Dissertations / Theses on the topic 'Flow of mortar'

Cette étude concerne l’ajout de billes de verre de dimension variant de 1 à 50 m dans des matrices cimentaires. Les travaux ont comme objectif dans un premier temps la caractérisation des propriétés physiques et rhéologiques à l’état frais des suspensions cimentaires à deux échelles : la pâte de ciment et le mortier. Puis dans un deuxième temps l’étude de l’influence des microbilles de verre sur les propriétés physiques, mécaniques et durabilité du mortier durci. Des séries d’expériences normalisées ont été faites pour caractériser l’influence des billes de verre sur les indicateurs à l’état frais : la consistance et la prise des pâtes de ciment. Les propriétés mécaniques et de durabilité sont quantifiées au jeune âge (de 3 à 28 jours) et à long terme (de 28 jours à 112 jours). L’étude sur les gels d’hydratation et sur la microstructure du mortier durci a été faite à l’aide de la technique de la microscopie électronique à balayage. Des méthodes de caractérisation complémentaires pour examiner la propagation d’onde, la ségrégation et l’étalement ont également été employées. Les résultats obtenus par l’ensemble des essais évaluent le rôle des microbilles de verre sur les comportements des suspensions de pâtes de ciment et du mortier à l’état frais, et du mortier à l’état durci. Ceci met en évidence l’intérêt rhéologique, mécanique et l’effet sur la durabilité des microbilles de verre dans un matériau cimentaire<br>The aim of this work is the valorisation of recycled waste materials in cement paste and mortar in order to reuse these resources for replacing natural aggregates in concrete. Our study concerns the use of a microsphere glass powder (MGP) with a particle size from 1 to 50 m into the cement matrix. This experimental work first focuses on the effect of the MGP on the workability properties of fresh cement paste and fresh mortar and on the physical, mechanical and durability properties of mortar. Many standard tests have been conducted for the characterisation of the behavior of the fresh cement paste i.e the consistency and the setting of fresh cement paste. The durability properties at early age (from 3 to 28 days) and at long time (from 28 days to 112 days) have been also quantified. We employed the scanning electron microscopy for the mortar microstructure analysis. Some supplementary tests like the ultrasonic wave propagation, the segregation and the flow properties on the vibrated table have been also used. The primary results have proved the effect of the MGP on the behaviour of the fresh cement paste, fresh mortar and mortar. The presence of MGP showed interesting modifications on the rheology, mechanical and durability properties of the cement system

The main purpose of this thesis was to propose and test a new approach that captures the features of single and multiple bubbles dynamics using the Shan and Chen-type lattice Boltzmann method (LBM). Two dimensional bubbles motions were simulated considering the buoyancy effect for which the topology of the bubble is characterized by the Eötvös (Eo), and Morton (M) numbers. A qualitative and quantitative validation were performed using the Level set method. Bubble shape deformation was captured and analysis based on terminal Reynolds number and degree of circularity show very good agreement with the experimental results and with available simulation results. In sum, this study presents crucial preliminary information to further analyze multiphase fluid flows in various contexts.

碩士<br>國立雲林科技大學<br>營建工程系碩士班<br>100<br>Fly ash is a very common admixture for concrete or mortar. Many cases show that adding fly ash can reduce cracks. This study is to find out the real reason why ash can reduce crack. There are two possibilities. The first is that ash improves workability, reduces water use and ends up with less shrinkage and cracks. The second is that some ingredient in ash expands during the setting that compensates the setting shrinkage. Fly ash is a mixture of several different material having different properties. This study grades ash into different groups by air flow and test them separately to evaluate their effect to mortar and also test the effect with and without same water ratio. The studied properties effected by ash including setting time, strength, setting shrinkage, etc.. Measuring setting shrinkage is not an easy task because of the softness of the tested material. A test is designed to measure setting shrinkage of mortar, which is similar to ASTM C827M-10 but much easier.

