Journal articles: 'Fumees de silice condensees'

1

Sabir, B. B. "High-strength condensed silica fume concrete." Magazine of Concrete Research 47, no. 172 (September 1995): 219–26. http://dx.doi.org/10.1680/macr.1995.47.172.219.

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YONEKURA, Asuo. "Use of condensed silica fume in concrete." Journal of the Society of Powder Technology, Japan 26, no. 7 (1989): 512–19. http://dx.doi.org/10.4164/sptj.26.512.

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Kwan, A. KH. "Use of condensed silica fume for making high-strength, self-consolidating concrete." Canadian Journal of Civil Engineering 27, no. 4 (August 1, 2000): 620–27. http://dx.doi.org/10.1139/l99-091.

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A high concrete strength can be achieved by lowering the water/binder ratio and a high workability by adding a higher dosage of superplasticizer. However, a high-performance concrete with both high strength and high workability cannot be produced by just these means because lowering the water/binder ratio leads to lower workability and there is a limit to the increase in workability that can be attained by adding superplasticizer. To produce a high-strength, high-workability concrete, the concrete strength needs to be increased without lowering the water/binder ratio. This can be done by adding condensed silica fume. In this study, a series of trial mixing aimed at developing high-strength, self-consolidating concrete (mean cube strength >80 MPa and needs no compaction for consolidation) was carried out. Several mixes suitable for making such high-performance concrete have been developed and it was found that the addition of condensed silica fume may, under favourable conditions, increase not only the strength but also the workability of the concrete mix. Based on the trial mix results, charts for the design of high-strength, high-workability concrete mixes made of the studied constituents are presented.Key words: condensed silica fume, high-strength concrete, self-consolidating concrete.

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Majling, Jan, Peter Znasik, Dinesh Agrawal, Jiping Cheng, and Rustum Roy. "Conventional and microwave sintering of condensed silica fume." Journal of Materials Research 10, no. 10 (October 1995): 2411–14. http://dx.doi.org/10.1557/jmr.1995.2411.

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Condensed silica fume, a by-product from the production of silicon alloys, was sintered by (i) conventional heating in a dilatometric furnace, both at constant heating rate and isothermal heating, and (ii) by the microwave heating. The dense products with relative density up to 95% of theoretical can be obtained only by short runs at high heating rates, preferentially accomplished by the microwave treatment. Prolonged heating leads to the devitrification of the original glassy phase to cristobalite, accompanied by an arrest of densification.

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Alexander, M. G., and B. J. Magee. "Durability performance of concrete containing condensed silica fume." Cement and Concrete Research 29, no. 6 (June 1999): 917–22. http://dx.doi.org/10.1016/s0008-8846(99)00064-2.

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Ng, P. L., W. W. S. Fung, J. J. Chen, and A. K. H. Kwan. "Adiabatic Temperature Rise of Condensed Silica Fume (CSF) Concrete." Advanced Materials Research 261-263 (May 2011): 788–95. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.788.

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Condensed silica fume (CSF) is often added into concrete mixes to enhance the properties of concrete. However, the effect of CSF on the heat evolution and temperature rise of concrete is not clearly known. Test results in the literature are insufficient and sometimes contradictory to enable any conclusion to be drawn regarding the role of CSF in heat generation behaviour of concrete. Moreover, since the chemical reactions of cement and CSF both involve water and hence cement and CSF are competing with each other in reacting with water, the water to binder (W/B) ratio may affect the temperature rise characteristics of concrete. This paper reports an experimental study of adiabatic temperature rise of CSF concrete conducted at The University of Hong Kong. Five concrete mixes without CSF and 10 concrete mixes with CSF dosages at 5% and 10% were tested with the recently developed semi-adiabatic curing test method. The adiabatic temperature rise was obtained by applying heat loss compensation to the test results. It was found that the addition of CSF could suppress the adiabatic temperature rise of concrete. At the same time, the strength of concrete could be enhanced. Based on the experimental results, prediction formula and design chart of adiabatic temperature rise of CSF concrete were developed.

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Slanička, Štefan. "The influence of condensed silica fume on the concrete strength." Cement and Concrete Research 21, no. 4 (July 1991): 462–70. http://dx.doi.org/10.1016/0008-8846(91)90094-x.

