Academic literature on the topic 'Aluminates de calcium hydraté'
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Journal articles on the topic "Aluminates de calcium hydraté"
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Madej, Dominika. "Strontium Retention of Calcium Zirconium Aluminate Cement Paste Studied by NMR, XRD and SEM-EDS." Materials 13, no. 10 (May 21, 2020): 2366. http://dx.doi.org/10.3390/ma13102366.
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This work concerns the hydration mechanism of calcium zirconium aluminate as a ternary compound appearing in the CaO-Al2O3-ZrO2 diagram besides the calcium aluminates commonly used as the main constitutes of calcium aluminate cements (CACs). Moreover, a state-of-the-art approach towards significant changes in hydraulic properties was implemented for the first time in this work, where the effect of structural modification on the hydration behavior of calcium zirconium aluminate was proved by XRD, 27Al MAS NMR and SEM-EDS. The substitution of Sr2+ for Ca2+ in the Ca7ZrAl6O18 lattice decreases the reactivity of Sr-substituted Ca7ZrAl6O18 in the presence of water. Since the original cement grains remain unhydrated up to 3 h (Ca7ZrAl6O18) or 72 h (Sr1.25Ca5.75ZrAl6O18) of curing period in the hardened cement paste structures, strontium can be considered as an inhibition agent for cement hydration. The complete conversion from anhydrous 27AlIV to hydrated 27AlVI species was achieved during the first 24 h (Ca7ZrAl6O18) or 7 d(Sr1.25Ca5.75ZrAl6O18) of hydration. Simultaneously, the chemical shift in the range of octahedral aluminum from ca. 4 ppm to ca. 6 ppm was attributed to the transformation of the hexagonal calcium aluminate hydrates and Sr-rich (Sr,C)3AH6 hydrate into the cubic phase Ca-rich (Sr,C)3AH6 or pure C3AH6 in the hardened Sr-doped cement paste at the age of 7 d. The same 27Al NMR chemical shift was detected at the age of 24 h for the reference hardened undoped Ca7ZrAl6O18 cement paste.
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Durczak, Karol, Michał Pyzalski, Tomasz Brylewski, and Agnieszka Sujak. "Effect of Variable Synthesis Conditions on the Formation of Ye’elimite-Aluminate-Calcium (YAC) Cement and Its Hydration in the Presence of Portland Cement (OPC) and Several Accessory Additives." Materials 16, no. 17 (September 3, 2023): 6052. http://dx.doi.org/10.3390/ma16176052.
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In the presented study, ye’elimite-aluminate-calcium (YAC) cement was synthesized. Complete synthesis of crystalline phases was achieved at a temperature of 1300 °C, which is 150 °C lower than the temperature standardly used in the processes of obtaining calcium aluminate cements (CAC). The greatest amount of ye’elimite phase (Klein complex), roughly 87% by mass, was acquired utilizing a sulphur ion transporter derived from artificial dihydrate gypsum obtained in the flue gas desulphurization process (variation I). In the case of anhydrite, the amount of synthesized crystalline ye’elimite in the clinker was 67% by weight (variant II). Depending on the synthesis conditions in the clinkers, the quantity of obtained calcium aluminates (C12A7, CA, and CA2) ranged from 20 to 40% by weight. Studies on the hydration process of YAC cement samples showed that the main products are hydrated calcium aluminates and dodecahydrate calcium alumino-sulphate. In sinters of YAC and OPC, no crystalline ettringite was observed. Hydration analysis of Chinese cement revealed the presence of crystalline ettringite and dodecahydrate calcium alumino-sulphate, as well as hydrated calcium silicates of the CSH type accompanied with pseudo-crystalline Al(OH)3. The obtained clinkers from variants I and II constitute a special binder, which, due to its phase composition after hydration, can be used in the construction of reactors for biogas production in eco-energy applications.
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Das, S. K., A. Mitra, and P. K. Das Poddar. "Thermal analysis of hydrated calcium aluminates." Journal of Thermal Analysis 47, no. 3 (September 1996): 765–74. http://dx.doi.org/10.1007/bf01981812.
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Liu, Peng, Zhi Wu Yu, Ling Kun Chen, and Zhu Ding. "Study on Hydration Mechanism of Phosphoaluminate Cement." Materials Science Forum 675-677 (February 2011): 701–4. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.701.
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Phosphoaluminate cement (PAC) is a kind of new cementitious material which has many special properties compared to Portland cement (PC). PAC sets quickly and develops early-high strength. In order to investigate the hydration mechanism, the hydration products and microstructure of PAC were studied with x-ray diffraction (XRD), electron scanning microscope (SEM) and electrochemical impedance spectroscopy (EIS). Heat evolution of PAC was also measured. The results show that the hydration mechanism of PAC is different from Portland cement, which is caused by the special minerals including CxP, CA(P), phase L, and so on. The main hydration products of PAC are calcium phosphorus aluminates hydrate (C-A-P-H), calcium phosphate hydrate (C-P-H), aluminates hydrate (C-A-H), the corresponding hydration microcrystal as well as gels. Also, there is no calcium hydroxide produced during hydration. The hydration procedure of PAC is divided into four stages which are dissolution and induction, acceleration, deceleration, stabilization.
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Dung Nguyen, Tien, and Jean Ambroise. "Contribution of calcium aluminates to the water resistance of hydrated calcium sulfates." IOP Conference Series: Materials Science and Engineering 869 (July 10, 2020): 032051. http://dx.doi.org/10.1088/1757-899x/869/3/032051.
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Torréns-Martín, David, Lucia Fernández-Carrasco, Sagrario Martínez-Ramírez, Jordi Ibáñez, Lluis Artús, and Thomas Matschei. "Raman Spectroscopy of Anhydrous and Hydrated Calcium Aluminates and Sulfoaluminates." Journal of the American Ceramic Society 96, no. 11 (October 1, 2013): 3589–95. http://dx.doi.org/10.1111/jace.12535.
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Segura Sierpes, Yasna, María Victoria Borrachero Rosado, José María Monzó Balbuena, and Jordi Payá Bernabeu. "Preliminary studies on hydrated cement for its reuse in geopolymers." DYNA 83, no. 196 (April 20, 2016): 229–38. http://dx.doi.org/10.15446/dyna.v83n196.54189.
