L’objectif de cette thèse est de développer une méthode Galerkine discontinue d’ordre élevé capable de prendre en considération des simulations réalistes liées à la nanophotonique. Au cours des dernières décennies, l’évolution des techniques de lithographie a permis la création de structure géométriques de tailles nanométriques, révélant ainsi une large gamme de phénomènes nouveaux nés de l’interaction lumière-matière à ces échelles. Ces effets apparaissent généralement pour des objets de taille égale ou (très) inférieure à la longueur d’onde du champ incident. Ce travail repose sur le développement et l’implémentation de modèles de dispersion appropriés (principalement pour les métaux), ainsi que sur un large éventail de méthodes computationnelles classiques. Deux développements méthodologiques majeurs sont présentés et étudiés en détails: (i) les éléments courbes, et (ii) l’ordre d’approximation local. Ces études sont accompagnées de plusieurs cas-tests réalistes tirés de la nanophotonique. / The goal of this thesis is to develop a discontinuous Galerkin time-domain method to be able to handle realistic nanophotonics computations. During the last decades, the evolution of lithography techniques allowed the creation of geometrical structures at the nanometer scale, thus unveiling a variety of new phenomena arising from light-matter interactions at such levels. These effects usually occur when the device is of comparable size or (much) smaller than the wavelength of the incident field. This work relies on the development and implementation of appropriate models for dispersive materials (mostly metals), as well as on a large panel of classical computational techniques. Two major methodological developments are presented and studied in details: (i) curvilinear elements, and (ii) local order of approximation. This work is complemented with several physical studies of real-life nanophotonics applications.

Most soil particles loses cohesion and split up the soil mass into individual soil grains when they come in contact with water and get saturated. In dispersive soils the particles detach more spontaneously from each other and go into suspension even in quiet water. Thus the phenomenon of dispersion is common to most soils, the degree varying from soil to soil. Dispersive soils are abundantly found in various parts of the world such as Thailand, United States, Australia, Mexico, Brazil, South Africa and Vietnam. Several geotechnical failures such as piping due to internal erosion, erosion and gullying in relatively flat areas, collapse of sidewalls and topsoil removal have been reported worldwide due to the construction in dispersive soil. Failures as reported could be prevented if such soils are identified before-hand or if the quantification of dispersivity in the soil is done accurately. There are several methods of measuring dispersivity in soils which include several physical tests, chemical tests and some common laboratory tests. It is reported in literature that no method could be completely relied upon to identify dispersive soils with absolute confidence. In addition, when these methods were studied in detail, several flaws surfaced needing a better estimation of dispersivity. In order to develop a new method of estimation of dispersivity, the mechanism of dispersion in soils was studied in depth, which revealed that the existing concepts regarding dispersivity are incomplete in many aspects. An exhaustive philosophy of dispersion which addresses every detail is non-existing. To solve these problems, the concept of dispersivity was investigated in detail. It was found out that the observed dispersivity is a result of repulsion in the soil overcoming the attractive force. Thus a list of factors that could possibly affect the repulsion and attraction (and hence the dispersivity) in soils were found out. Even though literature focuses on exchangeable sodium as the principal reason for dispersivity, from fundamental theoretical considerations several other factors such as Cation exchange capacity (CEC), pH, structure of the soil, electrolyte concentration in the pore fluid, presence of organic matter, clay minerals involved in the soil and dissolved salts in the soil could possibly have an influence on dispersivity. Several studies have reported soils of high dispersivity to possess a high pH, high CEC, high amounts of sodium. The influence of these factors on dispersivity of other soils (or generally in any soil) is not well explored. Research on understanding their mechanism of action led to the conclusion that these parameters could be generalized for any soil. Through the analysis of these parameters, it was found that the fundamental parameter governing the dispersivity of soils is the number of charges on clay particles and that the repulsion in the soils is mainly contributed by the electrostatic repulsion. The attractive force in a soil/clay mass is primarily contributed by the van der Waal’s attraction and dispersion occurs when the electrostatic repulsion (resulting due to permanent and pH dependent charges) dominates over the van der Waal’s attraction. A practical estimation of charge with least effort could be possibly carried out through the measurement of zeta potential of soils. In order to verify whether the effect of all the factors is completely and sufficiently reflected in the zeta potential values, experiments were conducted on various soils. Three soils namely Suddha soil (a