Grouting is performed in order to decrease the permeability and increase the stiffness of the material, especially soil and rock. For tunnelling and underground constructions, permeation grouting is done where cement based materials are pumped inside drilled boreholes under a constant pressure, higher than the ground water pressure. The aim of permeation grouting is to reduce the water flow into tunnels and caverns and to limit the lowering of the surrounding groundwater table. Cement based materials are commonly used as grout due to their availability and lower costs. To obtain a proper water sealing and reduce the lowering of the ground water table, a desired spread of grout must be achieved and the rheology of the cement grout is the governing factor for estimating the required spread. Rheological properties of cement grout such as viscosity and yield stress are commonly measured off-line using laboratory instruments, and some simple tools are available to make field measurements. Although the rheological properties of the grout that is used play a fundamental role in design and execution, no method has yet been developed to measure these properties in-line in field work. In addition to the real time measurement, there is no standard method for determining the yield stress for grouting applications. Despite the common usage of Bingham model fitting to determine the yield stress, the range of shear rate is often not specified or is neglected.   In this work, an in-line rheometry method combining the Ultrasound Velocity Profiling (UVP) technique with Pressure Difference (PD) measurements, known as “UVP+PD”, was successfully tested for continuous in-line measurements of concentrated micro cement based grouts. A major obstacle of using the ultrasound based methodology was the transducers, which would be capable of emitting sufficient acoustic energy and can be used in field conditions. The transducer technology was developed in a parallel project and the Flow-Viz industrial rheometer was found to be capable of detail measurement of the velocity profiles of cement grout. The shape of the velocity profiles was visualized, and the change in the shape of the profiles with concentration and time was observed. The viscosity and yield stress of the grout were determined using rheological models, e.g. Bingham and Herschel-Bulkley. In addition, rheological properties were determined using the non-model approach (gradient method) and the tube viscometry concept and were compared with results obtained using the rheological models. The UVP+PD method was found to be capable of determining the rheological behavior of cement grout regardless of the rheological model. The yield stress of cement grout was investigated using off-line rheometry techniques and UVP+PD in-line measurements. Tests were performed applying different shear histories and it was found that two ranges of yield stress indeed exist. Therefore, the design value of yield stress should be chosen with respect to the prevailing shear rate at the grout front for the required spread of grout. In addition, an appropriate shear rate range should be used when a Bingham fitting is done to determine the yield stress. In order to estimate the shear rate, plug thickness and velocity for one dimensional and two dimensional geometry, a non- dimensional nomogram was developed. The advantage of using the nomogram is that it does not depend on the applied pressure and the rheological properties of the grout and can therefore, be used as a simple design tool. Analytical approaches were used for the estimation and good agreements were found with numerical calculations and experimental results. In conclusion, in this work, it was found that it is possible to continuously measure the velocity profiles and determine the change of the rheological properties of cement grout using the ultrasound based UVP+PD method under field conditions. The yield stress was also investigated and it was found that two range of yield stress exist depending on the prevailing shear rate of the grout, which should be used for designing the grouting time at different conditions. In order to decide the design value of yield stress for grouting applications, a non-dimensional nomogram was developed that can be used to estimate the plug thickness, shear rate and velocity of the grout. / <p>Funding for the project was provided by the Swedish Rock Engineering Research Foundation (BeFo), The Swedish Research Council (FORMAS) and The Development Fund of the Swedish Construction Industry (SBUF), who are gratefully acknowledged. QC 20151112</p>

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The present dissertation investigates the flow behavior of concentrated Kaolin slurries and furthermore novel rheological measurement-, analysis-, and assessment procedures for characterizing static and dynamic flow behavior in industrial and research applica- tions. Ten different Kaolins with divergent property profiles were investigated in detail. At first, novel measurement and analysis procedures are presented and the raw material inherent properties are correlated with the resulting flow characteristics. The results describe the structural building and breakdown (in both static and dynamic states) of concentrated Kaolin slurry suspensions with and without deflocculant and also the determination of the point of optimal deflocculant concentration through the develop- ment of a novel analysis method and linking of the parameters to a condition matrix. The results lead to a better understanding of the flow behavior of concentrated Kaolin slurries. Due to the use of a strict measurement protocol with a focus on the elimination of external disturbances on the determination of flow behavior, the phases of dynamic structure construction and destruction (with exclusion of