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<p>The carbonation of hydrated ordinary Portland cement (OPC) allows the transformation of hydrated calcium aluminates and silicates into calcium carbonate and amorphous silica/ alumina. These carbonated materials are appropriate to being used as inorganic precursors for alkaline activation. The use of sodium silicate and hydroxide solutions enables the production of cementitious gels. Two ways of carbonation of hydrated cement were studied: in a dry environment, where relative humidity did not exceed 70% and in an aqueous medium at a temperature of 5 ± 1 ° C. Both materials were micro-structurally characterised and they have been used for the manufacturing of geopolymeric mortars. These mortars reached mechanical strength between 10 and 20 MPa, depending on the activating solution, the water/binder ratio and curing time/temperature. These results show the feasibility of reusing hydrated cement contained in construction and demolition wastes.</p>
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Dai, Lei, and Xiao Xuan Deng. "The Relationship between Calcium Hydroxide Concentration in Pore Solution and the Strength of Stabilized Soils." Advanced Materials Research 989-994 (July 2014): 19–22. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.19.
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Under the same cement content, the stabilized soils, made of the soils with similar physical properties, may be significant difference in the strength. In this research, three groups of soils were selected, and the soils in each group are similar in physical properties. Strength and ions concentration in pore solution of the stabilized soils were investigated. The result reveals that calcium hydroxide (CH) concentration in pore solution of the stabilized soils might not reach to saturation due to soil consuming Ca2+and thus cause calcium silicate hydrates gels (C-S-H) and calcium aluminates hydrates gels (C-A-H) to form less. The cementitious hydrates are the main strength contributors of the stabilized soils. The Strengths of stabilized soils, the soils bearing similar physical properties, were almost identical as long as the CH concentrations in pore solution were saturated. The effect of chemical factors of soil on the strength of stabilized soil can be briefly attributed to the change of CH concentration in pore solution, and be further attributed to the influence of CH concentration on the amount of C-S-H and C-A-H formed in stabilized soils.
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Costa, C., P. Marques, and P. A. Carvalho. "An SEM Investigation of the Pozzolanic Activity of a Waste Catalyst from Oil Refinery." Microscopy and Microanalysis 18, S5 (August 2012): 75–76. http://dx.doi.org/10.1017/s1431927612013037.
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The most active phase of the fluid catalytic cracking (FCC) catalyst, used in oil refinery, is zeolite-Y which is an aluminosilicate with a high internal and external surface area responsible for its high reactivity. Waste FCC catalyst is potentially able to be reused in cement-based materials - as an additive - undergoing a pozzolanic reaction with calcium hydroxide (Ca(OH)2) formed during cement hydration. This reaction produces additional strength-providing reaction products i.e., calcium silicate hydrate (C-S-H) and hydrous calcium aluminates (C-A-H) which exact chemical formula and structure are still unknown. Partial replacement of cement by waste FCC catalyst has two key advantages: (1) lowering of cement production with the associated pollution reduction as this industry represents one of the largest sources of man-made CO2 emissions, and (2) improving the mechanical properties and durability of cement-based materials. Despite these advantages, there is a lack of fundamental knowledge on pozzolanic reaction mechanisms as well as spatial distribution of porosity and solid phases interactions at the microstructural level and consequently their relationship with macroscopical engineering properties of catalyst/cement blends.
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Mazur, Anton, Peter Tolstoy, and Konstantinos Sotiriadis. "13C, 27Al and 29Si NMR Investigation of the Hydration Kinetics of Portland-Limestone Cement Pastes Containing CH3-COO−-R+ (R=H or Na) Additives." Materials 15, no. 6 (March 8, 2022): 2004. http://dx.doi.org/10.3390/ma15062004.
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The hydration kinetics of Portland-limestone cement pastes with organic additives in the form of acetic acid and sodium acetate were studied by using solid-state 13C, 27Al and 29Si NMR spectroscopy. The evolution of the relative content of various phases was monitored over the period of one month: amorphous and crystalline calcite (in 13C spectra), ettringite, aluminum in C-S-H gel, calcium aluminates and calcium hydroaluminates (in 27Al spectra), as well as alite, belite and silicon in C-S-H gel (in 29Si spectra). The retarding effect of the additives on cement hydration at early age was demonstrated. We show that the kinetics of phase assemblage formation is influenced by the acetate ion adsorption on the surface of the anhydrous cement components and hydrated phases. The kinetics of formation of ettringite in the cement paste, depending on the addition of acetic and or sodium acetate, is discussed in the context of potential thaumasite sulfate attack.
Dissertations / Theses on the topic "Aluminates de calcium hydraté"
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Budan, Birsen. "Investigation of the early age hydration of four calcium aluminates in the framework of radioactive waste conditioning." Electronic Thesis or Diss., Université Paris sciences et lettres, 2021. http://www.theses.fr/2021UPSLS067.