locally available dispersive soil), Black cotton soil and Red soil were selected for the study. These soils were chosen as the soil samples as they could display wide ranges of dispersivity values. In order to perform dispersivity tests, soil fraction finer than 75µ (75 micron meter sieve size) was fixed as the sample size as dispersivity pertaining to the finer fractions play a greater role than that of the coarser particles. All the three soil samples were treated with sodium hydroxide and urea solutions to alter the dispersivity so that the influence of all parameters could be studied. The dispersivity of the treated and untreated soils was found out through the various conventional tests and it was found that there exists a good correlation between the dispersivity and the zeta potential of soils. It was also observed that the increase in the dispersivity is higher when treated with salts of monovalent cations. Increase in the organic content also increased zeta potential, but not as significantly. One of the popularized theories on colloidal dispersions is the classical DLVO theory which has formulated the total interaction energy of colloidal particles by estimating the electrostatic repulsion and van der Waal’s attraction energy between two particles. The total interaction energy is then expressed as the difference between them. A similar approach as taken by the DLVO is adopted in this study. The total attractive energy existing in a soil mass is mathematically derived from the expression for van der Waal’s energy between two particles and the total repulsive energy from the zeta potential values. Two different approaches namely an infinitesimal particle approach and a finite particle approach is taken for finding the energy in a soil mass. In the infinitesimal particle approach, a clay particle is assumed to be infinitely small such that any soil particle of a finite radius could be conceived to be formed by a combination of infinite number of these infinitesimal particles. With this setting, the total energy in a soil mass is computed without really bothering about what exact particles constitute the mass. The increase in energy due to the increase in radius is then integrated to obtain the final expression. The dispersivity of the soil is then estimated under defined physical conditions of the soil. In the finite particle approach, each particle is considered to be of finite radius and to estimate the total energy, the total number of particle ombinations is then taken and the total energy is expressed as a sum of all the possible combinations. The dispersivity of a soil in both approaches is expressed as a release of energy when the repulsion rules over the attraction. In order to validate the derived propositions and expressions, experiments were conducted again on soils. The soils were treated with hydroxide salt of monovalent cations such as lithium, sodium and potassium. The dispersivity of the various treated and untreated soils was measured with the conventional methods and with the derived expressions of dispersivity through zeta potential. The similarity in the trend of the dispersivity values confirmed the validity of the derived expression. It was also concluded that the infinitesimal particle approach could be adopted when information about the physical properties are available and when they are not, the finite approach could be used. An accurate determination of zeta potential is critical for representation of dispersivity with zeta potential. Thus the procedure for measurement of zeta potential was standardized. The standardization was primarily focused on establishing the ideal conditions for zeta potential measurement. The role of Brownian motion, in electrophoretic mobility measurements were studied by employing the usage of zeta deviations. Untreated, potassium hydroxide treated, sodium hydroxide treated and lithium hydroxide treated samples of Suddha soil, Black Cotton soil and Red soil (finer than 75µ) were used for the study. Zeta potential measurements on unfiltered soil water suspensions, suspensions passing 2.5µ and suspensions passing 0.45µ were conducted along with recording their zeta deviations. It was observed that soil suspensions finer than 0.45µ show acceptable values of zeta deviations and thus could be used as a standard procedure for estimating zeta potentials. It was also concluded that the presence of Brownian motion makes the assessment of zeta potential through electrophoretic measurements easier and accurate. In an alternate perspective it as deduced that the amount of total monovalent ion concentration in the soil (dissolved and adsorbed) could adequately serves as an ideal parameter that could be used to quantify dispersion in soils. In order to verify the speculation, the variation of repulsive pressure with monovalent cation concentration was studied for the above mentioned treated and untreated soils. Within the monovalent cations, the role of ionic size in repulsion along with physical factors was also studied with the help of Atterberg limits, compaction characteristics, and dispersivity measurements. It could be concluded that even though there are several chemical factors such as CEC, pH, electrolyte concentration, type of clay minerals, dissolved salts etc. and physical factors such as plasticity, water holding capacity, density and structure which influence dispersion in soils, these factors affect either directly forces between the particles or