Дисертації з теми "Degree of silica hydration"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-20 дисертацій для дослідження на тему "Degree of silica hydration".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Stephant, Sylvain. "Etude de l'influence de l'hydratation des laitiers sur les propriétés de transfert gazeux dans les matériaux cimentaires." Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS090/document.
Повний текст джерелаCements with high slag content are currently studied as possible candidate for nuclear waste containment materials. In this context it is important to know their microstructure and the transport properties (permeability and diffusion) of the gases that are formed by the radiolysis of the water present in this material. According to literature, these properties are strongly impacted by the addition of blast furnace slag. The aim of this work is to correlate the hydration processes of slag blended cements with their transport properties. In the first part of this work, the hydration of the slag blended cements, for which only few results have been reported to date, has been studied. Silicon-29 and aluminium-27 Magic-Angle Spinning Nuclear Magnetic Resonance (MAS NMR) were used to follow the variations of anhydrous phases of clinker (C3S, C2S, C3A and C4AF) and of the main oxides of the slag (SiO2, Al2O3, CaO, MgO and SO3). The quantity of calcium dissolved from slag was deduced by fitting the quantity of portlandite [Ca(OH)2] calculated by a geochemical software (PHREEQC - coupled to a thermodynamic database) with TGA measurements. Our approach enabled the evolution of the hydration degree (percentage of reacted material) of various oxides of slag to be determined. A progressive and an incongruent dissolution (the rate of dissolution of the oxides is different) of the slag is observed. The low reactivity of slag could be linked, at a hydration time, to a lower content of bound water, chemical shrinkage and heat of hydration. Quantitatively accounting for the dissolution of clinker and oxide of slag yields a more accurate description of the hydration process. The second part of this work is focused on the microstructure evolution and its influence on the transport properties (diffusion and permeability). Time-evolution of the diffusion coefficients and the intrinsic permeability could be monitored and were then compared to that of the microstructure (global porosity, pore entry size distribution, specific surface area and the degree of connectivity). The results showed a decrease in the diffusion coefficient and permeability over time which is due to the progressive filling of the porosity. A decrease of these parameters with the slag content increasing was also observed. This is a consequence of the diminution of the capillary porosity and augmentation of the nanoporosity resulting from changes in the microstructure of C-S-H. The last part concerns the relation between the hydration processes, the microstructure and the transport properties. To this aim, volumetric balances of reactions involved in the hydration processes were made by considering globally or specifically the hydration of the different phases. Accounting for the hydration of each phase of the cement allowed us to determine the global porosity, the bound water content and the chemical shrinkage with accuracy of the order of 10 %. This description allows the understanding of the transport properties variations in time for a same material To establish this time evolutions for all the cements, the apparent volume of C-S-H was recalculated to account for the microstructure of these hydrates
Björnström, Joakim. "Influence of nano-silica and organic admixtures on cement hydration : a mechanistic investigation /." [Go̊teborg], Sweden : Dept. of Chemistry, Göteborg University, 2005. http://www.loc.gov/catdir/toc/fy0801/2006411318.html.
Повний текст джерелаBjörnström, Joakim. "Influence of nano-silica and norganic admixtures of cement hydration : a mechanistic investigation /." Göteborg : Göteborg University, Department of Chemistry, 2005. http://www.loc.gov/catdir/toc/fy0801/2006411318.html.
Повний текст джерелаHassanali, Ali. "WATER AT MOLECULAR INTERFACES: STRUCTURE AND DYNAMICS NEAR BIOMOLECULES AND AMORPHOUS SILICA." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1275314943.
Повний текст джерелаGonzalez-Rodriguez, Jesus Alberto. "The mechanical response to contact of Soda Lime Silica float glass and the effects of hydration and high temperature." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/10019/.
Повний текст джерелаCHAKRAVARTY, SRINIVAS L. N. "DEVELOPMENT OF SCRATCH RESISTANT PECVD SILICA-LIKE FILMS." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin973542599.
Повний текст джерелаChan, Lok. "Neutron scattering studies of water in biomolecules and biomaterials." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/neutron-scattering-studies-of-water-in-biomolecules-and-biomaterials(58d5b829-53dc-4a8d-97df-3529e2ecf097).html.
