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The number of people suffering from the unpleasant symptoms of allergic rhinitis is increasing due to environmental and other factors. This not only makes life difficult for the individual but also places a heavy burden on society, which is why treatment is needed. Rhinocort® is a nasal spray suspension manufactured by McNeil AB to reduce the severity of symptoms, and like all medicines, must undergo quality testing. One of these tests is viscosity measurement, which currently is only carried out 6-10 days after production. Therefore, the aim of my thesis was to increase the understanding of the rheology of Rhinocort® and to suggest strategies for shortening the waiting period prior to the viscosity assessment. A rotational rheometer was used to determine the viscosity of the product. Various methods were set up to evaluate the temperature dependence, recovery, and robustness of the product. In addition, tests were carried out to investigate the influence of different shaking times prior to the measurements. As sedimentation is a recurring phenomenon in the product, this was assessed by amplitude, frequency sweep, and particle size distribution tests. Placebos were also formulated to achieve a higher initial viscosity. All experiments were successful, as higher viscosity values were achieved by increasing the storage temperature. It was also found that the regeneration of the product after disturbance only takes less than one hour and the suspension itself is incredibly stable. Increasing the shaking time has been shown to have a negative effect on viscosity as it leads to structural destruction. Sedimentation has been shown to start as early as day 0, but this has nothing to do with the overall quality of the product as shown by particle size distribution tests. Additionally, a placebo formulation was done to see if a higher initial viscosity could be achieved by altering the sodium-carboxymethyl-cellulose (NaCMC) content, the excipient responsible for increasing v, The focus of my thesis work was Rhinocort®, which is a nasal spray for allergy treatment, which is a highly abundant disease and is often undertreated, thus can lead to missed school, -or workdays. Rhinocort® must be tested before it is marketed to ensure good quality and patient safety; one of these tests includes measuring its viscosity. The viscosity value must be within a certain acceptance limit for the product to be marketable, which is 5.0 - 8.5 mPas. Viscosity can be best understood as the resistance to flow; when we compare the flow properties of honey and water, we can conclude that honey is more viscous as it is much harder to pour out of the jar. Rhinocort® has a so-called thixotropic behaviour, which was assessed throughout some experiments. A thixotropic material becomes less viscous as the force applied to it increases, and this also depends on how long it is exposed to this force. According to the current test method, 10 days must pass by after production before viscosity tests can be carried out, which leads to high storage costs and hinders production. Therefore, my thesis aimed to shorten this period to save resources and money. Together seven different types of experiments were executed. For examining the temperature dependence and shaking time dependence, some scientific articles served as the basis, as these suggested an increase in viscosity by lowering the temperature and shortening the time of disturbance (shaking). The product’s flow behaviour and its resistance toward mechanical interferences were assessed by various tests, as well as the re-occurring problem, called sedimentation. Furthermore, placebos (the product without the active pharmaceutical ingredient) were mixed to experiment with achieving a higher initial viscosity value.

The fresh superfine-tailings cemented paste backfill (SCPB) exhibits strong thixotropy, but quantification of the resulting transient flow (non-steady state) and time-dependent yield stress is lacking. In this study, a simple qualitative model was developed to describe the transient flow and time-dependent yield stress of SCPB. The effect of pre-shear time on the rheological behavior of SCPB was investigated. In addition, the adaptability of conventional non-Newtonian rheological models to SCPB was also evaluated. The results showed the Herschel-Bulkley model provides the most stable dynamic yield stress estimation of SCPB compared to the Bingham and modified Bingham models. A longer pre-shear time (within 500 s) led to smaller initial static yield stress and delayed recovery kinetics of static yield stress, but hardly affected the steady state of SCPB and the time required to reach it. The proposed model provides a good quantification of the transient flow at a given shear rate and time-dependent yield stress of SCPB., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Rivers, Ports, Waterways and Dredging Engineering

Self-Compacting Concrete (SCC) offers favourable properties which help accelerate the casting time, especially in congested reinforced structures but when casting with SCC uncertainty remains a challenge on the behaviour of its formwork pressure. Researchers have introduced several design models to predict pressure and its behaviour. This research aims to assess the design models that have been reported in the literature. The assessment was carried out through a series of rigorous laboratory tests and the results from the tests served as input for the mathematical model evaluation. Twelve concrete columns with 2 m height were cast in the laboratory to study the effect of varying the input parameters in the existing design models. The formwork pressure was documented by a pressure monitoring system, with the capacity to produce instant results for real-time remote monitoring of the pressure development during and after concrete casting. The formwork pressures were calculated according to the current design models and were compared with pressure data acquitted from the laboratory tests. The results showed that the pressure predicted by the design models was typically greater than the pressure observed during the laboratory tests. The DIN18218 design model showed a relatively close approximation of the pressure distribution over the formwork height and casting time. The limitation of the models is observed when the casting rate varies, and models are sensitive to the input parameters. Thus, additional development of the current design models is needed to enable reliable estimations of the pressure, for example, in the case of low and high casting rates. The laboratory tests also showed that high casting rates and high slump flows generate higher pressures whereas higher thixotropy results in faster pressure reduction during construction., Validerad;2023;Nivå 2;2023-03-08 (joosat);Funder: NCC ABLicens fulltext: CC BY License

Self-Compacting Concrete (SCC) offers favourable properties which help accelerate the casting time, especially in congested reinforced structures but when casting with SCC uncertainty remains a challenge on the behaviour of its formwork pressure. Researchers have introduced several design models to predict pressure and its behaviour. This research aims to assess the design models that have been reported in the literature. The assessment was carried out through a series of rigorous laboratory tests and the results from the tests served as input for the mathematical model evaluation. Twelve concrete columns with 2 m height were cast in the laboratory to study the effect of varying the input parameters in the existing design models. The formwork pressure was documented by a pressure monitoring system, with the capacity to produce instant results for real-time remote monitoring of the pressure development during and after concrete casting. The formwork pressures were calculated according to the current design models and were compared with pressure data acquitted from the laboratory tests. The results showed that the pressure predicted by the design models was typically greater than the pressure observed during the laboratory tests. The DIN18218 design model showed a relatively close approximation of the pressure distribution over the formwork height and casting time. The limitation of the models is observed when the casting rate varies, and models are sensitive to the input parameters. Thus, additional development of the current design models is needed to enable reliable estimations of the pressure, for example, in the case of low and high casting rates. The laboratory tests also showed that high casting rates and high slump flows generate higher pressures whereas higher thixotropy results in faster pressure reduction during construction., Validerad;2023;Nivå 2;2023-03-08 (joosat);Funder: NCC ABLicens fulltext: CC BY License

Dysphagia affects a person's ability to swallow, and it causes health problems by directly limiting nutritional intake, being the elderly the most at-risk group and also likely to be deficient in nutrition. Diets for patients with dysphagia require textural modifications to offer soft and safe food to swallow. Puree is easily consumed by the elderly, being an alternative food preparation providing essential nutrition for people with dysphagia. In this study, we aimed to create different formulations with soy protein and agar added to potato puree to add nutritional value and end up with printable material by designing food for the elderly and people with dysphagia. Some enriched potato puree formulations were obtained by adding soy protein (3%, 5%, and 7%) and up to 0.2% agar. The use of three-dimensional food printing allows visual customization with appeal benefits of nutritional food formulations for specific consumers. The rheology and texture profile analysis of the different formulations has been performed. According to International Dysphagia Diet Standardisation Initiative (IDDSI) scales, the texture of all modified samples was suitable for people with swallowing difficulties. The samples with agar presented a better-printed shape and a more viscous-like behavior than the samples with soy protein. These findings highlight that soy protein could modify the texture and, from the nutritional point of view, add value to the formulations. The addition of 0.2% agar can establish good material for designing three-dimensional (3D)-printed food that allows the creation of textures in accordance with the needs of the elderly and people with dysphagia., Peer Reviewed, Postprint (published version)

Purpose The presence of organic matter in cohesive sediment results in the formation of clay-organic flocs, which eventually impart complex rheological behavior including shear-thinning, viscoelasticity, thixotropy and two-step yielding to mud. In this study, the influence of microbial degradation of sediment organic matter on the rheological properties of mud samples, having similar densities, was examined. Materials and methods Mud samples were collected from three different locations in the Port of Hamburg, Germany, displaying varying organic matter content. The rheological analysis of fresh and degraded mud samples was performed with the help of several tests including stress ramp-up tests, amplitude sweep tests, frequency sweep tests, time-dependent tests, and structural recovery tests. Results and discussion The results showed a significant decrease in rheological properties including yield stresses, complex modulus, etc. for degraded mud samples as compared to the fresh mud samples. The slopes of the line, correlating the change (degraded − fresh) in the above-mentioned rheological properties as a function of the same rheological property of the fresh mud, varied within the range of −0.28 to −0.49. The structural recovery tests displayed a better recovery (i.e., stronger system) in mud after the pre-shearing step for the degraded mud samples as compared to the fresh mud samples. The effect of degradation time on the rheological properties of mud samples showed two critical time periods (3 days and 150 days) after which a significant change in rheological properties of mud samples was observed. Conclusions This study provided a useful understanding about the influence of organic matter degradation on the rheological properties of mud, which can be used to optimize sediment management strategies in ports and waterways., Rivers, Ports, Waterways and Dredging Engineering, Geo-engineering, Environmental Fluid Mechanics

