Bibliographies thématiques / SiO2 cement

Littérature scientifique sur le sujet « SiO2 cement »

Auteur : Grafiati

Publié le 10 mars 2023

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Articles de revues sur le sujet "SiO2 cement"

Nori, J., S. Kakay et M. Belayneh. « Effect of SiO₂ and SiO₂/TiO₂ hybrid nanoparticles on cementitious materials ». IOP Conference Series : Materials Science and Engineering 1201, n^o 1 (1 novembre 2021) : 012054. http://dx.doi.org/10.1088/1757-899x/1201/1/012054.

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Abstract In this paper, we report the effect of SiO2 nanoparticle solution on the properties of the neat industry and environmental cements. Moreover, the hybrid SiO2/TiO2 nanoparticles solution impact on the Portland G-class cement. Both destructive and non-destructive tests were used to characterize the properties of the slurries and the cement plugs. Results indicate that the optimum concentration of the nanoparticles improved the elastic, energy absorption, rheological, heat development, and the mechanical load carrying capacity of the cements. The selected optimal nanoparticles concentrations results showed that • the addition of 0.56 % SiO2 by weight of cement (bwoc) increased the uniaxial compressive strength (UCS) of the neat industry cement by 16.7%. • the 0.13% SiO2 bwoc increased the UCS of the neat environmental cement by 50.2%. • the blending of 0.264 %SiO2/0.044% TiO2 bwoc increased the UCS of neat G-class cement by 8.5%. However, by changing the curing temperature and pressure, different results can be achieved.

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Zhang, Jie, Yongsheng Ji, Zhanguo Ma, Jianwei Cheng, Shengnan Xu, Zhishan Xu et Zhongzhe Zhang. « Strengthening Mechanism for the Mechanical Properties of Cement-Based Materials after Internal Nano-SiO2 Production ». Nanomaterials 12, n^o 22 (17 novembre 2022) : 4047. http://dx.doi.org/10.3390/nano12224047.

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This study focuses on overcoming the agglomeration issue of nano-SiO2 powder in cement, facilitating the strengthening mechanism of cement-based materials. A nano-SiO2 precursor solution (NSPS) was added to cement-based materials to replace nano-SiO2 powder. The influencing laws of the alkalinity and dosage of the NSPS on the mechanical properties of cement were investigated. Further, the strengthening mechanism of the mechanical properties of cement-based materials after internal nano-SiO2 production was analysed. The results show that (1) when the alkalinity of the precursor solution is a weak acid (pH = 6), the compressive strength of cement-based materials after internal nano-SiO2 production is 25%~36% higher than that of pure cement-based materials and 16%~22% higher than that of cement-based materials with silica fume; (2) when the solid content of SiO2 in the current displacement solution is about 0.16% of the cement mass, the compressive strength of the prepared cement-based material is the highest. With the continuous increase in the solid content of SiO2 in the precursor solution, the compressive strength of cement-based materials after internal nano-SiO2 production decreases but is always greater than the compressive strength of the cement-based material mixed with nano-SiO2 micro powder. According to a microstructural analysis, nano-SiO2 particles that precipitate from the precursor solution can facilitate the hydration process of cement and enrich the gel products formed on the cement particle surface. In addition, new network structures among cement particles are formed, and precipitated nano-SiO2 particles fill in the spaces among these cement particles as crystal nuclei to connect the cement particles more tightly and compact the cement-based materials. This reinforces the mechanical properties of cement-based materials.

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Mabeyo, Petro E., et Jun Gu. « Coupled effects of hydrophilic nano silica oxide and anatase nano titanium oxide on strengths of oilwell cement ». Tanzania Journal of Science 47, n^o 2 (11 mai 2021) : 568–82. http://dx.doi.org/10.4314/tjs.v47i2.13.

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The life of oil wells depends on the stability of cement sheath and bond strength with the formation and casing. Extreme subsurface conditions cause substantial stresses on the cement sheath resulting in a serious impact on well integrity. The recommended API cement for oilwell fails to provide the required durability of the cemented well due to such conditions. Supplementary cementitious materials such as nanoparticles are added to improve the cement for long-lasting zonal isolation. In this study, the compressive and shear bond strengths of oilwell cement containing nano-SiO2 and nano-TiO2 were studied at 80 °C for 3, 7, 14, and 28 days of hydration. The XRD, TG, and DSC were used for the analysis of cement hydration products. The results revealed that both nano-SiO2 and nano-TiO2 increased strength evolution. A ternary system made with 2% nano-SiO2 and 2% nano-TiO2 improved compressive strength by 22.6 and 48.4%, while the shear bond strength increased by 110.6 and 55% at age of 3 days and 28 days, respectively, compared to their corresponding binary systems. Therefore, these results remark the potential of replacing an appropriate proportion of oilwell cement with coupled nano-SiO2 and nano-TiO2 to ensure cement sheath structure durability in the annular and long-lasting zonal isolation. Keywords: Nano-silica, nano-titanium, compressive strength, shear bond strength, oilwell cement

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Wang, De Zhi, Yin Yan Zhang et Yun Fang Meng. « Properties of Cement Mortars Mixed with SiO₂ and CaCO₃ Nanoparticles ». Key Engineering Materials 539 (janvier 2013) : 244–48. http://dx.doi.org/10.4028/www.scientific.net/kem.539.244.

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Water requirement of normal consistency, setting time and soundness of cement pastes mixed with SiO2 and CaCO3 nanoparticle and the flexural strength and compressive strength of cement mortars mixed with SiO2 and CaCO3 nanoparticles were experimentally studied. Results indicated that the added nano-SiO2 and nano-CaCO3 with a mass account of 4.0 wt. % decreased the setting time and increased the water requirement of normal consistency, flexural strength and compressive strength. And these nanoscaled mineral admixtures did not have a negative impact on cement soundness. The optimal replacement levels of cement by SiO2 and CaCO3 nanoparticles for producing cement mortar with improved strength were 2.0 and 4.0 wt.% respectively.

