fluid</b></p><p>Density variations due to temperature or salinity greatly influence the dynamics of objects like particles, drops, and microorganisms in oceans. Density stratification hampers the vertical flow & substantially affects the sedimentation of an isolated object, the hydrodynamic interactions between a pair, and the collective behavior of suspensions in various ways depending on the relative magnitude of stratification inertia (advection), and viscous (diffusion) effects. This part investigates these effects and elicits the hydrodynamic mechanisms behind some commonly observed fluid-particle transport phenomena in oceans, like aggregation in horizontal layers. The physical understanding can help us better model these phenomena and, hence, predict their geophysical, engineering, ecological, and environmental implications. </p><p><br></p><p>We investigate the self-propulsion of an inertial swimmer in a linear density stratified fluid using the archetypal squirmer model, which self-propels by generating tangential surface waves. We quantify swimming speeds for pushers (propelled from the rear) and pullers (propelled from the front) by direct numerical solution. We find that increasing stratification reduces the swimming speeds of swimmers relative to their speeds in a homogeneous fluid while reducing their swimming efficiency. The increase in the buoyancy force experienced by these squirmers due to the trapping of lighter fluid in their respective recirculatory regions as they move in the heavier fluid is one of the reasons for this reduction. Stratification also stabilizes the flow around a puller, keeping it axisymmetric even at high inertia, thus leading to otherwise absent stability in a homogeneous fluid. On the contrary, a strong stratification leads to instability in the motion of pushers by making the flow around them unsteady 3D, which is otherwise steady axisymmetric in a homogeneous fluid. Data for the mixing efficiency generated by individual squirmers explain the trends observed in the mixing produced by a swarm of squirmers. </p><p><br></p><p>In addition, the ubiquitous vertical density stratification in aquatic environments significantly alters the swimmer interactions affecting their collective motion &consequently ecological and environmental impact. To this end, we numerically investigate the interactions between a pair of model swimming organisms with finite inertia in a linear density stratified fluid. Depending on the squirmer inertia and stratification, we observe that the squirmer interactions can be categorized as i) pullers getting trapped in circular loops, ii) pullers escaping each other with separating angle decreasing with increasing stratification, iii) pushers sticking to each other after the collision and deflecting away from the collision plane, iv) pushers escaping with an angle of separation increasing with stratification. Stratification also increases the contact time for squirmer pairs. The results presented can help understand the mechanisms behind the accumulation of planktonic organisms in horizontal layers in a stratified environment like oceans and lakes. </p><p><br></p><p>Much work has been done to understand the settling dynamics of spherical particles in a homogeneous and stratified fluid. However, the effects of shape anisotropy on the settling dynamics in a stratified fluid are not entirely understood. To this end, we perform numerical simulations for settling oblate and prolate spheroids in a stratified fluid. We find that both the oblate and prolate spheroids reorient to the edge-wise and partially