Повний текст джерелаMirzahosseini, Mohammadreza. "Glass cullet as a new supplementary cementitious material (SCM)." Diss., Kansas State University, 2014. http://hdl.handle.net/2097/17565.
Повний текст джерелаDepartment of Civil Engineering
Kyle A. Riding
Finely ground glass has the potential for pozzolanic reactivity and can serve as a supplementary cementitious material (SCM). Glass reaction kinetics depends on both temperature and glass composition. Uniform composition, amorphous nature, and high silica content of glass make ground glass an ideal material for studying the effects of glass type and particle size on reactivity at different temperature. This study focuses on how three narrow size ranges of clear and green glass cullet, 63–75 [mu]m, 25–38 [mu]m, and smaller than 25 [mu]m, as well as combination of glass types and particle sizes affects the microstructure and performance properties of cementitious systems containing glass cullet as a SCM. Isothermal calorimetry, chemical shrinkage, thermogravimetric analysis (TGA), quantitative analysis of X-ray diffraction (XRD), and analysis of scanning electron microscope (SEM) images in backscattered (BS) mode were used to quantify the cement reaction kinetics and microstructure. Additionally, compressive strength and water sorptivity experiments were performed on mortar samples to correlate reactivity of cementitious materials containing glass to the performance of cementitious mixtures. A recently-developed modeling platform called “[mu]ic the model” was used to simulated pozzolanic reactivity of single type and fraction size and combined types and particle sizes of finely ground glass. Results showed that ground glass exhibits pozzolanic properties, especially when particles of clear and green glass below 25 [mu]m and their combination were used at elevated temperatures, reflecting that glass cullet is a temperature-sensitive SCM. Moreover, glass composition was seen to have a large impact on reactivity. In this study, green glass showed higher reactivity than clear glass. Results also revealed that the simultaneous effect of sizes and types of glass cullet (surface area) on the degree of hydration of glass particles can be accounted for through a linear addition, reflecting that the surface area would significantly affect glass cullet reactivity and that the effects of SCM material interaction on reaction kinetics were minimal. However, mechanical properties of cementitious systems containing combined glass types and sizes behaved differently, as they followed the weaker portion of the two particles. This behavior was attributed to the pores sizes, distruibution, and connectiity. Simulations of combined glass types and sizes showed that more work on microstructural models is needed to properly model the reactivity of mixed glass particle systems.
Ferrer, Vall-llosada Íngrid. "Development of new reusable materials based on Ru complexes with catalytic activity for olefin epoxidation and nitrile hydration." Doctoral thesis, Universitat de Girona, 2015. http://hdl.handle.net/10803/322785.
Повний текст джерелаEn aquesta tesi es presenta la síntesi de diferents tipus de complexos de ruteni que contenen lligands N-donadors en combinació amb lligands dmso, Cl i H2O, i la seva completa caracterització mitjançant tècniques espectroscòpiques i electroquímiques. Els complexos han estat avaluats com a catalitzadors en epoxidació d'olefines i hidròlisi de nitrils en fase homogènia. Per altra banda, tenint en compte la importància i els avantatges de la catàlisi heterogènia, s’ha dut a terme la immobilització d’alguns d’aquests complexos sobre suports tipus sílice i se n'ha avaluat l'activitat catalítica, comparant-los amb els anàlegs en fase homogènia. És destacable l'activitat dels complexos amb lligands dmso i pirazole en la hidròlisi de nitrils a amides en aigua com a dissolvent. Els sistemes Ru-OH2 heterogenis s'han avaluat en l'epoxidació d'olefines i s'han pogut reutilitzar durant diversos cicles mantenint alts valors de selectivitat per l'epòxid.
Kleib, Joelle. "Ecoconception des ciments : synthèse, hydratation et durabilité." Thesis, Ecole nationale supérieure Mines-Télécom Lille Douai, 2018. http://www.theses.fr/2018MTLD0009/document.