yes<br>Test results of thirty six ground granulated blast-furnace slag (GGBS)-based mortars and eighteen fly ash (FA)-based mortars activated by sodium silicate and/or sodium hydroxide powders are presented. The main variables investigated were the mixing ratio of sodium oxide (Na2O) of the activators to source materials, water-to-binder ratio, and fine aggregate-to-binder ratio. Test results showed that GGBS based alkali-activated (AA) mortars exhibited much higher compressive strength but slightly less flow than FA based AA mortars for the same mixing condition. Feed-forward neural networks and simplified equations developed from nonlinear multiple regression analysis were proposed to evaluate the initial flow and 28-day compressive strength of AA mortars. The training and testing of neural networks, and calibration of the simplified equations were achieved using a comprehensive database of 82 test results of mortars activated by sodium silicate and sodium hydroxide powders. Compressive strength development of GGBS-based alkali-activated mortars was also estimated using the formula specified in ACI 209 calibrated against the collected database. Predictions obtained from the trained neural network or developed simplified equations were in good agreement with test results, though early strength of GGBS-based alkali-activated mortars was slightly overestimated by the proposed simplified equations.

We use Darcy's law and conservation of mass to model the flow of a fluid through a porous medium. It is a second order elliptic system with a heterogeneous coefficient. We consider the equations written in mixed form. In the heterogeneous case, we define a new multiscale mortar space that incorporates purely local information from homogenization theory to better approximate the solution along the interfaces with just a few degrees of freedom. In the case of a locally periodic heterogeneous coefficient of period epsilon, we prove that the new method achieves both optimal order error estimates in the discretization parameters and good approximation when epsilon is small. Moreover, we present numerical examples to assess its performance when the coefficient is not obviously locally periodic. We show that the new mortar method works well, and better than polynomial mortar spaces. On the other hand, we also propose to use multiscale mortars as a coarse component to construct a two-level preconditioner for the saddle point linear system arising from the fine scale discretization of the mixed finite element system. The two-level preconditioners are constructed based on the interfaces. We propose a framework to define the interpolation operators for the face based two-level preconditioners for different combination of coarse and fine scale mortar spaces for matching and nonmatching grids. In this dissertation, we show that for quasi-homogeneous problems and matching grids, the condition number of the preconditioned interface operator is bounded by (log(H/h))², which is the same as the traditional two-level preconditioners, for quasi-homogeneous problems. We show several numerical examples to demonstrate that for the strongly heterogeneous porous media, it is often desirable and even necessary to use a higher dimensional coarse mortar space to construct the coarse preconditioner to achieve convergence. We apply our ideas to study slightly compressible single phase and two-phase flow in a porous medium. We find that for the nonlinear single phase problem, the two-level preconditioners could be successfully applied to the symmetrized linear system. For the two-phase problem, using the fine scale, instead of multiscale, velocity solutions from the flow problem can greatly benefit the transport problem.<br>text

碩士<br>國立勤益科技大學<br>企業管理系<br>105<br>As the income level has increased steadily over the past decades, consumers have started to show tendency to purchase things, not they need, but they desire. In order to attract customers and raise their willingness to buy, business owners focus on product appeals and create a shopping environment that provides entertainment and intrinsic enjoyment, experiential shopping has then emerged. Besides that, with the advancement of informational technology, people are able to start their businesses online at a lower cost, anytime, anywhere, resulting in more competition among retailers. Price comparability and home delivery provides time efficiency and great convenience causing consumers to turn to online shopping, further threatening the survival of brick and mortar stores. This study examined six experiential values to find out which can successfully enhance patronage intention, then further investigate whether patrons have gone into flow based on their experience. Also if the experiential values stimulate repurchase intention and positive word-of-mouth. The study surveyed consumers repurchase at bookstores and used Amos to conduct Structural Equation Model analysis, in order to understand the relationship between different aspects. Lastly, using Chi-square difference test to investigate experiential differences between the two channels. The result shows all six experiential values have significant impact on flow and affect repurchase intention. Chi-square difference test reveals that the significant difference between online shopping and the other is aesthetics and service excellence; the rest show no difference between the two channels. This study can provide a conceptual framework for bookstore owners in different channels to self-reflect if they are lacking any experiential values, improve customers’ shopping experience in order to increase their loyalty which shall then boost the business.

