Academic literature on the topic 'Degree of silica hydration'
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Journal articles on the topic "Degree of silica hydration"
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Bach, Quoc Si. "Investigation of Blended Cement Hydration in the Reactive Powder Concrete with Increasing Levels of Silica Fume Addition." Applied Mechanics and Materials 889 (March 2019): 304–12. http://dx.doi.org/10.4028/www.scientific.net/amm.889.304.
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Hydration is a chemical reaction in which the major compounds in cement form chemical bonds with water molecules and become hydration products. By the process of hydration Portland cement mixed with sand, gravel and water produces the synthetic rock we call concrete. The Therefore, the concrete properties always accompanies with the hydration degree of cement. This paper presents some experimental test results on how silica fume affects the cement hydration in cement pastes of the Reactive Powder Concrete as increasing levels of silica fume addition with the content from 0% to 30% of cement mass. The hydration process of cement/silica fume paste was followed from the estimation of heat of hydration, rate of heat evolution, of binder pastes obtained by isothermal calorimetry (TAM-Air). In addition, the portlandite content, the hydration degree of pure cement, reaction degree of binder paste as well as reaction degree of silica fume were investigated. The quantitative assessment on these characteristics are due to the simulation of the hydration of Portland cement pastes containing silica fume.
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Wu, Cheng Zhu, Yong He Liang, Yu Cheng Yin, Man Fei Cai, Jian Hua Nie, and Sen Cai Shen. "Characterization of Hydrolysis Process of a Silane Coupling Agent KH-570." Key Engineering Materials 768 (April 2018): 279–85. http://dx.doi.org/10.4028/www.scientific.net/kem.768.279.
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The hydrolysis process of a silane coupling agent KH-570 in deionized water, ethanol, and their mixed medium was characterized by continuous online conductivity testing, respectively. In addition, hydration products of KH-570 in different mediums were analyzed by Fourier transform infrared spectroscopy (FTIR) to correlate with its hydration process. Results indicate that the KH-570 hydrates fast and to a large degree in deionized water, but at the same time, its hydrolysis products condensate together with increasing rate during the hydration process. However, the introduction of ethanol could significantly reduce the degree of the condensation. The hydrolysis degree of KH-570 was relatively large in a mix medium of deionized water and ethanol with the mass ratio of 5:1, and condensation degree of hydrolysis products was also small. KH-570 would hydrate quickly in a hydration medium of colloidal silica, and subsequently, its hydration products would directly react with colloidal silica, which could accelerate the formation of Si-O-Si three-dimensional network structure, and thus promoting the setting of colloidal silica. The hydration of 0.9wt% KH-570 in colloidal silica could be sufficient, and correspondingly, its effect on the coagulation of colloidal silica was better.
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Wang, Feng, Pingan Chen, Xiangcheng Li, and Boquan Zhu. "Effect of Colloidal Silica on the Hydration Behavior of Calcium Aluminate Cement." Materials 11, no. 10 (September 28, 2018): 1849. http://dx.doi.org/10.3390/ma11101849.
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The effect of colloidal silica (CS) on the hydrate phases and microstructure evolution of calcium aluminate cement (CAC) was investigated. Samples hydrated with CS were obtained and characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared spectroscopy (FT-IR), hydration heat measurement and Nuclear Magnetic Resonance (NMR). The results revealed that SiO2 nanoparticles may affect the hydrates crystallization process. There was a compact structure in the CAC paste with CS, while petal-shaped hydrates with a porous structure were formed in the pure CAC paste. The maximum value of electrical conductivity for CAC paste with CS suggested that the early stage of hydration for CAC was accelerated. However, the hydration heat curves revealed that the late stage of the CAC hydration process was inhibited, and the hydration degree was reduced, this result was in accordance with Thermogravimetry-Differential scanning calorimetry(TG-DSC) curves. The fitting results of hydration heat curves further showed that the hydration degree at NG (nucleation and crystal growth) process stage was promoted, while it was limited at the phase boundaries stage, and the diffusion stage in the hydration reaction was brought forward due to the addition of CS. According to these results and analyses, the differences in the hydration process for CAC with and without CS can be attributed to the distribution and nucleation effect of SiO2 nanoparticles.
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Skripkiūnas, Gintautas, Žymantas Rudžionis, and Vitoldas Vaitkevičius. "COMPLEX ADMIXTURES FOR HIGH-STRENGTH CONCRETE." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 8, no. 4 (December 31, 2002): 276–80. http://dx.doi.org/10.3846/13923730.2002.10531288.
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The influence of naphthalene formaldehyde superplasticizers (NFS), lignosulfonate plasticizers (LSP) and silica fume on cement paste properties and complex usage of these admixtures for high-strength concrete production are investigated in this research. These admixtures influence the cement hydration products morphology and properties of hardened cement paste. The degree of cement hydration and Ca(OH)2 content in hardened cement paste were determined for analysis of cement hydration process with admixtures. Mechanical properties and porosity of hardened cement paste with the admixtures were tested. Optimal dosages of plasticizing admixtures and silica fume were estimated and the most efficient method of silica fume adding to concrete mixture was proposed. The results of investigation have been used for high-strength concrete production.
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Huang, Ruixing, Chengxue Ma, Qiang He, Jun Ma, Zhengsong Wu, and Xiaoliu Huangfu. "Ion specific effects of monovalent cations on deposition kinetics of engineered nanoparticles onto the silica surface in aqueous media." Environmental Science: Nano 6, no. 9 (2019): 2712–23. http://dx.doi.org/10.1039/c9en00251k.
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Kang, Hyunuk, Nankyoung Lee, and Juhyuk Moon. "Elucidation of the Hydration Reaction of UHPC Using the PONKCS Method." Materials 13, no. 20 (October 19, 2020): 4661. http://dx.doi.org/10.3390/ma13204661.