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8

Chaudhary, Satish Kumar, and Ajay Kumar Sinha. "Effect of Silica Fume on Permeability and Microstructure of High Strength Concrete." Civil Engineering Journal 6, no. 9 (September 1, 2020): 1697–703. http://dx.doi.org/10.28991/cej-2020-03091575.

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The important concrete structure in the vicinity of industry, thermal power plant suffers deterioration by the acid rain cause due to combination of CO2, SOx and NOx with rain water. A combined attack that is from acid as well as sulphate can be observed under impact of sulphuric acid. It attacks on Calcium hydroxide and form Calcium sulphate, which can be leached out easily and make Interfacial Transition Zone (ITZ) poor. The water retaining structure such as dam, weir should be impermeable and that can be achieved by binary cementitious blends, using Silica fume (SF). Silica fume a by product of silicon industry, proves very effective in improving the microstructure of concrete due to their finer particle size, approximately 100 times finer than cement particles. The SEM image of binary blended high strength concrete (HSC) with Silica fume shows the condensed packing of cement hydration product and a dense microstructure as compare to control mix. The water permeability test result reveals that there is about 87 percent reduction in the coefficient of permeability achieved by inclusion of 10% Silica fume (SF) by weight of cement. Rapid chloride penetration test (RCPT) has been performed to investigate the ingress of chloride ions into the concrete. There was significant reduction in chloride ions penetration recorded due to SF inclusion.

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Venkateshwaran, A., and K. Nandhini. "Study on Steel Fibre Reinforced Self Compacting Concrete." Asian Journal of Engineering and Applied Technology 7, no. 1 (March 5, 2018): 11–15. http://dx.doi.org/10.51983/ajeat-2018.7.1.871.

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Self Compacting Concrete (SCC) consists of a higher amount of fine content and admixtures, thus eliminating the time for compaction and labour cost. Micro silica is a by-product of the industrial manufacture of ferrosilicon and metallic silicon that is been made in high-temperature electric arc furnace. The ferrosilicon is drawn from 2000°C furnace, thus after when it cools down, the particles are condensed and are trapped in huge cloth bags. The condensed fume is processed by removing impurities and thus micro silica is being formed. Micro silica, as a waste by-product, being used for land filling, instead it can be used as an additive to concrete. The overall weight of the concrete increases up to 15 percent, thus increasing the unit weight of concrete. In addition, nano silica and steel fibres have been used to improve the strength and durability of concrete. Addition of silica to a concrete mix alters the cement paste structure. The resulting paste contains more of the calcium-silicate hydrates and less of the easily soluble calcium hydroxides. Due to its smaller size particle distribution, they disperse among and separate the cement particles. In the present study, different mix ratio using micro silica, nano silica and steel fibres has been prepared to study the fresh and hardened properties of SCC respectively.

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Fournier, B., and Marc-André Bérubé. "Évaluation du potentiel de réactivité alcaline des granulats à béton produits dans les Basses-Terres du Saint-Laurent du Québec (Canada)." Canadian Journal of Civil Engineering 18, no. 2 (April 1, 1991): 282–96. http://dx.doi.org/10.1139/l91-033.

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Seventy-one samples of aggregates representative of the various sedimentary rock types exploited in the St. Lawrence Lowlands were submitted to standard and experimental laboratory tests to evaluate their potential alkali-reactivity in concrete. Among these, only the Trenton and Black River limestones with more than 6% insoluble residues produced excessive expansion in the concrete prism test, the most reliable method in assessing the alkali-reactivity potential of concrete aggregates. Expansion values of 0.1 and 0.15%, obtained respectively after 14 days in the accelerated mortar bar test (1 M NaOH at 80 °C) and 5 h of autoclave curing (0.17 MPa at 130 °C and 100% relative humidity), can only be used as acceptance limits, since nonexpansive aggregates (as per the concrete prism test) from the Black River, Chazy and Beekmantown Groups induced excessive expansion in these tests. Limiting the reactive alkali content of the concrete mix to 3 kg/m3 or using cements containing between 5 and 10% of condensed silica fume can reduce the risks of deleterious reactions associated with the siliceous limestone aggregates produced in the St. Lawrence Lowlands. Key words: concrete, aggregates, alkali–aggregate reaction, accelerated test methods, preventive measures, condensed silica fume.