碩士<br>國立高雄應用科技大學<br>土木工程與防災科技研究所<br>104<br>With the changing times and economic development, increasing demand for steel, and the steel-making process is accompanied by industrial waste, and can effectively dispose of in order to reduce carbon dioxide emissions, making it a renewable green building materials thus achieving environmental benefits. This study uses three water binder ratio (0.45,0.5,0.55), the Slag of Baosteel Slag Short Flow (SB) by different proportions (0%, 25%, 50%, 75%, 100%) to replace sand and slag portion fixed to replace 20% cement, mix made of composite cement mortar and fresh test(Slump flow、Setting time test), at age 3,7,28,56 and 91 days of hard solid test(Compressive strength、Ultrasonic pulse velocity、Thermal conductivity test), durability test(The resistance value、Auto clave and microwave catalytic、weight loss、high temperature catalytic test). The results showed that composite cement mortar Slump flow will increase by the amount of SB substituted and Water binder ratio rises, the amount of each substituted group were higher than the control (1.01 to 1.09 times)； Setting time along with Water binder ratio increased and extended. Compressive strength and ultrasonic velocity increases both the amount of the increase SB substitution；Thermal conductivity due to the substitution of the SB rise reduced from 0.65 to 0.92 times; The resistance value due to an increased amount of substitution of SB rise 1.02 to 1.58 times, and the resistance value with the increase of the Water binder ratio but lower；Auto clave and microwave catalytic test amount of expansion of both will increase the amount of the SB substituted rise, because SB contains free lime (f-CaO), after the reaction with water will swell behavior；weight loss in water binder ratio is 0.45 when substitution SB amounted to 100% of the minimum 1.13%, representing the best of its durability；high temperature catalytic amount of expansion increases the number of days which followed increases.