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This study explored the hydration reaction of ultra-high-performance concrete (UHPC) by using X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA) as analysis methods. The partial- or no-known crystal structure (PONKCS) method was adopted to quantify the two main amorphous phases of silica fume and C-S-H; such quantification is critical for understanding the hydration reaction of UHPC. The measured compressive strength was explained well by the degree of hydration found by the PONKCS method, particularly the amount of amorphous C-S-H. During heat treatment, the pozzolanic reaction was more intensified by efficiently consuming silica fume. After heat treatment, weak but continuous hydration was observed, in which the cement hydration reaction was dominant. Furthermore, the study discussed some limitations of using the PONKCS method for studying the complicated hydration assemblage of UHPC based on the results of TGA and NMR. Generally, the PONKCS method underestimated the content of silica fume in the early age of heat treatment. Furthermore, the structural evolution of C-S-H, confirmed by NMR, should be considered for more accurate quantification of C-S-H formed in UHPC. Nevertheless, PONKCS-based XRD could be useful for understanding and optimizing the material properties of UHPC undergoing heat treatment.
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Turov, V. V., V. M. Gun'ko, and T. V. Krupska. "Methane adsorption onto silicas with various degree of hydrophobicity." Surface 13(28) (December 30, 2021): 94–126. http://dx.doi.org/10.15407/surface.2021.13.094.
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The methane adsorption onto a hydrated surface of hydrophobic silica AM1 alone and impregnated by arginine, and silica gel Si-100 has been studied using low-temperature 1H NMR spectroscopy. It has been shown that the methane adsorption onto the AM1 surface depends on the degree of hydration and pretreatment type. The maximum adsorption (up to 80 mg/g) is observed for a sample hydrated after complete drying. It has been established that the adsorption is determined by a number of clusters of bound water of small radii. Based on a shape of the temperature dependence of the adsorption, it has been assumed that not only physical adsorption occurs, but also the quasi-solid methane hydrates are formed. It has been established that the amount of methane adsorbed onto a surface of a composite system AM1/arginine under isobaric conditions increases by tens of times (from 0.5 to 80 mg/g) in the presence of pre-adsorbed water pre-adsorbed at the surface. Probable mechanisms of the methane adsorption are physical adsorption on a surface, condensation in narrow voids between silica nanoparticles and nano-scaled (1-10 nm) water clusters, and the formation of solid (clathrate) methane hydrates. Water, adsorbed at a surface in a wide range of hydration, forms various clusters. This water is mainly strongly associated and characterized by chemical shifts in the range dH = 4-6 ppm. The hydrate structures with methane/water are quite stable and can exist even in the chloroform medium. However, in this case, a part of water transforms into a weakly associated state and it is observed at dH = 1.5-2 ppm.
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Zhou, Yue, Zhongping Wang, Zheyu Zhu, Yuting Chen, Linglin Xu, and Kai Wu. "Impacts of Space Restriction on the Microstructure of Calcium Silicate Hydrate." Materials 14, no. 13 (June 30, 2021): 3645. http://dx.doi.org/10.3390/ma14133645.
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The effect of hydration space on cement hydration is essential. After a few days, space restriction affects the hydration kinetics which dominate the expansion, shrinkage and creep of cement materials. The influence of space restriction on the hydration products of tricalcium silicate was studied in this paper. The microstructure, morphology and composition of calcium silicate hydrate (C-S-H) were explored from the perspective of a specific single micropore. A combination of Raman spectra, Fourier transform infrared spectra, scanning electron microscopy and energy dispersive X-ray spectroscopy were employed. The results show that space restriction affects the structure of the hydration products. The C-S-H formed in the micropores was mainly composed of Q3 silicate tetrahedra with a high degree of polymerization. The C-S-H formed under standard conditions with a water to cement ratio of 0.5 mostly existed as Q2 units. Space restriction during hydration is conducive to the formation of C-S-H with silica tetrahedra of a high polymerization degree, while the amount of water filling the micropore plays no obvious role on the polymeric structure of C-S-H during hydration.
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Pyeon, Sujeong, Gyuyong Kim, Sangsoo Lee, and Jeongsoo Nam. "Internal Curing Effect of Waste Glass Beads on High-Strength Cement Composites." Applied Sciences 12, no. 16 (August 22, 2022): 8385. http://dx.doi.org/10.3390/app12168385.
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High-strength concrete (HSC) uses binders and microfillers with ultrafine particles, such as silica fume. The resulting dense internal hydration structure rapidly decreases HSC humidity, causing shrinkage cracks and affecting internal hydration. Herein, the hydration degree inside high-strength cement composites (HSCCs) was examined using waste glass beads (WGBs) as lightweight aggregates (LWAs). Moreover, unreacted hydrate reduction and hydrate formation tendencies were investigated. WGBs with particle sizes within 2.00–6.00 mm were added at ratios of 5%, 10%, and 20% after pre-wetting. The increased number of hydrates inside the specimens were examined under steam curing (80 °C) and room temperature curing (25 °C). The strength decreased as the WGB content increased. Thermogravimetric, X-ray diffraction, and Si nuclear magnetic resonance analyses revealed that the hydration degree of Si inside HSCCs changed when the content of pre-wetted LWAs changed. A visual inspection of the specimen cross-section and scanning electron microscopy–energy-dispersive X-ray spectrometry (SEM–EDS) analysis revealed the moisture trapped inside WGB pores and the hydration tendency. Under steam curing and room temperature curing, the paste contained different amounts of hydrates, depending on WGB content. Moreover, water-absorbed WGBs were continuously desorbed through SEM–EDS, and hydrates were present in WGB pores.