temporal structure effects and vice versa) can be analyzed. It was identified that the construction of particle networks requires less energy than their destruction. Furthermore it could be demonstrated that the occurrence of a transient shear stress peak in kaolin slurries is the cause for the breakdown of an existing particle network and not, as conventionally reported, due to an insufficient measurement time. Moreover, through the combination and modification of two measurement protocols described here, manufacturing companies have a potentially useful tool for composition development and quality control without the necessity of purchasing a highly precise research rheometer. / In der vorliegenden Arbeit wird das Fließverhalten von konzentrierten Kaolinsuspensio- nen untersucht und neuartige rheologische Mess-, Analyse- und Bewertungsverfahren zur Charakterisierung der Belastungs- und Zeitabhängigkeit für Industrie- und Forschungsanwendungen vorgestellt. Hierzu wurden zehn Kaoline mit divergierenden Eigenschaftsprofilen untersucht. Zunächst werden neuartige Mess- und Analyseverfahren vorgestellt und die Eigenschaften der Rohstoffe mit den ermittelten Fließcharakteristika korreliert. Die Ergebnisse beschreiben den strukturellen Auf- und Abbau (zeit- und belastungsabhängig) von konzentrierten Kaolinsuspensionen mit und ohne Dispergierhilfsmitteleinsatz und darüber hinaus die Ermittlung der optimalen Dispergierhilfsmittelkonzentration durch Entwicklung einer neuartigen Analyse und Verknüpfung von Parametern an eine Bedingungsmatrix. Die Erkenntnisse tragen zum besseren Verständnis des Fließverhaltens konzentrierter Kaolinsuspensionen bei. Aufgrund der entwickelten Messvorschriften und der darin elementar verankerten Elimination von Störgrößen auf die Ermittlung des Fließverhaltens konnten die Phasen des strukturellen Auf- und Abbaus unter Belastung (unter Ausschluss von temporalen Struktureffekten und umgekehrt) analysiert werden. Es wurde festgestellt, dass die Konstruktion von Partikelnetzwerken weniger Energie benötigt, als deren Destruktion und das Auftreten des Schubspannungshügels auf den Zusammenbruch des Partikelnetzwerkes und nicht, wie allgemein beschrieben auf zu geringe Messzeiten zurück zu führen ist. Darüber hinaus wird der produzierenden Industrie, durch Abwandlung und Kombination zweier Messvorschriften ein Werkzeug zur Versatzentwicklung und Qualitätskontrolle, auch ohne die Notwendigkeit des Erwerbs von hochpräzisen Forschungsrheometern bereitgestellt.

L’objectif de cette thèse est d’étudier l’influence de la température sur la thixotropie des bétons autoplaçants (BAP). L’intérêt de ce travail s’inscrit dans la perspective d’optimiser les formulations des BAP dans une large gamme de température. Un plan factoriel composite centré a été adopté dans le but de minimiser le nombre d’essais tout en étudiant les effets des facteurs (température et dosage en agent de viscosité (AV)) et leurs interactions sur les propriétés rhéologiques des BAP.La première phase de l’étude consistait à quantifier la thixotropie du béton juste après le malaxage et durant la période dormante en fonction du dosage en AV à des températures comprises entre 11.3 et 30.7°C selon le protocole proposé par Wallevik sur le rhéomètre BML4. Les résultats ont montré que l’indice de thixotropie présente un minimum respectivement pour un dosage en AV de 0.28 % (par rapport à la masse d’eau) et une température de 24°C. Cependant, ce protocole ne permet pas d’étudier la déstructuration des BAP, facteur recherché par exemple dans les coulages multicouches. Nous avons donc été amenés à retenir un protocole utilisé dans les gels et appelé protocole Dolz. L’application de ce dernier aux pâtes de ciment et aux BAP a permis de mettre en évidence une nouvelle grandeur, le potentiel de déstructuration K. Les valeurs du potentiel K montrent qu’au delà d’un certain dosage en AV et d’une certaine température, apparaissent des phénomènes d’encombrement qui réduisent le potentiel K. Ainsi, le potentiel K apporte des informations complémentaires pour l’aide à la sélection de dosages adéquats du couple superplastifiant – agent de viscosité en fonction de la température de coulage. / The aim of this thesis was to study the influence of the temperature on the thixotropy of self-consolidating concrete (SCC). The research significance comes within the perspective to optimize the design of SCC in a wide range temperature. A factorial composite experimental plan was carried out in order to minimize the total number of tests while studying the effects of factors (temperature and dosage of viscosity modifying admixture (VMA)) and their interactions on the rheological properties of SCC. The first phase of the study was to quantify the thixotropy of concrete proportioned with various dosage of VMA at different temperatures ranging from 11.3 to 30.7°C just after mixing and at different time during the dormant period using the protocol proposed by Wallevik in BML4 rheometer. The results indicated that the values of thixotropy index present a minimum respectively with a VMA dosage of 0.28 % (by mass of water) and a temperature of 24°C.On the other hand, this protocol does not allow studying the destructuration of SCC, useful factor needed for example in the multi-layer casting. We therefore had to retain a protocol used in gels and called Dolz protocol. The application of this last to cement pastes and SCC has revealed a new grandeur, the potential of destructuration K. The values of K show that beyond a certain dosage in VMA and a certain temperature, the congestion phenomena appear that reduce the potential K. In this case, the potential of destructuration provides complementary information to assist in the selection of appropriate dosages of couple superlasticizer-VMA whatever the casting temperature may be.