Повний текст джерелаSulfoaluminate cements are hydraulic binders that, until today, are not standardized and therefore do not have a fixed composition. The content of ye'elimite - the main compound of this cement - can vary from 5 to 70 %. However, the composition of sulfoaluminate cement (clinker composition as well as the percentage of added gypsum) is a critical parameter that controls its reactivity, mechanical performance, as well as its durability. The main objective of this thesis is to study the influence of sulfoaluminate cements composition on their technical properties, such as mechanical performances and durability. Three main axes were discussed in this work. First, the influence of the sulfoaluminate cement composition (25-75 wt. % of ye'elimite) on its hydraulic and mechanical properties, as well as on the threshold limit of Zn, was studied. For this purpose three sulfoaluminate cements (25, 50 and 75 wt. % of ye'elimite) were synthesized. Then the effect of the variability of this cement on its durability in pure and sulphated water was investigated compared to a commercial sulfoaluminate cement. Finally, a study of the potentialities of commercial sulfoaluminate cement to inhibit the alkali silica reaction in mortars, when using a reactive aggregate (flint), was conducted. This study reveals that an increase in ye'elimite content in the sulfoaluminate cement increases the mechanical performance. The threshold limit of Zn is 0.3 % independently of the sulfoaluminate cement composition. Contrariwise, the sulfoaluminate cement composition influences the durability of these cements. Although the formulation containing 75 % of ye’elimite gives the best mechanical performances, its durability was lowest due to the absence of stratlingite in its cement matrix. Finally, the use of sulfoaluminate cement has good potential towards the inhibition of the alkali silica reaction
Moustachi, Om Elkhaïat. "Influence de la microstructure des mortiers de ciment portland armes de fibres sur leur comportement mecanique en flexion." Toulouse, INSA, 1986. http://www.theses.fr/1986ISAT0002.
Повний текст джерелаVeleba, Ondřej. "Studium vlivu složení na mechanické vlastnosti vysokohodnotného betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2008. http://www.nusl.cz/ntk/nusl-216217.
Повний текст джерелаPetrinolis, Z. "Diagenetic effects on the molecular structure of biogenic silica: Implications for palaeoclimate research." Thesis, 2016. http://hdl.handle.net/2440/121126.
Повний текст джерелаBiogenic silica is abundantly preserved in sediment and is found in diatoms and many higher plants. The isotopic composition (δ18Osilica) of biogenic silica is used widely in paleoclimate research to infer conditions in which the organism grew. However, previous studies show that secondary alterations within the matrix of biogenic silica complicate the structural and geochemical analysis of silica. This study investigates how the hydrated structure of silica changes at different temperature with time. A statistical model is constructed that quantifies the degree of silica hydration (Q4/Q3) by calibrating Fourier transform infrared (FTIR) measurements against nuclear magnetic resonance. This study also conducts an investigation of various oxidation techniques to find an optimal method to be used to remove organics within biogenic silica, although residual contamination proved challenging to remove in most cases. These contaminants hinder the quantification of silica hydration using FTIR which is also used in the statistical modelling of Q4/Q3 measurements. The experimental results showed a relationship between time and the relative increase of the relative hydroxylation/dehydroxylation of biogenic silica. However, silica condensation is not a linear reaction, but reversible, potentially implying that the structure of silica readily undergoes temporary absorption/desorption at its surface in the presence of water.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2016
Wang, Gwo-Tzong, and 王國宗. "Hydration Mechanisms and Strength Growth of Silica Fume-Cement dened through Dry-Mix/Steam-Injection Process." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/13771966365776518709.
Повний текст джерела(8065844), Jedadiah Floyd Burroughs. "Influence of Chemical and Physical Properties of Poorly-Ordered Silica on Reactivity and Rheology of Cementitious Materials." Thesis, 2019.
Знайти повний текст джерелаSilica fume is a widely used pozzolan in the concrete industry that has been shown to have numerous benefits for concrete including improved mechanical properties, refined pore structure, and densification of the interfacial transition zone between paste and aggregates. Traditionally, silica fume is used as a 5% to 10% replacement of cement; however, newer classes of higher strength concretes use silica fume contents of 30% or greater. At these high silica fume contents, many detrimental effects, such as poor workability and inconsistent strength development, become much more prominent.