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Zhou, Haiyun, Hongbo Zhu, Hongxiang Gou, and Zhenghong Yang. "Comparison of the Hydration Characteristics of Ultra-High-Performance and Normal Cementitious Materials." Materials 13, no. 11 (June 6, 2020): 2594. http://dx.doi.org/10.3390/ma13112594.
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The hydration mechanism of ultra-high-performance cementitious materials (UHPC) departs considerably from that of normal cementitious materials (NC). In this study, the strength, isothermal calorimetry, chemical shrinkage, X-ray diffraction (XRD), and thermogravimetry (TG) methods are used to determine the hydration characteristics of UHPC and NC that contain silica fume (SF). A simple device was modified to test the chemical shrinkage for long-term growth, and the ultimate chemical shrinkage is obtained by semi-empirical formula fitting. It is found that the degree of hydration of UHPC is significantly lower than that of NC. The hydration kinetics analyzed using the Krstulovic-Dabic model shows that the hydration process of NC is type NG-I-D, which is characterized by gentle and prolonged hydration. However, the hydration of UHPC is type NG-D with the distinguishing features of early sufficiency and later stagnation. The growth of the strength, exothermic evolution, and phase development of UHPC is decelerated as the hydration process proceeds, which confirms the weak development tendency of hydration at the later stage. In addition, the effect of SF on the hydration of UHPC is minor, and the higher content of SF is beneficial to the hydration at the later stage.
Dissertations / Theses on the topic "Degree of silica hydration"
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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.
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L’utilisation de ciment à haute teneur en laitier est envisagée dans le cadre du conditionnement des déchets nucléaires. Dans ce contexte, il est nécessaire de connaître les propriétés structurales et de transport des gaz formés par la radiolyse de l’eau contenue dans cette matrice. Selon la littérature, ces propriétés sont impactées par l’ajout de laitier de haut-fourneau. L’objectif de cette thèse est de relier les processus d’hydratation des ciments au laitier aux propriétés de transport des gaz. La première partie de cette étude est consacrée à l’étude de l’hydratation des ciments au laitier. La Résonance Magnétique Nucléaire (RMN) du silicium et de l’aluminium a été utilisée pour suivre l’évolution de la quantité des différentes phases anhydres du clinker (C3S, C2S, C3A et C4AF) et des principaux oxydes de la phase vitreuse du laitier (SiO2, Al2O3, MgO et SO3). La quantité de calcium dissoute provenant du laitier a, quant à elle, été déduite en comparant la quantité de portlandite [Ca(OH)2] mesurée par ATG avec celle calculée par un logiciel de spéciation chimique (Phreeqc). Cette approche a permis de déterminer l’évolution du degré d’hydratation des principaux oxydes de la phase vitreuse du laitier dont une dissolution progressive (comparé au clinker) et incongruente (la vitesse de dissolution des différents oxydes et différente) a ainsi pu être mise en évidence. Cette plus faible réactivité du laitier a pu être mise en relation, pour un temps donné, avec la diminution de la quantité d’eau liée au ciment, de la contraction chimique et de la chaleur dégagée. La prise en compte quantitative de la dissolution des phases du clinker et des oxydes du laitier permet une description plus précise de la minéralogie. La deuxième partie de ce travail porte sur l’évolution de la microstructure et de son influence sur les propriétés de transport en phase gazeuse (diffusion et perméabilité). L’évolution du coefficient de diffusion effectif à l’hélium et à l’azote et de la perméabilité intrinsèque a été suivie au cours du temps et comparée à l’évolution de certaines grandeurs, telles que la porosité globale, le diamètre d’entrée critique, la surface spécifique et le degré de connectivité des pores. Les résultats montrent une diminution du coefficient de diffusion effectif et de la perméabilité au cours du temps, ce qui a pu être relié, pour un même matériau, à la diminution de la porosité totale. Une réduction de ces propriétés avec la teneur croissante de laitier a également été observée. Cette baisse est liée à une diminution de la porosité capillaire et à une augmentation de la nanoporosité, due à une modification de la microstructure des C-S-H. La dernière partie de ce projet concerne la relation entre les processus d’hydratation, la microstructure et les propriétés de transport. Dans ce but, des bilans volumiques des réactions d’hydratation ont été réalisés en considérant de façon indifférenciée ou séparée chaque phase du ciment. La prise en compte séparée des différentes phases du ciment permet d’évaluer avec une précision de 10 % la porosité totale, la teneur en eau liée et le volume de contraction chimique. Cette description permet d’expliquer les variations des propriétés de transport d’un même matériau dans la durée. Pour établir ce lien au cours du temps et pour tous les ciments, le volume apparent des C-S-H a été recalculé pour rendre compte de la microstructure de ces hydratesCements 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
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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.
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Björnström, 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.
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Hassanali, 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.
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Gonzalez-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/.
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The response of the surface of the Soda Lime Silica float glass to contact was studied by means of instrumented indentation. The research was focused on two specific conditions to which the glass can be exposed during manufacturing and use, first, the change in the hardness and elastic modulus of the near surface of glass exposed to different periods of accelerated weathering at 40°C and 95% relative humidity, and second, changes in the mechanical properties at 520, 540 and 560°C, the latter being the glass transition temperature of this type of glass. There is an extensive literature about the effects that weathering has on the chemical composition of the air and tin sides surfaces of float glass. Nevertheless, research into the mechanical properties of weathered glass is rather limited. In this study it was found that the air side of the float glass showed an evolution of the nanoindentation hardness and elastic modulus with the exposure time, while in the tin side, the change was almost negligible under the same experimental conditions. Regarding the contact at elevated temperature on glass, it is possible to find several studies in which hardness is reported over a wide range of temperatures from below 0 up to 700°C. There are discrepancies in the reported results at high temperatures due to the different experimental conditions used by the researchers. This study investigated the effect of the testing parameters such as loading and unloading rate, dwell time, and temperature. The creep behaviour was also studied using mechanical models with Maxwell and Kelvin elements. Such models were fitted to the creep curves and explained well the viscoelastic behaviour near the glass transition temperature. The experiments were carried out on a specially developed apparatus, which has the ability to perform micro and macro-indentations with Vickers and Hertzian indenters from room temperature up to 560°C.