The final publication is available at Springer via http://dx.doi.org/10.1617/s11527-022-01936-6, This paper discusses the analysis of uniaxial tension–compression cyclic strain sweep test results for the characterisation of bituminous materials. The test results of one bitumen and two mastics, at different oxidative ageing levels, at three different temperatures are used in the study. The damage mechanisms leading to failure were shown to vary with the temperature, and the transition from slow to fast damage accumulation could be clearly seen in the evolution plots of different mechanical variables with loading cycles. It was shown that the plot of test results in the Black diagram provides an excellent viewpoint for the damage and non-damage related mechanisms affecting the material’s response to increasing loading amplitude. Before significant damage has accumulated in the specimen, the stiffness modulus-phase angle curve, at different temperatures, follows very closely the linear viscoelastic curve of the undamaged material, and heating was identified as the most important reversible mechanism. The thixotropic effect was clearly observed in mastics. The curve shape during fast progression to failure was related to the level of deformation around the crack zone. The slope of the stiffness modulus-phase angle curve was found to provide a consistent indicator of the material’s resistance to cumulative loading, as it is sensitive to the material’s ageing state and the test temperature, and a unique relationship between this factor and the number of cycles to failure was found for all materials and test conditions., Peer Reviewed, Postprint (author's final draft)

Dysphagia patients might need to thicken drinks. The viscosity of these thickened drinks varies among commercial thickeners and drinks compromising the ingesta safety. The aim of this study was to investigate how temperature and resting time affect the rheological properties of thickened drinks. Four commercial thickeners were used to thicken water, coffee, orange juice, and milk at two concentration levels used in dysphagia drinks (nectar and pudding). To study the effect of temperature, flow curves of thickened drinks at 10°C and 50°C were obtained and to study the effect of resting time, flow curves of thickened drinks at 25°C were obtained at different times (0, 30, and 60 min). All samples displayed shear-thinning and time-dependent behavior (thixotropy or antithixotropy). The effect of temperature on viscosity values and relative thixotropic area (RTA) depended on the thickener and the drink. Overall, apparent viscosity showed higher values at 50°C than 10°C, especially in thickeners containing starch and in drinks with higher soluble solids (milk and orange juice). This was attributed to the water absorption of pregelatinized starch granules favored by temperature. Antithixotropy was mainly observed at pudding concentration for the starch-containing thickeners, and decreased with temperature. The effect of resting time on apparent viscosity and RTA depended also on the drink and thickener. Mostly, apparent viscosity values increased with resting time and antithixotropic behavior decreased. Both effects, increase in viscosity and decrease of antithixotropy with time, indicated that thickening action was being developed over the resting time.

Este proyecto tiene como objetivo desarrollar un estudio reológico de la aleación de aluminio A356 durante su formación en estado semisólido, mediante el proceso de rheocasting, para ser utilizada en una máquina de impresión de piezas en 3D. A través de la investigación teórica y experimentación, se pretende controlar los parámetros que influyen en la calidad final del material y conseguir que obtenga mejoras en sus propiedades mecánicas. Se define lo que es un material en estado semisólido, sus características principales y su relación con la fabricación de piezas en la industria. Se estudia el concepto de reología examinando a fondo sus propiedades más relevantes y se hace una revisión de la viscosidad y de la clasificación de los fluidos existentes. Se citan ejemplos de rutas de tixo y rheo casting empleadas en la industria del conformado de SSM y se discute el papel que cumplen las aleaciones de aluminio en este contexto. Se describe el intento de realización de la fase experimental, consistida en analizar la morfología y el comportamiento de los parámetros del A356 fundido y sometido a varios experimentos a diferentes velocidades y tiempo de agitación mecánica. Se especifican los problemas sucedidos en este periodo y se discute propuestas de mejora para sus futuras y/o posibles soluciones. Se lleva a cabo el diseño de una mesa de altura regulable cumpliendo con los requerimientos del departamento de ciencia de materiales de la universidad EPSEVG y se describen los impactos positivos y negativos que este proyecto puede ser capaz de ocasionar al medioambiente. Por último, se informa los aspectos más relevantes que han sido observados y que se deben de tener en cuenta en los proyectos posteriores y relacionados con este. En conclusión, debido a problemas eléctricos y mecánicos que se presentan durante el montaje y desmontaje del prototipo PMSM, no se alcanza realizar la parte experimental de esta investigación. Sin embargo, se logra entender la teoría del procesam, The objective of this project is to develop a rheological study of the aluminum alloy A356 during its formation in semi-solid state, by means of the rheocasting process, to be used in a 3D printing machine. Through theoretical research and experimentation, the aim is to control the parameters that influence the final quality of the material and to obtain improvements in its mechanical properties. It is defined what is a material in semi-solid state, its main characteristics and its relation with the manufacture of parts in the industry. The concept of rheology is studied by examining in depth its most relevant properties and a review of viscosity and the classification of existing fluids is made. Examples of thixo and rheo casting routes employed in the SSM forming industry are cited and the role of aluminum alloys in this context is discussed. The attempt to perform the experimental phase, consisting of analyzing the morphology and parameter behavior of molten A356 subjected to various experiments at different speeds and mechanical stirring time, is described. The problems that occurred during this period are specified and improvement proposals for future and/or possible solutions are discussed. The design of a height adjustable table is carried out in compliance with the requirements of the materials science department of the EPSEVG university and the positive and negative impacts that this project may be able to cause to the environment are described. Finally, the most relevant aspects that have been observed and that should be taken into account in subsequent projects related to this one are reported. In conclusion, due to electrical and mechanical problems that occurred during the assembly and disassembly of the PMSM prototype, the experimental part of this research could not be carried out. However, it is possible to understand the theory of the processing of parts in semi-solid state and how the rheological parameters can affect the final quality of the eleme

Purpose The presence of organic matter in cohesive sediment results in the formation of clay-organic flocs, which eventually impart complex rheological behavior including shear-thinning, viscoelasticity, thixotropy and two-step yielding to mud. In this study, the influence of microbial degradation of sediment organic matter on the rheological properties of mud samples, having similar densities, was examined. Materials and methods Mud samples were collected from three different locations in the Port of Hamburg, Germany, displaying varying organic matter content. The rheological analysis of fresh and degraded mud samples was performed with the help of several tests including stress ramp-up tests, amplitude sweep tests, frequency sweep tests, time-dependent tests, and structural recovery tests. Results and discussion The results showed a significant decrease in rheological properties including yield stresses, complex modulus, etc. for degraded mud samples as compared to the fresh mud samples. The slopes of the line, correlating the change (degraded − fresh) in the above-mentioned rheological properties as a function of the same rheological property of the fresh mud, varied within the range of −0.28 to −0.49. The structural recovery tests displayed a better recovery (i.e., stronger system) in mud after the pre-shearing step for the degraded mud samples as compared to the fresh mud samples. The effect of degradation time on the rheological properties of mud samples showed two critical time periods (3 days and 150 days) after which a significant change in rheological properties of mud samples was observed. Conclusions This study provided a useful understanding about the influence of organic matter degradation on the rheological properties of mud, which can be used to optimize sediment management strategies in ports and waterways., Rivers, Ports, Waterways and Dredging Engineering, Geo-engineering, Environmental Fluid Mechanics

The rheological properties of cement-based grouts play a crucial role indetermining the final spread in grouted rock formations. In rheological terms,cement grouts are known to be complex time-dependent yield stress fluids,but their steady flow behavior is often described by the simple Binghamconstitutive law. The Bingham parameters obtained from the linear curvefitting to flow curve data are then used in grout propagation calculationsduring the design phase, e.g., for rock fracture grouting in tunnel construction.Since cement grouts are time-dependent and thixotropic suspensions, theinterpretation of their flow curves during conventional rotational rheometryis often complicated by the presence of wall slip, thixotropy, flow localization,and sedimentation, particularly at low shear rates. A systematic approachwas carried out as part of the research work to study these effects within theconstraints of the concentric cylinder geometry (Couette) and for differentcement grout concentrations. Of particular interest were the influence ofgeometry and flow sweep measurement interval on flow curves, includingthe characteristic unstable flow branch that appears at applied shear ratesthat are below the critical shear rate. The unstable flow branch observedbelow the critical shear rate has been described as a characteristic feature inthe flow curves of thixotropic suspensions, e.g., cement grouts and laponite.From a practical standpoint, these crucial shear rate aspects, including wallslip, have not been considered during grouting design calculations whileusing the common Bingham model. Thus, the research also considered theseshear rate aspects as part of grouting design by incorporating them into thedesign approach within the existing framework of the Real Time GroutingControl (RTGC) method. Another interesting part of the research work presented in this thesis relatesto studies on the radial flow of yield stress fluids. The radial flow betweenparallel plates is an idealized f, Cementbaserade injekteringsmedels reologiska egenskaper har en stor påver-kan på strömning och inträngningslängd i sprickigt berg. Medlens reologi ärkomplex, inklusive tixotropi, men strömningen och inträngningen beskrivsändå oftast med den enkla linjära Bingham modellen i injekteringssam-manhang. De två parametrarna från denna modell, flytgräns och viskositet,används sedan inom injekteringsprojektering, för t.ex. tunnlar och dam-mar, för att bedöma inträngningen. Eftersom cementbaserade medel ärtixoptropa suspensioner försvåras utvärderingen vid mätning med konventio-nella rotationsviskometrar på grund av glidning vid fasta begränsningsytor,sedimentation/separation av partiklarna och instabila flöden vid låga defor-mationshastigheter. En systematisk mätprocedur för att studera ovanståendeproblem med rotationsviskometer och koncentriska cylindrar samt olika van-liga vattencementtal, har utförts inom ramen för detta doktorandarbete.Av särskilt intresse har varit att studera effekten av olika geometrier ochtidsintervallet mellan mätningarna, inklusive den instabila delen av flödes-kurvan då deformationshastigheten är lägre än ett kritiskt värde. Dennadel av kurvan har i litteraturen beskrivits som karakteristisk för tixotropasuspensioner, som t.ex. cementbaserade injekteringsmedel. Praktiskt kanovanstående kunskap användas för att förbättra mätningen av de reologiskaegenskaperna. Existensen av en kritisk deformationshastighet under vilkendet inte finns något stabilt flöde, i kombination med glidning vid fasta be-gränsningsytor, diskuteras särskilt med hänsyn till dess påverkan på faktiskinträngning i släta och råa bergsprickor. Ett annat fokus i doktorandarbetet har varit att studera icke-Newtonskamodellvätskors (Carbopol) radiella strömning mellan parallella plattor. Den-na typ av strömningsgeometri används ofta som en idealiserad konfigurationför strömning i bergsprickor. I jämförelse med andra enklare geometrier,finns endast en begränsad forskning utförd för denna, QC 211110