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Lorsque des déchets nucléaires irradiants sont conditionnés en matrice cimentaire, l’eau contenue dans la solution porale et dans les hydrates peut être radiolysée, conduisant notamment à la production de dihydrogène. Dans le cas de déchets fortement irradiants, la maitrise de ce terme source hydrogène dans un site d’entreposage et/ou de stockage peut constituer un enjeu de sûreté. Ce terme source hydrogène peut-être limité en diminuant la quantité d’eau mise en œuvre pour élaborer les matrices cimentaires de conditionnement, ou en choisissant un liant cimentaire dont les produits d’hydratation présentent un faible rendement de production radiolytique de dihydrogène. De ce point de vue, les ciments alumineux pourraient présenter un intérêt significatif par rapport aux ciments silico-calciques. En effet, l’hydratation des ciments alumineux conduit à des assemblages minéralogiques dont les hydrates présentent une bonne stabilité sous irradiation. Toutefois, la vitesse d’hydratation de ces ciments est parfois élevée et incompatible avec les contraintes d’un atelier de cimentation industriel. Il convient donc de mieux comprendre les mécanismes d’hydratation de ces phases pour éventuellement mieux les contrôler.Dans le cadre de ce travail, le déroulement de l’hydratation de quatre aluminates de calcium anhydres synthétiques, se distinguant l’un de l’autre par leur rapport C/A, a été étudié. En particulier, ont été examiné, leur vitesse d’hydratation, leur degré d’hydratation et l’assemblage minéralogique formé. Les suivis d’hydratation ont été réalisés par microcalorimétrie isotherme et conductimétrie quand les phases ont été caractérisées par analyse thermogravimétrique, par diffraction des rayons-x et par résonance magnétique du solide. Toutes les expériences ont été réalisées à 25 °C. Les résultats du suivi de l’hydratation de pâtes de ciment et de suspensions cimentaires nous ont permis de conclure que les vitesses d’hydratation sont d’autant plus grandes que le rapport C/A de l’anhydre considéré est élevé. De plus, l’étude de l’hydratation de ces phases anhydres en suspension a permis d’identifier les chemins réactionnels suivis par chacun des systèmes étudiés. Notamment, il a été démontré que la formation d'hydroxyde d'aluminium limite la cinétique d'hydratation des phases anhydres dont le rapport C/A est inférieur ou égal à 1. Les résultats obtenus dans le cadre de ce travail pourront permettre à terme d’orienter le choix du ciment alumineux à mettre en œuvre pour le conditionnement de déchets irradiantsThis Ph-D project takes place in the framework of nuclear waste conditioning in cementitious matrices. When an irradiating nuclear waste is stabilized and solidified in a cementitious matrix, the radiolysis of water molecules from the pore solution and from the hydrates themselves yields dihydrogen. In the case of highly irradiating wastes, the release of dihydrogen raises safety issues for storage and/or disposal facilities. The release of hydrogen gas by radiolysis can be limited by reducing the amount of water used for the elaboration of the cement or by choosing a cement binder with hydrates showing a good stability under irradiation. As far as radiolysis is concerned, calcium aluminate-based cements are of significant interest in comparison to calcium silicate cements. The hydration of calcium aluminate cements leads to mineralogical assemblages with a low radiolytic yield of dihydrogen. However, the hydration of these cements is sometimes too fast and incompatible with the industrial process requirements. The objective of this thesis is thus to better understand the underlying mechanisms of the hydration of the calcium aluminates present in calcium aluminate-based cements.Specifically, the course of hydration of four synthetic anhydrous calcium aluminates, varying one from each other by their C/A ratio, is studied at 25°C from the point of view of their hydration rate, their degree of hydration and the resulting mineralogical assemblages by a combination of isothermal calorimetry, thermogravimetric analysis, x-ray diffraction and solid-state nuclear magnetic resonance. Monitoring the hydration by isothermal calorimetry in pastes and by conductimetry in suspensions show that the higher the C/A ratio of the considered anhydrous phase, the higher the hydration rate. Finally, studying the hydration of each of these phases in suspension makes it possible to point out the reaction path followed by each studied system. This work also demonstrated that aluminium hydroxide formation limits the kinetics of hydration of anhydrous phases with a C/A ratio lower than or equal to 1. The results obtained in the framework of this thesis can help optimizing the design of a calcium aluminate cement-based matrix to be used for the conditioning of irradiating wastes
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Nguyen, Tien Dung. "Apport des aluminates de calcium vis-à-vis de la résistance à l'eau des sulfates de calcium hydratés." Thesis, Lyon, INSA, 2012. http://www.theses.fr/2012ISAL0002.
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Les sulfates de calcium sont des matériaux économiques et écologiques. Pourtant leur utilisation dans le domaine de la construction est assez limitée du fait de leur sensibilité à l’eau. La capacité des ciments alumineux (CAC) à diminuer la sensibilité à l’eau des sulfates de calcium ainsi que les mécanismes d’insensibilisation ont été étudiés. L’insensibilisation à l’eau des sulfates de calcium a été réalisée par ajout de faibles quantités de ciment alumineux (≤ 30%). Quatre sulfates de calcium de nature différente : gypse, hémi-hydrate α et β, anhydrite synthétique ont été étudiés. L’étude des mécanismes d’insensibilisation à l’eau des sulfates de calcium par ajout du ciment Fondu, menée à différentes analyses de la microstructure : IR, DRX, ATD-TG, MEB, a mis en évidence deux approches : la formation de l’ettringite insoluble et la formation du gel d’AH3 qui colle les grains de sulfate de calcium soluble. La nature des phases cristallochimiques du ciment alumineux a des influences sur les caractéristiques mécaniques, la sensibilité à l’eau ainsi que la durabilité des mélanges [sulfate de calcium / CAC]. L’étude des mélanges [anhydrite synthétique / laitier / CAC] offrent des perspectives intéressantes notamment concernant le développement des liants à faible empreinte CO2Calcium sulphate materials are economical and ecological. But their use in the construction is quite limited because of their sensibility to water. The capacity of aluminate cement (CAC) to decrease the water sensibility of calcium sulphate and the mechanisms of insensibilisation were investigated. Waterproofing of gypsum base materials was carried out by addition of small amounts of aluminate cement (≤ 30%). Different nature of calcium sulphates : gypsum, hemihydrate α and β, synthetic anhydrite was studied. The study of mechanisms of insensibilisation to water of calcium sulphate by adding cement Fondu, with different analysis of microstructure : IR, DRX, ATD-TG, MEB, revealed two approaches : formation of ettringite insoluble and formation of gel AH3 that stick soluble grains of calcium sulphate. The nature of phases of aluminate cement has influences on the mechanical properties, sensibility to water and durability of mixtures [calcium sulphate / CAC]. The studies of mixtures [synthetic anhydrite / slag / CAC] offer interesting perspectives for the development of binders with low imprint CO2
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Chen, Xiaolin. "Influence des ions aluminates sur la composition, la structure et les propriétés cohésives des hydrosilicates de calcium, constituants principaux de la pate de ciment Portland hydratée." Dijon, 2007. http://www.theses.fr/2007DIJOS072.