This diploma thesis investigates the suitability of relaxation tests as a part of complex characterization of hydrogel materials using classical rheology methods. With respect to the current research, creep and three interval thixotropy tests were taken into account. For them, general optimization was done aiming to find an ideal parameter settings. The optimization was performed using physically crosslinked agarose (AG) hydrogel and the tuned tests were also applied to two more samples: hyaluronan (HyA) and polyvinyl alcohol (PVAl) gel. These materials were selected due to their mutually different crosslinking principle. The experiments showed, the AG gel proved to have the best ability to recover after deformation of all studied samples. On the other hand, the HyA gel relaxed the worst. Although the final results of both tests were comparable, the regeneration process itself was different. Hence, the complex relaxation characteristics cannot be described using one of the performed tests alone and both the creep and three interval thixotropy tests have great importance in the scope of complex relaxation behaviour. The obtained results may lead to more precise description of deformation and relaxation, which are frequent phenomena occurring during treatment and application of hydrogel materials.

Předložená diplomová práce je zaměřená na studium viscoelastického chování kostních past na bázi fosforečnanu vápenatého a vodného roztoku termosenzitivního triblokového kopolymeru, zlepšujícího tokové vlastnosti pasty. V teoretické části je zpracována stručná charakteristika cementů na bázi fosforečnanu vápenatého. Rovněž se zabývá charakteristikou reologických vlastností injektabilních kostních past. Součástí je také stručný přehled aditiv ovlivňujících právě reologické a mechanické vlastnosti past. Experimentální část je zaměřena na charakterizaci triblokového kopolymeru pomocí nukleární magnetické rezonanční spektroskopie a reologie. Dále byly připravovány modifikované fosfátové cementy, u kterých byly posléze studovány viskoelastické vlastnosti. Kostní pasta byla modifikována přídavkem adhezivních sloučenin (dopamin a jodičnan sodný) a antibakteriálním činidlem (selenové nanočástice). Analýza viskoelastických vlastností byla provedena reologickou analýzou, během níž byl primárně sledován proces vytvrzování a tixotropní chování jak nemodifikovaných, tak modifikovaných fosfátových past. Proces vytvrzování probíhal při teplotě 23 °C a 37 °C, imitující fyziologické prostředí. Morfologie fosfátové keramiky byla charakterizována pomocí rastrovací elektronové mikroskopie a velikost částic byla zjištěna pomocí laserového analyzátoru částic. Bylo prokázáno, že výše zmíněná aditiva mají pozitivní vliv na kinetiku procesu vytvrzování kostních past. Selenové nanočástice navíc vylepšily tixotropní chování polymer-fosfátových past. Z tohoto důvodu jsou tyto nové injektabilní kompozitní pasty vhodné pro miniinvazivní chirurgii. Díky aditivům, vykazujících adhezivní vlastnosti, mají potenciál uplatnit se při léčbě zlomenin. Stejně tak se nabízí možnost využít pasty při léčbě osteomyelitidy, a to díky možnému uvolňování antibakteriálních nanočástic.