When a ship reaches the shore, the water depth reduces and thus the under-keel clearance also reduces. The ship keel clearance influences the maneuverability of the sailing ship. In this thesis project, the link between the fluid mud rheology and its density is first investigated. The exponential relation reformulated between the density and yield stress necessitates the direct measurement of rheology for navigability. It was confirmed true that the yield strength grows exponentially with the density of the fluid mud. However, at higher densities of mud, more thixotropy is observed in the flow curves. Besides, the Power-law relations were found for the relation with volumetric concentration, for yield stress in agreement with fractal dimension theory. Second, quantification of the thixotropy effect of fluid mud is conducted to justify the importance of the time-dependency effect in the rheological modeling. We found that an unremolded fluid mud has high thixotropy even at high shear rates. However, diluted and remolded fluid mud at high shear rates found a negligible thixotropy effect. We also observed that Houska's modeling curve coincides perfectly with the flow curve of fluid mud at high shear rates, and also it integrates the thixotropy into the modeling. Third, the total resistance of a plate moving through fluid mud is measured and compared to the frictional forces calculated using the available analytical formulas of a plate moving in Bingham fluids and Power-law fluids. The moving plate is an abstraction of a vessel's keel sailing through the fluid mud. We found that the total resistance of the plate moved in fluid mud at low velocity agrees with the frictional force of a plate moved in Bingham fluids. As the velocity increases, the stagnation pressure becomes significant, and the deviation of the total resistance of plate and frictional force of a plate increases. Thus, to estimate the total resistance of a plate moved in mud, nor, Offshore and Dredging Engineering

Accurate rheological characterisation of sewage waste activated sludge (WAS) is of high importance for downstream processing related to optimised sludge pumping and mixing, assessment of energy demands and overall process design. However, to elaborate rheological behaviour is often challenging under dynamic operational conditions in practice. In this study, two practical influencing factors were investigated: long-term shearing and temperature. Compared to anaerobic digestate (DGT), concentrated WAS had more complex and stronger thixotropic behaviour. Under the long-term shearing conditions, the sludge thixotropic behaviour was well characterised by two quantified limitation states. Temperature had a striking impact on the rheological properties, which was strongly correlated to solids content and digestion process. The impact discrepancy between the long-term shearing and temperature, implied different mechanisms to shift the equilibrium of hydrodynamic and non-hydrodynamic interactions for structure deformation and recovery. The distinct rheological properties between the two determined states were clearly reflected in pipe flow behaviour, revealing a concrete link between lab-measured sludge rheology and its practical flow performance. The pipe flows were well assessed using the developed Computational Fluid Dynamics model with effective rheological data integration, which is promising for practical design and optimisation of sewage sludge systems., ChemE/Transport Phenomena, Sanitary Engineering, Environmental Fluid Mechanics

The extrusion of highly filled elastomers is widely used in the automotive industry. In this paper, we numerically study the effect of thixotropy on 2D planar extrudate swell for constant and fluctuating flow rates, as well as the effect of thixotropy on the swell behavior of a 3D rectangular extrudate for a constant flowrate. To this end, we used the Finite Element Method. The state of the network structure in the material is described using a kinetic equation for a structure parameter. Rate and stress-controlled models for this kinetic equation are compared. The effect of thixotropy on extrudate swell is studied by varying the damage and recovery parameters in these models. It was found that thixotropy in general decreases extrudate swell. The stress-controlled approach always predicts a larger swell ratio compared to the rate-controlled approach for the Weissenberg numbers studied in this work. When the damage parameter in the models is increased, a less viscous fluid layer appears near the die wall, which decreases the swell ratio to a value lower than the Newtonian swell ratio. Upon further increasing the damage parameter, the high viscosity core layer becomes very small, leading to an increase in the swell ratio compared to smaller damage parameters, approaching the Newtonian value. The existence of a low-viscosity outer layer and a high-viscosity core in the die have a pronounced effect on the swell ratio for thixotropic fluids.

In this paper, an experimental strategy is presented to characterize the rheological behavior of filled, uncured rubber compounds. Oscillatory shear experiments on a regular plate-plate rheometer are combined with a phenomenological thixotropy model to obtain model parameters that can be used to describe the steady shear behavior. We compare rate- and stress-controlled kinetic equations for a structure parameter that determines the deformation history-dependent spectrum and, thus, the dynamic thixotropic behavior of the material. We keep the models as simple as possible and the characterization straightforward to maximize applicability. The model can be implemented in a finite element framework as a tool to simulate realistic rubber processing. This will be the topic of another work, currently under preparation. In shaping processes, such as rubber- and polymer extrusion, with realistic processing conditions, the range of shear rates is far outside the range obtained during rheological characterization. Based on some motivated choices, we will present an approach to extend this range.

The rheological properties of cement-based grouts play a crucial role indetermining the final spread in grouted rock formations. In rheological terms,cement grouts are known to be complex time-dependent yield stress fluids,but their steady flow behavior is often described by the simple Binghamconstitutive law. The Bingham parameters obtained from the linear curvefitting to flow curve data are then used in grout propagation calculationsduring the design phase, e.g., for rock fracture grouting in tunnel construction.Since cement grouts are time-dependent and thixotropic suspensions, theinterpretation of their flow curves during conventional rotational rheometryis often complicated by the presence of wall slip, thixotropy, flow localization,and sedimentation, particularly at low shear rates. A systematic approachwas carried out as part of the research work to study these effects within theconstraints of the concentric cylinder geometry (Couette) and for differentcement grout concentrations. Of particular interest were the influence ofgeometry and flow sweep measurement interval on flow curves, includingthe characteristic unstable flow branch that appears at applied shear ratesthat are below the critical shear rate. The unstable flow branch observedbelow the critical shear rate has been described as a characteristic feature inthe flow curves of thixotropic suspensions, e.g., cement grouts and laponite.From a practical standpoint, these crucial shear rate aspects, including wallslip, have not been considered during grouting design calculations whileusing the common Bingham model. Thus, the research also considered theseshear rate aspects as part of grouting design by incorporating them into thedesign approach within the existing framework of the Real Time GroutingControl (RTGC) method. Another interesting part of the research work presented in this thesis relatesto studies on the radial flow of yield stress fluids. The radial flow betweenparallel plates is an idealized f, Cementbaserade injekteringsmedels reologiska egenskaper har en stor påver-kan på strömning och inträngningslängd i sprickigt berg. Medlens reologi ärkomplex, inklusive tixotropi, men strömningen och inträngningen beskrivsändå oftast med den enkla linjära Bingham modellen i injekteringssam-manhang. De två parametrarna från denna modell, flytgräns och viskositet,används sedan inom injekteringsprojektering, för t.ex. tunnlar och dam-mar, för att bedöma inträngningen. Eftersom cementbaserade medel ärtixoptropa suspensioner försvåras utvärderingen vid mätning med konventio-nella rotationsviskometrar på grund av glidning vid fasta begränsningsytor,sedimentation/separation av partiklarna och instabila flöden vid låga defor-mationshastigheter. En systematisk mätprocedur för att studera ovanståendeproblem med rotationsviskometer och koncentriska cylindrar samt olika van-liga vattencementtal, har utförts inom ramen för detta doktorandarbete.Av särskilt intresse har varit att studera effekten av olika geometrier ochtidsintervallet mellan mätningarna, inklusive den instabila delen av flödes-kurvan då deformationshastigheten är lägre än ett kritiskt värde. Dennadel av kurvan har i litteraturen beskrivits som karakteristisk för tixotropasuspensioner, som t.ex. cementbaserade injekteringsmedel. Praktiskt kanovanstående kunskap användas för att förbättra mätningen av de reologiskaegenskaperna. Existensen av en kritisk deformationshastighet under vilkendet inte finns något stabilt flöde, i kombination med glidning vid fasta be-gränsningsytor, diskuteras särskilt med hänsyn till dess påverkan på faktiskinträngning i släta och råa bergsprickor. Ett annat fokus i doktorandarbetet har varit att studera icke-Newtonskamodellvätskors (Carbopol) radiella strömning mellan parallella plattor. Den-na typ av strömningsgeometri används ofta som en idealiserad konfigurationför strömning i bergsprickor. I jämförelse med andra enklare geometrier,finns endast en begränsad forskning utförd för denna, QC 211110