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Suprompituk, Wanchart, et Papot Jaroenapibal. « Improvement of Early Compressive Strength in Belite Cement by Incorporating Silica Coated Single-Walled Carbon Nanotubes ». Key Engineering Materials 718 (novembre 2016) : 157–62. http://dx.doi.org/10.4028/www.scientific.net/kem.718.157.

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This work demonstrated the improvement of belite cement compressive strength by incorporating nanosilica coated single-walled carbon nanotubes (SWNTs@SiO2) into the cement paste. The structure and chemical compositions of SWNTs@SiO2 materials were characterized by transmission electron microscopy and energy dispersive X-ray spectroscopy techniques, respectively. Belite cement composites were prepared by mixing belite cement paste with different loadings of SWNTs@SiO2 ranging from 0.02 – 0.1 wt%. In order to measure the early strength of cement composites, the samples were aged for 7 days, and then subjected to compression tests. Effects of uncoated SWNTs and silica coated SWNTs loadings on the compressive strength of belite cement composites were studied. Without pre-coating SWNTs with nanosilica, the SWNTs additives led to large decrease in compressive strength of belite cement composite. Improvements in compressive strength of belite cement are shown in samples that incorporated SWNTs@SiO2 loadings. The coating layer helps enhance bonding strength between reinforced SWNTs and the matrix, as well as promote hydration reactions in the cement paste. The highest increase in the compressive strength of 18.8 % is found in the sample with the minimal SWNTs@SiO2 loading of 0.02%.

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Gu, Yue, Qian Ping Ran, Xin Shu, Cheng Yu, Hong Lei Chang et Kai Lv. « Synthesis of SiO₂-PCE Core-Shell Nanoparticles and its Modification Effects on Cement Hydration ». Key Engineering Materials 711 (septembre 2016) : 249–55. http://dx.doi.org/10.4028/www.scientific.net/kem.711.249.

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NanoSiO2 was widely used to modify the property of cementitious materials, however, for nanoparticles used in cement-based materials, key problem is the effective dispersion. The surface modification technology can be introduced to promote dispersion of nanoparticles in aqueous system, especially in cement pore solution, which possess high concentration of ions. In this study, at first, NanoSiO2-polycarboxylate superplasticizer (SiO2-PCE) core-shell nanoparticle was synthesized from silanized polycarboxylate superplasticizer and colloidal nanoSiO2 by the “grafting to” method, then SiO2-PCE was testified by UV-Vis, FTIR, and TGA. Additionally, stability of SiO2-PCE and its effect on cement hydration were investigated. Results shows: SiO2-PCE possess higher stability in saturated calcium hydroxide solution compared to nanoSiO2, and heat development of cement hydration can be regulated by shell structure of SiO2-PCE. The research implied a new approach for nanoSiO2 to optimize cement-based composites.

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Bodnarova, Lenka, Rudolf Hela et Daniel Sedlacek. « Effect of Inorganic SiO2 Nanofibers in High Strength Cementitious Composites ». MATEC Web of Conferences 278 (2019) : 01009. http://dx.doi.org/10.1051/matecconf/201927801009.

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The paper deals with the verification of the effect of the addition of inorganic SiO2 nanofibers to cement composites. In the first stage, a stable suspension of SiO2 nanofibers was prepared in an aqueous medium. It is important to distribute nanofibers so that the nanofibers do not appear in the form of clumps and at the same time do not get damaged during the dispersion process. The ultrasonification process was used for dispersion. The dispersed suspension of SiO2 nanofibers and water was dosed together with the superplasticizing admixtures into the dry components of the cement composite and the components were homogenized. The properties of the cement composite with SiO2 nanofibers have been tested – compressive strength, flexural strength, density. Composites with the addition of SiO2 nanofibers at a dose of 0.008 % by weight of cement exhibited an increased compressive strength of up to 33 % and a 19 % greater flexural strength at doses of 0.016 and 0.032 % of cement weight than the reference sample without nanofibers. The presence of SiO2 nanofibers in the composite was monitored by scanning electron microscopy (SEM).

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Alireza Naji Givi, Suraya Abdul Rashid, Farah Nora A. Aziz et Mohamad Amran Mohd Salleh. « Particle size effect on the permeability properties of nano-SiO2 blended Portland cement concrete ». Journal of Composite Materials 45, n^o 11 (8 novembre 2010) : 1173–80. http://dx.doi.org/10.1177/0021998310378908.

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In this study, nano-SiO2 has been used as a high reactive pozzolan to develop the microstructure of the interfacial transition zone between the cement paste and the aggregate. Mechanical tests of blended cement-based concretes exposed that in addition of the pozzolanic reactivity of nano-SiO2 (chemical aspect), its particle grading (physical aspect) also revealed considerable influences on the blending effectiveness. It was concluded that the relative permeability reduction (relative to the control concrete made with plain cement) is higher for coarser nano-SiO2 after 90 days of moisture curing. However, finer nano-SiO2 particles showed better effects in early ages. These phenomena can be due to the free spacing between mixture particles that was associated with the global permeability of the blended cement-based concretes. This article presents the results of the effects of particle size ranges involved in nano-SiO2 blended Portland cement on the water permeability of concrete. It is revealed that the favorable results for coarser nano-SiO2 reflect enhanced particle packing formation accompanied by a reduction in porosity and particularly in particle spacing after 90 days.

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Kirgiz, Mehmet Serkan. « Effects of Blended-Cement Paste Chemical Composition Changes on Some Strength Gains of Blended-Mortars ». Scientific World Journal 2014 (2014) : 1–11. http://dx.doi.org/10.1155/2014/625350.