Solides élastiques au repos, les fluides à seuil s’écoulent comme un liquide au-delà d’une certaine contrainte. Plusieurs applications industrielles concernent l’écoulement de ces fluides dans des milieux poreux. On peut citer par exemple les émulsions dans le processus de récupération du pétrole, les opérations de cimentation dans le sol, ou le nettoyage d’un sol contaminé par une boue. Pour ces applications, il est nécessaire de connaitre la pression nécessaire pour un débit voulu à la sortie du milieu poreux. Dans de tels cas, l’écoulement est perturbé par la complexité de la géométrie. Les modèles développés pour décrire la loi de Darcy supposent une loi rhéologique appliquée localement, mais ces modèles décrivent mal ce type d’écoulement. De plus, des effets complexes peuvent s’ajouter comme le glissement à la paroi ou la thixotropie. Dans cette thèse, nous étudions l’écoulement de carbopol (ETD 2050) à travers différentes géométries. Tout d’abord au rhéomètre, nous montrons que le fluide, sous certaines conditions, correspond bien à un fluide à seuil modèle. Nous démontrons que le protocole expérimental utilisé est très important et qu’un comportement thixotropique peut apparaitre s’il n’est pas respecté. Ce comportement apparait notamment lorsque le fluide reste sous le seuil, l’impact augmentant avec le temps d’attente. Ensuite, nous comparons la loi d’écoulement obtenue au rhéomètre à l’écoulement dans un canal droit obtenu par microfabrication. Nous montrons alors l’importance du glissement proche du seuil et ses conséquences sur la loi d’écoulement. Enfin nous étudions l’écoulement du carbopol dans un milieu poreux. Le milieu poreux de 5x5cm est obtenu par microfabrication. La largeur moyenne des canaux est égale à celle du canal droit. Nous avons développé une nouvelle méthode de mesure des champs de vitesse. Nous montrons l’apparition d’une chenalisation de l’écoulement à travers quelques canaux du milieu poreux. Nous comparons ensuite la loi d’écoulement du milieu poreux à celle obtenue dans le canal droit. On remarque que la vitesse d’écoulement est plus faible dans le milieu poreux que dans le canal droit. / Elastic solids at rest, yield stress fluids flow like a liquid beyond a certain stress. Many industrial applications required the flow of these fluids in porous media, for example: the emulsion flow in oil recovery processes, the cementing operations in the ground, or the cleaning of sludge in a contaminated soil. For many applications, it could be interesting to know the pressure required for a desired flow rate. In such cases, the flow behavior of the fluid is complicated by the complexity of the geometry. The models developed to describe Darcy's law assume a rheological law applied locally, but these models poorly describe this type of flow. Furthermore, complex effects can be added like the wall slip or the thixotropy. In this thesis, we study the flow of carbopol (ETD 2050) through different geometries. First we show that the fluid, for some conditions, corresponds to model yield stress fluids. The experimental protocol used is very important and a thixotropic behavior can appear if it is not respected. This behavior appears especially when the fluid remains below the yield stress, the impact increases with the waiting time. We then compare the flow law obtained by rheometer in a straight channel obtained by microfabrication. We show the importance of the wall slip near the yield stress and the impact on the flow law. Finally, using a new method to measure the velocity fields developed during this thesis, we study the flow of carbopol in a porous medium. This porous medium of 5x5cm is obtained by microfabrication. The mean width of the channels is equivalent to the one of the straight channel. We show the emergence of a channeling flow through some channels of the porous medium. We then compare the flow law of the porous medium to the one obtained in the straight channel. It can be observed that the flow rate is lower in the porous medium than in the straight channel.