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CHAKRAVARTY, 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.
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Chan, 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.
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It is increasingly important to identify the nature of the interfacial water in biology in order to explain how biological functions and systems work. It is not simply a matter of which biomolecules are present in a cell, but also of how these biomolecules interact with one another. This body of work uses neutron scattering techniques to explain the nature of the vibrational dynamics of water interacting with biomolecules and systems that mimic the biological molecular crowding environment of a cell. Recent work in science has seen the synthesis of periodic mesoporous organosilicas with organic groups attached. In the first paper in this thesis, the use of one of these materials is highlighted to look at confined water, equivalent to the water found in a crowded cellular environment. Here it is shown that the properties of the water within the pores and water molecules around the surface were shown to be different and then identified as interfacial and bulk water respectively. In order to develop the investigation of interfacial water with biological matter, it seemed appropriate to start with the most basic molecules, amino acids. The second paper presents a complete survey of the 20 biologically important amino acids using one of the world's highest resolution neutron scattering spectrometer (TOSCA at ISIS, Rutherford Appleton Laboratory). Computer simulation of the experimental work through molecular dynamics, allows many vibrational modes to be assigned for the first time and correlated with the broader vibrational peaks previously observed for proteins. Comparison of the dry states with the hydrated states of amino acids, gives some insight into the sites within the amino acid side chains where water molecules are likely to bind. For serine this is the hydroxyl group in the side chain. The third paper focuses on IINS data of serine in more detail and discusses several low energy vibrational modes that have been assigned and for the first time, shows how the presence of water molecules changes the dynamic behaviour of librational and torsional modes differently. The combination of these studies allows a clearer picture of how water in biology interacts with biomolecules and of the importance of water to our existence.
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Mirzahosseini, Mohammadreza. "Glass cullet as a new supplementary cementitious material (SCM)." Diss., Kansas State University, 2014. http://hdl.handle.net/2097/17565.
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Doctor of PhilosophyDepartment 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.
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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.
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In this thesis we present the synthesis and characterization of different types of ruthenium complexes containing N-donor ligands together with dmso, Cl and H2O ligands, along with their complete characterization through spectroscopic and electrochemical techniques. The complexes have been evaluated as catalysts for olefin epoxidation and nitrile hydration in homogeneous phase. On the other hand, taking into account the importance and advantages of the heterogeneous catalysis, we have carried out the immobilization of some of these complexes on silica-type supports and we have evaluated their catalytic activity, comparing them with the analogous homogeneous systems. It is outstanding the activity of complexes with dmso and pyrazolyl ligands in nitrile hydration to the amide products using water as solvent. The heterogeneous Ru-OH2 systems have been tested in olefin epoxidation and have been reused for several runs maintaining high values of selectivity for the epoxide.En 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.
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Kleib, Joelle. "Ecoconception des ciments : synthèse, hydratation et durabilité." Thesis, Ecole nationale supérieure Mines-Télécom Lille Douai, 2018. http://www.theses.fr/2018MTLD0009/document.
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Les ciments sulfoalumineux sont des liants hydrauliques qui, jusqu’aujourd’hui ne sont pas normalisés et ne possèdent donc pas une composition fixe. La teneur en ye’elimite – la phase principale de ce ciment- peut varier de 5 à 70 %. Or la composition du ciment sulfoalumineux (la composition du clinker ainsi que le pourcentage de gypse ajouté) est un paramètre critique qui contrôle sa réactivité, ses performances mécaniques, ainsi que sa durabilité. L’objectif principal de cette thèse est donc l’étude de l’influence de la composition des ciments sulfoalumineux sur leurs propriétés techniques, telles que les performances mécaniques et durabilité. Trois axes principaux ont été abordés. Tout d’abord une étude de l’influence de la composition du ciment sulfoalumineux (25-75 % en masse de ye’elimite) sur ses propriétés hydrauliques et mécaniques ainsi que sur la valeur limite en élément trace (Zn) a été menée. Dans ce but trois ciment sulfoalumineux (25, 50 et 75 % en masse de ye’elimite) ont été synthétisés. Ensuite l’effet de la variabilité de ce ciment sur sa durabilité dans l’eau pure et sulfatée a été investigué par rapport à un ciment sulfoalumineux commercial. Enfin, une étude des potentialités du ciment sulfoalumineux commercial à inhiber la réaction alcali silice dans les mortiers, lors de l’utilisation d’un granulat réactif (Silex), a été conduite. Il en résulte de cette étude qu’une augmentation de taux de ye’elimite dans le ciment sulfoalumineux engendre une augmentation des performances mécaniques. La valeur limite en Zn est de 0,3 % indépendamment de la composition du ciment sulfoalumineux. Par contre cette dernière influence la durabilité de ces ciments. Les résultats révèlent que même si la formulation contenant 75 % en ye’elimite confère les meilleures performances mécaniques, sa durabilité était la plus faible due à l’absence de stratlingite dans sa matrice cimentaire. Enfin, l’utilisation du ciment sulfoalumineux présente des bonnes potentialités à inhiber la réaction alcali siliceSulfoaluminate 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
Books on the topic "Degree of silica hydration"
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Cao, Yajuan (Jan). Hydration and microstructure of cements containing silica or slag cured at different temperatures. Ottawa: National Library of Canada, 1993.