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11

Priya, C. Chandana, M. V. Seshagiri Rao, V. Srinivasa Reddy, and S. Shrihari. "High Volume Fly Ash Self Compacting Concrete with Lime and Silica Fume as Additives." E3S Web of Conferences 184 (2020): 01109. http://dx.doi.org/10.1051/e3sconf/202018401109.

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SCC is expensive when compared with normal conventional concrete. Hence, it is desired to produce low cost SCC by replacing cement with higher percentages of fly ash, which is a no cost material and available in abundance. At the same time to achieve higher grade HVFASCC, micro silica which is otherwise condensed silica fume can also be used along with fly ash to enhance the strength properties of HVFASCC. By replacing fly ash in high volumes in the mix, high amount of pozzolanic material becomes available, majorly reactive silica, for which more calcium hydroxide is necessary for further pozzolanic reaction. As we are reducing cement quantity, the amount of calcium hydroxide available is reduced thus demanding external addition of hydrated lime which can be supplied as additive to cater to the need of calcium hydroxide required for reactive silica in fly ash.The present investigation aims to achieve strength for high volume fly ash self-compacting concrete. The replacement of cement with fly ash is made in 45%, 50%, 55%, 60%, 65% and 70% with 20% hydrated lime and 10% silica fume in one trial. In another trial, 30% hydrated lime and 10% silica fume is added with replacement of fly ash to cement varying in same percentages. The design mix is tested for workability and flowability and cubes are casted for compression strength test and tested at 28 day,, 56 day, and 90 day,.

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12

BOMBARD, ANTONIO J. F., MARCELO KNOBEL, and MARIA REGINA ALCÂNTARA. "PHOSPHATE COATING ON THE SURFACE OF CARBONYL IRON POWDER AND ITS EFFECT IN MAGNETORHEOLOGICAL SUSPENSIONS." International Journal of Modern Physics B 21, no. 28n29 (November 10, 2007): 4858–67. http://dx.doi.org/10.1142/s0217979207045761.

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Two types of carbonyl iron powders, (CIP's, BASF AG), the HS and HS-I (I = insulated, due a coating with phosphate), and two kinds of silica, one hydrophobic (Cab-O-Sil® TS610) and other hydrophilic (Cab-O-Sil® M5), were used to evaluate the influence of the surface treatment of the magnetic particle and the kind of fumed silica on the formulation of some magnetorheological suspensions (MRS). Oscillatory measurements at no field showed an evident difference between the silicas, but not a specific interaction with the phosphate coating on HSI. On the other hand, steady flow experiments also without magnetic field showed that the kind of silica and its specific interactions with the coating on iron powder drove the rheological behavior of the MRS on all region of the shear rate. Under magnetic field, the flow curves differences will be due to the iron particles and its magnetic properties, mainly on the region of higher shear rate.

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13

Scano, Alessandra, Federico Ebau, Valentina Cabras, Franca Sini, and Guido Ennas. "Alternative Silica Sources in the Synthesis of Ordered Mesoporous Silica." Journal of Nanoscience and Nanotechnology 21, no. 5 (May 1, 2021): 2847–54. http://dx.doi.org/10.1166/jnn.2021.19059.

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In this work, the influence of the use of alternative inexpensive silica sources on the structural, morphological and textural properties of MCM-41 like mesoporous materials to be used for biomedical applications has been investigated. The Liquid Crystal Template Method has been used to prepare the ordered mesoporous structured materials according to a novel composition starting from fumed silica or granular silica gel as alternative silica sources. The obtained materials have been characterized by X-ray Powder Diffraction, Transmission and Scanning Electron Microscopy, and nitrogen sorption, which showed for both samples the formation of the ordered hexagonal pore arrangement typical of a MCM-41 material. However, when using fumed silica, higher long-range hexagonal pore ordering as well as higher surface area have been obtained (1030 vs. 763 m2/g). For comparison, the features of a commercial silica mesostructured MCM-41 type have been investigated as well. Again, the silica fumed based sample has showed higher long-range hexagonal pore ordering, higher surface area and wall thickness. Preliminary stability studies on the fumed silica based material showed a decrease in the pore ordering at the end of the third year after the synthesis.