The present dissertation investigates the flow behavior of concentrated Kaolin slurries and furthermore novel rheological measurement-, analysis-, and assessment procedures for characterizing static and dynamic flow behavior in industrial and research applica- tions. Ten different Kaolins with divergent property profiles were investigated in detail. At first, novel measurement and analysis procedures are presented and the raw material inherent properties are correlated with the resulting flow characteristics. The results describe the structural building and breakdown (in both static and dynamic states) of concentrated Kaolin slurry suspensions with and without deflocculant and also the determination of the point of optimal deflocculant concentration through the develop- ment of a novel analysis method and linking of the parameters to a condition matrix. The results lead to a better understanding of the flow behavior of concentrated Kaolin slurries. Due to the use of a strict measurement protocol with a focus on the elimination of external disturbances on the determination of flow behavior, the phases of dynamic structure construction and destruction (with exclusion of temporal structure effects and vice versa) can be analyzed. It was identified that the construction of particle networks requires less energy than their destruction. Furthermore it could be demonstrated that the occurrence of a transient shear stress peak in kaolin slurries is the cause for the breakdown of an existing particle network and not, as conventionally reported, due to an insufficient measurement time. Moreover, through the combination and modification of two measurement protocols described here, manufacturing companies have a potentially useful tool for composition development and quality control without the necessity of purchasing a highly precise research rheometer.:1. Einleitung und Problembeschreibung 1 2. Stand des Wissen 3 2.1. ToneundKaoline.............................. 4 2.1.1. EntstehungvonKaolinen...................... 5 2.1.2. KaolinalsRohstoff ......................... 6 2.1.3. DasMineralKaolinit........................ 6 2.2. BeschreibungderRheologie ........................ 8 2.2.1. DasZwei-Platten-Modell...................... 8 2.2.2. FließverhaltenundModelle .................... 9 2.2.3. Messsgeräte und Systeme für die Messung rheologischer Eigen- schaften ............................... 16 2.2.4. RheometrischeMessmethoden................... 21 2.3. ElektrostatischstabilisierteDispersionen . . . . . . . . . . . . . . . . . 25 2.4. Tonmineral-Wasser-Interaktionen ..................... 28 2.5. FließverhaltenvonKaolindispersionen................... 30 3. Rohstoffuntersuchungen 31 3.1. Reindichtebestimmung ........................... 31 3.2. Partikelgrößenanalyse............................ 32 3.2.1. SedimentationimSchwerefeld ................... 33 3.2.2. Laserbeugungs-Partikelgrößenanalyse . . . . . . . . . . . . . . . 34 3.3. SpezifischeOberfläche ........................... 35 3.4. BestimmungderlöslichenSalze ...................... 36 3.5. Kationenaustauschkapazität ........................ 37 3.6. Röntgenfluoreszenzanalyse ......................... 37 3.7. Röntgenbeugungsanalyse.......................... 38 4. Experimentelle Methodik 40 4.1. NormativeMineralphasenanalyse ..................... 40 ii 4.2. BerechnungderPartikelgrößenverteilung . . . . . . . . . . . . . . . . . 4.2.1. AuswertungnachDingerundFunk ................ 4.2.2. DasRRSB-Modell ......................... 4.3. HerstellungderDispersionen........................ 4.4. RheologischeUntersuchungen ....................... 4.4.1. DasMalvernKinexuspro+ .................... 4.4.2. Messmethode zur Bestimmung der Zeitabhängigkeit . . . . . . . 4.4.3. Messmethode zur Bestimmung der Belastungsabhängigkeit . . . 4.5. AuswertungdesSprungversuches ..................... 4.6. AuswertungderScherratenrampe ..................... 5. Wiederholbarkeit der entwickelten Messregime 6. Anpassung der Messregime an industrielle Bedingungen 6.1. RohrströmungeinerPotenzflüssigkeit ................... 6.2. NachweisderMesssystemfähigkeit..................... 7. Versuchsreihenentwicklung 7.1. UntersuchungdesFeststoffanteileinflusses. . . . . . . . . . . . . . . . . 7.2. Untersuchung des Einflusses des Verflüssigeranteils . . . . . . . . . . . . 8. Ergebnisse und Diskussion 8.1. Einfluss der Rohstoffparameter auf das Fließverhalten . . . . . . . . . . 8.1.1. Einfluss der Partikelgrößenverteilung . . . . . . . . . . . . . . . 8.1.2. EinflussderPGV-Modellparameter ................ 8.1.3. Einfluss der spezifischen Oberfläche auf das Fließverhalten . . . 8.1.4. Einfluss der Rohstoffmineralogie auf das Fließverhalten . . . . . 8.2. Untersuchung des Dispergierhilfsmitteleinfusses . . . . . . . . . . . . . 8.3. UntersuchungdesFeststoffanteileinflusses. . . . . . . . . . . . . . . . . 