The rheological properties of cement-based grouts play a crucial role indetermining the final spread in grouted rock formations. In rheological terms,cement grouts are known to be complex time-dependent yield stress fluids,but their steady flow behavior is often described by the simple Binghamconstitutive law. The Bingham parameters obtained from the linear curvefitting to flow curve data are then used in grout propagation calculationsduring the design phase, e.g., for rock fracture grouting in tunnel construction.Since cement grouts are time-dependent and thixotropic suspensions, theinterpretation of their flow curves during conventional rotational rheometryis often complicated by the presence of wall slip, thixotropy, flow localization,and sedimentation, particularly at low shear rates. A systematic approachwas carried out as part of the research work to study these effects within theconstraints of the concentric cylinder geometry (Couette) and for differentcement grout concentrations. Of particular interest were the influence ofgeometry and flow sweep measurement interval on flow curves, includingthe characteristic unstable flow branch that appears at applied shear ratesthat are below the critical shear rate. The unstable flow branch observedbelow the critical shear rate has been described as a characteristic feature inthe flow curves of thixotropic suspensions, e.g., cement grouts and laponite.From a practical standpoint, these crucial shear rate aspects, including wallslip, have not been considered during grouting design calculations whileusing the common Bingham model. Thus, the research also considered theseshear rate aspects as part of grouting design by incorporating them into thedesign approach within the existing framework of the Real Time GroutingControl (RTGC) method. Another interesting part of the research work presented in this thesis relatesto studies on the radial flow of yield stress fluids. The radial flow betweenparallel plates is an idealized f, Cementbaserade injekteringsmedels reologiska egenskaper har en stor påver-kan på strömning och inträngningslängd i sprickigt berg. Medlens reologi ärkomplex, inklusive tixotropi, men strömningen och inträngningen beskrivsändå oftast med den enkla linjära Bingham modellen i injekteringssam-manhang. De två parametrarna från denna modell, flytgräns och viskositet,används sedan inom injekteringsprojektering, för t.ex. tunnlar och dam-mar, för att bedöma inträngningen. Eftersom cementbaserade medel ärtixoptropa suspensioner försvåras utvärderingen vid mätning med konventio-nella rotationsviskometrar på grund av glidning vid fasta begränsningsytor,sedimentation/separation av partiklarna och instabila flöden vid låga defor-mationshastigheter. En systematisk mätprocedur för att studera ovanståendeproblem med rotationsviskometer och koncentriska cylindrar samt olika van-liga vattencementtal, har utförts inom ramen för detta doktorandarbete.Av särskilt intresse har varit att studera effekten av olika geometrier ochtidsintervallet mellan mätningarna, inklusive den instabila delen av flödes-kurvan då deformationshastigheten är lägre än ett kritiskt värde. Dennadel av kurvan har i litteraturen beskrivits som karakteristisk för tixotropasuspensioner, som t.ex. cementbaserade injekteringsmedel. Praktiskt kanovanstående kunskap användas för att förbättra mätningen av de reologiskaegenskaperna. Existensen av en kritisk deformationshastighet under vilkendet inte finns något stabilt flöde, i kombination med glidning vid fasta be-gränsningsytor, diskuteras särskilt med hänsyn till dess påverkan på faktiskinträngning i släta och råa bergsprickor. Ett annat fokus i doktorandarbetet har varit att studera icke-Newtonskamodellvätskors (Carbopol) radiella strömning mellan parallella plattor. Den-na typ av strömningsgeometri används ofta som en idealiserad konfigurationför strömning i bergsprickor. I jämförelse med andra enklare geometrier,finns endast en begränsad forskning utförd för denna, QC 211110

The rheological properties of cement-based grouts play a crucial role indetermining the final spread in grouted rock formations. In rheological terms,cement grouts are known to be complex time-dependent yield stress fluids,but their steady flow behavior is often described by the simple Binghamconstitutive law. The Bingham parameters obtained from the linear curvefitting to flow curve data are then used in grout propagation calculationsduring the design phase, e.g., for rock fracture grouting in tunnel construction.Since cement grouts are time-dependent and thixotropic suspensions, theinterpretation of their flow curves during conventional rotational rheometryis often complicated by the presence of wall slip, thixotropy, flow localization,and sedimentation, particularly at low shear rates. A systematic approachwas carried out as part of the research work to study these effects within theconstraints of the concentric cylinder geometry (Couette) and for differentcement grout concentrations. Of particular interest were the influence ofgeometry and flow sweep measurement interval on flow curves, includingthe characteristic unstable flow branch that appears at applied shear ratesthat are below the critical shear rate. The unstable flow branch observedbelow the critical shear rate has been described as a characteristic feature inthe flow curves of thixotropic suspensions, e.g., cement grouts and laponite.From a practical standpoint, these crucial shear rate aspects, including wallslip, have not been considered during grouting design calculations whileusing the common Bingham model. Thus, the research also considered theseshear rate aspects as part of grouting design by incorporating them into thedesign approach within the existing framework of the Real Time GroutingControl (RTGC) method. Another interesting part of the research work presented in this thesis relatesto studies on the radial flow of yield stress fluids. The radial flow betweenparallel plates is an idealized f, Cementbaserade injekteringsmedels reologiska egenskaper har en stor påver-kan på strömning och inträngningslängd i sprickigt berg. Medlens reologi ärkomplex, inklusive tixotropi, men strömningen och inträngningen beskrivsändå oftast med den enkla linjära Bingham modellen i injekteringssam-manhang. De två parametrarna från denna modell, flytgräns och viskositet,används sedan inom injekteringsprojektering, för t.ex. tunnlar och dam-mar, för att bedöma inträngningen. Eftersom cementbaserade medel ärtixoptropa suspensioner försvåras utvärderingen vid mätning med konventio-nella rotationsviskometrar på grund av glidning vid fasta begränsningsytor,sedimentation/separation av partiklarna och instabila flöden vid låga defor-mationshastigheter. En systematisk mätprocedur för att studera ovanståendeproblem med rotationsviskometer och koncentriska cylindrar samt olika van-liga vattencementtal, har utförts inom ramen för detta doktorandarbete.Av särskilt intresse har varit att studera effekten av olika geometrier ochtidsintervallet mellan mätningarna, inklusive den instabila delen av flödes-kurvan då deformationshastigheten är lägre än ett kritiskt värde. Dennadel av kurvan har i litteraturen beskrivits som karakteristisk för tixotropasuspensioner, som t.ex. cementbaserade injekteringsmedel. Praktiskt kanovanstående kunskap användas för att förbättra mätningen av de reologiskaegenskaperna. Existensen av en kritisk deformationshastighet under vilkendet inte finns något stabilt flöde, i kombination med glidning vid fasta be-gränsningsytor, diskuteras särskilt med hänsyn till dess påverkan på faktiskinträngning i släta och råa bergsprickor. Ett annat fokus i doktorandarbetet har varit att studera icke-Newtonskamodellvätskors (Carbopol) radiella strömning mellan parallella plattor. Den-na typ av strömningsgeometri används ofta som en idealiserad konfigurationför strömning i bergsprickor. I jämförelse med andra enklare geometrier,finns endast en begränsad forskning utförd för denna, QC 211110

The extrusion of highly filled elastomers is widely used in the automotive industry. In this paper, we numerically study the effect of thixotropy on 2D planar extrudate swell for constant and fluctuating flow rates, as well as the effect of thixotropy on the swell behavior of a 3D rectangular extrudate for a constant flowrate. To this end, we used the Finite Element Method. The state of the network structure in the material is described using a kinetic equation for a structure parameter. Rate and stress-controlled models for this kinetic equation are compared. The effect of thixotropy on extrudate swell is studied by varying the damage and recovery parameters in these models. It was found that thixotropy in general decreases extrudate swell. The stress-controlled approach always predicts a larger swell ratio compared to the rate-controlled approach for the Weissenberg numbers studied in this work. When the damage parameter in the models is increased, a less viscous fluid layer appears near the die wall, which decreases the swell ratio to a value lower than the Newtonian swell ratio. Upon further increasing the damage parameter, the high viscosity core layer becomes very small, leading to an increase in the swell ratio compared to smaller damage parameters, approaching the Newtonian value. The existence of a low-viscosity outer layer and a high-viscosity core in the die have a pronounced effect on the swell ratio for thixotropic fluids.

Дисертаційна робота присвячена вивченню закономірностей контрольованого регулювання реологічних властивостей воднодисперсних лакофарбових матеріалів з функціональними наповнювачами та загусниками різних розмірів та формою часток і фізико-хімічними властивостями в присутності ПАР. Досліджено реологічні властивості водних дисперсій силікатів в залежності від їх структурної групи, анізотропії часток, стану та енергії поверхні, відношенню до води, здатності до агрегації тощо. Порівняно ступінь впливу ПАР різного хімічного типу і призначення з поверхнею силікатів. Встановлено найефективніші синергетичні пари наповнювач-загусник для підвищення тиксотропних властивостей ВДФ. Розроблено та оптимізовано рецептури лакофарбових матеріалів на основі синергетичних пар силікатний наповнювач-загусник в присутності модифікатора поверхні з контрольованими реологічними властивостями та опосередковано покращеними параметрами бар’єрних властивостей та міцності покриття. Протестовані основні експлуатаційні характеристики лакофарбових покриттів, такі як адгезія до ряду різних субстратів, міцність покриття, бар’єрні властивості, стійкість до УФ- випромінювання, паропроникність тощо. Здійснено промислову реалізацію розроблених складів реологічних лакофарбових матеріалів у вигляді випуску дослідної партії в об'ємі 15 тон та їх випробування в умовах експлуатації.