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Effects of chemical compositions changes of blended-cement pastes (BCPCCC) on some strength gains of blended cement mortars (BCMSG) were monitored in order to gain a better understanding for developments of hydration and strength of blended cements. Blended cements (BC) were prepared by blending of 5% gypsum and 6%, 20%, 21%, and 35% marble powder (MP) or 6%, 20%, 21%, and 35% brick powder (BP) for CEMI42.5N cement clinker and grinding these portions in ball mill at 30 (min). Pastes and mortars, containing the MP-BC and the BP-BC and the reference cement (RC) and tap water and standard mortar sand, were also mixed and they were cured within water until testing. Experiments included chemical compositions of pastes and compressive strengths (CS) and flexural strengths (FS) of mortars were determined at 7th-day, 28th-day, and 90th-day according to TS EN 196-2 and TS EN 196-1 present standards. Experimental results indicated that ups and downs of silica oxide (SiO2), sodium oxide (Na2O), and alkali at MP-BCPCC and continuously rising movement of silica oxide (SiO2) at BP-BCPCC positively influenced CS and FS of blended cement mortars (BCM) in comparison with reference mortars (RM) at whole cure days as MP up to 6% or BP up to 35% was blended for cement.

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Wang, Yaying, Wei Wang, Yinuo Zhao, Na Li, Jiale Luo, Asefa Mulugeta Belete et Jiang Ping. « Modification Effect of Nano-Clay on Mechanical Behavior of Composite Geomaterials : Cement, Nano-Silica and Coastal Soft Soil ». Materials 15, n^o 24 (7 décembre 2022) : 8735. http://dx.doi.org/10.3390/ma15248735.

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To study the modification effect of nano-clay and nano-SiO2 on cement-reinforced coastal soft soil, the effects of the nano-SiO2 and nano-clay on the mechanical properties of cement soil were studied through unconfined compressive and unconsolidated undrained shear tests, and the Duncan–Chang model was used to fit the test results. Results show that adding nano-clay and nano-SiO2 to cement soil improved its compressive and shear strength. The compressive strength and shear strength increased by 18–57% and 3–32%, respectively, with the increase in nano-clay content in a content range of 0–10%. Additionally, nano-clay can enhance the ductility of cement soil. Moreover, nano-clay and nano-SiO2 improve the shear strength by increasing the internal friction angle by 1°–2° and cohesion of 9–25%, and the cement-stabilized coastal soft soil enhanced by nano-SiO2 and nano-clay conforms to the Duncan–Chang model well.

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Thèses sur le sujet "SiO2 cement"

Zimmermann, Štěpán. « Reologické vlastnosti cementových past s přídavkem amorfního SiO2 ». Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265357.

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The subject of this thesis are the rheological properties of cement paste with the addition of amorphous silicon dioxide. The basic rheological parameters are that describe the behavior of cement pastes in the fresh state. The work also included rheological tests including measurement principle and method of evaluation. Effect of mineral admixtures with high content of amorphous SiO2 is summarized the available scientific articles. In the experimental part, the effects of impurities with a high content of amorphous SiO2 on the rheological properties of fresh cement paste. It was tested by substitution of up to 10 % by weight of cement in the cement pastes mineral admixtures of different chemical composition, particle size and pozzolanic activity. Flow measurement was measured yield value, viscosity, and flow index. The stability of cement pastes was investigated oscillatory measurements. To complement the behavior pastes in the fresh state was determined by calorimetry. Test results were compared with those determined by reference samples and compared the effect of various ingredients.

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Dolores, Gonzalo Mármol de los. « Low-alkalinity matrix composites based on magnesium oxide cement reinforced with cellulose fibres ». Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/74/74133/tde-17082017-113846/.