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Björnström, Joakim. Influence of nano-silica and organic admixtures on cement hydration: A mechanistic investigation. [Go̊teborg], Sweden: Dept. of Chemistry, Göteborg University, 2005.
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Turner, Neil. Exercise-related pseudonephritis. Edited by Neil Turner. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199592548.003.0049.
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Vigorous and prolonged physical exercise can produce a range of urinary abnormalities which would normally be considered alarming. They include haematuria, haemoglobinuria, the appearance in urine of red cells in urine, some fragmented in a ‘glomerular’ manner, red cell cast formation, and proteinuria. A variety of names have been given to these syndromes, including march haematuria and march haemoglobinuria. Mostly these changes seem benign and self-limiting. Rarely they are associated with acute kidney injury but this is often in the context of other renal insults, extreme dehydration, or hyperpyrexic conditions. Vigorous exercise is also commonly associated with various electrolyte changes related to both over- and under-hydration. These can complicate assessment. Transient proteinuria in the absence of haematuria appears to be a physiological response to even short-term exercise, its degree related to the intensity of the exercise. Causation of these syndromes is mixed and not fully explained. There is good evidence for physical trauma to red cells being a significant part, but this cannot explain the appearance of glomerular red cells and red cell casts. Exercise-related changes mostly resolve within less than a day, and almost all by 72 hours.
Book chapters on the topic "Degree of silica hydration"
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Singh, L. P., S. K. Bhattacharyya, S. P. Shah, and U. Sharma. "Studies on Hydration of Tricalcium Silicate Incorporating Silica Nano-particles." In Nanotechnology in Construction, 151–59. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-17088-6_18.
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De Schutter, G. "Degree of hydration concept for early age concrete using DIANA." In Finite Elements in Civil Engineering Applications, 523–26. London: CRC Press, 2021. http://dx.doi.org/10.1201/9781003211365-69.
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Quercia Bianchi, G., H. J. H. Brouwers, and K. Luke. "Hydration Kinetics Study of Class G Oil-Well Cement and Olivine Nano-silica Mixtures at 20–60 °C." In Nanotechnology in Construction, 179–85. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-17088-6_22.
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Yehdego, Tesfamichael, and Sulapha Peethamparan. "The Role of Nano Silica in Modifying the Early Age Hydration Kinetics of Binders Containing High Volume Fly Ashes." In Nanotechnology in Construction, 399–405. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-17088-6_52.
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Yanagisawa, Norio, Koichiro Fujimoto, Satoru Nakashima, Yoshiaki Kurata, Norio Sanada, and J. H. Thomassin. "Depth profiles of different water species for the hydration of silica glass under supercritical conditions by means of micro FT-IR." In Water-Rock Interaction, 131–34. London: Routledge, 2021. http://dx.doi.org/10.1201/9780203734049-31.
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Kaucsar, Tamas, Adam Hosszu, Erdmann Seeliger, Henning M. Reimann, and Andrea Fekete. "Preparation and Monitoring of Small Animals in Renal MRI." In Methods in Molecular Biology, 45–55. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-0978-1_3.
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AbstractRenal diseases remain devastating illnesses with unacceptably high rates of mortality and morbidity worldwide. Animal models are essential tools to better understand the pathomechanism of kidney-related illnesses and to develop new, successful therapeutic strategies. Magnetic resonance imaging (MRI) has been actively explored in the last decades for assessing renal function, perfusion, tissue oxygenation as well as the degree of fibrosis and inflammation. This chapter aims to provide an overview of the preparation and monitoring of small animals before, during, and after surgical interventions or MR imaging. Standardization of experimental settings such as body temperature or hydration of animals and minimizing pain and distress are essential for diminishing nonexperimental variables as well as for conducting ethical research.This publication is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers.
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Turov, Vladimir V., Tetyana V. Krupska, Vladimir M. Gun'ko, and Mykola T. Kartel. "Supramolecular interactions in the mixtures of hydrophobic and hydrophilic pyrogenic silicas." In NEW FUNCTIONAL SUBSTANCES AND MATERIALS FOR CHEMICAL ENGINEERING, 93–107. PH “Akademperiodyka”, 2021. http://dx.doi.org/10.15407/akademperiodyka.444.093.
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In order to study the peculiarities of the interaction of hydrophobic particles with water, the binding of water in composite systems based on structurally modified mixtures of 1/1 hydrophilic (A-300) and hydrophobic (AM-1-300) silica was studied by low-temperature 1H NMR spectroscopy. It is shown that with equal amounts of hydrophobic and hydrophilic components, the dependence of the interfacial energy on the value of surface hydration has a bell-shaped appearance with a maximum at h = 3000 mg/g. The obtained dependence is explained from the point of view of restructuring of the composite system under the influence of mechanical loads and the possibility of air removal and adsorption processes in the interparticle gaps of hydrophobic and hydrophilic components, as well as the phenomenon of nanocoagulation. Increasing the concentration of the hydrophilic component does not increase the binding energy of water. Under the influence of liquid hydrophobic substances, depending on the bulk density of the composite, there may be an increase or decrease in interfacial energy. The growth is due to the restructuring of the hydrophobic and hydrophilic components (nanocoagulation), and the decrease is due to the displacement of water from the surface into pores of larger radius. For n-decane, the effect of increasing the melting temperature by several tens of degrees was registered in the interparticle gaps.
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Milanova, Denitsa, Xuan Wu, and Ranganathan Kumar. "Effect of Surface Hydration and Interfusion of Suspended Silica Nanoparticles on Heat Transfer." In 2007 Cleantech Conference and Trade Show Cleantech 2007, 25–28. CRC Press, 2019. http://dx.doi.org/10.1201/9780429187469-7.