Дисертаційна робота присвячена вивченню закономірностей контрольованого регулювання реологічних властивостей воднодисперсних лакофарбових матеріалів з функціональними наповнювачами та загусниками різних розмірів та формою часток і фізико-хімічними властивостями в присутності ПАР. Досліджено реологічні властивості водних дисперсій силікатів в залежності від їх структурної групи, анізотропії часток, стану та енергії поверхні, відношенню до води, здатності до агрегації тощо. Порівняно ступінь впливу ПАР різного хімічного типу і призначення з поверхнею силікатів. Встановлено найефективніші синергетичні пари наповнювач-загусник для підвищення тиксотропних властивостей ВДФ. Розроблено та оптимізовано рецептури лакофарбових матеріалів на основі синергетичних пар силікатний наповнювач-загусник в присутності модифікатора поверхні з контрольованими реологічними властивостями та опосередковано покращеними параметрами бар’єрних властивостей та міцності покриття. Протестовані основні експлуатаційні характеристики лакофарбових покриттів, такі як адгезія до ряду різних субстратів, міцність покриття, бар’єрні властивості, стійкість до УФ- випромінювання, паропроникність тощо. Здійснено промислову реалізацію розроблених складів реологічних лакофарбових матеріалів у вигляді випуску дослідної партії в об'ємі 15 тон та їх випробування в умовах експлуатації., The dissertation work is devoted to the study of the regularities of the controlled regulation of the rheological properties of water-dispersed paints and varnishes with functional fillers and thickeners of various sizes and particle shapes and physicochemical properties in the presence of surfactants. When performing the work, modern and reliable instrumental methods of quantitative and qualitative analysis were used (IR spectroscopy, X-ray structural and X-ray fluorescence analysis, sedimentation studies, force electron microscopy, determination of the specific surface area using the BET method, a comprehensive study of the surface properties of minerals by the Deryagin method, studies of the structural and mechanical properties of suspensions and dispersed on the Rheotest - II device). It is known that silicate fillers, depending on their crystalline structure, have different particle shapes. A wide anisotropic variety of particles significantly affects the structural and mechanical properties of suspensions and dispersions filled with silicates. In addition to the various forms of particles, silicates, depending on the structure of the package, have a high energy potential and active groups on the surface determine their ability to adsorb and interact with South Africa, thickeners and polymer latex. Modification of aqueous dispersions of silicates with surfactants of various nature has been carried out. In particular, the efficiency of reducing the adsorptioncoagulation structure of fillers with the addition of anionic ammonium polyacrylate and potassium methylsiliconate, nonionic siloxane polyester and cationic cetyltrimethylammonium bromide was investigated. It was revealed that the highest efficiency was shown by ammonium polyacrylate. To improve rheological properties, in particular, to provide thixotropic properties to paints and varnishes, high molecular weight thickeners were added to the model formulations. Thickeners were combined with fillers in terms

Accurate rheological characterisation of sewage waste activated sludge (WAS) is of high importance for downstream processing related to optimised sludge pumping and mixing, assessment of energy demands and overall process design. However, to elaborate rheological behaviour is often challenging under dynamic operational conditions in practice. In this study, two practical influencing factors were investigated: long-term shearing and temperature. Compared to anaerobic digestate (DGT), concentrated WAS had more complex and stronger thixotropic behaviour. Under the long-term shearing conditions, the sludge thixotropic behaviour was well characterised by two quantified limitation states. Temperature had a striking impact on the rheological properties, which was strongly correlated to solids content and digestion process. The impact discrepancy between the long-term shearing and temperature, implied different mechanisms to shift the equilibrium of hydrodynamic and non-hydrodynamic interactions for structure deformation and recovery. The distinct rheological properties between the two determined states were clearly reflected in pipe flow behaviour, revealing a concrete link between lab-measured sludge rheology and its practical flow performance. The pipe flows were well assessed using the developed Computational Fluid Dynamics model with effective rheological data integration, which is promising for practical design and optimisation of sewage sludge systems., ChemE/Transport Phenomena, Sanitary Engineering, Environmental Fluid Mechanics

In this paper, an experimental strategy is presented to characterize the rheological behavior of filled, uncured rubber compounds. Oscillatory shear experiments on a regular plate-plate rheometer are combined with a phenomenological thixotropy model to obtain model parameters that can be used to describe the steady shear behavior. We compare rate- and stress-controlled kinetic equations for a structure parameter that determines the deformation history-dependent spectrum and, thus, the dynamic thixotropic behavior of the material. We keep the models as simple as possible and the characterization straightforward to maximize applicability. The model can be implemented in a finite element framework as a tool to simulate realistic rubber processing. This will be the topic of another work, currently under preparation. In shaping processes, such as rubber- and polymer extrusion, with realistic processing conditions, the range of shear rates is far outside the range obtained during rheological characterization. Based on some motivated choices, we will present an approach to extend this range.

The rheological properties of cement-based grouts play a crucial role indetermining the final spread in grouted rock formations. In rheological terms,cement grouts are known to be complex time-dependent yield stress fluids,but their steady flow behavior is often described by the simple Binghamconstitutive law. The Bingham parameters obtained from the linear curvefitting to flow curve data are then used in grout propagation calculationsduring the design phase, e.g., for rock fracture grouting in tunnel construction.Since cement grouts are time-dependent and thixotropic suspensions, theinterpretation of their flow curves during conventional rotational rheometryis often complicated by the presence of wall slip, thixotropy, flow localization,and sedimentation, particularly at low shear rates. A systematic approachwas carried out as part of the research work to study these effects within theconstraints of the concentric cylinder geometry (Couette) and for differentcement grout concentrations. Of particular interest were the influence ofgeometry and flow sweep measurement interval on flow curves, includingthe characteristic unstable flow branch that appears at applied shear ratesthat are below the critical shear rate. The unstable flow branch observedbelow the critical shear rate has been described as a characteristic feature inthe flow curves of thixotropic suspensions, e.g., cement grouts and laponite.From a practical standpoint, these crucial shear rate aspects, including wallslip, have not been considered during grouting design calculations whileusing the common Bingham model. Thus, the research also considered theseshear rate aspects as part of grouting design by incorporating them into thedesign approach within the existing framework of the Real Time GroutingControl (RTGC) method. Another interesting part of the research work presented in this thesis relatesto studies on the radial flow of yield stress fluids. The radial flow betweenparallel plates is an idealized f, Cementbaserade injekteringsmedels reologiska egenskaper har en stor påver-kan på strömning och inträngningslängd i sprickigt berg. Medlens reologi ärkomplex, inklusive tixotropi, men strömningen och inträngningen beskrivsändå oftast med den enkla linjära Bingham modellen i injekteringssam-manhang. De två parametrarna från denna modell, flytgräns och viskositet,används sedan inom injekteringsprojektering, för t.ex. tunnlar och dam-mar, för att bedöma inträngningen. Eftersom cementbaserade medel ärtixoptropa suspensioner försvåras utvärderingen vid mätning med konventio-nella rotationsviskometrar på grund av glidning vid fasta begränsningsytor,sedimentation/separation av partiklarna och instabila flöden vid låga defor-mationshastigheter. En systematisk mätprocedur för att studera ovanståendeproblem med rotationsviskometer och koncentriska cylindrar samt olika van-liga vattencementtal, har utförts inom ramen för detta doktorandarbete.Av särskilt intresse har varit att studera effekten av olika geometrier ochtidsintervallet mellan mätningarna, inklusive den instabila delen av flödes-kurvan då deformationshastigheten är lägre än ett kritiskt värde. Dennadel av kurvan har i litteraturen beskrivits som karakteristisk för tixotropasuspensioner, som t.ex. cementbaserade injekteringsmedel. Praktiskt kanovanstående kunskap användas för att förbättra mätningen av de reologiskaegenskaperna. Existensen av en kritisk deformationshastighet under vilkendet inte finns något stabilt flöde, i kombination med glidning vid fasta be-gränsningsytor, diskuteras särskilt med hänsyn till dess påverkan på faktiskinträngning i släta och råa bergsprickor. Ett annat fokus i doktorandarbetet har varit att studera icke-Newtonskamodellvätskors (Carbopol) radiella strömning mellan parallella plattor. Den-na typ av strömningsgeometri används ofta som en idealiserad konfigurationför strömning i bergsprickor. I jämförelse med andra enklare geometrier,finns endast en begränsad forskning utförd för denna, QC 211110

The thixotropy of cellulose nanocrystal (CNC) water suspensions is intrinsically dependent on the hierarchical structure of the suspension. The diverse hierarchies that comprise individual CNC nanoparticles and mesophase liquid crystalline domains, chiral nematic and nematic structures, contribute selectively to the rheological material response. Here, we combine rheology with polarized light imaging (PLI) to elucidate the thixotropic behavior of CNCs suspended in water. The simultaneous monitoring of PLI and rheological tests enables the observation of mesogens and their orientation dynamics. Creep, dynamic time sweep, ramped hysteresis loop, and thixotropic recovery tests combined with PLI aim to differentiate the contribution of the different hierarchical levels of CNC suspensions to their thixotropy. The range of concentrations investigated comprised biphasic (4 and 5 wt. %) and liquid crystalline phase suspensions (6, 7, and 8 wt. %). The CNC suspensions exhibited complex thixotropy behavior, such as viscosity bifurcations in creep tests and overshoot in ramped hysteresis loop tests. The restructuring and destructuring appeared to correspond to different levels of their hierarchical structure, depending mainly on the phase, in agreement with previous studies. Restructuring was attributed to re-organizations of an individual CNC, e.g., in the isotropic fraction of biphasic suspensions and at the mesogen interfaces in liquid crystalline phase suspensions. However, by increasing liquid crystalline fraction in the biphasic concentrations, restructuring could also involve mesogens, as indicated in the creep tests. For flow conditions above the yield stress, as evidenced by the ramped hysteresis and thixotropy recovery tests, destructuring was dominated by orientation in the flow direction, a process that is readily observable in the form of PLI "Maltese-cross" patterns. Finally, we show that a simple thixotropy model, while unable to capture the finer details of the

