The fiber suspensions in the production line from wood topaper are subjected to many types of chemical and mechanicalprocesses, in which the flow of the suspension is of vitalimportance. The flow of the suspension determines the degree ofuniformity of the fibers through the processing, which inreturn affects the properties of the fiber suspension. In orderto optimise the process, thorough knowledge of the suspensionflow is necessary, both on the level of suspension, fibernetworks and individual fibers. Knowledge of the fibersuspension behaviour combined with commercial CFD simulationprovides an efficient design method for any unit operation inthe papermaking process. This work concentrates on macroscopic modeling of thebehaviour of fiber suspensions from 0.5-5% dry content, purefiber suspensions without fillers or additives. Any mechanismscausing the characteristic behaviour of the pulp suspensionhave not been included, they are only included through theirinfluence on the suspension parameters. Excluded mechanismsare, for instance, the fiber-fiber coupling mechanisms that arethe reason for the formation of fiber networks and parts offiber network, flocs. By combining a rheology model for the bulk suspension, awall function that accounts for the slip layer and finallyintroducing turbulence, a model has been created that is ableto simulate the flow of most fiber suspensions. The flow of thesuspension is not constrained to any particular flowconditions; the models discussed in this work aim at describingthe behaviour of the suspension for all flow rates and flowtypes. The models are developed under simple flow conditions,where all variables can be controlled, but the models areintended for usage within the industry-based flows in real pulpand papermaking applications. Keywords:rheology, fiber, suspension, CFD, model, wall,slip, turbulence / <p>QCR 20161026</p>

In underground construction grouting is performed to seal tunnels and caverns against excessive water inflow or to reduce the lowering of the ground water table. The rheological properties, such as viscosity and yield stress, of the used grouts play a fundamental role in grouting. No method has been developed yet to measure these properties in-line in the field during grouting. Methods used today are rather primitive and not robust enough for field use and they are mainly performed in order to verify and fulfil stipulated quality criteria. Modern grouting rigs are today equipped with continuous measurement of flow and pressure but instruments for continuous monitoring of rheological properties and their changes with time in the field are still lacking. A relatively new method, known as ‘UVP-PD’, for continuous in-line measurements of the rheological properties of cement grouts, was tested in this work. Standard grouting equipment (UNIGROUT) and flow meter (LOGAC) was used to ensure field conditions. The objective of this work was to determine the feasibility of the ‘UVP-PD’ method for cement based grouts. After performing full scale experimental works, this method was found feasible for measuring the rheological properties of cement based grouts directly in-line.

Various national and international standards recommend potable water for mixing concrete; however, the availability of potable water is virtually a daunting task in some developing communities. Concrete workers in such environments tend to utilize any available water for mixing concrete, and this may be detrimental to the quality of the concrete being produced. This study investigates the rheological, mineralogical and strength variability of concrete due to construction water impurities. Water samples were collected from four different construction sites within Southwestern region of Nigeria for production of concrete. The physical and chemical properties of the waters were determined so as to measure their rate of contamination, prior to their use for mixing concrete. The rheological properties of the fresh concrete, compressive strength, split tensile strength, and microscale features of hardened concrete, that were produced with each water sample were determined. From the results, the rheological features of concrete were found not to be affected by water impurities, however, the mechanical test results revealed about 10% reduction in strength between concrete made with water having least and higher concentration of impurities. Also, it was evident from the microscale tests that the water impurities do alter the hydration rate of concrete, which results in strength reduction. The study suggests pretreatment of concrete mixing water before use in order to avoid its damaging effect on concrete life. / Revisión por pares