edge-wise orientations, respectively, as they settle in a stratified fluid completely different from the steady-state broad-side on orientation observed in a homogeneous fluid. We observe that reorientation instabilities emerge when the velocity magnitude of the spheroids falls below a particular threshold. We also report the enhancement of the drag on the particle from stratification. The torque due to buoyancy effects tries to orient the spheroid in an edge-wise orientation, while the hydrodynamic torque tries to orient it to a broad-side orientation. The buoyancy torque dominates below the velocity threshold, resulting in reorientation instability.<br></p>

Pumping is the most efficient transportation and placing method for concrete. Despite the immense progress in the field of concrete technology in the last years, so far there are still neither official regulations nor verified theoretical foundations to be used for the assessment and accurate prediction pumping behaviour of ordinary and high performance concretes. This thesis aims at purposefully investigating pumping of modern concretes and bridging the existing knowledge gap. The main achievement of the present research is the development and verification of a sitecompliant and scientifically based methodology for characterisation and prediction of fresh concrete pumping behaviour. The research focus is set on the importance of the forming lubricating layer (LL) during pumping. Within an extended experimental program, the properties of the LL are captured and quantified. They determine the reduction of friction at the pipe wallconcrete interface and thereby govern the concrete flow. It is proven that the composition and the rheological properties of the forming LL exert an enormous impact on pumping since most of the induced shear stress by pumping pressure is concentrated in this layer. In a further step, the flow pattern of concrete is analytically and numerically determined. The concrete exhibits various principal flow types which are already defined at low flow rates: plug flow in case of strainhardening cementbased composite (SHCC), partial concrete bulk shear in ordinary concretes and pronounced bulk shear for selfcompacting concrete (SCC). The results from the fullscale pumping campaign are confronted with the existing pressure performance nomogram on the determination of pumping parameters. The nomogram’s prediction capacity is extended and verified for highly flowable concretes by replacing the slump and flow table results with the viscosity parameter of the LL. Furthermore, the challenges during pumping of concrete, inter alia, priming of the pipeline, blockage formation and final cleaning, are exemplified, and recommendations for the practitioners are provided. Finally, the transfer of the developed scientifically based and ready to use methodology on site is strongly advocated as a part of the future in situ rheology monitoring concept towards envisaged full automation of concrete production and casting processes.:ZUSAMMENFASSUNG V ABSTRACT VII VORWORT DES HERAUSGEBERS IX DANKSAGUNG XI SYMBOLS XVII INTRODUCTION 1 1.1 FLASHLIGHTS ON HISTORY 1 1.2 MOTIVATION 1 1.3 RESEARCH FIELD 3 1.4 RESEARCH CONCEPT 6 1.5 ECONOMIC RELEVANCE 8 1.6 STRUCTURE AND BOUNDARIES OF THE THESIS 10 STATE OF THE ART 13 2.1 GENERAL 13 2.2 CONCRETE FLOW IN PIPELINE 13 2.3 INFLUENCE OF CONCRETE RHEOLOGY ON PUMPING BEHAVIOUR 16 2.3.1 CEMENT HYDRATION 16 2.3.2 MIXTURE COMPOSITION 17 2.3.2.1 WATER-TO-BINDER RATIO AND PASTE VOLUME 18 2.3.2.2 AGGREGATES 20 2.3.2.3 ADMIXTURES AS PUMPING AIDS 22 2.3.3 HYDRODYNAMIC INTERACTIONS 