9. Modellierung der belastungsabhängigen Fließeigenschaften 10.Zusammenfassung und Ausblick Literaturverzeichnis Anhang / In der vorliegenden Arbeit wird das Fließverhalten von konzentrierten Kaolinsuspensio- nen untersucht und neuartige rheologische Mess-, Analyse- und Bewertungsverfahren zur Charakterisierung der Belastungs- und Zeitabhängigkeit für Industrie- und Forschungsanwendungen vorgestellt. Hierzu wurden zehn Kaoline mit divergierenden Eigenschaftsprofilen untersucht. Zunächst werden neuartige Mess- und Analyseverfahren vorgestellt und die Eigenschaften der Rohstoffe mit den ermittelten Fließcharakteristika korreliert. Die Ergebnisse beschreiben den strukturellen Auf- und Abbau (zeit- und belastungsabhängig) von konzentrierten Kaolinsuspensionen mit und ohne Dispergierhilfsmitteleinsatz und darüber hinaus die Ermittlung der optimalen Dispergierhilfsmittelkonzentration durch Entwicklung einer neuartigen Analyse und Verknüpfung von Parametern an eine Bedingungsmatrix. Die Erkenntnisse tragen zum besseren Verständnis des Fließverhaltens konzentrierter Kaolinsuspensionen bei. Aufgrund der entwickelten Messvorschriften und der darin elementar verankerten Elimination von Störgrößen auf die Ermittlung des Fließverhaltens konnten die Phasen des strukturellen Auf- und Abbaus unter Belastung (unter Ausschluss von temporalen Struktureffekten und umgekehrt) analysiert werden. Es wurde festgestellt, dass die Konstruktion von Partikelnetzwerken weniger Energie benötigt, als deren Destruktion und das Auftreten des Schubspannungshügels auf den Zusammenbruch des Partikelnetzwerkes und nicht, wie allgemein beschrieben auf zu geringe Messzeiten zurück zu führen ist. Darüber hinaus wird der produzierenden Industrie, durch Abwandlung und Kombination zweier Messvorschriften ein Werkzeug zur Versatzentwicklung und Qualitätskontrolle, auch ohne die Notwendigkeit des Erwerbs von hochpräzisen Forschungsrheometern bereitgestellt.:1. Einleitung und Problembeschreibung 1 2. Stand des Wissen 3 2.1. ToneundKaoline.............................. 4 2.1.1. EntstehungvonKaolinen...................... 5 2.1.2. KaolinalsRohstoff ......................... 6 2.1.3. DasMineralKaolinit........................ 6 2.2. BeschreibungderRheologie ........................ 8 2.2.1. DasZwei-Platten-Modell...................... 8 2.2.2. FließverhaltenundModelle .................... 9 2.2.3. Messsgeräte und Systeme für die Messung rheologischer Eigen- schaften ............................... 16 2.2.4. RheometrischeMessmethoden................... 21 2.3. ElektrostatischstabilisierteDispersionen . . . . . . . . . . . . . . . . . 25 2.4. Tonmineral-Wasser-Interaktionen ..................... 28 2.5. FließverhaltenvonKaolindispersionen................... 30 3. Rohstoffuntersuchungen 31 3.1. Reindichtebestimmung ........................... 31 3.2. Partikelgrößenanalyse............................ 32 3.2.1. SedimentationimSchwerefeld ................... 33 3.2.2. Laserbeugungs-Partikelgrößenanalyse . . . . . . . . . . . . . . . 34 3.3. SpezifischeOberfläche ........................... 35 3.4. BestimmungderlöslichenSalze ...................... 36 3.5. Kationenaustauschkapazität ........................ 37 3.6. Röntgenfluoreszenzanalyse ......................... 37 3.7. Röntgenbeugungsanalyse.......................... 38 4. Experimentelle Methodik 40 4.1. NormativeMineralphasenanalyse ..................... 40 ii 4.2. BerechnungderPartikelgrößenverteilung . . . . . . . . . . . . . . . . . 4.2.1. AuswertungnachDingerundFunk ................ 4.2.2. DasRRSB-Modell ......................... 4.3. HerstellungderDispersionen........................ 4.4. RheologischeUntersuchungen ....................... 4.4.1. DasMalvernKinexuspro+ .................... 4.4.2. Messmethode zur Bestimmung der Zeitabhängigkeit . . . . . . . 4.4.3. Messmethode zur Bestimmung der Belastungsabhängigkeit . . . 4.5. AuswertungdesSprungversuches ..................... 4.6. AuswertungderScherratenrampe ..................... 5. Wiederholbarkeit der entwickelten Messregime 6. Anpassung der Messregime an industrielle Bedingungen 6.1. RohrströmungeinerPotenzflüssigkeit ................... 6.2. NachweisderMesssystemfähigkeit..................... 7. Versuchsreihenentwicklung 7.1. UntersuchungdesFeststoffanteileinflusses. . . . . . . . . . . . . . . . . 7.2. Untersuchung des Einflusses des Verflüssigeranteils . . . . . . . . . . . . 8. Ergebnisse und Diskussion 8.1. Einfluss der Rohstoffparameter auf das Fließverhalten . . . . . . . . . . 8.1.1. Einfluss der Partikelgrößenverteilung . . . . . . . . . . . . . . . 8.1.2. EinflussderPGV-Modellparameter ................ 8.1.3. Einfluss der spezifischen Oberfläche auf das Fließverhalten . . . 8.1.4. Einfluss der Rohstoffmineralogie auf das Fließverhalten . . . . . 8.2. Untersuchung des Dispergierhilfsmitteleinfusses . . . . . . . . . . . . . 8.3. UntersuchungdesFeststoffanteileinflusses. . . . . . . . . . . . . . . . . 9. Modellierung der belastungsabhängigen Fließeigenschaften 10.Zusammenfassung und Ausblick Literaturverzeichnis Anhang