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Le ciment Portland est un matériau comportant des phases silicates et aluminates. Les hydrosilicates de calcium (C-S-H), issus de l’hydratation des phases silicates, sont majoritaires et assurent la cohésion de la pâte de ciment. L’hydratation des phases aluminates conduit à la présence d’ions aluminates en solution, qui peuvent se substituer aux silicates des C-S-H, donnant ainsi un alumino-silicate de calcium hydraté noté C-S-A-H. Cette thèse consiste à étudier l’influence de la substitution Al/Si sur la composition, la structure et les propriétés cohésives des particules de C-S-H. Des C-S-H ont été équilibrés dans des solutions d’hydratation de Ca3Al2O6 (C3A, une des phases du ciment) pour tenter une substitution Si/Al dans le solide. La caractérisation des solides obtenus et de leur solution d’équilibre indique que des C-S-A-H de stoechiométrie Al/Si contrôlée et de structure cristallographique analogue à celle des C-S-H ont été obtenus. Une étude de l’interface C-S-A-H/solution a été menée par AFM et mesures de mobilité életrophorétique des particules. Grâce à une nouvelle méthode de décomposition des spectres RMN MAS 27Al permettant une quantification de chaque type d’aluminium dans le solide, une répartition de l’aluminium a été proposée dans l’hypothèse d’une structure de type tobermorite. A partir de cette répartition, une simulation des spectres RMN 29Si a été réalisée. Les spectres expérimentaux sont conformes à la prédiction, ce qui valide l’hypothèse de structure des C-S-A-H et l’attribution des sites pour l’aluminium. Enfin, l’analyse quantitative globale indique que le taux de substitution Al/Si du C-S-H dans une pâte de ciment est de 0,04Portland cement is mostly constituted of silicates and aluminates phases. When cement is hydrated, the main appearing component is calcium silicate hydrate (C-S-H) which results from the silicate phases hydration. The C-S-H is responsible for the cement paste setting. Aluminate phases after hydration, will produce the aluminate ions in the solution. It is well known that aluminate ions may substitute Si in C-S-H to form calcium alumino-silicate hydrate which is called C-S-A-H. This work aims to determine the effect of the Al/Si substitution on composition, structure and cohesion of C-S-H particles. C-S-H powders have been equilibrated in Ca3Al2O6 (C3A, one of cement components) hydration solutions in order to involve the Al/Si substitution in the solid. The analyses of the equilibrium solutions and solids show that C-S-A-H with tobermorite-like crystallographic structure and different Al/Si ratios have been obtained. AFM and electrokinetic investigations have been performed to describe the C-S-A-H/solution interface. An aluminum speciation on the solid has been achieved thanks to a new decomposition method of NMR 27Al spectra. By this method, we can distinguish and quantify each aluminum site in the solid and give a hypothesis of the structure based on tobermorite. With this structure, we have simulated the NMR 29Si spectra. These calculated spectra are in very good agreement with the experimental ones, which corroborates our C-S-A-H structure hypothesis. Finally, the overall quantitative analysis shows that the Al/Si ratio of C-S-H in a cement paste is around 0. 04
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Kirchheim, Ana Paula. "Aluminatos tricálcico cúbico e ortorrômbico : análise da hidratação in situ e produtos formados." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/14404.
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A composição do clínquer controla a cinética da hidratação do cimento, devido às fases potencialmente mais reativas. O aluminato tricálcico (C3A) é a fase que reage mais rápido quando em contato com a água, formando rapidamente os aluminatos de cálcio hidratado (C3AH6, C4AH19 e C2AH8), com a liberação de elevada quantidade de calor. Para casos práticos, o sulfato de cálcio é adicionado ao clínquer para retardar esta reação. Na presença do sulfato de cálcio, o produto formado da reação com o C3A é o trissulfoaluminato de cálcio hidratado (etringita). Geralmente, a forma cristalina do C3A sintetizado durante o processo de clinquerização é cúbica. No entanto, o íon Na+, pode ser incorporado na estrutura cristalina do C3A, em substituição ao Ca2+, levando à modificação da forma cristalina de cúbica para ortorrômbica. Alguns estudos realizados apresentam interessantes resultados sobre a interferência desta fase modificada na hidratação do cimento, afetando o início de pega e a trabalhabilidade da matriz cimentícia. Os maiores problemas são observados em cimentos Portland branco onde, em função da necessidade de redução da quantidade de ferroaluminato tetracálcico (C4AF), ocorre um incremento na quantidade de C3A. Existe uma grande lacuna referente às características específicas de cada aluminato na ausência e na presença de gipsita e hidróxido de cálcio. Desta forma, mostra-se interessante a observação das características das fases do clínquer, principalmente quando se trata dos aluminatos, visto que este seria um passo importante no entendimento dos problemas de início de pega. O presente estudo utiliza fases puras (C3A cúbico e ortorrômbico) sintetizadas em laboratório, para, desta forma, focar as reações independentemente, isolando-as das demais. A associação de diferentes técnicas que possibilitam avaliar a hidratação in situ, com dois métodos originais de análise, utilizando radiações síncrotron, bem como análise de características reológicas e utilização de técnicas clássicas possibilitaram traçar algumas contribuições. Os resultados mostraram que existem grandes diferenças na hidratação de cada aluminato, sendo o ortorrômbico mais reativo nas primeiras idades quando em presença de gipsita, formando primeiramente a etringita. Na ausência de gipsita, o C3A cúbico se mostrou mais reativo, formando primeiro os aluminatos de cálcio hidratados e com maior liberação de calor. O hidróxido de cálcio, saturando a água da mistura, retardou as reações iniciais do C3A ortorrômbico na ausência de gipsita e, em maiores idades, retardou a formação de etringita em pastas de C3A com gipsita e 10% de hidróxido de cálcio.The clinker composition controls the kinetics of cement hydration mainly due to the presence of potentially more reactive phases. The reaction of tricalcium aluminate C3A with water is almost immediate. Crystalline hydrates, such as C3AH6, C4AH19 and C2AH8 are quickly formed with generation of a large amount of heat. In presence of calcium sulfate, the product formed from the C3A reaction is ettringite or high-sulfate calcium aluminate. The alkalis can be incorporated into a number of phases in the clinker and often Na2O is taken up by the C3A. When C3A is synthesized in the presence of these elements, it changes its crystal lattice and the formation of the orthorhombic phases occurs. Earlier studies have already shown interesting interference from this phase on the cement hydration. Significant problems are found in white Portland cement, where the necessity of reducing the amount of tetracalcium ferroaluminate (C4AF) leads to an increase of the C3A content. There is a large gap in understanding the specific characteristics of each crystalline form of C3A in presence and absence of gypsum and calcium hydroxide. Therefore, characterization of the cement phases is important, especially when it is related to the aluminates (cubic and orthorhombic), since this would be a step to further understand the setting problems. The present study uses pure phases (cubic and orthorhombic C3A) synthesized in laboratory, to focus on the reactions independently, isolating the reactions of the others phases. The experimental research integrated two different synchrotron radiation techniques that enable the study of the hydration in situ with rheological analysis and classical techniques allowing to obtain contributions in the hydration of each C3A. The results showed that there are significant differences in the hydration of each aluminate, and the orthorhombic C3A is more reactive in early ages when in presence of gypsum, by forming ettringite first. In absence of gypsum the cubic C3A was more reactive, forming first calcium aluminates hydrates and generating a higher amount of heat. The ettringite formation and the heat evolution of pastes in presence and absence of gypsum were delayed when calcium hydroxide was present in the mixture.