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14

Ghosh, Sujit, and K. W. Nasser. "Creep, shrinkage, frost, and sulphate resistance of high strength concrete." Canadian Journal of Civil Engineering 22, no. 3 (June 1, 1995): 621–36. http://dx.doi.org/10.1139/l95-071.

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A comprehensive study was undertaken to determine the shrinkage, creep, and durability of high strength concrete (50–70 MPa) containing silica fume and lignite fly ash. The concrete mixtures contained normal CSA type 10 (ASTM type 1) portland cement, 10% condensed silica fume, and different amounts of fly ash that varied between 0 and 80% of the weight of binder in the mixture. The aggregates-to-binder ratio by weight was maintained at 5 and the weight of the superplasticizer was varied between 1.5% and 2.2% of the binder while the water-to-binder ratio was maintained at 0.27. The test program consisted of compressive strength tests at various ages on concrete cylinders; drying shrinkage tests at room temperature; creep tests of sealed and unsealed concrete at room temperature (21 °C (70°F)) and at high temperatures (up to 232 °C (450°F)) under three different stress regimes; frost resistance tests on concrete prisms up to 300 freezing and thawing cycles; and sulphate resistance tests on concrete prisms immersed in 5% Na2SO4 solution for up to 10 months. The results indicated that up to 60% fly ash replacement with 10% silica fume showed either superior or similar 28- and 56-day compressive strengths when compared with the 100% cement control mixture. Fly ash + silica fume concrete indicated lower shrinkage and long-term creep. Creep increased with increase in temperature due to physico-chemical processes, which were confirmed by microstructure analysis using the scanning electron microscope. The creep and shrinkage data of high fly ash + silica fume concrete fitted well to the current ACI creep and shrinkage model. Replacement of cement by up to 35% fly ash and 10% silica fume indicated enhanced frost resistance, without any air-entrainment. The addition of 8% air-entrainment to the 20% fly ash + 10% silica fume mixture increased the durability factor by about 10%. For the 50% fly ash + 10% silica fume mixture, the frost durability factor was found comparable to that of the 100% cement control mixture, and air entrainment did not improve its value appreciably. Sulphate resistance of concrete made with 100% CSA type 10 cement was found satisfactory; however, with increasing fly ash contents (up to 50%), the expansion due to sulphate action was suppressed. A study of matrix morphology and microstructure bonding, using the scanning electron microscope, helped to explain the observed results in a comprehensive manner. Key words: creep, shrinkage, compressive strength, frost resistance, durability factor, sulphate resistance, fly ash, silica fume, high-strength concrete, SEM micrograph, matrix morphology.

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Ishihara, Satoru, Hidehiko Tanaka, and Toshiyuki Nishimura. "Synthesis of silicon carbide powders from fumed silica powder and phenolic resin." Journal of Materials Research 21, no. 5 (May 1, 2006): 1167–74. http://dx.doi.org/10.1557/jmr.2006.0138.

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Silicon carbide powders were synthesized by application of sol-gel processing. Fumed silica powder was used as the starting material for the silicon source, and phenolic resin was used for the carbon source. The effects of mixing ratio and difference between hydrophilic and hydrophobic types of fumed silica powders were investigated. The stirred mixtures of fumed silica powders and phenolic resin became apparent sol states owing to homogeneous distribution. SiC powders were formed derived from both the types of fumed silica powders after the gelation and pyrolysis up to 1800 °C. The hydrophilic silica powder was effective to synthesize more homogeneous SiC powders than the hydrophobic type. Single-phase SiC was obtained in the C/Si (molar ratio after pyrolysis at 1000 °C) range between 1.0 and 2.5, while free carbon was contained in the obtained powders of C/Si > 2.5. In contrast, formation of SiC was insufficient, and SiO2 was retained at ratios of C/Si < 1.0.

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Park, Jin-Hyung, Hao Cui, Sok-Ho Yi, Jea-Gun Park, and Ungyu Paik. "Effect of abrasive material properties on polishing rate selectivity of nitrogen-doped Ge2Sb2Te5to SiO2film in chemical mechanical polishing." Journal of Materials Research 23, no. 12 (December 2008): 3323–29. http://dx.doi.org/10.1557/jmr.2008.0397.