The thixotropy of cellulose nanocrystal (CNC) water suspensions is intrinsically dependent on the hierarchical structure of the suspension. The diverse hierarchies that comprise individual CNC nanoparticles and mesophase liquid crystalline domains, chiral nematic and nematic structures, contribute selectively to the rheological material response. Here, we combine rheology with polarized light imaging (PLI) to elucidate the thixotropic behavior of CNCs suspended in water. The simultaneous monitoring of PLI and rheological tests enables the observation of mesogens and their orientation dynamics. Creep, dynamic time sweep, ramped hysteresis loop, and thixotropic recovery tests combined with PLI aim to differentiate the contribution of the different hierarchical levels of CNC suspensions to their thixotropy. The range of concentrations investigated comprised biphasic (4 and 5 wt. %) and liquid crystalline phase suspensions (6, 7, and 8 wt. %). The CNC suspensions exhibited complex thixotropy behavior, such as viscosity bifurcations in creep tests and overshoot in ramped hysteresis loop tests. The restructuring and destructuring appeared to correspond to different levels of their hierarchical structure, depending mainly on the phase, in agreement with previous studies. Restructuring was attributed to re-organizations of an individual CNC, e.g., in the isotropic fraction of biphasic suspensions and at the mesogen interfaces in liquid crystalline phase suspensions. However, by increasing liquid crystalline fraction in the biphasic concentrations, restructuring could also involve mesogens, as indicated in the creep tests. For flow conditions above the yield stress, as evidenced by the ramped hysteresis and thixotropy recovery tests, destructuring was dominated by orientation in the flow direction, a process that is readily observable in the form of PLI "Maltese-cross" patterns. Finally, we show that a simple thixotropy model, while unable to capture the finer details of the

Concrete 3D printing introduces a brand-new technic of concrete elements production. The advantages of this technic over the conventional formwork-based method are (1) easier and less costly production of the elements with complex geometry, (2) a higher level of customization, (3) lower concrete and formwork materials waste, and (4) lower rate of manpower injuries. However, there are still several challenges toward the industrialization of concrete 3D printing, one of which is materials engineering. The main objective of this study is to develop cementitious materials that fulfill the two important requirements of the large-scale 3D printing process namely extrudability and buildability. Additionally, this study aims to develop suitable testing methods to refine the optimized cement-based materials subjected to 3D printing. The development of novel test methods to evaluate the rheology of the 3D printing materials is necessary to overcome the inadaptability of the existing testing methods. Indeed, the 3D printing mixtures exhibit a behavior described as extrudable yet stable in shape, thus require customized and adapted test methods to quantify their properties. In addition, the interaction between the material and the robot (3D printer) must be considered. To address this matter, cement-based materials with adapted thixotropic behavior were developed using chemical and mineral additives. Indeed, these materials greatly contribute to solving the problems of extrudability and shape stability of printing materials which have proven to be a major challenge in the case of the material-robot interaction. This study was conducted in 4 different and complementary phases. Phase 1 involved a comprehensive literature review and scanning the major problematics in the field regarding the materials engineering. In addition, a buy-or-make decision analysis was conducted in this phase to evaluate various alternatives to develop a large-scale concrete 3D printer at the U, L'impression 3D béton introduit une toute nouvelle technique de production d'éléments en béton. Les avantages de cette technique par rapport à la méthode de construction conventionnelle basée sur l’utilisation de coffrage sont (1) une production plus facile et moins coûteuse des éléments à géométrie complexe, (2) un niveau de personnalisation plus élevé, (3) moins de déchets de béton et de matériaux de coffrage, et (4 ) un faible risque de blessure de la main-d'œuvre. Cependant, il existe encore plusieurs défis vers l'industrialisation de l'impression 3D du béton, notamment l'ingénierie des matériaux. L'objectif principal de cette étude est de développer des matériaux cimentaires qui répondent aux deux exigences importantes du processus d'impression 3D à grande échelle, à savoir l'extrudabilité et la constructibilité. De plus, l'étude vise à développer des méthodes d'essai appropriées pour affiner les matériaux à base de ciment optimisés soumis à l'impression 3D. Le développement de nouvelles méthodes d’essais pour évaluer la rhéologie des matériaux d'impression 3D est nécessaire pour surmonter l'inadaptabilité des méthodes existantes. En effet, les matériaux imprimables doivent être extrudables (i.e. pompable), mais de forme stable, nécessitent donc des méthodes d’essais personnalisées et adaptées pour quantifier leurs propriétés. De plus, l'interaction entre le matériau et le robot (imprimante 3D) doit être prise en compte. Pour répondre à ce problème, des matériaux cimentaires ayant un comportement thixotropique adapté ont été développés à l'aide des adjuvants et additions minérales. En effet, ces matériaux contribuent grandement à résoudre les problèmes d'extrudabilité et de stabilité de forme des matériaux d'impression, qui se sont avérés être un défi majeur dans le cas de l'interaction matériau-robot. Cette étude est réalisée en quatre différentes phases complémentaires. La Phase 1 comporte une revue de littérature complète et une analyse des principales probl

The rheological properties of fresh cement paste are highly influenced by a large number of parameters, among which the most important factors are the applied shear stress, and the shear history, the age of the sample and the temperature. The effects of these parameters on the yield stress (designated as structural limit stress in this work), the viscosity and the structural recovery rate (i.e., the change in dynamic viscosity with time at rest) were studied. In parallel, the changes in ion composition of the carrier liquid, mineral phase content and granulometry were investigated. The results reveal that all investigated rheological parameters exhibit an approximated bi-linear trend with respect to the degree of hydration, with a period of quasi-constant properties until a degree of hydration of approximately 0.07, followed by a non-linear increase. This increase could be attributed to the formation of calcium hydroxide (CH) and calcium-silicate-hydrate (C-S-H) via calorimetry results. With regard to the effect of the shear history of the sample on the rheological properties, the structural limit stress showed a minor dependency on the shear history immediately after the end of shearing, which, however, vanished within the first minute at rest. The same is true for the structural recovery rate. The presented results give detailed insights into the influences of hydration and shear on the rheological properties-especially the thixotropy-of fresh cement pastes.

Fine glass waste has been found to be a suitable addition to lime mortars because of the high amorphous content. The behavior of fresh air lime mortars and natural hydraulic lime mortars modified by foam glass dust is assessed with the purpose of exploring a new application of this waste dust as lime mortar admixture. The rheological parameters were correlated with relative density measurements, water retention abilities of mortars and air content in mortars. The effect of foam glass dust was found to be dosage-dependent. The fresh mortars behave generally as Hershel–Bulkley fluids with an evolution of the rheological parameters with admixture content. The replacement of lime by foam glass dust caused a reduction in mixing water reducing the yield stress simultaneously; however, the viscosity of the resulting mortars slightly increased. A change in behavior of mortars from shear-thickening to shear-thinning was observed. The natural hydraulic lime based mortars showed a gradual change from thixotropic to rheopectic behavior with increasing glass dust addition. The foam glass dust appears to be well suited to air lime plaster mixtures used in machine thin-layer rendering due to its plasticizing properties, and ability to increase water retention and reduce air content in the mortars.

The effects of agar, alginate, butter, olive oil, and carrots on the mechanical and rheological properties of potato puree prepared by two different cooking methods (microwave heating (MP) and boiling (BP)) were investigated and interpreted in terms of starch microstructural changes. Microscopic observations revealed more aggregated and densely concentrated starch granules in MP samples. This consequently led to a significant increase (p < 0.05) in mechanical and rheological properties up to five times more than BP samples. All samples exhibited shear thinning non-Newtonian behavior, Postprint (published version)

Modification of thermogelling biodegradable copolymers with functional groups enables further covalent crosslinking of physical micelle-based hydrogels formed at specific temperature in water. The resulting hybrid hydrogel network exhibits an increase in stiffness and degradation stability. In this work, synthesized well-defined thermoresponsive alpha,omega-itaconyl-poly(d,l-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) (alpha,omega-itaconyl-PLGA-PEG-PLGA) macromonomers with a high degree of itaconyl-substitution providing free double bonds are photocrosslinked in water at both 25 and 37 degrees C using lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LiTPO) acting as water-soluble non-toxic photoinitiator. The effect of LiTPO on the thixotropic behavior of macromonomer in water at 25 degrees C without irradiation is evaluated. With the addition of a low amount of the photoinitiator (0.1 wt%), the degree of copolymer thixotropy increases. However, further increase in the photoinitiator concentration (0.5-3 wt%) leads to a lower degree of thixotropy. The photoinitiator is presumably interfering with the micellar self-assembly of the copolymer. This trend is also reflected in photocrosslinking efficiency, where the hybrid hydrogel networks with the highest storage moduli are achieved with very low concentrations of the photoinitiator (0.1 wt%) at 25 degrees C, while this trend is reversed at 37 degrees C. The hydrolytic stability of hydrogels prepared at 37 degrees C from 17 wt% macromonomer solution with 1% LiTPO exceeds 22 days., Modifikace termosenzitivních biodegradabilních kopolymerů s funkčními skupinami umožňuje další kovalentní zesíťování fyzikálních hydrogelů na bázi micel vytvořených ve vodě při specifické teplotě. Výsledná hybridní hydrogelová síť vykazuje zvýšení tuhosti a degradační stability. V této práci byly syntetizováné dobře definované termoresponzivní , itaconylPLGAPEGPLGA) makromonomery s vysokým stupněm substituce kyseliny itakonové s volnými dvojnými vazbami, které byly fotosíťovány ve vodě při 25 i 37 ° C v přítonosti ve vodě rozpustného netoxického fotoiniciátoru lithium-fenyl 2,4,6-trimethylbenzoylfosfinátu (LiTPO).