In order to understand the fundamental reasons why high silica fume contents can have these detrimental effects on concrete mixtures, eight commercially available silica fumes were characterized for their physical and chemical properties. These included traditional properties such as density, particle size, and surface area. A non-traditional property, absorption capacity, was also determined. These properties or raw material characteristics were then related to the hydration and rheological behavior of pastes and concrete mixtures. Other tests were performed including isothermal calorimetry, which showed that each silica fume reacted differently than other silica fumes when exposed to the same reactive environment. Traditional hydration models for ordinary portland cement were expanded to include the effects that silica fumes have on water consumption, volumes of hydration products, and final degree of hydration.
As a result of this research, it was determined necessary to account for the volume and surface area of unhydrated cement and unreacted silica fume particles in water-starved mixture proportions. An adjustment factor was developed to more accurately apply the results from hydration modeling. By combining the results from hydration modeling with the surface area adjustments, an analytical model was developed to determine the thickness of paste (hydration products and capillary water) that surrounds all of the inert and unreacted particles in the system. This model, denoted as the “Paste Thickness Model,” was shown to be a strong predictor of compressive strength results. The results of this research suggest that increasing the paste thickness decreases the expected compressive strength of concretes at ages or states of hydration.
The rheological behavior of cement pastes containing silica fume was studied using a rotational rheometer. The Herschel-Bulkley model was fit to the rheological data to characterize the rheological behavior. A multilinear model was developed to relate the specific surface area of the silica fume, water content, and silica fume content to the Herschel-Bulkley rate index. The Herschel-Bulkley rate index is practically related to the ease at which the paste mixes. This multilinear model was shown to have strong predictive capability when used on randomly generated paste compositions.
Additionally, an analytical model was developed that defines a single parameter, idealized as the thickness of water surrounding each particle in the cementitious system. This model, denoted as the “Water Thickness Model,” incorporated the absorption capacity of silica fumes discovered during the characterization phase of this study and was shown to correlate strongly with the Herschel-Bulkley rate index. The Water Thickness Model demonstrates how small changes in water content can have a drastic effect on the rheology of low w/c or high silica fume content pastes due to the combined effects of surface area and absorption. The effect of additional water on higher w/c mixtures is significantly less.
Liu, Changling, Yuguang Ye, Xunhua Zhang, Hailong Lu, and John A. Ripmeester. "RAMAN SPECTROSCOPIC OBSERVATIONS ON THE STRUCTURAL CHARACTERISTICS AND DISSOCIATION BEHAVIOR OF METHANE HYDRATE SYNTHESIZED IN SILICA SANDS WITH VARIOUS SIZES." 2008. http://hdl.handle.net/2429/1100.
Повний текст джерелаTselios, Nikolaos. "The effect of hydration on the strength of all ceramic porcelain crowns a thesis submitted in partial fulfillment ... for the degree of Master of Science in Prosthodontics ... /." 2003. http://catalog.hathitrust.org/api/volumes/oclc/68962650.html.
Повний текст джерелаLopes, João Miguel Vasco. "Síntese e aplicação de nanopartículas de sílica, a partir de silicato de sódio, em argamassas." Master's thesis, 2020. http://hdl.handle.net/10316/90185.
Повний текст джерелаThe present work aims to optimize a simple and economical method of synthesis of silica nanoparticles and to study the influence of their addition on cement formulations in terms of physical, chemical, thermal and mechanical properties, in order to improve them .Regarding the synthesis of nanoparticles, a sol-gel method was used, using sodium silicate (recognized as an economically accessible precursor) and hydrochloric acid, with parameters such as temperature and time of synthesis, as well as the volume of acid used being studied. and the concentration of the precursor. All the synthesized particles were characterized in terms of their size and zeta potential. In all tests performed, their nanometric size was confirmed, obtaining average sizes between 30 and 100 nm. Regarding the stability of the dispersions, all of them were characterized as being stable, obtaining values of zeta potential between -30 and -60 mV. The test where the best results were found in these two properties (test 3) had the following synthesis parameters: synthesis temperature of 27ºC, synthesis time of 5 minutes, precursor concentration of 6% by weight, and acid volume of 15 mL .The nanoparticles were further characterized using FTIR and SEM. Through infrared spectroscopy it was possible to identify the main functional groups present and prove the effectiveness of the washing step. With the microscopic analysis of the nanoparticles it was possible to confirm their nanometric size, as well as to obtain information about the geometry of the particles. Regarding the effects of applying nanoparticles in cement mortars, physical, chemical, thermal and mechanical properties were studied. A thermogravimetric analysis was carried out on one of the specimens, which allowed the improvement in the hydration of the test piece with nanoparticles. The thermal conductivity of the specimens showed a tendency to decrease with the addition of the nanoparticles as intended, reaching a decrease of about 11% for one of the specimens produced. Regarding the microstructure and the mechanical properties of the specimens, the addition of nanoparticles resulted in an improvement of these properties, with the best result being obtained for the test where the nanoparticles with smaller sizes were produced, reaching 11% and 70%, in relation to Young's modulus and maximum compressive strength, respectively.