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Benabdillah, Jalil. "Le système alumine khi-CaO-H2O, les aluminates de calcium hydrates et les processus d'hydratation : influence de la composition, de la température et du temps." Montpellier 2, 1997. http://www.theses.fr/1997MON20126.
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Une nouvelle approche pour l'etude du systeme caoal#2o#3h#2o a ete adoptee en utilisant l'alumine de transition khi dont la filiation avec la bayerite a permis d'explorer de nouveaux equilibres. La synthese et l'hydratation des composes c#3a, c#1#2a#7 et ca, equivalents anhydres de c#3ah#6, c#2ah#8 et cah#1#0, a permis l'etablissement des chemins de leurs cristallisations. Les caracterisations des 4 principaux hydrates cah#1#0, c#2ah#8, c#4ah#1#3 et c#3ah#6, ont ete effectuees grace a 3 techniques croisees : rayons x, atdatg et meb. L'etude des comportements thermiques de ces hydrates a mis en evidence leur tres grande labilite. Les hydrates alumino-calciques sont tous metastables et donnent par decomposition la gibbsite et la vaterite. En outre, le suivi de l'hydratation des melanges chaux-alumine khi en systeme statique a 20c, representatif des processus qui gerent l'hydratation du ciment alumineux, a permis de confirmer la metastabilite de c#2ah#8, c#4ah#1#3 et surtout celle de c#3ah#6.
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Renaudin, Guillaume. "I/ Etude d'un hydroxyde simple d'aluminium : La bayerite II/ Etude d'une famille d'hydroxydes doubles lamellaires d'aluminium et de calcium : les phases AFM (Aluminates Tétracalciques Hydrates)." Nancy 1, 1998. http://docnum.univ-lorraine.fr/public/SCD_T_1998_0302_RENAUDIN.pdf.
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Deux études sont développées dans ce mémoire. Une première étude sur la bayerite (un hydroxyde d'aluminium) qui nous a permis : (1) de mettre au point un procédé de synthèse original par électrolyse à membrane catio-sélective, (2) de détailler le comportement thermique de ce composé, et (3) de proposer un chemin réactionnel expliquant le passage de l'aluminate solvate en solution à l'hydroxyde solide. La seconde étude porte sur la cristallochimie d'une famille d'hydroxydes doubles lamellaires (HDL) : les phases AFM, des aluminates calciques hydrates dont la structure est composée de feuillets principaux chargés positivement ca#2al(oh)#6#+ entre lesquels viennent s'insérer des anions et des molécules d'eau. Les phases AFM saturées en carbonate, nitrate, chlorure et aluminate ont été étudiées. Les principaux résultats sont : (1) l'intérêt d'une synthese hydrothermale pour l'étude structurale, (2) l'intérêt de la diffusion raman pour compléter l'étude DRX, (3) l'existence d'un site anionique lié au feuillet principal, (4) l'orientation différente des groupements co#3#2# et no#3# interfoliaire, (5) l'existence de deux modifications pour le monocarboaluminate c#4a$$ch#1#1 (l'une est ordonnée, l'autre présente un désordre statistique dans l'inter feuillet), (6) un désordre important dans l'inter feuillet du compose c#4a$$n#2h#1#0 (désordre statistique couplé à un désordre dynamique), a 60c l'hydrate c#4a$$n#2h#7##8 se forme en liant les feuillets principaux entre eux via no#3#, (7) la transition structurale du sel de Friedel vers 30c a été observée par DRX sur poudre et par microscopie en lumière polarisée. La structure haute température a été résolue à 37c. L'échange sélectif cl#-i# sur ce compose a été étudie et se révèle fort prometteur, (8) réalisation d'un premier modèle structural pour c#2ah#8, et (9) résolution structurale de la rouille verte sulfatée de type 2.
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Aydin, Gunay Semra. "Influence de la cinétique d'hydratation des phases aluminates en présence de sulfate de calcium sur celles des phases silicates : conséquences sur l'optimum de sulfatage des ciments." Thesis, Dijon, 2012. http://www.theses.fr/2012DIJOS007/document.