the surface charge of clays which again affect the forces. The two phenomena can be combined through the hydration behaviour of the adsorbed cations on the clay surface in view of dispersivity. It is that force due to hydration which acts as the principal reason to separate the clay particles apart. As the radius of the inner hydration shell is higher for monovalent cations than those of higher valency ions, more force would be offered by the monovalent ions. Higher the charge and higher is the number of monovalent cations, higher will be the repulsion and thus the dispersivity. The repulsive force offered by the monovalent cations in soil was calculated through osmotic pressure differences and the dispersivity was expressed as the release of energy as earlier. In order to validate the proposal, the dispersivity of the samples as measured with the conventional methods was compared and studied with the derived expression. The similarity in the trend of the dispersity values confirmed the validity of the derived expressions. Thus, it can be seen that there are primarily two different methods of quantifying dispersivity of soils. When one method estimates dispersivity by calculating the electrostatic repulsion through zeta potential, the other method gives a dispersivity value based on the repulsive pressure offered by the monovalent cations in the soil. Two methods could be regarded as two different measurements of the electrical double layer. Any method could be used based on the property that could be easily quantified. The applicability of the new approaches – calculation of monovalent cations and zeta potential- for estimating the dispersivity in soils through a complete development of philosophy of dispersion and is presented, in this thesis, in nine chapters as follows: In Chapter 1 the background of the study and review of literature connected with the present study is presented. The mechanism of dispersion and the geotechnical problems associated with dispersion is elaborately presented in this section. As the dispersive soils cannot be identified through conventional tests, a description about the various tests designed to identify dispersive soils is presented. Earlier works relevant to the topic and the shortcomings of those studies are discussed. Finally, the objectives of the current research along with the scope of the work are explained in the concluding part of this chapter. Various factors that could have influence on the dispersivity of soils and their mechanism of action are presented in Chapter 2. The relationship of the factors with zeta potential is discussed. Theories dealing with dispersivity, conventional methods of measurement, role of geotechnical characteristics in assessing dispersivity are being presented. Chapter 3 deals with the various materials and methods used for the study. A locally available dispersive soil called Suddha soil along with Black Cotton soil and Red soil were chosen as the soils for the study of dispersion. The basic material properties and testing programs adopted for the study are presented in this chapter. The codal procedures followed to determine the physical, chemical, index and engineering properties are described in detail. The experimental investigations carried to bring out the role of zeta potential in dispersivity of soils are described in Chapter 4. Detailed analysis of the results showed estimation of zeta potential is possible and can sufficient quantify dispersivity of soils. The formulation of the equation for estimating dispersivity from zeta potential is described in Chapter 5. The estimation dispersivity based on attraction and repulsion energies in a soil mass is presented here. The adoption of the approach and methodologies used based on classical DLVO theory for the current work is explained in detail. The values of dispersivity obtained from the derived equation are compared with those obtained from the conventional tests. The validity of the expression is confirmed with the results of the experiments. Chapter 6 deals with the standardization of the measurement procedure of zeta potential. Role of Brownian motion in the accurate measurement of electrophoretic mobilities are brought out here. Chapter 7 brings out an alternate perspective of quantifying dispersivity through monovalent cations. The role of monovalent cations and the mechanism in which they contribute to the repulsive pressures (hence the dispersivity) are discussed. Experimental research design adopted has brought that the effect of monovalent and ionic size on repulsive pressures leading to dispersivity is described. The results of the experiments added with the inferences drawn are explained at the end. The estimation of repulsive pressures for measuring dispersivity from monovalent cations is discussed in Chapter 8. The dispersivity of a soil mass is derived from monovalent ion concentration and experiments were carried out for verification purposes. The experimental investigation procedure adopted followed by the results are presented in this chapter. It was observed that a good co-relation exists with the dispersivity obtained from the monovalent ion concentration and that obtained from conventional methods. Chapter 9 compares the dispersivity obtained through the various methods proposed in this thesis. The comparison is made in light of the classical electrical double layer theory. The major conclusions of the study are brought out at the end of this chapter.