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A lower-alkalinity cement based on MgO and SiO2 blends is analysed to develop clinker-free Fibre Reinforced Cementitious Composites (FRCC) with cellulosic fibres in order to solve the durability problems of this type of fibres when used in FRCC with Portland cement. Hydration evolution from 7 to 28 days of different MgO-SiO2 formulations is assessed. The main hydration products are Mg(OH)2 and M-S-H gels for all the formulations studied regardless of age. Hardened pastes are obtained with pH values < 11 and good mechanical properties compared to conventional Portland cement. 60% MgO-40% SiO2 system is chosen as optimal for the development FRCC since is the most mechanical resistant and is less alkaline compared with 70% MgO-30% SiO2. FRCC based on magnesium oxide and silica (MgO-SiO2) cement with cellulose fibres are produced to study the durability of lignocellulosic fibres in a lower pH environment than the ordinary Portland cement (PC). Flexural performance and physical tests (apparent porosity, bulk density and water absorption) of samples at 28 days and after 200 accelerated ageing cycles (aac) are compared. Two types of vegetable fibres are utilised: eucalyptus and pine pulps. MgO-SiO2 cement preserves cellulosic fibres integrity after ageing, so composites made out of MgO-SiO2 exhibit significant higher performance after 200 cycles of accelerated ageing than Portland cement composites. High CO2 concentration environment is evaluated as a curing treatment in order to optimise MgO- SiO2 matrices in FRCC. Samples are cured under two different conditions: 1) steam water curing at 55°C and 2) a complementary high CO2 concentration (20% by volume). In carbonated samples, Mg(OH)2 content is clearly lowered while new crystals of hydromagnesite [Mg5 (CO3)4⋅(OH) 2⋅4H2O] are produced. After carbonation, M-S-H gel content is also reduced, suggesting that this phase is also carbonated. Carbonation affects positively to the composite mechanical strength and physical properties with no deleterious effects after ageing since it increases matrix rigidity. The addition of sepiolite in FRCC is studied as a possible additive constituent of the binding matrix. Small cement replacement (1 and 2% wt.) by sepiolite is introduced and studied in hardened cement pastes and, later, in FRCC systems. When used only in cement pastes, it improves Dynamic Modulus of Elasticity over time. Bending tests prove the outcome of this additive on the mechanical performance of the composite: it improves composite homogeneity. Ageing effects are reported after embedding sisal fibres in MgO-SiO2 and PC systems and submitting them to different ageing conditions. This comparative study of fibre degradation applied in different cementitious matrices reveals the real compatibility of lignocellulosic fibres and Mg-based cements. Sisal fibres, even after accelerated ageing, do neither suffer a significant reduction in cellulose content nor in cellulose crystallinity and crystallite size, when exposed to MgO-SiO2 cement. Fibre integrity is preserved and no deposition of cement phases is produced in MgO-SiO2 environment.
Um cimento de baixa alcalinidade à base de blendas de MgO e SiO2 é analisado para o desenvolvimento de Compósitos Cimentícios Reforçados com Fibras (CCRF) celulósicas sem clínquer para resolver os problemas de durabilidade de este tipo de fibras quando são usadas em CCRF com cimento Portland. A evolução da hidratação, desde 7 aos 28 dias, das diferentes formulações é avaliada. Os principais produtos hidratados são o Mg(OH)2 e o gel M-S-H para todas as formulações independentemente da idade estudada. As pastas endurecidas apresentam valores de pH < 11 e bom desempenho mecânico comparado com o cimento Portland convencional. O sistema 60% MgO-40% SiO2 é escolhido como a formulação ótima para o desenvolvimento de CCRF já que é a mais resistente e menos alcalina comparada com 70% MgO-30% SiO2. CCRF com cimento à base de óxido de magnésio e sílica (MgO-SiO2) e fibras celulósicas são produzidos para a análise da durabilidade das fibras lignocelulósicas em ambientes com valores de pH mais baixos comparados com o cimento Portland (PC). O desempenho mecânico a flexão e os ensaios físicos (porosidade aparente, densidade aparente e absorção de água) são comparados aos 28 dias e após de 200 ciclos de envelhecimento acelerado. O cimento à base de MgO-SiO2 preserva a integridade das fibras após o envelhecimento. Os compósitos produzidos com este cimento exibem melhores propriedades após 200 ciclos de envelhecimento acelerado que os compósitos produzidos com cimento Portland. Ambientes com alta concentração de CO2 são avaliados como tratamento de cura para otimizar as matrizes MgO- SiO2 nos CCRF. As amostras são curadas sob 2 condições diferençadas: 1) cura com vapor de água a 55oC e 2) cura com alta concentração de CO2 (20% do volume). As amostras carbonatadas apresentam teores reduzidos de Mg(OH)2 enquanto é produzida uma nova fase cristalina: hidromagnesita [Mg5 (CO3)4⋅(OH) 2⋅4H2O]. Após a carbonatação, o conteúdo de gel M-S-H é reduzido também, indicando uma carbonatação desta fase. A carbonatação aumenta a rigidez da matriz o que influi positivamente no desempenho mecânico e as propriedades físicas dos compósitos sem efeitos prejudiciais ao longo prazo. A adição de sepiolita em CCRF é estudada como possível adição na composição da matriz aglomerante. Baixos teores (1 e 2% em massa) de cimento são substituídos por sepiolita para o estudo das pastas de cimento hidratado e, posteriormente, dos compósitos. O Módulo Elástico Dinâmico das pastas é incrementado com o tempo pela adição de sepiolita. Os ensaios a flexão demostram que a adição de sepiolita melhora a homogeneidade dos compósitos. Reportam-se os efeitos das fibras de sisal após da exposição a sistemas MgO-SiO2 e PC e submetidas a diferentes condições de envelhecimento. Este estudo comparativo da degradação das fibras expostas a diferentes matrizes cimentícias mostra a compatibilidade das fibras lignocelulósicas com os cimentos à base de Mg. As fibras de sisal, inclusive após o envelhecimento acelerado, não apresentam nem redução significativa no conteúdo de celulose nem na cristalinidade da celulose assim como do tamanho de cristalito, quando expostas a cimentos MgO-SiO2.

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Myers, Rupert J. « Thermodynamic modelling of CaO-Al2O3-SiO2-H2O-based cements ». Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/9175/.

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Most concrete is produced using calcium (alkali) aluminosilicate hydrate (C-(N-)A-S-H)-based cement. However, the chemistry of this phase in many cement-based materials is still not fully understood. This thesis presents a structural and thermodynamic investigation of C-(N-)A-S-H and C-(N-)A-S-H-based cements to provide insight into the chemistry of these materials. A mixed cross-linked and non-cross-linked tobermorite-like structural model for C-(N)-A-S-H is developed (the CSTM), which more appropriately describes the spectroscopic information available for this phase. Application of the CSTM to a Na2SiO3-activated slag cement cured for 56 and 180 days indicates the presence of a poorly-crystalline zeolite-like phase. The role of Al in cross-linking of C-(N-)A-S-H is also studied, which provides a more advanced description of the chemistry and structure of C-(N-)A-S-H than previously reported. A thermodynamic model for C-(N-)A-S-H (CNASH_ss) is derived, which greatly advances the utility of thermodynamic modelling of C-(N-)A-S-H-based cements by explicitly defining Al and alkali uptake in this phase. The chemistry of alkali-activated slag (AAS)-based cements is simulated using CNASH_ss and an ideal solid solution thermodynamic model for MgAl-OH-LDH that is also developed in the thesis. This analysis provides a good description of Na2SiO3-activated slag cement chemistry and accurately predicts chemical shrinkage in this material. Phase diagrams for NaOH, Na2SiO3, Na2Si2O5 and Na2CO3-activated slag-based cements are also simulated. These results can be used to design the chemistry of AAS-based materials. A detailed analysis of C-(N-)A-S-H solubility is presented, for Ca, Al, Si and alkali concentrations most relevant to C-(N-)A-S-H-based cements and at temperatures of 7-80°C. Solubility products for alkali-free C-(N-)A-S-H change slightly between 7°C and 80°C and as a function of Al/Si ratio. However, less soluble C-(N-)A-S-H is formed at higher Ca and alkali content. These results are important for understanding the stability of C-(N-)A-S-H in the majority of cement-based materials used worldwide.