25 2.3.4 SHEAR HISTORY 27 2.3.5 TEMPERATURE 28 2.4 FORMATION OF LUBRICATING LAYER 30 2.4.1 FLOW-INDUCED PARTICLE MIGRATION 30 2.4.2 PROPERTIES 31 2.4.3 EXPERIMENTAL CHARACTERISATION 32 2.5 BOUNDARY CONDITIONS 32 2.6 PUMPING EQUIPMENT 34 2.7 PRIMING 35 3 APPLIED METHODS 37 3.1 GENERAL 37 3.2 RHEOMETRY 37 3.3 DIRECT DETERMINATION OF PUMPING PRESSURE 40 3.4 SAMPLING AND PRODUCTION OF LUBRICATING MATERIAL 42 3.5 MEASUREMENT OF FILTRATE AMOUNT 45 3.6 ANALYTICAL DETERMINATION OF LUBRICATING LAYER THICKNESS 47 3.7 SMALL-SCALE PUMPING 49 3.8 FULL-SCALE PUMPING 50 3.9 NUMERICAL METHOD 56 3.9.1 MATERIAL MODEL 56 3.9.2 NUMERICAL IMPLEMENTATION 58 4 CHARACTERISATION OF CONCRETE PUMPABILITY 63 4.1 GENERAL 63 4.2 MIXTURE DESIGN PARAMETERS 63 4.3 COMPARISON BETWEEN REFERENCE AND DESIGN MORTARS 65 4.4 RESULTS AND DISCUSSION 65 4.4.1 RHEOLOGICAL BEHAVIOUR OF CONCRETES AND DESIGN MORTARS 65 4.4.2 INFLUENCE OF WALL ROUGHNESS ON RHEOLOGICAL PARAMETERS 67 4.4.3 PREDICTION OF PUMPING PRESSURE 72 4.5 SUMMARY 74 5 LUBRICATING LAYER THICKNESS AND CONCRETE FLOW 75 5.1 GENERAL 75 5.2 MIXTURE DESIGN PARAMETERS 75 5.3 RESULTS AND DISCUSSION 76 5.3.1 CONCRETE FLOW TYPE 76 5.3.2 PREDICTION AND VERIFICATION OF PUMPING PRESSURE 77 5.3.3 QUANTIFICATION OF LUBRICATING LAYER THICKNESS 79 5.4 SUMMARY 82 6 FULL-SCALE PUMPING EXPERIMENTS 83 6.1 GENERAL 83 6.2 MIXTURES AND DESIGN PARAMETERS 83 6.3 RESULTS AND DISCUSSION 85 6.3.1 PRESSURE LOSS AND PRESSURE-FLOW RATE CURVES 85 6.3.2 NUMERICAL SIMULATION RESULTS 86 6.3.3 PRESSURE PREDICTION USING MODIFIED NOMOGRAM 88 6.3.4 COMPARISON BETWEEN PREDICTED AND ACTUAL PRESSURE-FLOW RATE CURVES 90 6.4 SUMMARY 92 7 EFFECT OF PUMPING ON FRESH PROPERTIES OF CONCRETE AND FILTRATE FORMATION 95 7.1 GENERAL 95 7.2 MIXTURES DESIGN PARAMETERS 95 7.3 INFLUENCE OF PUMPING ON PROPERTIES OF FRESH CONCRETE 97 7.4 INFLUENCE OF CONCRETE PROPERTIES ON KINETICS OF FILTRATE FORMATION 98 7.5 IMPACT OF FILTRATE AMOUNT ON PUMPABILITY 101 7.6 SUMMARY 104 8 CHALLENGES RELATED TO PUMPING OF CONCRETE 105 8.1 GENERAL 105 8.2 PRIMING GROUT 105 8.3 PIPELINE GEOMETRY 108 8.4 BLOCKAGES 113 8.5 FILLING DEGREE OF PUMP PISTONS 116 8.6 TEMPERATURE CONTROL 117 8.7 VERTICAL PUMPING 118 8.8 CLEANING THE PIPELINE 119 8.9 SUMMARY 120 9 FINAL CONCLUSIONS AND OUTLOOK 121 9.1 GENERAL 121 9.2 CONCRETE FLOW TYPE 121 9.3 LUBRICATING LAYER PROPERTIES 121 9.4 RHEOLOGICAL DEVICES 122 9.5 FILTRATE FORMATION 122 9.6 NUMERICAL SIMULATIONS 122 9.7 MODIFIED NOMOGRAM 123 9.8 RELEVANCE OF PUMPING EXPERIMENTS 123 9.9 INFLUENCE OF PUMPING ON FRESH CONCRETE PROPERTIES 124 9.10 GENERATED DATABASE 124 9.11 IMPROVING NUMERICAL MODEL 124 9.12 TODAY AND TOMORROW 124 BIBLIOGRAPHY 127 APPENDIX A 135 A.1 MATERIALS DESCRIPTION, CHAPTERS 4 AND 5 135 A.2 MATERIALS DESCRIPTION, CHAPTERS 6, 7 AND 8 136 APPENDIX B 137 APPENDIX C 141 LIST OF SELECTED PUBLICATIONS 143 JOURNALS 143 CONFERENCE PAPERS 143 CURRICULUM VITAE 145 / Das Pumpen stellt die effektivste Methode für das Fördern und Einbringen von Frischbeton auf der Baustelle dar. Trotz der in den letzten Jahren erreichten deutlichen Fortschritte auf betontechnologischem Gebiet existieren für die Beurteilung der Pumpbarkeit von Beton bisher weder offiziell gültige Vorschriften noch abgesicherte theoretische Grundlagen, die eine zielsichere Vorhersage des Pumpverhaltens von Normal- als auch Hochleistungsbetonen ermöglichen. Die vorliegende Arbeit schließt entsprechende Wissenslücken und befasst sich gezielt mit dem Pumpen moderner Betone. Grundlegenden Erkenntnisgewinn stellt die Entwicklung einer wissenschaftlich fundierten, baustellengerechten Prüfmethodik zur Charakterisierung