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We investigated the polishing rate and selectivity of nitrogen-doped Ge2Sb2Te5(NGST) to SiO2film for different abrasive materials (colloidal silica, fumed silica, and ceria abrasives). They both were strongly dependant on abrasive material properties. The polishing rate of nitrogen-doped NGST decreased in the order ceria, fumed silica, and colloidal silica abrasives, which was determined by abrasive material properties, such as abrasive hardness, crystal structure, and primary and secondary abrasive sizes. In addition, the polishing rate slope of NGST film was not significantly different for different abrasive materials, indicating that the polishing of NGST film is mechanical dominant polishing. In contrast, the polishing rate slope of SiO2film decreased in the order ceria, fumed silica, and colloidal silica abrasives, indicating that the polishing of SiO2film is chemical dominant polishing. Furthermore, the difference in polishing rate slopes between NGST and SiO2film gave a polishing rate selectivity of NGST to SiO2film higher than 100:1 with colloidal silica abrasive.

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Nochaiya, Thanongsak, Tanokwan Jeenram, Panisara Disuea, and Pincha Torkittikul. "Microstructure, compressive strength, and permeability of Portland-condensed silica fume cement." Monatshefte für Chemie - Chemical Monthly 148, no. 7 (June 1, 2017): 1363–70. http://dx.doi.org/10.1007/s00706-017-1976-y.

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Altcin, Pierre-Claude, and Micheline Regourd. "The use of condensed silica fume to control alkali-silica reaction — a field case study." Cement and Concrete Research 15, no. 4 (July 1985): 711–19. http://dx.doi.org/10.1016/0008-8846(85)90073-0.

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Deepak, F. L., Gautam Gundiah, Md Motin Seikh, A. Govindaraj, and C. N. R. Rao. "Crystalline silica nanowires." Journal of Materials Research 19, no. 8 (August 2004): 2216–20. http://dx.doi.org/10.1557/jmr.2004.0285.

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α-Cristobalite nanowires of 50–100 nm diameter with lengths of several microns have been synthesized for the first time by the solid-state reaction of fumed silica and activated charcoal. The nanowires have been characterized by x-ray diffraction, electron microscopy, photoluminescence, and Raman scattering. The nanowires are single crystalline as revealed by high-resolution electron microscope images. The crystalline nanowires are clad by an amorphous silica sheath when the carbon to fumed silica ratio in the starting mixture is small. Use of hydrogen along with Ar helps to eliminate the amorphous sheath.

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Monteiro, P. J. M., O. E. Gjorv, and P. K. Mehta. "Effect of condensed silica fume on the steel-cement paste transition zone." Cement and Concrete Research 19, no. 1 (January 1989): 114–23. http://dx.doi.org/10.1016/0008-8846(89)90071-9.

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Elahi, Kamar, and Harsh Gupta. "A REVIEW OF STUDY AND ANALYSIS OF STRENGTH PROPERTIES OF CALCINED KAOLIN AND SILICA FUME WITH COMPOSITION." International Journal of Engineering Technologies and Management Research 8, no. 1 (February 8, 2021): 45–48. http://dx.doi.org/10.29121/ijetmr.v8.i1.2021.860.

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Cement is used in any construction and can be hydraulic or non-hydraulic, which directly depends on the cement's ability to use the presence of water. When high purity quartz is reduced to silicon at temperatures of up to 2000 ° C, SiO2 vapors are formed, which are oxidized and condensed in the low temperature zone into tiny particles made of non-crystalline silica.

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Page, J. H., W. J. L. Buyers, G. Dolling, P. Gerlach, and J. P. Harrison. "Neutron inelastic scattering from fumed silica." Physical Review B 39, no. 9 (March 15, 1989): 6180–85. http://dx.doi.org/10.1103/physrevb.39.6180.

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23

Barthel, Herbert, Mario Heinemann*, Michael Stintz, and Benno Wessely. "Particle Sizes of Fumed Silica." Particle & Particle Systems Characterization 16, no. 4 (August 1999): 169–76. http://dx.doi.org/10.1002/(sici)1521-4117(199908)16:4<169::aid-ppsc169>3.0.co;2-h.