Orientador: Prof. Dr. Hugo Barbosa Suffredini / Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência e Tecnologia/Química, Santo André, 2018. / Este trabalho descreve a realizacao de estudos eletroquimicos fundamentais em interfaces do tipo liquido/liquido. Primeiramente, pretendeu-se compreender as diferencas na oxidacao de uma molecula modelo (ferroceno) por meio de estudos eletroquimicos relacionados a cinetica e termodinamica em diferentes situacoes. A primeira situacao enfoca a oxidacao direta do ferroceno em um eletrolito de suporte convencional aquoso e a segunda e relacionada ao ferroceno sendo adicionado diretamente em oleo mineral que quando em contato com o eletrolito de suporte aquoso, forma uma interface do tipo oleo/agua. Experimentos adicionais tambem foram conduzidos em uma emulsao, que foi constituida por ferroceno em oleo misturados com eletrolitos convencionais e cloreto de tetrabutilamonio (CTBA). Uma placa de diamante dopado com boro (DDB) foi usada como eletrodo de trabalho. Observou-se um deslocamento de aproximadamente 0,07 V quando a oxidacao do ferroceno foi conduzida na interface oleo/agua em comparacao com a oxidacao direta na fase aquosa convencional. Esta mudanca de potencial tambem foi calculada usando a Teoria do Funcional da Densidade (DFT) como ferramenta teorica. Uma comparacao adicional foi realizada em relacao a interface e as emulsoes, constatando que a forca ionica e um fator determinante nesses tipos de estudos. Finalmente, as curvas de Tafel indicaram que as coordenadas da reacao do ferroceno sao diferentes quando o eletrodo e colocado na interface versus diretamente na fase aquosa, sendo que a energia de ativacao obtida para o ferroceno na agua foi de 129 kJ mol L-1 e na interface igual a 53,0 kJ mol L-1. Posteriormente, mostrou-se o uso da microextracao liquido-liquido dispersiva (DLLME) combinada com a eletroquimica de interface oleo/agua, utilizando ferroceno como molecula- modelo. Uma mistura de 150 ¿ÊL de etanol (solvente dispersante) e 50 ¿ÊL de 1-undecanol (solvente de extracao) foi injetada em 9 mL de uma solucao aquosa de ferroceno preparada em H2SO 4 1,0 x10 -3 mol L -1. Uma gota da fase organica contendo ferroceno foi inserida diretamente na superficie de um eletrodo de carbono impresso, e uma curva analitica foi obtida, ponto a ponto, com boa linearidade. O eletrodo de DDB foi utilizado para promover o calculo do coeficiente de particao, em que foi possivel calcular as concentracoes finais de ferroceno nas fases aquosa e organica como sendo iguais a 4,2 ~ 10 -4 mol L-1 e 0,15 mol L -1, respectivamente. Ao usar estes valores, o coeficiente de particao (log P) de 2,5 foi calculado. Por fim, a eletroquimica de interface oleo/agua foi aplicada para estudar a influencia do acido naftenico na corrosao do aco API-5L-X70 a temperatura ambiente a partir de um sistema bifasico constituido por petroleo/solucao aquosa. Um estudo in-situ baseou-se na espectroscopia de impedancia eletroquimica (EIS), enquanto medidas localizadas de impedancia eletroquimica (LEIS) e microscopia eletroquimica de varredura (SECM) foram utilizadas para estudar o efeito da pre-exposicao do aco ao sistema bifasico. Os resultados de LEIS e SECM mostraram que a pre-exposicao ao petroleo com acido naftenico produz uma superficie mais ativa do que apenas a solucao de sulfato. A adicao de acido naftenico ao oleo provoca corrosao. A morfologia da corrosao e caracterizada por tres regioes: i) na fase de oleo; ii) na fase aquosa e iii) em torno da interface. A corrosao foi mais evidente em torno da interface. Propoe-se um mecanismo no qual as moleculas de acidos naftenicos se auto-organizam na interface oleo/agua, gerando acidificacao local no contato trifasico entre oleo / fase aquosa / metal. / This work describes the realization of fundamental electrochemical studies at a liquid / liquid interface. Firstly, it was intended to understand the differences in the oxidation of a model molecule (ferrocene) through electrochemical studies related to kinetics and thermodynamics in different situations. The first situation focuses the direct oxidation of ferrocene in an aqueous conventional support electrolyte and the second one is when ferrocene is directly placed in mineral oil, subsequently placed in contact with an aqueous support electrolyte thereby forming an oil/water interface. Additional experiments were also conducted in an emulsion, which was constituted by ferrocene in oil and mixed with conventional electrolytes and tetrabutylammonium chloride (TBAC). A Boron-Doped Diamond