und Vorhersage des Pumpverhaltens von Frischbeton dar. Der Untersuchungsfokus richtet sich auf die Wirkung der sich beim Pumpvorgang ausbildenden Gleitschicht. Ein umfangreiches Untersuchungsprogramm gestattet die Erfassung und Quantifizierung der Eigenschaften dieser Schicht. Sie bestimmen infolge deutlicher Reduzierung der Reibung an der Grenzfläche zwischen Rohrwandung und Beton die Betonströmung entscheidend. Bewiesen wird, dass Betonzusammensetzung und rheologische Eigenschaften der Gleitschicht maßgebende Auswirkungen auf den Pumpvorgang haben, da sich die pumpdruckinduzierte Scherspannung in dieser Schicht konzentriert. Weiterhin erfolgt sowohl eine analytische als auch numerische Charakterisierung der Betonströmung im Rohr. Nachgewiesen wird, dass sich beim Pumpvorgang betonspezifisch unterschiedliche Strömungsarten einstellen, die bereits bei niedrigen Durchflussmengen definiert sind: Pfropfenströmung in hochduktilen Betonen, partielle Scherung des Kernbetons in Normalbetonen und signifikante Scherung in selbstverdichtenden Betonen. Aus großtechnisch durchgeführten Pumpversuchen gewonnene Ergebnisse werden dem derzeit vorhandenen, verbesserungsbedürftigen Betondruck-Leistungs-Nomogramm zur Einstellung von Parametern an der Betonpumpe gegenübergestellt. Die Vorhersagekapazität des Nomogramms kann durch den Ersatz der Ausbreit- bzw. Setzfließmaßangaben mit Viskositätsangaben der Gleitschicht erweitert und verifiziert werden. Des Weiteren werden baustellenbezogene Herausforderungen im Gesamtprozess des Betonpumpvorgangs, u. a. Vorbereitung der Rohrleitung vor dem Pumpen, Auftreten von Stopfern und Endreinigung exemplarisch dargestellt sowie Empfehlungen für die Praktiker erarbeitet. Schließlich wird der Transfer der in dieser Arbeit entwickelten wissenschaftlich basierten und anwendungsbereiten Methodik als Teil des zukünftigen Konzeptes für die in-situ Rheologie-Überwachung hinsichtlich einer angestrebten vollständigen Automatisierung von Fertigungs- und Einbringprozessen von Beton mit Nachdruck empfohlen.:ZUSAMMENFASSUNG V ABSTRACT VII VORWORT DES HERAUSGEBERS IX DANKSAGUNG XI SYMBOLS XVII INTRODUCTION 1 1.1 FLASHLIGHTS ON HISTORY 1 1.2 MOTIVATION 1 1.3 RESEARCH FIELD 3 1.4 RESEARCH CONCEPT 6 1.5 ECONOMIC RELEVANCE 8 1.6 STRUCTURE AND BOUNDARIES OF THE THESIS 10 STATE OF THE ART 13 2.1 GENERAL 13 2.2 CONCRETE FLOW IN PIPELINE 13 2.3 INFLUENCE OF CONCRETE RHEOLOGY ON PUMPING BEHAVIOUR 16 2.3.1 CEMENT HYDRATION 16 2.3.2 MIXTURE COMPOSITION 17 2.3.2.1 WATER-TO-BINDER RATIO AND PASTE VOLUME 18 2.3.2.2 AGGREGATES 20 2.3.2.3 ADMIXTURES AS PUMPING AIDS 22 2.3.3 HYDRODYNAMIC INTERACTIONS 25 2.3.4 SHEAR HISTORY 27 2.3.5 TEMPERATURE 28 2.4 FORMATION OF LUBRICATING LAYER 30 2.4.1 FLOW-INDUCED PARTICLE MIGRATION 30 2.4.2 PROPERTIES 31 2.4.3 EXPERIMENTAL CHARACTERISATION 32 2.5 BOUNDARY CONDITIONS 32 2.6 PUMPING EQUIPMENT 34 2.7 PRIMING 35 3 APPLIED METHODS 37 3.1 GENERAL 37 3.2 RHEOMETRY 37 3.3 DIRECT DETERMINATION OF PUMPING PRESSURE 40 3.4 SAMPLING AND PRODUCTION OF LUBRICATING MATERIAL 42 3.5 MEASUREMENT OF FILTRATE AMOUNT 45 3.6 ANALYTICAL DETERMINATION OF LUBRICATING LAYER THICKNESS 47 3.7 SMALL-SCALE PUMPING 49 3.8 FULL-SCALE PUMPING 50 3.9 NUMERICAL METHOD 56 3.9.1 MATERIAL MODEL 56 3.9.2 NUMERICAL IMPLEMENTATION 58 4 CHARACTERISATION OF CONCRETE PUMPABILITY 63 4.1 GENERAL 63 4.2 MIXTURE DESIGN PARAMETERS 63 4.3 COMPARISON BETWEEN REFERENCE AND DESIGN MORTARS 65 4.4 RESULTS AND DISCUSSION 65 4.4.1 RHEOLOGICAL BEHAVIOUR OF CONCRETES AND DESIGN MORTARS 65 4.4.2 INFLUENCE OF WALL ROUGHNESS ON RHEOLOGICAL PARAMETERS 67 4.4.3 PREDICTION OF PUMPING PRESSURE 