The dynamic solution of multiphase flow through porous media is of special interest to several fields of science and engineering, such as petroleum, geology and geophysics, bio-medical, civil and environmental, chemical engineering and many other disciplines. A natural application is the modeling of the flow of two immiscible fluids (phases) in a reservoir. Others, that are broadly based and considered in this work include the hydrodynamic dispersion (as in reactive transport) of a solute or tracer chemical through a fluid phase. Reservoir properties like permeability and porosity greatly influence the flow of these phases. Often, these vary across several orders of magnitude and can be discontinuous functions. Furthermore, they are generally not known to a desired level of accuracy or detail and special inverse problems need to be solved in order to obtain their estimates. Based on the physics dominating a given sub-region of the porous medium, numerical solutions to such flow problems may require different discretization schemes or different governing equations in adjacent regions. The need to couple solutions to such schemes gives rise to challenging domain decomposition problems. Finally, on an application level, present day environment concerns have resulted in a widespread increase in CO₂capture and storage experiments across the globe. This presents a huge modeling challenge for the future. This research work is divided into sections that aim to study various inter-connected problems that are of significance in sub-surface porous media applications. The first section studies an application of mortar (as well as nonmortar, i.e., enhanced velocity) mixed finite element methods (MMFEM and EV-MFEM) to problems in porous media flow. The mortar spaces are first used to develop a multiscale approach for parabolic problems in porous media applications. The implementation of the mortar mixed method is presented for two-phase immiscible flow and some a priori error estimates are then derived for the case of slightly compressible single-phase Darcy flow. Following this, the problem of modeling flow coupled to reactive transport is studied. Applications of such problems include modeling bio-remediation of oil spills and other subsurface hazardous wastes, angiogenesis in the transition of tumors from a dormant to a malignant state, contaminant transport in groundwater flow and acid injection around well bores to increase the permeability of the surrounding rock. Several numerical results are presented that demonstrate the efficiency of the method when compared to traditional approaches. The section following this examines (non-mortar) enhanced velocity finite element methods for solving multiphase flow coupled to species transport on non-matching multiblock grids. The results from this section indicate that this is the recommended method of choice for such problems. Next, a mortar finite element method is formulated and implemented that extends the scope of the classical mortar mixed finite element method developed by Arbogast et al [12] for elliptic problems and Girault et al [62] for coupling different numerical discretization schemes. Some significant areas of application include the coupling of pore-scale network models with the classical continuum models for steady single-phase Darcy flow as well as the coupling of different numerical methods such as discontinuous Galerkin and mixed finite element methods in different sub-domains for the case of single phase flow [21, 109]. These hold promise for applications where a high level of detail and accuracy is desired in one part of the domain (often associated with very small length scales as in pore-scale network models) and a much lower level of detail at other parts of the domain (at much larger length scales). Examples include modeling of the flow around well bores or through faulted reservoirs. The next section presents a parallel stochastic approximation method [68, 76] applied to inverse modeling and gives several promising results that address the problem of uncertainty associated with the parameters governing multiphase flow partial differential equations. For example, medium properties such as absolute permeability and porosity greatly influence the flow behavior, but are rarely known to even a reasonable level of accuracy and are very often upscaled to large areas or volumes based on seismic measurements at discrete points. The results in this section show that by using a few measurements of the primary unknowns in multiphase flow such as fluid pressures and concentrations as well as well-log data, one can define an objective function of the medium properties to be determined, which is then minimized to determine the properties using (as in this case) a stochastic analog of Newton’s method. The last section is devoted to a significant and current application area. It presents a parallel and efficient iteratively coupled implicit pressure, explicit concentration formulation (IMPEC) [52–54] for non-isothermal compositional flow problems. The goal is to perform predictive modeling simulations for CO₂sequestration experiments. While the sections presented in this work cover a broad range of topics they are actually tied to each other and serve to achieve the unifying, ultimate goal of developing a complete and robust reservoir simulator. The major results of this work, particularly in the application of MMFEM and EV-MFEM to multiphysics couplings of multiphase flow and transport as well as in the modeling of EOS non-isothermal compositional flow applied to CO₂sequestration, suggest that multiblock/multimodel methods applied in a robust parallel computational framework is invaluable when attempting to solve problems as described in Chapter 7. As an example, one may consider a closed loop control system for managing oil production or CO₂sequestration experiments in huge formations (the “instrumented oil field”). Most of the computationally costly activity occurs around a few wells. Thus one has to be able to seamlessly connect the above components while running many forward simulations on parallel clusters in a multiblock and multimodel setting where most domains employ an isothermal single-phase flow model except a few around well bores that employ, say, a non-isothermal compositional model. Simultaneously, cheap and efficient stochastic methods as in Chapter 8, may be used to generate history matches of well and/or sensor-measured solution data, to arrive at better estimates of the medium properties on the fly. This is obviously beyond the scope of the current work but represents the over-arching goal of this research.<br>text

Flow and transport phenomena in the subsurface often span a wide range of length (nanometers to kilometers) and time (nanoseconds to years) scales, and frequently arise in applications of CO₂ sequestration, pollutant transport, and near-well acid stimulation. Reliable field-scale predictions depend on our predictive capacity at each individual scale as well as our ability to accurately propagate information across scales. Pore-scale modeling (coupled with experiments) has assumed an important role in improving our fundamental understanding at the small scale, and is frequently used to inform/guide modeling efforts at larger scales. Among the various methods, there often exists a trade-off between computational efficiency/simplicity and accuracy. While high-resolution methods are very accurate, they are computationally limited to relatively small domains. Since macroscopic properties of a porous medium are statistically representative only when sample sizes are sufficiently large, simple and efficient pore-scale methods are more attractive. In this work, two Eulerian pore-network models for simulating single-phase flow and solute transport are developed. The models focus on capturing two key pore-level mechanisms: a) partial mixing within pores (large void volumes), and b) shear dispersion within throats (narrow constrictions connecting the pores), which are shown to have a substantial impact on transverse and longitudinal dispersion coefficients at the macro scale. The models are verified with high-resolution pore-scale methods and validated against micromodel experiments as well as experimental data from the literature. Studies regarding the significance of different pore-level mixing assumptions (perfect mixing vs. partial mixing) in disordered media, as well as the predictive capacity of network modeling as a whole for ordered media are conducted. A mortar domain decomposition framework is additionally developed, under which efficient and accurate simulations on even larger and highly heterogeneous pore-scale domains are feasible. The mortar methods are verified and parallel scalability is demonstrated. It is shown that they can be used as “hybrid” methods for coupling localized pore-scale inclusions to a surrounding continuum (when insufficient scale separation exists). The framework further permits multi-model simulations within the same computational domain. An application of the methods studying “emergent” behavior during calcite precipitation in the context of geologic CO₂ sequestration is provided.<br>text