Electrode (BDD) was used as the working electrode. We observed an approximately 0.07 V shift when the ferrocene oxidation was conducted at the oil/water interface compared with the direct oxidation in the conventional aqueous phase. This potential shift was also calculated using the Density Functional Theory (DFT) as a theoretical tool. An additional comparison was conducted related to the interface and emulsions, finding that the ionic strength is determining factor in these types of studies. Finally, Tafel plots indicated that reaction coordinates of the ferrocene are different when the electrode is placed at the interface versus directly in the aqueous phase, in which the activation energy obtained for ferrocene in water was 129 kJ mol L-1 and at the interface equal to 53.0 kJ mol L-1. Posteriorly, we showed the use of dispersive liquid-liquid microextraction (DLLME) combined with organic/water interface electrochemistry by using ferrocene as a model-molecule. A mixture of 150 ¿ÊL of ethanol (disperser solvent) and 50 ¿ÊL of 1-undecanol (extractant solvent) was injected into 9 mL of a ferrocene aqueous solution prepared in 1.0~10.3 mol L.1 H2SO4. Afterward, a drop of the organic phase containing ferrocene was directly inserted on a screen-printed carbon electrode and the analytical curve was obtained, point-to-point, with a good linearity. Besides that, a BDD electrode was used to promote the partition coefficient calculation, and it was possible to calculate the final concentrations of ferrocene in the aqueous and organic phases as being equal to 4.2~10.4 mol L.1 and 0.15 mol L.1, respectively. By using these values, the partition coefficient (log P) was calculated as 2.5. Finally, the oil/water interface was applied to study the role of naphthenic acid in the API.5L.X70 steel corrosion at room temperature from a biphasic system consisting of petroleum/aqueous solution. An in-situ study was based on electrochemical impedance spectroscopy, while localized measures of electrochemical impedance (LEIS) and scanning electrochemical microscopy (SECM) were used for the effect of pre-exposure from steel to biphasic system. The results LEIS and SECM showed that the pre-exposure to oil with acid produces a more active surface than just sulfate medium. Corrosion morphology is characterized by three regions: i) in oil phase; ii) in the aqueous phase, and iii) around the interface. Naphthenic acid corrosion was restricted to the area around the interface. A mechanism is proposed in which naphthenic acids self-assemble at the oil/water interface, generating local acidification at the oil/aqueous phase/metal three-phase contact.

Dans cette thèse, on a d’abord considéré une équation d'onde. On a premièrement montré que l’équation est bien-posée presque sûre par la méthode de décomposition de fréquence de Bourgain sous l’hypothèse de régularité que s > 2(p−3)/(p-1). Ensuite, nous avons réduit de cette exigence de régulation à (p-3)/(p−1) en appelant une estimation probabiliste a priori. Nous considérons également l’approximation des solutions obtenues ci-dessus par des solutions lisses et la stabilité de cette procédure d’approximation. Et nous avons conclu que l’équation est partout mal-posée dans le régime de super-critique. Nous avons considéré ensuite l’équation du faisceau quintique sur le tore 3D. Et nous avons montré que cette équation est presque sûr bien-posée globalement dans certain régimes de super-critique. Enfin, nous avons prouvé que la mesure de l’image de la mesure gaussienne sous l’application de flot de l’équation BBM généralisé satisfait une inégalité de type log-Sobolev avec une petit peu de perte de l’intégrabilité. / In this thesis, we consider a wave equation. We first showed that the equation is almost sure global well-posed via Bourgain’s high-low frequency decomposition under the regularity assumption s > 2(p−3)/(p−1). Then we lowered down this regularity requirement to be (p−3)/(p−1) by invoking a probabilistic a priori estimate. We also consider approximation of the above achieved solutions by smooth solutions and the stability of this approximating procedure. And we concluded that this equation is everywhere ill-posed in the super-critical regime. Next, we considered the quintic beam equation on 3D torus. And we showed that this equation is almost sure global well-posed in certain super-critical regime. Lastly, we proved that the image measure of the Gaussian measure under the generalized BBM flow map satisfies a log-Sobolev type inequality with a little bit loss of integrability.