[pt] Muitas suspensões de partículas se comportam como materiais tixotrópicos e estão presente em muitos processos industriais, incluindo aplicações de revestimentos de filmes finos. Especificamente, operações de extrusão de fluidos tixotrópicos estão envolvidos na produção de eletrodos de baterias. Na maioria dos casos, o escoamento de suspensões de partículas é descrito por modelos independentes no tempo, que assumem que a viscosidade como uma função somente da taxa local de deformação local. No entanto, a viscosidade dos fluidos tixotrópicos é associada com a evolução do seu nível de microestruturação que não muda instantaneamente com a tensão (ou taxa de deformação). No caso da imposição de uma tensão constante (ou taxa de cisalhamento), a microstrutura evolui até alcançar um estado de equilíbrio, porém este processo leva tempo. Mesmo em escoamentos em regime permanente, o líquido escoa através de regiões onde tem mudanças significativas nos níveis de tensão, sendo assim o escoamento transiente de um ponto de vista Lagrangiano. Então, assumir que a viscosidade, em todo ponto do escoamento, é à viscosidade em regime permanente pode gerar uma descrição errada do escoamento. A magnitude relativa do tempo de resposta do líquido e do seu tempo de residência torna-se num parâmetro importante, especialmente em escoamentos em pequena escala com tempos de residência muito curtos. O escoamento de um líquido tixotrópico através de um microcapilar com constrição e no processo de revestimento por extrusão foram analisados aqui, usando dois modelos reológicos: um modelo independente no tempo (TIM) e um modelo tixotrópico que leva em conta a resposta transiente do líquido. O conjunto de equações não lineares foi resolvido utilizando o método de Galerkin/SUPG de elementos finitos. Os resultados mostram que o uso de um modelo simples TIM para descrever materiais tixotrópicos, como suspensões de partículas, pode levar a erros muito significativos na predição do comportamento de escoamento. Além disso, os modelos independentes no tempo não têm a capacidade de predizer certos fenômenos de escoamento, como a histerese, que pode gerar escoamentos instáveis. Essas imprecisões indicam a necessidade de usar um modelo mais completo que considere a resposta transiente do líquido. / [en] Many particle suspensions behave as thixotropic-viscous materials and they are present in different industrial processes, including coating applications. Specifically, the production of battery electrodes involves slot coating of a thixotropic liquid. In most cases, the flow of slurries and other particle suspensions is described by using a time-independent model that assumes the viscosity to be solely a function of the local deformation rate. However, the viscosity of thixotropic fluids is associated to the evolution of its microstructuring level, which does not change instantaneously with the shear stress (or deformation rate). In the case of imposing constant shear stress (or shear rate), the microstructure evolves until reaching an equilibrium state; but this process takes time. Even in a steady-state flow, the liquid flows through regions where there are significant changes in the levels of shear stress and the flow is transient in a Lagrangian point of view. Therefore, assuming that the viscosity at each point of the flow is the steady-state viscosity described by a time-independent model may lead to an inaccurate flow description. The relative magnitude of the characteristic response time of the liquid and the residence time of the flow becomes an important parameter. This is particularly relevant in small scale flows with very small residence time. Flows of a thixotropic-viscous liquid through a constricted microcapillary and in a slot coating process were analyzed here using two rheological models: a time-independent model (TIM) and a thixotropic model that takes into account the liquid time-dependent response. The resulting set of fully coupled, non-linear equations was solved by the Galerkin and SUPG Finite Element Method. The results show that the use of a TIM to describe thixotropic viscous materials, such as some particle suspensions, can lead to very large errors on the predicted flow behavior. Furthermore, time-independent models are not able to predict complex flow phenomena, like hysteresis, which could lead to unstable flows. These inaccuracies highlight the need for a more complete model that takes into account time-dependency of the flowing liquid in a certain range of flow parameters.