O presente trabalho tem como objetivos a otimização de um método de síntese simples e económico de nanopartículas de sílica e o estudo da influência da sua adição em formulações de cimento ao nível das propriedades físicas, químicas, térmicas e mecânicas, com o intuito de as melhorar. Em relação à síntese das nanopartículas, foi utilizado um método sol-gel, com recurso a silicato de sódio (reconhecido como precursor economicamente acessível) e ácido clorídrico, sendo estudados parâmetros como a temperatura e tempo de síntese, bem como o volume de ácido usado e a concentração do precursor. Todas as partículas sintetizadas foram caracterizadas relativamente ao seu tamanho e ao potencial zeta. Em todos os ensaios realizados confirmou-se o seu tamanho nanométrico, obtendo-se tamanhos médios entre 30 e 100 nm. Em relação à estabilidade das dispersões, todas elas se caracterizaram como sendo estáveis, obtendo-se valores de potencial zeta entre -30 e -60 mV. O ensaio onde se verificaram melhores resultados nestas duas propriedades (ensaio 3) teve os seguintes parâmetros de síntese: temperatura de síntese de 27ºC, tempo de síntese de 5 minutos, concentração de precursor de 6% em massa, e volume de ácido de 15 mL.As nanopartículas foram ainda caracterizadas com recurso a espetroscopia de infravermelho por transformada de Fourier e microscopia eletrónica de varrimento. Através da espetroscopia de infravermelho foi possível identificar os principais grupos funcionais presentes e comprovar a eficácia da etapa de lavagem. Com a análise microscópica das nanopartículas foi possível confirmar o seu tamanho nanométrico, bem como obter informações acerca da geometria das partículas.Em relação aos efeitos da aplicação das nanopartículas em argamassas, foram estudadas propriedades físicas, químicas, térmicas e mecânicas. A um dos provetes foi realizada uma análise termogravimétrica, sendo que esta permitiu comprovar a melhoria ao nível da hidratação do provete com nanopartículas. A condutividade térmica dos provetes revelou uma tendência para diminuir com a adição das nanopartículas como era pretendido, atingindo uma diminuição de cerca de 11% para um dos provetes produzidos. Em relação à microestrutura e às propriedades mecânicas dos provetes, a adição de nanopartículas traduziu-se numa melhoria destas propriedades, sendo o melhor resultado obtido para o ensaio onde se produziram as nanopartículas com tamanhos inferiores, atingindo os 11% e 70%, em relação ao módulo de Young e à resistência máxima à compressão, respetivamente.
Ngaji-Okumu, Walter. "Thermal compatibility of a silica enriched ceramic (Magcor) thesis submitted in partial fulfillment ... for the degree of Master of Science (School of Dentistry) in Dental/Biomaterials ... /." 1995. http://catalog.hathitrust.org/api/volumes/oclc/68798178.html.
Повний текст джерелаO'Kray, Hal. "The hydration of a high alkali porcelain and its effect on In Vitro human enamel wear, flexure and impact strength a study submitted in partial fulfillment ... for a Master of Science degree in Biomaterials ... /." 2001. http://catalog.hathitrust.org/api/volumes/oclc/68944131.html.
Повний текст джерела