Full textAbstract:
Les propriétés mécaniques des ciments hydratés nécessitent d'être optimisées suivant la nature des ciments produits. Parmi les facteurs d'optimisation, l'ajout de sulfate de calcium destiné à réguler la réactivité de l’aluminate tricalcique (C3A), en quantité et en qualité, dans le ciment est un paramètre primordial. Enjeu industriel majeur, cette notion d'Optimum de sulfatage mérite aujourd'hui du fait de l'avancement des connaissances sur les mécanismes d'hydratation de chacune des phases du ciment qu'une étude lui soit entièrement consacrée. La démarche adoptée pour répondre à cette problématique a été l’étude de système simple que l’on a compliqué petit à petit. L’évolution de l’hydratation du ciment, de la porosité et des propriétés mécaniques du ciment ont été déterminés à différentes échéances. Le premier système étudié était le mélange C3S/gypse, l'objectif était de déterminer s'il existait un effet optimal du sulfate de calcium sur l'hydratation et les résistances mécaniques du C3S tel que présenté dans la littérature [1]. Les résultats ont montré qu’il n’existait pas d’optimum de sulfatage dans le système C3S/gypse mais qu’il existait un effet spécifique du sulfate de calcium sur l’hydratation et les propriétés mécaniques du C3S. L’adsorption des sulfates à la surface des C-S-H serait à l’origine de la modification du processus de germination croissance des C-S-H qui aurait pour conséquence l’augmentation du degré d’hydratation du C3S et des résistances en compression. Le deuxième système étudié était le clinker biphasique C3S/C3A cobroyé avec du semi-hydrate et avec du gypse. Un optimum de sulfatage a bien été observé, cet optimum se décale avec le temps vers les fortes teneurs en sulfate comme dans les cimenteries. L’optimum de sulfatage a été constaté lorsque l’hydratation du C3S, pendant la période accélérée, a lieu simultanément ou légèrement avant le pic exothermique dû à la forte dissolution du C3A et à la précipitation d’Afm. Il a été montré que la présence d’AFm pendant la période accélérée de l’hydratation du C3S, serait à l’origine de la modification observée de la microstructure de la pâte de ciment : la porosité augmente avec l’ajout du sulfate de calcium mais l’assemblage des hydrates est plus denseThe mechanical properties of hydrated cements need to be optimized according to the nature of cement products. Among the factors of optimization, the addition of calcium sulphate intended to regulate the reactivity of tricalcium aluminate (C3A), in quantity and quality in cement is an essential parameter.The advancement of knowledge on the mechanisms of hydration of each cement phase allows a study devoted entirely to the concept of optimum of sulphate. We studied simple system that we complicated and we studied the evolution of hydration, porosity and mechanical properties of cement at different age. The first system studied was the mixture C3S/gypsum, the objective was to determine whether there was an optimal effect of calcium sulfate on hydration and mechanical strength of C3S as presented in the literature [1]. The results showed there was not optimum sulfate in the C3S/gypsum system but there was a specific effect of calcium sulfate on the hydration and the mechanical properties of C3S. The sulfate adsorption on the C-S-H surface is the cause of the change nucleation and growth process of C-S-H. This has resulted in increasing hydration degree of C3S and compressive strength. The second system studied was biphasic clinker C3S/C3A ground with hemi-hydrate and gypsum. An optimum sulfate has been observed, which move out with time to high rate of sulfate. The optimum sulfate was observed when the hydration of C3S, during the accelerated period, takes place simultaneously or slightly before the exothermic peak due to the high dissolution of C3A and precipitation of AFm. We showed the presence of AFm during the accelerated hydration of C3S, is the cause of the microstructure modification in the cement paste: the porosity increases with calcium sulfate addition but the hydrate assembly is more dense
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Beau, Daniel-Louis. "Action du dioxyde de carbone et des granulats calcaires sur les aluminates de calcium hydratés à l'équilibre de solubilité : influence des ions sulfates, réaction du calcaire finement pulverisé avec le silicate de sodium en solution alcaline." Dijon, 1991. http://www.theses.fr/1991DIJOS001.
Full textAbstract:
La mise en équations des équilibres de solubilité des différents aluminates de calcium hydratés et du gel d'alumine permet de construire leurs courbes d'équilibre dans les domaines métastables du diagramme chaux-alumine-eau. La prise en compte de l'action du dioxyde de carbone atmosphérique oblige à établir un diagramme tri-dimensionnel. Les courbes d'équilibre de solubilité des différentes phases hydratées sont des courbes gauches, dont les projections sur le plan chaux-alumine sont facilement exploitables. Dans un système isolé du dioxyde de carbone atmosphérique, mais en présence de granulats calcaires, les équilibres de solubilité des hydrates, du monocarboaluminate et du carbonate de calcium sont représentés par des surfaces dont les interactions donnent les équilibres communs à deux des phases hydratées ou carbonatées. L'extension des calculs et du même type de diagramme au système chaux-alumine-eau-sulfate permet de délimiter les domaines de stabilité de l'ettringite et du monosulfoaluminate de calcium hydraté. On a étudié experimentalement et abordé par le calcul thermodynamique les possibilités de formation de silicate de calcium hydraté susceptible de faire prise par injection dans le sol d'une solution de silicate de soude alcalinisée et d'une suspension de carbonate de calcium. Les conditions favorables à cette formation ont été précisées.
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Gunay, Semra. "Influence de la cinétique d'hydratation des phases aluminates en présence de sulfate de calcium sur celles des phases silicates : conséquences sur l'optimum de sulfatage des ciments." Phd thesis, Université de Bourgogne, 2012. http://tel.archives-ouvertes.fr/tel-00767768.
Full textAbstract:
Les propriétés mécaniques des ciments hydratés nécessitent d'être optimisées suivant la nature des ciments produits. Parmi les facteurs d'optimisation, l'ajout de sulfate de calcium destiné à réguler la réactivité de l'aluminate tricalcique (C3A), en quantité et en qualité, dans le ciment est un paramètre primordial. Enjeu industriel majeur, cette notion d'Optimum de sulfatage mérite aujourd'hui du fait de l'avancement des connaissances sur les mécanismes d'hydratation de chacune des phases du ciment qu'une étude lui soit entièrement consacrée. La démarche adoptée pour répondre à cette problématique a été l'étude de système simple que l'on a compliqué petit à petit. L'évolution de l'hydratation du ciment, de la porosité et des propriétés mécaniques du ciment ont été déterminés à différentes échéances. Le premier système étudié était le mélange C3S/gypse, l'objectif était de déterminer s'il existait un effet optimal du sulfate de calcium sur l'hydratation et les résistances mécaniques du C3S tel que présenté dans la littérature [1]. Les résultats ont montré qu'il n'existait pas d'optimum de sulfatage dans le système C3S/gypse mais qu'il existait un effet spécifique du sulfate de calcium sur l'hydratation et les propriétés mécaniques du C3S. L'adsorption des sulfates à la surface des C-S-H serait à l'origine de la modification du processus de germination croissance des C-S-H qui aurait pour conséquence l'augmentation du degré d'hydratation du C3S et des résistances en compression. Le deuxième système étudié était le clinker biphasique C3S/C3A cobroyé avec du semi-hydrate et avec du gypse. Un optimum de sulfatage a bien été observé, cet optimum se décale avec le temps vers les fortes teneurs en sulfate comme dans les cimenteries. L'optimum de sulfatage a été constaté lorsque l'hydratation du C3S, pendant la période accélérée, a lieu simultanément ou légèrement avant le pic exothermique dû à la forte dissolution du C3A et à la précipitation d'Afm. Il a été montré que la présence d'AFm pendant la période accélérée de l'hydratation du C3S, serait à l'origine de la modification observée de la microstructure de la pâte de ciment : la porosité augmente avec l'ajout du sulfate de calcium mais l'assemblage des hydrates est plus dense
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Rapin, Jean-Philippe. "Synthèse et étude cristallochimique de quelques aluminates et ferrites calciques hydratés de formule [Ca2 M(OH)6]+, [X,nH2O]- avec X=Cl, Br, I, ClO4, 1/2CO3 1/2CrO4 et 1/2SO4 et M=Al et Fe." Nancy 1, 2001. http://docnum.univ-lorraine.fr/public/SCD_T_2001_0124_RAPIN.pdf.