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Jolivet, Jean-Pierre. "Aluminum Oxides: Alumina and Aluminosilicates." In Metal Oxide Nanostructures Chemistry. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190928117.003.0009.
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Aluminum is the third most abundant element in Earth’s crust (8.3% in mass), behind oxygen (45.5%) and silicon (27.2%). It forms in nature various oxygenated mineral phases: hydroxides Al(OH)3, oxyhydroxides AlOOH, of which bauxite is the main ore, and oxides, Al2O3, alumina. Corundum, α- Al2O3, is the component of many gems: sapphire (pure Al2O3, perfectly colorless), ruby (red colored due to the presence of Cr3+ ions), and blue sapphire (blue colored by the presence of Ti4+ and Fe2+ ions), among many others. The content of foreign elements substituted for Al3+ ions in these phases accounts for only a small percentage of the total. Aluminum also forms many natural phases in combination with various elements, especially silicon in aluminosilicates, such as feldspars, clays, zeolites, allophanes, and imogolites. The biochemical cycling of the elements involves many soluble complexes of aluminum in natural waters [1, 2]. Aluminum oxides and oxy(hydroxi)des are important materials and nanomaterials used in many fields: for instance, as active phase for adsorption in water treatment; as inert support and active phase in catalysis; as active phase in flame-retardant polymers; as refractory material for laboratory tools and in the ceramics industry; and as abrasives [3, 4]. Alumina Al2O3 is produced in various forms (tubes, balls, fibers, and powders) for numerous industrial uses (laboratory tools, filtration membranes, ball bearings, fine powders as catalysis supports, etc.). The structural chemistry of aluminum oxy(hydroxi)des is rich. There are various hydroxides, Al(OH)3 (gibbsite, also named hydrargillite, bayerite, and some other polytypes such as nordstrandite and doyleite), oxyhydroxides, AlOOH (boehmite and diaspore), and a series of oxides, Al2O3, so-called transition aluminas. These last phases have different degrees of hydration and different degrees of order of the Al3+ cations within the cubic close packing of oxygen atoms according to the temperature at which they have been submitted. They belong to various structural types (γ, δ, θ, η, κ, etc.). These aluminas of huge specific surface areas are usually used in catalysis, especially γ-alumina of spinel crystal structure.
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Li, Tianyu, Fangying Shi, Xiaoyan Liu, Xunhuan Lian, Jingying Zhang, Zheng Zhu, Yuhan Hu, Dezhi Wang, and Tengfei Bao. "Evolution of Mechanical Property and Microstructure of Fibre-Reinforced Ultra High Strength Mortar with Desert Sand." In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220375.
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Previous research showed that the concrete’s strength is obviously decreased when river sand was substituted by desert sand in abundance. In this paper, a new type of fibre-reinforced ultra high-strength desert sand mortar is studied. In the mix design of mortar, low W/B was used to save water. Also, fly ash and silica fume were adopted to partly replace cement, and desert sand was used to completely take the place of river sand. At the same time, steel fibre was used to improve the toughness. The pore structure changes of different desert sand ultra high strength mortar were studied by MIP. SEM and XRD were adopted to study the microstructure and hydration product changes. The results are as follows: the mortar’s mechanical properties are improved when the desert sand content rise. When desert sand was adopted to substitute river sand completely, the mortar’s compressive strength was increased by 36.91%, which reached 149.08 MPa. With the desert sand’s addition, the mortar’s porosity decreases and its pore structure is optimized. Desert sand played an active part in promoting the hydration of mortar, increasing hydration products, densifying the mortar structure and improving the mortar’s mechanical properties..The research in this paper solves the problem that the high-content desert sand mortar’s mechanical properties cannot meet the demand, and provides the actual application of desert sand in mortar a theoretical basis.
Conference papers on the topic "Degree of silica hydration"
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"Nonevaporable Water and Degree of Cement Hydration in Silica Fume-Cement Systems." In "SP-153: Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete Proceedings Fifth International Conference Milwauk". American Concrete Institute, 1995. http://dx.doi.org/10.14359/1028.
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Koenders, Eduardus, Camila Aparecida Abelha Rocha, Romildo Dias Toledo Filho, and Neven Ukrainczyk. "Modeling Pozzolanic Systems for Subsurface Cementitious Systems." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10916.
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The secondary pozzolanic reaction mechanism has been modeled explicitly in the Delft hydration model Hymostruc. The model calculates the progress of the hydration process as a function of the particle size distribution, the water cement ratio, the temperature and the cement and pozzolanic chemistry. The consumption of portlandite due to the activation of the pozzolanic materials is shown in detail. The numerical results are validated by an experimental testing plan on G-cement and 8% of silica fume and a water to cementitious ratio of 0.44. The simulated development of portlandite and degree of hydration and the experimental results are in good agreement.
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Anthony, E. J., E. M. Bulewicz, D. Go´ra, and J. Najman. "Observations on the Hydration Behaviour of a Selection of Bed and Fly Ashes From FBC Installations." In 18th International Conference on Fluidized Bed Combustion. ASMEDC, 2005. http://dx.doi.org/10.1115/fbc2005-78102.