The characteristics of fine aggregates, such as shape, angularity, and surface texture, have been shown to influence the performance of concrete and asphalt mixtures and to play an important role in obtaining valuable properties of early age concrete such as workability, and compatibility. However, the measurement of fine aggregate characteristics is not easy. In the present study, 26 fine aggregates, covering a wide spectrum of mineralogy, were examined using direct and indirect test methods in order to evaluate the shape, angularity, and surface texture, as well as to analyze the gradation. The direct test methods, such as AIMS and Camsizer, which provide a digital image of the aggregates proved to be the best. However, the cost of such systems can limit the use of digital imagining systems in practice. The indirect test methods which provide an estimate of aggregate surface characteristics, such as uncompacted void test, mortar flow test, compressive strength test, and flakiness test gave variable results. The uncompacted void test (Method A) was shown to be the most accurate indirect test method. The Camsizer and the sieve analysis test produced identical gradation analysis results when an adequate sample was used. General correlations were developed between the direct and indirect test methods. The non-approved fine aggregates on the TxDOT’s list were analyzed and compared to those of the approved fine aggregates to see whether they could be successfully used. It was found that both LS-5 and LS-8 had good results—even better than the results of some of the approved fine aggregates. Thus, they could be successfully used.<br>text

Oil well blow outs are investigated to determine methods to quickly and accurately respond to an emergency situation. Flow rate is needed to guide containment and dispersal operations. The Stratified Integral Multiphase Plume, SIMP, model was used to investigate the range of initial conditions available to integral modeling. Sensitivity to initial conditions is modest, but without experimental data at the appropriate scale the most accurate condition is unable to be determined. Flow rates are difficult to directly measure in blow out situations, so another method must be determined; therefore, sensitivity of several parameters to flow rate was also evaluated. Methane concentration in the first intrusion can be used in conjunction with velocity and trap height measurements to determine flow rate using an integral model. Plume width and temperature were determined to have little sensitivity. Separately, a containment dome was tested in the laboratory to determine if a full scale dome can be used to contain an oil leak in the field. The dome was found to have satisfactory entrapment in the designed position.

<p>Mining for gold and copper was undertaken for nearly 100 years from 1882 at Mount Morgan in Central Queensland. Re -processing of. tailings ceased in the early 1990s and no</p> <p>mining has been conducted since. The legacy of the historical mining practices is an open cut (threatening to overflow) and acid mine drainage (AMD) extending for a considerable distance along the -Dee River.</p> <p>The first -18 km- of the river downstream- of- the mine, to its junction with Fletcher Creek, is severely impacted with pH consistently below 3.5. Water metal concentrations are many times higher than the water quality standards for freshwater biota. For example, the filtered mean concentrations of Al and Cu at 4 sites in this section of the river were 87.3 and 6.45 mg/L, respectively. Fish, molluscs and shrimp were absent and macroinvertebrate species richness was limited to only insects in this severely impacted region. Water quality of the river improves at the junction with Fletcher Creek and downstream the water quality is only severely impacted during periods of flow following rain events.</p> <p>This study examined the biological impacts downstream of the mine including the response of biota to flows in the river. Whilst previous studies had investigated spatial variations in macroinvertebrate communities this study also examined temporal variation and response to flow. The metal content of fish and mussels from the river were determined for the first time.</p>