72 4.5 SUMMARY 74 5 LUBRICATING LAYER THICKNESS AND CONCRETE FLOW 75 5.1 GENERAL 75 5.2 MIXTURE DESIGN PARAMETERS 75 5.3 RESULTS AND DISCUSSION 76 5.3.1 CONCRETE FLOW TYPE 76 5.3.2 PREDICTION AND VERIFICATION OF PUMPING PRESSURE 77 5.3.3 QUANTIFICATION OF LUBRICATING LAYER THICKNESS 79 5.4 SUMMARY 82 6 FULL-SCALE PUMPING EXPERIMENTS 83 6.1 GENERAL 83 6.2 MIXTURES AND DESIGN PARAMETERS 83 6.3 RESULTS AND DISCUSSION 85 6.3.1 PRESSURE LOSS AND PRESSURE-FLOW RATE CURVES 85 6.3.2 NUMERICAL SIMULATION RESULTS 86 6.3.3 PRESSURE PREDICTION USING MODIFIED NOMOGRAM 88 6.3.4 COMPARISON BETWEEN PREDICTED AND ACTUAL PRESSURE-FLOW RATE CURVES 90 6.4 SUMMARY 92 7 EFFECT OF PUMPING ON FRESH PROPERTIES OF CONCRETE AND FILTRATE FORMATION 95 7.1 GENERAL 95 7.2 MIXTURES DESIGN PARAMETERS 95 7.3 INFLUENCE OF PUMPING ON PROPERTIES OF FRESH CONCRETE 97 7.4 INFLUENCE OF CONCRETE PROPERTIES ON KINETICS OF FILTRATE FORMATION 98 7.5 IMPACT OF FILTRATE AMOUNT ON PUMPABILITY 101 7.6 SUMMARY 104 8 CHALLENGES RELATED TO PUMPING OF CONCRETE 105 8.1 GENERAL 105 8.2 PRIMING GROUT 105 8.3 PIPELINE GEOMETRY 108 8.4 BLOCKAGES 113 8.5 FILLING DEGREE OF PUMP PISTONS 116 8.6 TEMPERATURE CONTROL 117 8.7 VERTICAL PUMPING 118 8.8 CLEANING THE PIPELINE 119 8.9 SUMMARY 120 9 FINAL CONCLUSIONS AND OUTLOOK 121 9.1 GENERAL 121 9.2 CONCRETE FLOW TYPE 121 9.3 LUBRICATING LAYER PROPERTIES 121 9.4 RHEOLOGICAL DEVICES 122 9.5 FILTRATE FORMATION 122 9.6 NUMERICAL SIMULATIONS 122 9.7 MODIFIED NOMOGRAM 123 9.8 RELEVANCE OF PUMPING EXPERIMENTS 123 9.9 INFLUENCE OF PUMPING ON FRESH CONCRETE PROPERTIES 124 9.10 GENERATED DATABASE 124 9.11 IMPROVING NUMERICAL MODEL 124 9.12 TODAY AND TOMORROW 124 BIBLIOGRAPHY 127 APPENDIX A 135 A.1 MATERIALS DESCRIPTION, CHAPTERS 4 AND 5 135 A.2 MATERIALS DESCRIPTION, CHAPTERS 6, 7 AND 8 136 APPENDIX B 137 APPENDIX C 141 LIST OF SELECTED PUBLICATIONS 143 JOURNALS 143 CONFERENCE PAPERS 143 CURRICULUM VITAE 145

The objective of this research is to develop a water-based processing method for incorporating large filler loadings into nanocomposite systems. Specifically, cellulose nanocrystal/poly(vinyl alcohol) (CNC/PVA) nanocomposite aqueous suspensions and films were processed and characterized at CNC loadings up to 67 wt.% with respect to polymer concentration. Both aqueous suspended and freeze-dried CNCs were studied with this method. Two methods for incorporating the CNCs were investigated: solution processing and batch mixing of aqueous suspensions. The materials produced by these methods were characterized using rheology of aqueous suspensions and a method for understanding the morphology of these aqueous suspension through rheological characterization was developed. The CNC/PVA suspensions were dried and the structure of the film studied using x-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry. With regard to characterization of polymer structure by these methods, PVA crystallinity was seen to increase with increasing CNC loading. Finally, dynamic mechanical analysis and micro-tensile testing were conducted on consolidated films and CNCs were seen to increase modulus, yield stress but decrease strain at failure. Biodegradation studies were also conducted and CNCs were seen to increase the biodegradation characteristics of PVA. While the general trends in experimental data were the same, differences in properties between systems made with solution processing and batch mixing were observed, attributed to differences in the CNC dispersion. Overall, results indicated that this methodology is feasible for the industrially scalable production of highly loaded nanocomposites.