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Ce travail porte sur la synthèse et l'étude cristallographique de quelques aluminates et ferrites de calcium hydratés de formule structurale [Ca2Al1-xFex(OH)6]+ [X, nH2O]-, appelés "phase AFm" par les cimentiers. Ces composés appartiennent à la famille des hydroxydes doubles lamellaires (HDL) et sont formés par l'empilement de feuillets rigides chargés positivement, entre lesquels diverses espèces anioniques peuvent être insérées. La transition structurale de la phase AFm-Cl, a pour origine une organisation du réseau de liaisons hydrogène. Les structures cristallographiques de nombreuses phases, AFm-(Cl, Br), AFm-(Cl, CO3), AFm-(Cl, SO4) et AFm-(CrO4) ont été résolues. Une application de la phase AFm-Cl comme détecteur d'iodure par voltampérométrie a été réalisé. L'étude des ferrites de calcium a montré qu'une solution solide Al et Fe existe. Cependant la substitution de Al3+ par Fe3+ engendre des perturbations structurales mises en évidences par spectrométrie Mössbauer et EXAFSThis work deals with the synthesis and the crystallographic study of some calcium aluminate and calcium ferrite with structural formulae [Ca2Al1-xFex(OH)6]+ [X, nH2O]-, commonly named "AFm phases" by the cement workers. These compounds belong to the layered double hydroxide (LDH) family and are composed by the stacking of positively charged main layers, and negatively charged interlayers. It was shown that the structural transition of the AFm-Cl phase is due to an ordering of the hydrogen bonds network. The crystallographic structures of several phases, AFm-(Cl, Br), AFm-(Cl, CO3), AFm-(Cl, SO4) and AFm-(CrO4) are given. An application of AFm-Cl like iodide sensor by voltammetric detection is detailed. Finally, calcium ferrite study has shown that a solid solution between aluminium and iron exists. However the substitute of Al3+ by Fe3+ gives some structural modifications, which are clearly emphasised by Mössbauer spectrometry and EXAFS
Books on the topic "Aluminates de calcium hydraté"
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Mangabhai, Raman, and Charles Fentiman. Calcium Aluminates: Proceedings of the International Conference 2020. Whittles Publishing Ltd, 2022.
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Fentiman, C. H. (Charles Hubert), editor, Mangabhai R. J. editor, and Scrivener K. L. editor, eds. Calcium aluminates: Proceedings of the international conference 2014, Palais des Papes, Avignon, France, 18-21 May 2014. Bre Press, 2014.
Find full textBook chapters on the topic "Aluminates de calcium hydraté"
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Liu, Y., Y. Zhuge, and W. Duan. "Reusing Alum Sludge as Cement Replacement to Develop Eco-Friendly Concrete Products." In Lecture Notes in Civil Engineering, 75–82. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-3330-3_10.
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AbstractAlum sludge is a typical by-product of the water industry. The traditional sludge management method, disposing of sludge in landfill sites, poses a critical environmental and economic concern due to a significant increase in sludge amount and disposal cost. In this paper, the feasibility of reusing sludge as cement replacement is investigated, and the physical performance and microstructure modification of concrete products made with sludge is discussed. The obtained results indicated that a satisfying pozzolanic reactivity of sludge after calcination at high temperatures and grinding to the appropriate size was identified. When 10% cement was replaced with sludge, the reaction degree of sludge was up to 39%, and the obtained concrete blocks exhibited superior mechanical performance. Based on the microstructural analysis, e.g., x-ray diffraction, thermogravimetric analysis, and advanced nanoindentation method, the high aluminum content in sludge was incorporated into C–(A)–S–H gel; the original “Al-minor” C–(A)–S–H gel in pure cement paste was converted to ‘Al-rich’ C–(A)–S–H gel. Also, sludge promoted the formation of aluminum-bearing hydrates, such as ettringite and calcium aluminate hydrates (C–A–H). Although the Al incorporation had no significant effect on the hardness and modulus of C–(A)–S–H gel, the homogeneous mechanical properties (hardness and modulus measured with nanoindentation) of binder paste degraded with increasing sludge ash content above 10%, attributing to the lower hardness of unreacted sludge than cement clinker and the relatively lower reaction degree. Using sludge in concrete products offers an economical and environmentally friendly way to dispose of sludge and preserve diminishing natural resources. Also, the reduction of cement usage may contribute to achieving carbon neutrality.
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Hou, Dongshuai. "Models for the Cross-Linked Calcium Aluminate Silicate Hydrate (C–A–S–H) Gel." In Molecular Simulation on Cement-Based Materials, 131–57. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-8711-1_6.
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Song, Shengqiang, and Andrie Garbers-Craig. "Reaction Between Synthesized Calcium Aluminates and Cr2O3in Air and CO2." In Advances in Molten Slags, Fluxes, and Salts, 855–63. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119333197.ch91.
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Stöber, Stefan, and Herbert Pöllmann. "Crystal Chemistry of Lamellar Calcium Aluminate Sulfonate Hydrates: Fixation of Aromatic Sulfonic Acid Anions." In Minerals as Advanced Materials II, 115–30. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-20018-2_11.