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Bouregaya, Souad. « Synthèse d'un ciment alitique à moindre impact environnemental à partir de vase de barrage et utilisant le sulfate de zinc comme minéralisateur ». Thesis, Toulouse, INSA, 2018. http://www.theses.fr/2018ISAT0026/document.

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L’objectif de cette étude est de réaliser la synthèse d’un ciment riche en phases réactives, obtenu par cuisson à une température inférieure ou égale à 1300°C d’un cru constitué de vase de barrage et d’un complément de chaux et utilisant du sulfate de zinc comme minéralisateur. Cette étude donne les caractéristiques minéralogiques et les propriétés physico- mécaniques du ciment synthétisé. L’analyse qualitative et quantitative par diffraction des rayons X a été utilisée pour caractériser les matériaux bruts et les minéraux du ciment. L’évolution du durcissement des pâtes de ce ciment a été suivie et quantifiée par calorimétrie isotherme, DTG, diffraction des rayons X et au moyen d’essais mécaniques en compression sur éprouvettes de pâte pure. Les résistances obtenues à 7 et 28 jours permettent de viser une classification CEM II 32,5 N
The objective of this study is the synthesis of a cement rich in reactive phases, obtained by burning, at a temperature lower than or equal to 1300 °C, a raw material composed of sludge from a dam with a complement of lime, and using zinc sulphate as a mineralizer. This study gives the mineralogical, physical and mechanical characteristics and properties of the synthesized cement. Qualitative and quantitative X-ray diffraction analysis was used to characterize the raw materials and the minerals of the cement. The evolution of its hardening was monitored and quantified by isothermal calorimetry, DTG, X-ray diffraction and mechanical compression tests on pure paste samples. The strengths obtained at 7 and 28 days make it possible to aim at a CEM II 32.5 N classification

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Jiang, Jian-Ming, et 江健銘. « Epoxy--SiO2 Hybrid Material via Sol-Gel for Bone Cement Application ». Thesis, 1999. http://ndltd.ncl.edu.tw/handle/69853158659343478955.

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碩士
國立臺灣科技大學
纖維及高分子工程研究所
87
The experiment consist of many stage。Firstly，DGEBA and APTS was combine to from as one component。Secondly，through the process of SGP，the component was transform into INPs。The INPs was then crashed into powder from and mix with the right amount of liquid creating free radical reaction forming a new material known as Epoxy-SiO2 bone cement。The main purpose of this experiment is to use basic property of organic and inorganic material to improve the mechanical property of bone cement。 The result of the experiment found that component form after Sol-gel reaction does not have any obvious Tg。This prove that INPs has been form。Furthermore，the outcome of the TGA test shows that the composite of organic and inorganic material shows sign of increase in IDT as the quantity of SiO2 increase。 The composite resin has change，the bone cement from by Epoxy-SiO2 filler has stronger resistance against pressure，impact and hardness compare to the bone cement than those that are available in the market。As Bis-GMA resin quantity increase，the bending strength，young's models，tensile strength and absorption rate showed sign of first rising then falling later。After absorb water，the mechanical property of composite resin became stronger then before。When BPO quantity increase，if also increase the mechanical property of the bone cement。The heat release by the organic-inorganic composite is around 20℃lower than the PMMA。 The Epoxy-SiO2 bone cement show stronger sign of acidic property on pH balance the SiO2 increase。

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Lu, Hsing-Cheng, et 盧幸成. « Effect of ZnO on Cement Manufacture from Pure CaO-Al2O3-SiO2 Mixtures ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/f6cbfg.

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碩士
國立成功大學
環境工程學系碩博士班
90
To investigate the role of ZnO played in CaO-Al2O3-SiO2 sintering system, experimental mixture design was applied. Pure CaO, Al2O3, SiO2 were mixed according to three component mixture design and all mixtures were doped with several doses of ZnO. After been sintered at 1450°C for three hours, sintered sample was examined with X-ray diffraction (XRD). Combined with lithium fluoride (LiF) XRD semi-quantification technique and hydration observation, the effect ZnO on cement manufacture was established. On the other hand, aluminum hydroxide was selected as alternative material to investigate the feasibility of utilizing aluminum replacement in cement production. The result shows that major crystalline phase of sintered samples doped with 3%(w/w) ZnO experienced no phase transformation except sample batched with molar ratio 2:3 (CaO:SiO2). ZnO seems to have little interference on characteristic phase formation with 3% addition. In the experiments of aluminum hydroxide replacement, the semi-quantification analysis shows that major crystalline phase is mainly the same. Sludge produced from aluminum series coagulant, which contains mostly aluminum hydroxide, might have the potential of being used as cement manufacturing alternative raw material. With microwave digestion followed by inductively coupled plasma spectrometer, ZnO gas-solid phase distribution was analyzed. The results show that raw materials with molar ratio of 3:2 (SiO2:Al2O3), 5:12:3 (CaO:SiO2:Al2O3) and 2:3:3 (CaO:SiO2:Al2O3) have better ability of constraining ZnO in the solid phase.

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Ahmed, Mohammed Moeeduddin. « Effect of firing cycle and etching condition on resin cement tensile bond strength of Li2O-SiO2 system glass ceramics ». Thesis, 2019. https://hdl.handle.net/2144/37067.