Modification of thermogelling biodegradable copolymers with functional groups enables further covalent crosslinking of physical micelle-based hydrogels formed at specific temperature in water. The resulting hybrid hydrogel network exhibits an increase in stiffness and degradation stability. In this work, synthesized well-defined thermoresponsive alpha,omega-itaconyl-poly(d,l-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) (alpha,omega-itaconyl-PLGA-PEG-PLGA) macromonomers with a high degree of itaconyl-substitution providing free double bonds are photocrosslinked in water at both 25 and 37 degrees C using lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LiTPO) acting as water-soluble non-toxic photoinitiator. The effect of LiTPO on the thixotropic behavior of macromonomer in water at 25 degrees C without irradiation is evaluated. With the addition of a low amount of the photoinitiator (0.1 wt%), the degree of copolymer thixotropy increases. However, further increase in the photoinitiator concentration (0.5-3 wt%) leads to a lower degree of thixotropy. The photoinitiator is presumably interfering with the micellar self-assembly of the copolymer. This trend is also reflected in photocrosslinking efficiency, where the hybrid hydrogel networks with the highest storage moduli are achieved with very low concentrations of the photoinitiator (0.1 wt%) at 25 degrees C, while this trend is reversed at 37 degrees C. The hydrolytic stability of hydrogels prepared at 37 degrees C from 17 wt% macromonomer solution with 1% LiTPO exceeds 22 days., Modifikace termosenzitivních biodegradabilních kopolymerů s funkčními skupinami umožňuje další kovalentní zesíťování fyzikálních hydrogelů na bázi micel vytvořených ve vodě při specifické teplotě. Výsledná hybridní hydrogelová síť vykazuje zvýšení tuhosti a degradační stability. V této práci byly syntetizováné dobře definované termoresponzivní , itaconylPLGAPEGPLGA) makromonomery s vysokým stupněm substituce kyseliny itakonové s volnými dvojnými vazbami, které byly fotosíťovány ve vodě při 25 i 37 ° C v přítonosti ve vodě rozpustného netoxického fotoiniciátoru lithium-fenyl 2,4,6-trimethylbenzoylfosfinátu (LiTPO).

Fine glass waste has been found to be a suitable addition to lime mortars because of the high amorphous content. The behavior of fresh air lime mortars and natural hydraulic lime mortars modified by foam glass dust is assessed with the purpose of exploring a new application of this waste dust as lime mortar admixture. The rheological parameters were correlated with relative density measurements, water retention abilities of mortars and air content in mortars. The effect of foam glass dust was found to be dosage-dependent. The fresh mortars behave generally as Hershel–Bulkley fluids with an evolution of the rheological parameters with admixture content. The replacement of lime by foam glass dust caused a reduction in mixing water reducing the yield stress simultaneously; however, the viscosity of the resulting mortars slightly increased. A change in behavior of mortars from shear-thickening to shear-thinning was observed. The natural hydraulic lime based mortars showed a gradual change from thixotropic to rheopectic behavior with increasing glass dust addition. The foam glass dust appears to be well suited to air lime plaster mixtures used in machine thin-layer rendering due to its plasticizing properties, and ability to increase water retention and reduce air content in the mortars.

Fine glass waste has been found to be a suitable addition to lime mortars because of the high amorphous content. The behavior of fresh air lime mortars and natural hydraulic lime mortars modified by foam glass dust is assessed with the purpose of exploring a new application of this waste dust as lime mortar admixture. The rheological parameters were correlated with relative density measurements, water retention abilities of mortars and air content in mortars. The effect of foam glass dust was found to be dosage-dependent. The fresh mortars behave generally as Hershel–Bulkley fluids with an evolution of the rheological parameters with admixture content. The replacement of lime by foam glass dust caused a reduction in mixing water reducing the yield stress simultaneously; however, the viscosity of the resulting mortars slightly increased. A change in behavior of mortars from shear-thickening to shear-thinning was observed. The natural hydraulic lime based mortars showed a gradual change from thixotropic to rheopectic behavior with increasing glass dust addition. The foam glass dust appears to be well suited to air lime plaster mixtures used in machine thin-layer rendering due to its plasticizing properties, and ability to increase water retention and reduce air content in the mortars.

As a food processing lines manufacturer with diverse product complexity, an understanding of fluid dynamics in a pipe system corresponding to the rheological properties and flow behavior is substantial. This will be beneficial to design suitable equipment and prevent processing-related issues, i.e. lowering filling performance, over-dimensioning pumps, excess energy consumption, etc. Therefore, the objectives of this study were (1) to obtain a better understanding of the time-dependent behavior consisted of thixotropy and rheopexy of liquid products with different complexities, (2) to predict the pressure drop in the straight pipe by using the rheological parameters, and (3) to investigate the correlation between the rheological parameters of liquid food products and their filling behavior responses systematically. This study consisted of three main parts involving different complexity of liquid food products, i.e. orange juice concentrate, fermented milk or yoghurt, and tomato puree. First, rheology measurement by using a rotational rheometer to investigate time-dependent behavior through hysteresis loop, breakdown, and build-up test. The second part included pressure drop measurement by using a pressure drop rig, pressure drop prediction calculated from the rheology measurement, and comparison of the experimental and calculated pressure drop values. The last part was a filling experiment to correlate between rheology parameters of fermented milk products and filling behavior responses such as splashing, drippings, and filamentation. The time-dependent behavior of the three liquid food products could be investigated through the hysteresis loop, breakdown, and build up test. Naturell lätt yoghurt had the highest thixotropy properties, followed by orange juice concentrate, and tomato puree with a slight rheopexy behavior at a certain shear rate range. The build-up test captured a clear structural recovery especially by the products with the time-dependent behavior. F, As a worldwide company, Tetra Pak sells more food processing lines while more diverse products are packed in Tetra Pak packages. However, some available liquid food products on the market become more complicated with complex rheological properties that can lead to some issues in both the processing and filling lines. An understanding of liquid food rheological properties is fundamental to explain and predict how the food products behave in the manufacturers’ machines with appropriate measurement. As a big picture, this rheological understanding such as pressure drop through the pipe and in the filling machine plays an important role to determine the system design, efficiency, and longevity, also daily energy consumption. It is also substantial to ensure the long-term reliability of the processing line and cost-saving potential. In addition, this study is a continuation of two previous Master Thesis studies: (1) Characterizing the rheology of fermented dairy products during filling and (2) Approaches for improving the rheological characterization of fermented dairy products. The main ideas of this project were to gain an understanding of different liquid food products rheology (characteristics) including their flow behavior in the pipes and to correlate systematic rheological parameters with the filling behaviors (splashing, dripping, and filamentation). This study consisted of three main research activities involving different complexity of liquid food products, i.e. orange juice concentrate, fermented milk or yoghurt, and tomato puree. First, rheology measurement by using a rotational rheometer to investigate time-dependent behavior. The second activity consisted of pressure drop measurement by using a pressure drop rig, pressure drop prediction calculation from the rheology measurement and theoretical equations of the Power Law and Herschel-Bulkley prediction model, and a comparison of the experimental and calculated pressure drop values. The last part was a filli

The rheological properties of fresh cement paste are highly influenced by a large number of parameters, among which the most important factors are the applied shear stress, and the shear history, the age of the sample and the temperature. The effects of these parameters on the yield stress (designated as structural limit stress in this work), the viscosity and the structural recovery rate (i.e., the change in dynamic viscosity with time at rest) were studied. In parallel, the changes in ion composition of the carrier liquid, mineral phase content and granulometry were investigated. The results reveal that all investigated rheological parameters exhibit an approximated bi-linear trend with respect to the degree of hydration, with a period of quasi-constant properties until a degree of hydration of approximately 0.07, followed by a non-linear increase. This increase could be attributed to the formation of calcium hydroxide (CH) and calcium-silicate-hydrate (C-S-H) via calorimetry results. With regard to the effect of the shear history of the sample on the rheological properties, the structural limit stress showed a minor dependency on the shear history immediately after the end of shearing, which, however, vanished within the first minute at rest. The same is true for the structural recovery rate. The presented results give detailed insights into the influences of hydration and shear on the rheological properties-especially the thixotropy-of fresh cement pastes.