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Song, Shengqiang, and Andrie Garbers-Craig. "Reaction between Synthesized Calcium Aluminates and Cr2O3 in Air and CO2." In Advances in Molten Slags, Fluxes, and Salts: Proceedings of the 10th International Conference on Molten Slags, Fluxes and Salts 2016, 855–63. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48769-4_91.
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Goswami, Bindiya, and Rachna Ahlawat. "Effect of Doping on Structural and Luminescence Behavior of Calcium Aluminates." In Springer Proceedings in Physics, 289–98. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-7691-8_29.
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Simonin, F., J. Mahiaoui, O. Pawlig, and M. Szepizdyn. "Practical Experience of time Stable Calcium Aluminates in Low Cement Castable Applications." In Proceedings of the Unified International Technical Conference on Refractories (UNITECR 2013), 1001–6. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118837009.ch170.
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Skibsted, Jørgen, and Hans J. Jakobsen. "Characterization of the Calcium Silicate and Aluminate Phases in Anhydrous and Hydrated Portland Cements by 27Al and 29Si MAS NMR Spectroscopy." In Nuclear Magnetic Resonance Spectroscopy of Cement-Based Materials, 3–45. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-80432-8_1.
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Yamazaki, Kengo, Toshihiko Nakazawa, Masahiro Yoshimura, and Shigeyuki Sōmiya. "Hydration of Calcium Aluminates (3:1, 12:7, 1:1, 1:2 and 1:6) in Phosphoric Acid Solutions at Various Temperatures." In Hydrothermal Reactions for Materials Science and Engineering, 337–47. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-0743-0_56.
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"Hydration of Calcium Aluminates in Presence of Granulated Blastfurnace Slag." In Calcium Aluminate Cements, 275–87. CRC Press, 1990. http://dx.doi.org/10.1201/9781482288872-31.
Full textConference papers on the topic "Aluminates de calcium hydraté"
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Vasiliev, Vladimir. "APPLICATION OF CALCIUM HYDROCARBON-ALUMINATES FOR WASTE WATER TREATMENT IN HYDRO-METALLURGICAL PRODUCTION." In 17th International Multidisciplinary Scientific GeoConference SGEM2017. Stef92 Technology, 2017. http://dx.doi.org/10.5593/sgem2017/11/s04.147.
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Sene, Frank F., Vinicius O. Santos, and Claudio C. Motta. "Synthesis and characterization of high purity barium calcium aluminates for TWT impregnated cathodes." In 2012 IEEE Ninth International Vacuum Electron Sources Conference (IVESC). IEEE, 2012. http://dx.doi.org/10.1109/ivesc.2012.6264172.
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Al Dandan, Esam, and Md Mofazzal Hossain. "Understanding of Geochemical Reactions in Hydrogen-Injected Wells: Cement Integrity for Safe Underground Hydrogen Storage." In International Petroleum Technology Conference. IPTC, 2024. http://dx.doi.org/10.2523/iptc-23620-ms.
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Abstract As the world transitions to clean energy sources, Underground Hydrogen Storage (UHS) has emerged as a leading solution for large-scale hydrogen storage. While the depleted oil or gas reservoirs are ideal for UHS, the effect of geochemical reactions among injected hydrogen, wellbore, and cement is not documented. This study aims to assess cement and well integrity by examining the geochemical interaction between API cement and hydrogen near the wellbore under varying temperature and pressure conditions. The numerical simulation was carried out to study the geochemical reaction between hydrogen and API class G/H cement minerals using the PHREEQC version 3 simulator. The dissolution reactions of hydrogen with the initial cement components, namely calcium tetra calcium alumino-ferrite (C4AF), tricalcium aluminate (C3A), tricalcium silicate (C3S), and dicalcium silicate (C2S) were modelled at various pressure and temperature conditions. The simulation assumed continuous cement hydration over an infinite time to assess the long-term effects of hydrogen-cement interactions and its impact on cement integrity near the wellbore. Based on this numerical simulation, we found that at 56.2oC, the formation of calcium silicate hydrate(CSH), portlandite, C3AH6, Mackinawite, magnetite, and hydrotalcite. At 95°C, similar minerals were formed with slightly higher amounts of CSH and slightly less portlandite, while others did not exhibit a noticeable difference. At 119°C, it was observed that a noticeable increase in CSH and a noticeable reduction in portlandite amount. Additionally, the formation of ettringite was observed at elevated temperatures. These findings highlight the temperature- dependent changes in mineral composition near the wellbore, which may have implications for the long-term integrity of the cement matrix in hydrogen-affected environments. Based on comprehensive numerical simulation studies, this paper highlights critical insights for a better understanding of hydrogen-cement interactions in the context of underground hydrogen storage, and its impact on the long-term-integrity of wellbores in hydrogen storage application, essential for enhancing the knowledge base for safe and effective implementation of underground hydrogen storage technologies.
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Martins, Natalia Pires, Burhan Cicek, Coralie Brumaud, and Guillaume Habert. "Self-Desiccation of a Vernacular CSA Binder." In 4th International Conference on Bio-Based Building Materials. Switzerland: Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/www.scientific.net/cta.1.339.
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The fast precipitation of ettringite in conventional Calcium Sulfo Aluminate (CSA) cement causes rapid stiffening of the cement paste and is directly associated with short setting times and self-desiccation. To extend the time during which those types of cement remain workable, retarding admixtures can be used. However, retarders may affect the amounts and types of hydration products formed and as a consequence the ability of hydrated cement to chemically bind water. This work investigates the influence of two natural-based admixtures on the self-desiccation ability of a vernacular CSA ternary binder used as earth stabilization. Vicat measurements were used to study the efficiency of citric acid and sucrose as retarding admixtures on the setting time of stabilized earth. A quantitative study of the self-desiccation ability of the binder was performed on dried binder pastes using thermogravimetric analysis (TGA). Results show that both admixtures have a significant impact on the setting time of the binder. Furthermore, TGA showed that the self-desiccation ability of this vernacular CSA binder is significantly reduced when citric acid at high dosages is used, both at early hydration and after 14 days. On the contrary, the use of sucrose does not affect the water chemically bound at an early age but can maximize bound water after 14 days of hydration.
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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.