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OBJECTIVE: To evaluate if the firing cycles and etching conditions have an effect on the tensile bonding strength (TBS) of IPS e.max-CAD and CeltraDUO. METHODS: Lithium-disilicate (IPS e.max-CAD) ceramic blocks and zirconia reinforced lithium-disilicate (CeltraDUO) were sectioned into rectangular tiles. The tiles were randomly assigned to various treatment groups and heat treated (1, 5, or 9 firing cycles) or (0, 1 or 5 firing cycle) respectively. e.max-CAD and CeltraDUO tiles were etched for different times (20,160, 300 seconds) and (20, 50, 80 seconds) respectively with hydrofluoric-acid gel (9.6% or 5%). Titanium-pins were sand-blasted on the flat end and cemented on the etched tiles using self-adhesive resin cement (TheraCem). A vertical load of 12N was placed for 40 minutes. All the cemented specimens were stored in incubator at 37°C for 48 hours. A tensile test was performed using a mechanical testing machine (Instron-5566A). The load at failure was recorded and the TBS was calculated. The same procedure was followed on another set of 18 e.max-CAD (fired for 5 firing cycles) and 21 CeltraDUO tiles (fired for 1 firing cycle). The same cementation procedure was followed and TBS was calculated. RESULTS: The TBS of both CeltraDUO and e.max-CAD was significantly affected by etching duration and firing cycles (p<0.001), but not significantly affected by etchant concentration (p=0.31). The highest load to failure was observed around 50 and 60 seconds of etching respectively. CONCLUSION: The etching time and firing cycle directly affect the TBS of both materials whereas the etchant concentration does not.
2021-07-15T00:00:00Z

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Lu, Wei-Ting, et 呂韋霆. « Forming passivation film on AZ91D Mg alloy in a solution prepared by Ordinary Portland cement containing modified desulfurization slag/SiO2 ». Thesis, 2017. http://ndltd.ncl.edu.tw/handle/36800484205997670512.

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碩士
國立中興大學
材料科學與工程學系所
105
Passivation film on surface of AZ91D Mg alloy is prepared by electrochemical method, using Ordinary Portland cement (code C) containing modified desulfurization slag (code M) and SiO2 (code S). The results of polarization test show that there is a passivation phenomena for AZ91D in C+12S and C+12S+30M alkaline aqueous solution. The passivation interval decrease with increasing of C+12S and C+12S+30M contents. Amount of sulphate ion increase with increasing of C+12S and C+12S+30M contents, which leads to the destruction of the passivation film. There is a golden passivation film formed on the surface of AZ91D after potentiostatic polarization test at room temperature. The results of polarization test show that the corrosion density of the passivation film drop from 115 mAcm-2(AZ91D) to 8.836 mAcm-2. After raising the temperature of potentiostatic polarization test from room temperature to 50°C, the corrosion density of passivation film drop from 8.836 mAcm-2 to 4.673 mAcm-2, which indicate that the temperature aiding the growth of passivation film. In addition, by changed the surface roughness of substrate before forming the passivation film affect the surface corrosion resistance. The thickness of passivation film is about 50 nm obtained by transmission electron microscope. Contact angle analysis show that the contact angle of passivation film is 64°, which is relative hydrophobic compared to substrate (25°). Salt spray test show that the anti-salt spray time of passivation film is improved to 48 hour. The studies show that passivation film retains the primary color of magnesium alloy and has the ability to modify the surface of AZ91D, while enhancing the surface corrosion resistance.

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Feng, Shung-Kein, et 馮宗根. « Effect of the Engineering Properties by Add the Nano-SiO2 Materials for the Cement Paste of Water Works Sludge Ash ». Thesis, 2006. http://ndltd.ncl.edu.tw/handle/28988772633060989968.

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碩士
國立高雄應用科技大學
土木工程與防災科技研究所
94
This research attempt increases after 800℃ high temperatures agglutinates only the water works sludge ash to increase nano-SiO2 to carry on the compression-test, the endurance test and the microscopic analysis, expected can the affiliation by a succession of experiment, understand increases nano-SiO2 to only influence the water works sludge ash mortar, by takes only material of nature reference the water works sludge ash substitution cement. Increases the excessively many only water works sludge ash to be able to interfere with the work, when 10% increases 1% nano-SiO2, the overall fluidity value still permissible control above 90%, in the fluidity in the whole substitution quantity is the best proportion.Increases nano-SiO2 to join also can increase along with the quantity but time gradually reduces regarding Water Works Sludge Ash final the setting, except accelerates final the setting time, shrinks section initial setting and final the setting time.Water Works Sludge Ash intensity aspect compares good regarding Salt the Tolerance which comes to the common cement mortar, also can enhance when the early time after nano-SiO2 Salt Tolerance ability.On the MIP analysis, increases along with the age time, the hole volume changes slightly, of void volume the straight cement mortar increases along with the nano-SiO2 increment reduces.From the XRD analysis may understand by 10% substitution quantity best, increases 3%nano-SiO2 Alum of Sludge increases the C-S-H crystallization content to be obviously more.

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TONELLI, MONICA. « Investigation of the structural properties of magnesium silicate hydrate cements and assessment of strategies for their development ». Doctoral thesis, 2018. http://hdl.handle.net/2158/1117678.

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During my PhD I focused my work on the investigation of MgO/SiO2 cements. In the last decades, research on cement formulations alternative to traditional Portland cement has progressively grown, both with the aim of reducing the environmental impact due to the CO2 emissions associated with its production and in view of solving specific needs in particular fields of application. Formulations based on reactive periclase (MgO) and silica (SiO2) in the presence of water hydrate and form a binder phase, M-S-H (magnesium silicate hydrate), analogue to calcium silicate hydrate, C-S-H, present in traditional cements. In spite of its potential importance, there is still little knowledge about its structural features and formulation design. I focused my PhD on this class of cement, aiming to extent the knowledge on this material, which could pave the way for tailoring its macroscopic properties by means of a bottom-up approach, and a multi-technique approach has been used to accomplish this purpose.

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Chapitres de livres sur le sujet "SiO2 cement"

Flores-Vivián, Ismael, et Konstantin Sobolev. « The Effect of Nano-SiO2 on Cement Hydration ». Dans Nanotechnology in Construction, 167–72. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-17088-6_20.

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Awadalseed, Waleed, Jin Zhang et Honghua Zhao. « Experimental Study on Nano SiO2 and Cement Modified Expansive Soil ». Dans Proceedings of GeoShanghai 2018 International Conference : Fundamentals of Soil Behaviours, 209–17. Singapore : Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0125-4_23.