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The behaviour of FBC ash/water systems is complex and the hydration behaviour of FBC ashes attracts attention both for environmental reasons and because hydration could be used to reactivate the ashes for further use in SO2 capture. In a recent study, hydration of 16 FBC bed and fly ashes from industrial installations firing high-ash coal and mine wastes was studied. Saturated steam at ∼165°C was employed; samples were analyzed chemically and investigated by X-ray diffraction (XRD) and thermal analysis (TGA). One of the more important results was that in some of the ashes there was no unreacted CaO and no Ca(OH)2 after hydration, and they could even consume CaO added to them before hydration. XRD evidence was also obtained to show that a hydrated calcium silico-aluminate (katoite) was formed during the hydration of ashes high in excess, unreacted CaO. The same ashes were used in the present study. The methods used were the same, but the bed ashes were divided into three size fractions and hydration by saturated steam at 100°C was employed. The results generally confirmed the earlier findings. Differences were small but could be significant. First, no katoite could be detected after hydration, so its formation (and possibly that of other compounds of that type) may require more drastic hydration conditions. Second, small quantities of Ca(OH)2 were detected in most hydrated samples. Third, systematic differences between bed ash size fractions were found. In particular, the proportion of anhydrite and the degree of CaO to CaSO4 conversion steadily increased with decreasing particle size fraction, but in the corresponding fly ash was lower and for lime-rich ashes, much lower.
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Gaurina-Međimurec, Nediljka, Krunoslav Sedić, Anel Čajić, and Ante Matijević. "Effect of Microblock on the Compressive Strength of Portland Cement at Elevated Temperatures." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-62455.
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Cementation of casing string depends on composition and properties of cement slurry. The properties of Portland cements must often be modified to meet the demands of a particular well application. These modifications are accomplished by the admixing of additives that effectively alter the hydration chemistry. Silica (SiO2) is used most frequently for the prevention of strength retrogression. It can have a different particle size (“silica sand”, with an average particle size of about 100 μm; “silica flour”, with an average particle size of about 15 μm; and “silica fume”, with mean particle size between 0,1 μm and 0,2 μm). Commercially available additive “Microblock” was used in lab tests. It is a liquid cement additive made from a finely divided, high surface-area silica (D50: cca 0.15 μm; D90: cca 0.75 μm). “Microblock” can help prevent high-temperature strength retrogression, control lost circulation as well as gas migration and can provide a degree of fluid-loss control. The Portland cement slurries with 10%, 20%, 30% and 40% of “Microblock” have been tested. Results of laboratory tests have shown that silica fume (also known as microsilica) affects the slurry properties such as thickening time, rheology, fluid loss, free water, slurry stability, and set cement compressive strength. The development of high early compressive strength is important to ensure structural support to casing and hydraulic/mechanical isolation of downhole intervals. The development of compressive strength of Portland cement slurries with and without “Microblock” at different curing temperature (90 °C, 120 °C and 150 °C) has been determined by Ultrasonic cement analyzer. Results have shown that “Microblock” affects the properties of cement slurry and set cement. The compressive strength has been higher with the addition of “Microblock” than compressive strength of neat PC slurry, but negative effect has been exhibited on slurry rheology and early strength development at elevated temperatures.
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Kronrod, E., V. Kronrod, and O. Kuskov. "Thermal evolution of the cores of the icy satellites of the giant planets." In ASTRONOMY AT THE EPOCH OF MULTIMESSENGER STUDIES. Proceedings of the VAK-2021 conference, Aug 23–28, 2021. Crossref, 2022. http://dx.doi.org/10.51194/vak2021.2022.1.1.085.
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Modern models of satellites of the giant planets include a water-ice shell and an iron silicate core with the possible presenceof an inner Fe-FeS core. During missions to Jupiter and Saturn (Galileo, Cassini-Huygens), new data were obtained thatimpose restrictions on the structure of the ice giant satellites Ganymede, Callisto and Titan. However, questions about thecomposition, size, and physical properties of satellite cores and their thermal evolution are still the subject of numerousdiscussions. Temperature distributions in the cores of satellites largely determine the degree of hydration of their silicatecomponent, the presence or absence of internal metal cores. The thermal evolution of the cores is determined by their size,as well as physical properties - density, thermal conductivity, heat capacity, and radiogenic heat release. In this work, weconsidered two geochemical models of core composition and their combinations that are maximally different in physicalproperties: silicate models with the composition of matter of ordinary (L / LL) chondrites and hydrosilicate models closeto the composition of carbonaceous (CI) chondrites. The results of calculations of unsteady temperature regimes in thecores of ice satellites are presented, taking into account the composition, convective heat transfer, and possible processesof dehydration of hydrated silicates in the cores. Calculations of thermal evolution and dehydration processes in cores withconcentrations of hydrosilicates C Hsil = 0 - 1 and core radii R core = 500 - 2000 km were performed. Based on the resultsof numerical experiments, it can be concluded that the initial concentration of hydrosilicates (C Hsil ) and the radius of thecore (R core ) significantly affect the thermal evolution and dehydration of the core.
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"Fly Ash and Silica Fume Chemistry and Hydration." In "SP-114: Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete: Proceedings of the Third International Conference". American Concrete Institute, 1989. http://dx.doi.org/10.14359/1881.
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"Fly Ash-Silica Fume-Cement Paste- Kinetics of Hydration." In SP-242: 9th Canmet/ACI Fly Ash Conference. American Concrete Institute, 2007. http://dx.doi.org/10.14359/18718.
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"The Investigation of Nano Silica in the Cement Hydration Process." In SP-267: Nanotechnology of Concrete: The Next Big Thing is Small. American Concrete Institute, 2009. http://dx.doi.org/10.14359/51663285.
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"Monitoring Hydration of Alkali-Activated Slag and Fly Ash." In "SP-178: Sixth CANMET/ACI/JCI Conference: FLy Ash, Silica Fume, Slag & Natural Pozzolans in Concrete". American Concrete Institute, 1998. http://dx.doi.org/10.14359/6010.
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Ray, Shaumik, Nirmala Devi, Jyotirmayee Dash, Saptarshi Sasmal, and Bala Pesala. "Effect of Nano-silica Incorporation on Cement Hydration Dynamics Studied using Terahertz Spectroscopy." In International Conference on Fibre Optics and Photonics. Washington, D.C.: OSA, 2016. http://dx.doi.org/10.1364/photonics.2016.th3a.88.