Disertační práce se zabývá studiem strukturních a mechanických vlastností anorganických materiálů. Cílem je nalezení jednotlivých fází ve zkoumaném materiálu a hlavně lokalizace (mechanicky) nejslabšího místa, jeho ovlivnění a následně výroba materiálu o lepších mechanických vlastnostech. Z důvodu velkého množství použitých metod je základní teorie vložena vždy na začátku příslušné kapitoly. Taktéž z důvodu značného množství výsledků jsou na konci kapitol uvedeny dílčí závěry. Práce je rozdělena na tři části, kdy první se zabývá seznámením s možnostmi modelování mikro-mechanických vlastností a provedením experimentů umožňujících posouzení rozsahu platnosti některého modelu. V druhé části je provedeno shrnutí současných možností indentačních zkoušek pro měření mechanických vlastností strukturních složek betonu a praktické zvládnutí metodiky vhodné k užití pro výzkum materiálů zkoumaných domovským pracovištěm. V třetí části je navržena metoda identifikace nejslabších článků struktury anorganických pojiv a její ověření na konkrétním materiálu zkoumaném na domovském pracovišti. V této dizertační práci jsou použity tyto metody: kalorimetrie, ultrazvukové testování, jednoosá pevnost v tlaku, nanoindentace, korelativní mikroskopie a rastrovací elektronová mikroskopie s energiově disperzním spektrometrem. Dílčími výsledky jsou kompletní charakterizace cementových materiálů, upřesnění stávajících poznatků a nalezení optimálního postupu pro charakterizaci. Hlavním výsledkem je inovativní přístup vedoucí k pozitivnímu ovlivnění materiálu.

According to the 2019 Canadian infrastructure report card, a concerning amount of municipal infrastructure is in poor or very poor condition. The infrastructure in this condition requires immediate action for rehabilitation or replacement. For concrete infrastructure, an effective repair can extend its service life and ensure that the services it provides continue to meet the community expectations. However, unfavorable environmental factors such as repeated/cyclic loads and freezing and thawing cycles adversely affect the bond between substrate concrete and repair materials, which lowers the structural capacity of repaired structures. So far, researchers have found that bond strength of repair can be affected by surface roughness, surface moisture, chemical adhesion or cohesion, curing regime, properties of substrate and repair materials, use of bond agent, and curing regimes. These findings are mostly based on the studies that focused on cold-jointed cylinders or beams, but in real-life repair situations, repairs of beams or slabs are located at either tension or compression side of the structure. Currently, there is no comprehensive study that investigates the bond of concrete repair under a combination of freezing and thawing and repeated/cyclic loading conditions. In addition, it is challenging to provide a rapid and non-destructive evaluation of the bond deterioration of repair materials. To address these issues systematically, this dissertation breaks the task into four phases. Phase (I) focuses on the development of an engineered “crack-free” repair mix that contains polypropylene (PP) fiber. A novel method is used to surface treat the PP fibers with supplementary cementitious materials. The effectiveness of surface-treating fibers for improved bond strength and reduced cracking is investigated. The compressive, tensile, and flexural strength of this engineered repair mix are determined and compared with two commercially available repair materials. The results from Phase I show that by adding 0.2% (by weight) Metakaolin-treated fibers into concrete mix, the compressive strength improves by up to 15.7% compared to mixes with untreated fibers. This study achieved a strength increase of 13.5% as compared to the reported 3.3% in other studies that use 25 times the amount of metakaolin used in this study. The experimental results confirm that at 0.2% dosage level, the use of novel surface treating technique is a cost-effective way to improve the strength of repair materials. Phase (II) focuses on characterizing the bond strength of various repair systems after freezing-thawing (FT) damage using both non-destructive and destructive methods. Two innovative sounding methods, which overcome the subjectivity of the traditional chain drag method, are used to evaluate FT damage non-destructively. In the experimental study, beams with a U-shaped cut are made to simulate conditions experienced by a concrete structure during a typical repair project. Three types of repair materials are used including cementitious repair concrete, cementitious repair mortar, and polymer-modified cementitious mortar. After up to 300 cycles of freeze-thaw