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Sobolev, K., I. Flores, L. M. Torres-Martinez, P. L. Valdez, E. Zarazua et E. L. Cuellar. « Engineering of SiO2 Nanoparticles for Optimal Performance in Nano Cement-Based Materials ». Dans Nanotechnology in Construction 3, 139–48. Berlin, Heidelberg : Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-00980-8_18.

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Cao, Mingli, et Jianqiang Wei. « Effect of Nano-SiO2 on Microstructure, Interface and Mechanical Properties of Whisker-Reinforced Cement Composites ». Dans Ceramic Transactions Series, 173–81. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118144442.ch15.

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Raje Gowda, H. Narendra, R. Mourougane et B. M. Nagabhushana. « Performance of Nano-SiO2 and Nano-ZnO2 on Compressive Strength and Microstructure Characteristics of Cement Mortar ». Dans Lecture Notes in Civil Engineering, 13–22. Singapore : Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-3317-0_2.

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Wu, Bo, et Jishen Qiu. « Effect of Nano-SiO2 Coating on the Mechanical Recovery of Debonded Fiber-Cement Interface Under Water Curing ». Dans RILEM Bookseries, 879–88. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-83719-8_75.

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Vigna, Erika, et Jørgen Skibsted. « Optimization of Alkali Activated Portland Cement—Calcined Clay Blends Based on Phase Assemblage in the Na2O–CaO–Al2O3–SiO2–H2O System ». Dans RILEM Bookseries, 101–7. Dordrecht : Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-017-9939-3_13.

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Maagi, Mtaki Thomas, Nickson Nyamunaga Lushasi et Gu Jun. « Single and Combined Effects of Nano-SiO2, Nano-TiO2 and Nano-Fe2O3 Addition on Fluid Loss of Oil-Well Cement Slurry at High Temperature Condition ». Dans Springer Series in Geomechanics and Geoengineering, 3738–53. Singapore : Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-2485-1_340.

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M. Fadayini, Oluwafemi, Adekunle A. Obisanya, Gloria O. Ajiboye, Clement Madu, Tajudeen O. Ipaye, Taiwo O. Rabiu, Shola J. Ajayi et Joseph T. Akintola. « Simulation and Optimization of an Integrated Process Flow Sheet for Cement Production ». Dans Cement Industry - Optimization, Characterization and Sustainable Application. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95269.

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In this study the process flow diagram for the cement production was simulated using Aspen HYSYS 8.8 software to achieve high energy optimization and optimum cement flow rate by varying the flow rate of calcium oxide and silica in the clinker feed. Central composite Design (C.C.D) of Response Surface Methodology was used to design the ten experiments for the simulation using Design Expert 10.0.3. Energy efficiency optimization is also carried out using Aspen Energy Analyser. The optimum cement flow rate is found from the contour plot and 3D surface plot to be 47.239 tonnes/day at CaO flow rate of 152.346 tonnes/day and the SiO2 flow rate of 56.8241 tonnes/day. The R2 value of 0.9356 determined from the statistical analysis shows a good significance of the model. The overall utilities in terms of energy are found to be optimised by 81.4% from 6.511 x 107 kcal/h actual value of 1.211 x 107 kcal/h with 297.4 tonnes/day the carbon emission savings.

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Achyutha Kumar Reddy, Metta, et Veerendrakumar C. Khed. « Bentonite Clay Modified Concrete ». Dans Sand in Construction [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.103803.

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Replacing cement with pozzolanic materials to some extent in construction is found to be one of the sustainable approaches in the construction industry. Pozzolanic materials of industrial origin like fly ash and Ground Granulated Blast furnace Slag will have to be replaced with natural pozzolanic materials once the world moves towards renewable energy sources. Bentonite is one such pozzolanic clay material that is rich in SiO2 content. A little research was made to assess the performance of bentonite modified concrete. Based on those, an improvement in the fresh, hardened, durability properties was reported. This chapter presents the current scenario on the development of bentonite modified concrete. It also reviews the literature about the physical & chemical properties of bentonite, bentonite blended cement mortar, bentonite modified cement concrete, and reinforced concrete. The history and development of Bentonite modified concrete were also briefly presented in this chapter.

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Actes de conférences sur le sujet "SiO2 cement"

Pokorný, Jaroslav, Milena Pavlíková, Martina Záleská, Pavla Rovnaníková et Zbyšek Pavlík. « Coagulated silica - a-SiO2 admixture in cement paste ». Dans THERMOPHYSICS 2016 : 21st International Meeting. Author(s), 2016. http://dx.doi.org/10.1063/1.4955254.

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Kamei, G., W. R. Alexander, I. D. Clark, P. Degnan, M. Elie, H. Khoury, A. E. Milodowski, A. F. Pitty, E. Salameh et J. A. T. Smellie. « Natural Analogues of Cement : Overview of the Unique Systems in Jordan ». Dans ASME 2010 13th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2010. http://dx.doi.org/10.1115/icem2010-40063.

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In many radioactive waste repository designs, cement-based materials are expected to dominate the repository and models of cement evolution predict that leaching of the cementitious material in the repository by groundwater will produce an initial stage of hyperalkaline (pH∼13.3) leachates, dominated by alkali hydroxides, followed by a longer period of portlandite and C-S-H (CaO-SiO2-H2O) buffered (pH∼12.5) leachates. It has also been predicted that, as the hyperalkaline porewater leaches out of the near-field, significant interaction with the repository host rock and bentonite buffer and backfill may occur. This could possibly lead to deterioration of those features for which the host rock formation and bentonite were originally chosen (e.g. low groundwater flux, high radionuclide retardation capacity etc). The precise implications of cement leachate/repository host rock interaction has been studied in the laboratory and in underground research laboratories (URLs) and this work has been supported by study of natural cements in Jordan. These natural cements have been produced by the combustion of organic-rich clay biomicrites and are very close analogues of industrial cement. Following interaction with groundwaters, natural hyperalkaline leachates are produced and these move out of the cement into the surrounding host rock, subsequently interacting with and altering it.