Full textReports on the topic "Degree of silica hydration"
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Mazer, J. J., J. K. Bates, C. M. Stevenson, and J. P. Bradley. The effect of glass composition on the experimental hydration of obsidian between 110 and 230{degree}C. Office of Scientific and Technical Information (OSTI), December 1991. http://dx.doi.org/10.2172/10144526.
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Adams, Caitlin J., Baishakhi Bose, Ethan Mann, Kendra A. Erk, Ali Behnood, Alberto Castillo, Fabian B. Rodriguez, Yu Wang, and Jan Olek. Superabsorbent Polymers for Internally Cured Concrete. Purdue University, 2022. http://dx.doi.org/10.5703/1288284317366.
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Two commercial superabsorbent polymer (SAP) formulations were used to internally cure cement pastes, mortars, and concretes with a range of water-to-cement ratios (w/c 0.35–0.52). The following properties were determined as a function of cement chemistry and type, use of chemical admixtures, use of slag, and batching parameters: SAP absorption capacity, fresh mixture workability and consistency, degree of hydration, volumetric stability, cracking tendency, compressive and flexural strength, and pumpability. SAP internal curing agents resulted in cementitious mixtures with improved hydration, accelerated strength gain, greater volumetric stability, and improved cracking resistance while maintaining sufficient workability to be pumped and placed without sacrificing compressive or flexural strength. When using SAP, batching adjustments prioritized the use of water reducing admixture instead of extra water to tune workability. While the benefits of SAP internal curing agents for low w/c mixtures were expected, SAP-containing mixtures with w/c ≥ 0.42 displayed accelerated strength development and decreased cracking tendency.
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Huang, Cihang, Yen-Fang Su, and Na Lu. Self-Healing Cementitious Composites (SHCC) with Ultrahigh Ductility for Pavement and Bridge Construction. Purdue University, 2021. http://dx.doi.org/10.5703/1288284317403.
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Cracks and their formations in concrete structures have been a common and long-lived problem, mainly due to the intrinsic brittleness of the concrete. Concrete structures, such as rigid pavement and bridge decks, are prone to deformations and deteriorations caused by shrinkage, temperature fluctuation, and traffic load, which can affect their service life. Rehabilitation of concrete structures is expensive and challenging—not only from maintenance viewpoints but also because they cannot be used for services during maintenance. It is critical to significantly improve the ductility of concrete to overcome such issues and to enable better infrastructure quality. To this end, the self-healing cementitious composites (SHCC) investigated in this work could be a promising solution to the aforementioned problems. In this project, the team has designed a series of cementitious composites to investigate their mechanical performances and self-healing abilities. Firstly, various types of fibers were investigated for improving ductility of the designed SHCC. To enhance the self-healing of SHCC, we proposed and examined that the combination of the internal curing method with SHCC mixture design can further improve self-healing performance. Three types of internal curing agents were used on the SHCC mixture design, and their self-healing efficiency was evaluated by multiple destructive and non-destructive tests. Results indicated a significant improvement in the self-healing capacity with the incorporation of internal curing agents such as zeolite and lightweight aggregate. To control the fiber distribution and workability of the SHCC, the mix design was further adjusted by controlling rheology using different types of viscosity modifiers. The team also explored the feasibility of the incorporation of colloidal nano-silica into the mix design of SHCC. Results suggest that optimum amounts of nano-silica have positive influence on self-healing efficiency and mechanical properties of the SHCC. Better hydration was also achieved by adding the nano-silica. The bonding strength of the SHCC with conventional concrete was also improved. At last, a standardized mixing procedure for the large scale SHCC was drafted and proposed.
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He, Rui, Na (Luna) Lu, and Jan Olek. Development of In-Situ Sensing Method for the Monitoring of Water-Cement (w/c) Values and the Effectiveness of Curing Concrete. Purdue University, 2022. http://dx.doi.org/10.5703/1288284317377.
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As the most widely used construction material, concrete is very durable and can provide long service life without extensive maintenance. The strength and durability of concrete are primarily influenced by the initial water-cement ratio value (w/c), and the curing condition during the hardening process also influences its performance. The w/c value is defined as the total mass of free water that can be consumed by hydration divided by the total mass of cement and any additional pozzolanic material such as fly ash, slag, silica fume. Once placed, field concrete pavements are routinely cured with liquid membrane-forming compounds. For laboratory study, concrete samples are usually cured in saturated lime water or a curing room with a relative humidity (RH) value higher than 95%. Thus, the effectiveness of curing compounds for field concrete needs to be studied. In this study, the dielectric constant value of plastic concrete was measured by ground penetrating radar (GPR). The w/c value of the plastic concrete was calculated by a mathematical model from the measured dielectric constant value. The calculated w/c value was compared with the microwave oven drying measurement determined result in AASHTO T318. A modified coarse aggregate correction factor was proposed and applied in microwave oven drying measurement to determine the w/c value of plastic concrete in AASHTO T318. The effectiveness of curing compound was evaluated by field concrete slabs by GPR measurement. It was found that GPR can be a promising NDT method for In this study, the dielectric constant value of plastic concrete was measured by ground penetrating radar (GPR). The w/c value of the plastic concrete was calculated by a mathematical model from the measured dielectric constant value. The calculated w/c value was compared with the microwave oven drying measurement determined result in AASHTO T318. A modified coarse aggregate correction factor was proposed and applied in microwave oven drying measurement to determine the w/c value of plastic concrete in AASHTO T318. The effectiveness of curing compound was evaluated by field concrete slabs by GPR measurement. It was found that GPR can be a promising NDT method for w/c determination of plastic concrete and curing effectiveness evaluation method for hardened concrete.