The rheological properties of cement-based grouts play a key role in determining the final spread in grouted rock formations. Rheologically, cement grouts are known to be complex thixotropic fluids, but their steady flow behavior is often described by fitting the simple Bingham constitutive law to flow curve data. The resultant Bingham parameters are then used in grouting design of e.g. tunnels, to estimate the penetration length. Since cement grouts are thixotropic suspensions, the interpretation of their flow curves as obtained from flow sweeps in concentric cylinder rotational rheometers is often complicated by: the presence of wall slip, sedimentation and unstable flow at low shear rates. A systematic approach to study these effects within the constraints of the concentric cylinder geometry (Couette) and for different cement grout concentrations was carried out as part of the Licentiate research work. Of particular interest was the influence of geometry and flow sweep measurement interval on flow curves, including the characteristic unstable flow branch that appears at applied shear rates that are below the critical shear rate. The unstable flow branch observed below the critical shear rate has been described as a characteristic feature in the flow curves of thixotropic suspensions, e.g. cement grouts, laponite. From a practical standpoint, this information can then be readily used to improve rheological measurements of cement grouts. The existence of the critical shear rate below which no stable flow occurs, plus the complex wall slip phenomenon are then discussed by considering how they affect actual spread in rough and smooth rock fractures. Another major part of the research presented in this thesis relates to the measurement of model yield stress fluid (YSF), i.e. Carbopol, velocity profiles within the radial flow geometry. Radial flow between parallel plates, is an idealized fundamental flow configuration that is often used as a basis for grout spread estimation in planar rock fractures. Compared to other flow configurations with YSFs, e.g. channels, only a limited amount of work has presented analytical solutions, numerical models and especially experimental work for radial flow. Thus, as a first step towards more systematic studies of the plug flow region of YSFs in radial flow the current work presents the design, manufacture and for the first time velocity profile measurements that were conducted by using the pulsed Ultrasound Velocity Profiling (UVP) technique. The current observations for tests carried out with different disk spacings and flow rates show a distinct plug region, coupled with wall slip effects for the Carbopol model YSF fluid that was used. The theoretically predicted velocity profiles and the measured ones agree reasonably well, and the main discrepancies are discussed. Future studies, would then be targeted at improving the current experimental setup, for detailed measurements of the plug flow region along the radial length, which remains a challenging issue for studies on YSFs and engineering applications such as rock grouting design. / Cementbaserade injekteringsmedels reologiska egenskaper har en stor påverkan på strömning och inträngningslängd i sprickigt berg. Medlens reologi är komplex, inklusive tixotropi, men strömningen beskrivs ändå oftast med den enkla linjära Bingham modellen i injekteringssammanhang. De två parametrarna från denna modell, flytgräns och viskositet, används sedan inom injekteringsdesign, för t.ex. tunnlar och dammar, för att bedöma inträngningen. Eftersom cementbaserade medel är tixoptropa suspensioner försvåras utvärderingen vid mätning med konventionella rotationsviskometrar på grund av glidning vid fasta begränsningsytor, sedimentation/separation av partiklarna och instabila flöden vid låga deformationshastigheter. En systematisk mätprocedur för att studera ovanstående problem med rotationsviskometer och koncentriska cylindrar samt olika vanliga vattencementtal, har utförts inom ramen för detta licentiatarbete. Av särskilt intresse har varit att studera effekten av olika geometrier och tidsintervallet mellan mätningarna, inklusive den instabila delen av flödeskurvan då deformationshastigheten är lägre än ett kritiskt värde. Denna del av kurvan har i litteraturen beskrivits som karakteristisk för tixotropa suspensioner, som t.ex. cementbaserade injekteringsmedel. Praktiskt kan ovanstående kunskap användas för att förbättra mätningen av de reologiska egenskaperna. Existensen av en kritisk deformationshastighet under vilken det inte finns något stabilt flöde, i kombination med glidning vid fasta begränsningsytor, diskuteras särskilt med hänsyn till dess påverkan på faktisk inträngning i släta och råa bergsprickor. Ett annat fokus i licentiatarbetet har varit att studera icke-Newtonska modellvätskors (Carbopol) radiella strömning mellan parallella plattor. Denna typ av strömningsgeometri används ofta som en idealiserad konfiguration för strömning i bergsprickor. I jämförelse med andra enklare geometrier, finns endast en begränsad forskning utförd för denna geometri både då det gäller analytiska och numeriska beräkningar men framförallt då det gäller experiment. Som ett första steg inför en mer systematisk undersökning av icke-Newtonsk radiella strömning presenteras i detta arbete framtagandet av en fysisk laboratoriemodell där hastighetsprofilerna mellan plattorna för första gången visualiserats med hjälp av ultraljud. De utförda mätningarna med tre olika öppningar mellan plattorna sam tre olika värden på det konstanta flödet, visar på en distinkt plugg som är ett resultat av vätskans flytgräns samt glidning i gränsskiktet mellan vätskan och plattornas fasta begränsningsytor. En jämförelse mellan uppmätta hastighetsprofiler och analytiskt beräknade diskuteras där resultaten överensstämmer relativt väl, med beaktande av de långtgående förenklade antaganden som krävs för beräkningarna. Fortsatta studier kommer att fokuseras på att förbättra laboratoriemodellen för en mer detaljerad studie av icke-Newtonska vätskors strömning och hur pluggen utvecklas under den radiella inträngningen, vilket fortsättningsvis är av betydelse för design av injektering i bergsprickor. / <p>QC 20190521</p>