The effects of agar, alginate, butter, olive oil, and carrots on the mechanical and rheological properties of potato puree prepared by two different cooking methods (microwave heating (MP) and boiling (BP)) were investigated and interpreted in terms of starch microstructural changes. Microscopic observations revealed more aggregated and densely concentrated starch granules in MP samples. This consequently led to a significant increase (p < 0.05) in mechanical and rheological properties up to five times more than BP samples. All samples exhibited shear thinning non-Newtonian behavior, Postprint (published version)

This paper highlights the importance of the reversible phenomena in cyclic testing of asphalt mixtures. Several tests were designed to quantify the importance of these phenomena, focusing especially on heating due to viscous dissipation during cycling. Results showed that the decrease in stiffness observed during high frequency cyclic testing, and normally assumed by the conventional fatigue characterization procedures as damage, is in fact caused by reversible phenomena that are characteristic of visco-elasto-plastic materials under these conditions (heating, thixotropy, nonlinearity and healing). By obtaining the thermo-mechanical properties of the study mixture, the importance of heating within all reversible phenomena was studied., Peer Reviewed, Postprint (author's final draft)

A Master of Science thesis in Civil Engineering by Sara Khaled Ahmed entitled, “3D Printing Technology Utilizing Available Construction Materials in the UAE”, submitted in November 2019. Thesis advisor is Dr. Sherif Yehia. Soft copy is available (Thesis, Approval Signatures, Completion Certificate, and AUS Archives Consent Form)., College of Engineering, Department of Civil Engineering

A new viscoelastic constitutive model for subaqueous clay-rich gravity flows is presented. It is explained that for the materials which exhibit a minimum in their strain controlled flow curves the structure parameter must be a symmetric function of strain rate and stress. Therefore, the destruction of structure within the material is modeled using the dissipation energy. An expression for the elastic strain of the flowing structure is derived. The final set of equations can reproduce the viscosity bifurcation that clay suspensions may exhibit under a given load. This is explained to be important for prediction of the run-out distance of clay-rich gravity flows. The ability of the model to reproduce the general response of pasty materials to step stress and step shear rate tests is examined. The model requires four empirical parameters. A methodology is presented for obtaining these parameters and power law functions are given for their calculations for a limited rest time of 3000 seconds. The ability of the model to reproduce the rheological behavior that clay-rich suspensions exhibit under both stress and strain controlled conditions is examined using rheometry tests.

Purpose: An innovative way to define navigable fluid mud layers is to make use of their rheological properties, in particular their yield stress. In order to help the development of in situ measurement techniques, it is essential that the key rheological parameters are estimated beforehand. Is there only one yield stress? In which shear rate/shear stress range is yield expected to occur? How is yield stress dependent on depths and locations in the harbor? In order to answer these questions, we investigated the changes in the rheological properties of mud from along the river stream in the Port of Hamburg, Germany, using a recently developed laboratory protocol. Materials and methods: In this study, a detailed rheological analysis was carried out on the mud samples collected from different locations and depths of the Port of Hamburg. A variety of rheological tests was performed including: stress sweep tests, flow curves, thixotropic tests, oscillatory amplitude, and frequency sweep tests. Results and discussion: The yield stresses of sediments from different locations were significantly dissimilar from each other due to differences in densities and organic matter content. Two yield stresses (termed static and fluidic) were observed for every sample and linearly correlated to each other. The thixotropic studies showed that all mud samples, except from one location, displayed a combination of thixotropic and anti-thixotropic behaviors. The results of frequency sweep tests showed the solid-like character of the sediments within the linear viscoelastic limit. The yield stresses, thixotropy, and moduli of the mud samples increased by going deeper into the sediment bed due to the increase in density of the sediments. Conclusions: This study confirmed the applicability of the recently developed protocol as a fast and reliable tool to measure the yield stresses of sediments from different locations and depths in the Port of Hamburg. The fluid mud layer, in all the locatio, Rivers, Ports, Waterways and Dredging Engineering, Environmental Fluid Mechanics

Mud is a cohesive material which contains predominantly clay minerals, water, organic matter and some amounts of silt and sand. Mud samples can have complex rheological behaviour, displaying viscoelasticity, shear-thinning, thixotropy and yield stress. In this study, influence of organic matter on the rheological behaviour of different mud samples having similar densities is investigated. Four samples, collected from different locations and depths of Port of Hamburg (Germany) were selected. Two samples with the density of about 1210 kg/m3 and two samples with the density of about 1090 kg/m3 were analysed by different rheological tests, including stress ramp-up tests, flow curves, thixotropic tests, oscillatory amplitude and frequency sweep tests. Two yield stress regions (with two yield stress values stated as “static” and “fluidic” yield stresses) were identified for all the samples, and these regions, corresponding to a structural change of the samples were significantly different from sample to sample due to the differences in organic matter content. For lower density samples, the ratio of fluidic to static yield stress increased from 3 to 4.4 while it increased from 4.4 to 5.2 in case of higher density samples, by increasing the organic matter content. The thixotropic studies showed that the mud samples having lowest organic matter content (VH and KBZ) exhibit a combination of thixotropic and anti-thixotropic behaviours. The results of frequency sweep tests revealed the solid-like character of the mud within the linear viscoelastic regime. Mud samples having higher organic matter content (RV and RT) had a higher complex modulus (417 Pa and 7909 Pa) than the ones with lower organic matter content (13 Pa and 1774 Pa), for a given density. This study demonstrated that the density only is not a sufficient criterion to predict the rheology of different mud. Furthermore, even small amounts of organic matter content change significantly the mud, Rivers, Ports, Waterways and Dredging Engineering, Environmental Fluid Mechanics

The advent of digital concrete fabrication calls for advancing our understanding of the interaction of 3D printing with material rheology and print parameters, in addition to developing new measurement and control techniques. Thixotropy is the main challenge associated with printable material, which offers high yield strength and low viscosity. The higher the thixotropy, the better the shape stability and the higher buildability. However, exceeding a minimum value of thixotropy can cause high extrusion pressure and poor interface bond strength if the printing parameters are not optimized to the part design. This paper aims to investigate the effects of both material and process parameters on the buildability and inter-layer adhesion properties of 3D printed cementitious materials, produced with different thixotropy and print head standoff distances. Nano particles are used to increase the thixotropy and, in this context, a lower standoff distance is found to be useful for improving the bond strength. The low viscosity “control” sample is unaffected by the variation in standoff distances, which is attributed to its flowability and low yield stress characteristics that lead to strong interfacial bonding. This is supported by our microscopic observations., Materials and Environment

Submarine gravity flows constitute the last link in the source-to-sink sediment transport chain. They are the main mechanism for the transportation of sediment from the shallower to the deeper parts of the ocean. Due to their great volume, mobility, and power, they pose a formidable threat to the offshore infrastructures, and can generate tsunamis which can result in human mortality and cause great damage to onshore structures. In addition, deposits of ancient submarine gravity flows host many hydrocarbon reservoirs. The quality of these reservoirs is primarily controlled by the grain size and the clay con- centration of the flows that deposited the sediments. Due to the growing population and rise in the per capita energy consumption, connecting the dynamics of clay-laden density flows to their depositional characteristics has become important for oil and gas exploration purposes. The principle questions that were investigated in this study were: (1) How are the dynamics of subaqueous gravity flows related to their deposits?, and, (2) Why are these flows able to travel so far? ..., Applied Geology

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 esti, 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, QC 20190521

Mud is a cohesive material which contains predominantly clay minerals, water, organic matter and some amounts of silt and sand. Mud samples can have complex rheological behaviour, displaying viscoelasticity, shear-thinning, thixotropy and yield stress. In this study, influence of organic matter on the rheological behaviour of different mud samples having similar densities is investigated. Four samples, collected from different locations and depths of Port of Hamburg (Germany) were selected. Two samples with the density of about 1210 kg/m3 and two samples with the density of about 1090 kg/m3 were analysed by different rheological tests, including stress ramp-up tests, flow curves, thixotropic tests, oscillatory amplitude and frequency sweep tests. Two yield stress regions (with two yield stress values stated as “static” and “fluidic” yield stresses) were identified for all the samples, and these regions, corresponding to a structural change of the samples were significantly different from sample to sample due to the differences in organic matter content. For lower density samples, the ratio of fluidic to static yield stress increased from 3 to 4.4 while it increased from 4.4 to 5.2 in case of higher density samples, by increasing the organic matter content. The thixotropic studies showed that the mud samples having lowest organic matter content (VH and KBZ) exhibit a combination of thixotropic and anti-thixotropic behaviours. The results of frequency sweep tests revealed the solid-like character of the mud within the linear viscoelastic regime. Mud samples having higher organic matter content (RV and RT) had a higher complex modulus (417 Pa and 7909 Pa) than the ones with lower organic matter content (13 Pa and 1774 Pa), for a given density. This study demonstrated that the density only is not a sufficient criterion to predict the rheology of different mud. Furthermore, even small amounts of organic matter content change significantly the mud, Rivers, Ports, Waterways and Dredging Engineering, Environmental Fluid Mechanics

We review progress in designing and transforming multi-functional yield-stress fluids and give a perspective on the current state of knowledge that supports each step in the design process. We focus mainly on the rheological properties that make yield-stress fluids so useful and the trade-offs which need to be considered when working with these materials. Thinking in terms of “design with” and “design of” yield-stress fluids motivates how we can organize our scientific understanding of this field. “Design with” involves identification of rheological property requirements independent of the chemical formulation, e.g. for 3D direct-write printing which needs to accommodate a wide range of chemistry and material structures. “Design of” includes microstructural considerations: conceptual models relating formulation to properties, quantitative models of formulation-structure-property relations, and chemical transformation strategies for converting effective yield-stress fluids to be more useful solid engineering materials. Future research directions are suggested at the intersection of chemistry, soft-matter physics, and material science in the context of our desire to design useful rheologically-complex functional materials., QC 20191105

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 esti, 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, QC 20190521

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 esti, 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, QC 20190521

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 esti, 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, QC 20190521