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The research presented in this thesis seeks to address meaningful geodynamic problems related to the viscosity structure of the Earth’s interior. Isostatic adjustment is a process which is dependent upon the mechanical properties of the lithosphere and mantle. By performing computational simulations of the isostatic response for various surface-loading scenarios and numerous viscosity structures, insight can be gained into the mechanical structure of the Earth and geodynamic processes related to that structure. The modelled isostatic signal for a given set of Earth model parameters can be compared to real-world observational data in order to identify valid Earth model configurations. In Chapter 2, the “Transition Zone Water Filter” theory is tested by modelling the geophysical effects of a low-viscosity melt-rich layer atop the 410 km discontinuity. The thickness and viscosity of this layer, and the surrounding mantle, is constrained using observations of relative sea level and the geodetic J ̇_2 parameter, as well as multiple ice-loading scenarios by which the isostatic adjustment process is driven. The relative sea level data, being most sensitive to the upper mantle and the theorized melt-rich layer it contained, constrain layer properties more effectively than the J ̇_2 observation, which is strongly dependent on the lower mantle. Constraints on the viscosity of the melt-rich layer vary according to thickness, with thicker layers requiring stiffer viscosities to satisfy observations. For instance, a 20 km thick layer would require a viscosity of 10^17 Pas or greater, but any of the considered viscosities could be possible for a 1 km thick layer. Similarly, a broad range of upper mantle viscosities are possible, but they must be balanced by variations in the lower mantle. However, J ̇_2 results show a strong preference for a high-viscosity lower mantle (≥10^22 Pas). For every evaluated Earth model parameter, there is evidence of ice-model sensitivity in the inversion results. Although the results of this study demonstrate that observables related to glacial isostatic adjustment can provide constraints on the properties of this theorized melt-rich layer, the confounding effect of parameter trade-off prevents a more definitive test of this model of mantle geodynamics. The purpose of the study presented in Chapter 3 is to analyze the nature of solid-Earth deformation beneath the Lower Mississippi River, most crucially in the Mississippi Delta region where subsidence is an ongoing and costly problem. The study uses the displacement of the long profile of the Lower Mississippi River over the last 80 kyr to constrain isostatic deformation and determine constraints on the mechanical structure of both the mantle and lithosphere. Deformation recorded in the northern portion of the long profile is dominated by the effect of glacial isostatic adjustment, whereas the southern portion is governed by sediment isostatic adjustment. However, the southern portion is also potentially affected by past fault displacement, and to account for this the observational data are corrected using two distinct faulting scenarios. Displacement of the long profile is modelled using either an entirely elastic lithosphere or a lithosphere with internal viscoelastic structure, the latter of which is derived from two end-member geothermal profiles. Between the elastic and viscous lithosphere models, the viscous models are better able to replicate the observational data for each faulting scenario – both of which prefer a viscous lithosphere corresponding to the warmer geotherm. The chosen faulting scenario exerts no control over the optimal mantle model configuration, however the optimal mantle for the viscous lithosphere models is much stiffer than was determined for their elastic counterparts, reflecting significant parameter trade-off between mantle and lithosphere mechanical structure. These study results demonstrate the utility of the long profile displacement data set for constraining Earth viscosity structure, as well as the importance of considering more-complex models of lithosphere mechanical structure when addressing surface-loading problems similar to those encountered in the Mississippi Delta region.

Ce travail de thèse rentre dans le cadre de la problématique générale, en plein développement actuellement, concernant l’exploitation des nanotechnologies pour le développement d’écomatériaux, dont les propriétés sont significativement améliorées et élargies. A cause de leur surface spécifique particulièrement élevée, l’ajout d’une infime quantité (de l’ordre du % par rapport au ciment) de particules nanométriques à une formulation d’un matériau cimentaire peut entrainer des modifications significatives des propriétés du produit. Ces modifications peuvent intervenir à tout niveau de maturation du matériau en impactant les propriétés correspondantes : état frais (rhéologie), jeune âge (cinétique de prise, retrait, fissuration) et état durci (propriétés mécaniques, thermiques et durabilité).Le principal travail de cette thèse a consisté à étudier l’impact de nano particules isotropes (nano silice) et anisotropes (nano argile) sur la rhéologie des matériaux cimentaires à l’aide d’un nouveau protocole : la rhéologie oscillatoire aux grandes amplitudes. De plus, l’impact de celle-ci sur le processus d’hydratation des matériaux contenant de hauts dosages en laitier de haut fourneaux a aussi été étudié. / This PhD gets in the larger topic of the use of nano-technology to develop eco-friendly materials whose properties are improved. Due to their very high specific surface, a very low quantity (only a few percent) of nano particles into a cement-based material can induce significant changes of materials properties. These changes can take place at every ages of materials such as fresh state (rheology), young age (kinetic of hydration, shrinkage) or long term (mechanical, thermal properties and durability). During this PhD, different types of nano particles are considered: isotropic (nano silica) or anisotropic (nano clay). The main objective is to consider the impact of nano particles on rheological properties considering a new rheological protocol: large amplitude oscillation shear (LAOS). Besides, interaction between nano particles and hydration products in the case of cement based material containing high dosage of slag is also considered. This study will help to understand how nano particles change material properties at fresh state and young age. Indeed, it is at these ages that materials properties are lower when cement is replaced by other material.

A new method for determining the viscoelastic properties of materials was introduced and investigated. Results of three groups of samples obtained using one particle microrheology method, DLS microrheology method and classical rheology method were compared to be sure of correctness of measurements. As a model system were chosen mixtures of glycerol of different viscosities. In case of samples containing glycerol, results were also compared with tabulated values. Hyaluronan of various molecular weights was used as a biopolymer and polystyrene particles were used for microrheology. It was confirmed, that viscosity values of biopolymer samples obtaining by each method are comparable.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20580号 / 工博第4360号 / 新制||工||1678(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 安部 武志, 教授 阿部 竜, 教授 作花 哲夫 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

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