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Mutuk, Tuğba, Sinem Çevik et Başak Mesci Oktay. « High performance cement composites with nano-SiO2 and nano-Al2O3 powders ». Dans 4th International Symposium on Innovative Approaches in Engineering and Natural Sciences. SETSCI, 2019. http://dx.doi.org/10.36287/setsci.4.6.099.

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Khandaker, Morshed, Yanling Li, Ping Liu et Melville B. Vaughan. « Bioactive Additives and Functional Monomers Affect on PMMA Bone Cement : Mechanical and Biocompatibility Properties ». Dans ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64369.

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The most common bone cement material used clinically today for orthopedic surgeries is poly methyl methacrylate (PMMA). In general, poly Methyl MethAcrylate (PMMA) beads are added to MMA monomer with bead and monomer ratio of 2:1 to prepare the PMMA bone cement. Conventional PMMA bone cement has several mechanical and biological disadvantages. To overcome these disadvantages, researchers investigated several bioactive additives to PMMA bone cement, such as MgO, hydroxyapatite (HAp), chitosan (CS). Additionally, functional monomer, such as glycidyl methacrylate (GMA) was used in addition or substitution to MMA to enhance the properties of PMMA bone cement. A comparative study is required to evaluate the effect that different bioadditives and monomers have on the mechanical and biological performances on PMMA bone cement. The goal of this study is to determine the most suitable additives and alternative monomer for PMMA bone cement that can enhance the mechanical and biological performances of PMMA bone cement. Cobalt™ HV bone cement (referred as CBC), a commercial orthopedic bone cement, was used in this study as PMMA bone cement. MgO, hydroxyapatite (HAp), chitin (CT), chitosan (CS), Barium sulfate (BaSO4) and Silica (SiO2) were mixed with PMMA beads to prepare CBC-MgO, CBC-HAp, CBC-CT, CBC-CS, CBC-BaSO4 and CBC-SiO2 specimens. Additives included CBC were referred as composite specimen. CBC and composite specimens were further grouped according to the application of GMA as replacement of MMA monomer. Two groups of CBC and composite specimen were prepared. In the first group, CBC and composite specimens were prepared using MMA monomer only, referred as without GMA specimen. In the second group, CBC and composite specimens were prepared using GMA and MMA monomers, referred as with GMA specimen. There are three general research questions: (1) Is there a significant difference in the mechanical and biological performances between CBC (control) and different composite specimens that contain GMA? (2) Is there a significant difference in the in the mechanical and biological performances between CBC (control) and different composite specimens that do not contain GMA? and (3) Is there a significant difference in the mechanical and biological performances between specimens mixed with and without GMA? Elastic and fracture properties of different CBC and composite cements were calculated from three point bend experiments. Osteoblast cell adhesion experiments were performed on different CBC and composite cement on a custom made well plate. This study found that flexural strength and fracture toughness of the CBC specimens that contain GMA is significantly greater than the flexural strengths of all other specimens that contain GMA. In contrast, flexural strength and fracture toughness of the CBC-SiO2 specimens that do not contain GMA is significantly greater than the flexural strengths of all other specimens that contain GMA. This study also found that cell adhesion on the MgO impregnated CBC specimens is significantly greater than the cell adhesion of all other specimens for samples that contain GMA or do not contain GMA.

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Liu, Mingle, Zonghui Zhou, Xiuzhi Zhang, Xiangzi Yang et Xin Cheng. « The Effect of Nano-SiO2 Dispersed Methods on Mechanical Properties of Cement Mortar ». Dans International Conference on the Durability of Concrete Structures. Purdue University Press, 2016. http://dx.doi.org/10.5703/1288284316135.

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Gaurina-Međimurec, Nediljka, Krunoslav Sedić, Anel Čajić et Ante Matijević. « Effect of Microblock on the Compressive Strength of Portland Cement at Elevated Temperatures ». Dans 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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Bede, A., A. Pop, M. Moldovan et I. Ardelean. « The influence of silanized nano-SiO2 on the hydration of cement paste : NMR investigations ». Dans 10TH INTERNATIONAL CONFERENCE PROCESSES IN ISOTOPES AND MOLECULES (PIM 2015). AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4938459.

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« The Effect of Natural SiO2 Nanoparticles on the Performance of Portland Cement Based Materials ». Dans SP-326 : Durability and Sustainability of Concrete Structures (DSCS-2018). American Concrete Institute, 2018. http://dx.doi.org/10.14359/51710984.

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Belayneh, Mesfin, et Bernt S. Aadnøy. « Effect of Nano-Silicon Dioxide (SiO2) on Polymer/Salt Treated Bentonite Drilling Fluid Systems ». Dans ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54450.

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Recently the application of nanomaterial is attracting the oil and gas industry. The preliminary nanomaterials research results show an improving performance of cement, drilling fluid and Enhanced Oil Recovery. In this paper, the effect of nano Silicon dioxide (SiO2) on polymer (HV-CMC, Xanthan gum, LV-CMC) and salt (KCl, NaCl) treated bentonite drilling fluid systems has been studied at room temperature. The results show that the performance of nano SiO2 in bentonite mud system depends on its concentration and the types of salt and polymer systems used. In the considered fluid systems, it is also observed that the addition of about 0.06% SiO2 influences rheology, and filtrate loss of the drilling fluid systems. The viscoelasticity of the selected best system further studied and their hole -cleaning and hydraulics performances are simulated. The overall result shows that the formulated optimum concentration of nano-system shows good performances and rheological behavior.

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Li, Ran, Pengkun Hou, Zonghui Zhou et Xin Cheng. « Influence of SiO2@PMHS on the Water Absorption of Cement Mortar as a Surface Treatment Agent ». Dans International Conference on the Durability of Concrete Structures. Purdue University Press, 2016. http://dx.doi.org/10.5703/1288284316115.

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