exposure, resonant frequency and bond flexural strength of the prismatic specimens are determined. The empirical equations relating Non-destructive test (NDT) measurements and flexural bond strength of the repaired structures after freeze-thaw (FT) exposure are proposed. The results from Phase II show that the change in dynamic modulus of elasticity determined from NDTs agrees well with the change in other measurements including flexural bond strength, interfacial crack width, and mass loss after freeze-thaw exposure. In this study, linear relationships are established between dynamic modulus of elasticity and flexural bond strength for both cementitious and polymer-modified cementitious repair mortar with a coefficient of determination ranging between 0.87 and 0.95. The proposed empirical models can be used to predict bond flexural strength of repaired structures based on NDT measurement. Also, it was found that the samples repaired with polymer-modified cementitious mortar (Mix P) have superior FT resistance compared to other repaired samples. Phase (III) focuses on investigating the structural capacity and bond performance of repaired beams after cyclic/repeated loading. To accelerate the test process, a novel modified loading regime consisting of cycle groups of increasing cyclic/repeated stress amplitude is proposed. The models proposed by literature and current codes and standards are used to validate the results. Phase (IV) focuses on the development of the damage models for both individual and combined FT and cyclic loading exposure on repaired concrete structures. The results in phase III show the feasibility of using the Palmgren-Miner rule and Goodman linear model to estimate the fatigue life of repaired structures. This was confirmed within the context of this study. This study established the usefulness of using groups of increasing cyclic stress amplitude to accelerate the fatigue test process. The two-million cycle fatigue endurance limit estimated using cycle groups of Mix S (70.8%) was very similar to what was reported in the literature (71%) using the traditional time-consuming cyclic loading method. This study found that the formulas proposed by CSA 23.3 can effectively predict the moment resistance of both intact (control) and repaired RC beams. The ratio of experimental moment resistance values to its predictions ranges from 0.91 to 1.04. Based on the experimental results of previous three phases, an empirical model that predicted the fatigue service life of FT-damaged concrete structures is proposed. Future research requires a more comprehensive study on the FT performance of various polymer-modified cementitious mortars of different mix designs in repairing concrete structures. By increasing the number of tested specimens, a better relationship could be established between destructive and NDT methods. Future research is also required to explore the combined effect of FT and cyclic loading on repaired RC structures experimentally. / Graduate / 2023-03-22

This work is focused on segregation processes in the matrix of spheroidal graphite cast iron with different silicon and nickel content during heat treatment. The aim of this work is to trace the redistribution of the elements of interest during homogenization annealing with different dwell time by comparison of the effective distribution coefficients. Comparison of some specific properties and description of structure development of spheroidal graphite cast iron matrix from initial state to the state after ferritization and homogenization annealing is included in this work.

This doctoral thesis deals with the comparison of different methods of alloying elements’ concentration measurement based on energy dispersive spectroscopy and also with the suitability of particular methods of quantitative assessment of heterogeneity of the spheroidal graphite cast iron matrix. The segregation curves construction, distribution coefficient and heterogeneity index formulation is also discussed. The notion “normalized distribution coefficient” is introduced newly. The goal of the thesis, which is to be achieved by means of evaluation of large experimental data sets, is the evaluation of applicability of homogenization annealing of spheroidal graphite cast iron with the aim to eliminate segregation of silicon, and mainly nickel, as pearlite- and carbide-forming agent at the border of an eutectic cell. The result is an optimized homogenization annealing schedule maximizing the suppression of silicon and nickel segregation while taking into account the minimization of financial expenses and risk of grain coarsening.

No description available.

博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University