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Chen, Junhong, Tong Li, Xiaoping Li, Kuo-Chih Chou, and Xinmei Hou. "Morphological Evolution of Low-Grade Silica Fume at Elevated Temperature." High Temperature Materials and Processes 36, no. 6 (July 26, 2017): 607–13. http://dx.doi.org/10.1515/htmp-2015-0206.

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AbstractTo solve the environmental pollution problem caused by low-grade silica fume (SiO2, < 86 mass%) and further expand its application field, the morphological development of low-grade silica fume from room temperature to 900 °C in air was investigated using TG-DTA, SEM and TEM techniques. The structural development of silica fume was further analyzed using FT-IR and Raman spectrum. The results show that silica fume contains many defects of broken bands such as Si-O or ≡Si at room temperature. When exposed to the moister or water, the broken bonds tend to react with water and result in the formation of Si-OH and adjacent hydroxyl groups of Si-OH•OH-Si. At elevated temperature up to 900 °C, the structure of silica fume becomes compact due to the reconstruction of the broken bonds caused by the dehydration reaction.

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Endawati, Jul. "Properties of GGBFS-Based Pervious Concrete Containing Fly Ash and Silica Fume." Solid State Phenomena 266 (October 2017): 278–82. http://dx.doi.org/10.4028/www.scientific.net/ssp.266.278.

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Pervious concrete primarily is used as a means of storm water management. Taking into consideration the environment issues, the binder can also be formed by partially replaced Portland cement by cementitious materials, such as blast furnace slag fine powder, fly ash and silica fume. The combination of the binder materials was determined based on previous work, which composed of 56% Portland Composite Cement, 15% fly ash Type F, 26% air-cooled blast furnace slag from a local steel Industry and 3% condensed silica fume. The compressive strength of specimens with coarser aggregate was lower compared with the control pervious concrete, but still within the range of the requirement compressive strength according to ACI 522R-2010. The difference of the aggregate size affected the enhancement of the compressive strength. The flexural strength of pervious concrete with aggregate size of 9.5mm-12.5mm tend to be higher compared with that of pervious concrete with smaller aggregate size. Furthermore, the addition of 6% natural fine aggregate while applying higher water/cement ratio could be a contribution to the enhancement of the compressive and the flexural strength.

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Khavryutchenko, Alexey V., and Vladimir D. Khavryutchenko. "Fumed silica synthesis. Influence of hydrogen chloride on the fumed silica particle formation process." Macromolecular Symposia 194, no. 1 (April 2003): 253–68. http://dx.doi.org/10.1002/masy.200390091.

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Zain, Asna Mohd, Shaaban Md Ghazaly, and Mahmud Hilmi. "Leachability of Metal Ions in TCLP Leachate of Solidified Petroleum Sludge." Key Engineering Materials 594-595 (December 2013): 1094–98. http://dx.doi.org/10.4028/www.scientific.net/kem.594-595.1094.

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Toxicity characteristic leaching procedure was executed on solidified petroleum sludge to investigate the metal ions release in leaching medium extractant fluid number 2, U.S.EPA SW-846 TCLP. Nine metal ions from solidified sludge in ordinary Portland cement were evaluated at water to cement ratio of 0.4 to 0.5 and incorporation of 5-15% cement replacement materials. Five cement replacement materials namely, rice husk ash, condense silica fume, activated carbon, fly ash and meta kaolin were selected for solidified sludge in the cement. Solidified sludge with cement replacement materials indicates minimum leachability of metal ions.

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Alexander, M. G. "Deformation properties of blended cement concretes containing blastfurnace slag and condensed silica fume." Advances in Cement Research 6, no. 22 (April 1994): 73–81. http://dx.doi.org/10.1680/adcr.1994.6.22.73.

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Asavapisit, Suwimol, Weena Nanthamontry, and Chongrak Polprasert. "Influence of condensed silica fume on the properties of cement-based solidified wastes." Cement and Concrete Research 31, no. 8 (August 2001): 1147–52. http://dx.doi.org/10.1016/s0008-8846(01)00541-5.

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Kwan, A. K. H., Jia Jian Chen, and L. G. Li. "Effects of Condensed Silica Fume and Superfine Cement on Flowability of Cement Paste." Applied Mechanics and Materials 121-126 (October 2011): 2695–700. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.2695.

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Addition of supplementary cementitious materials (SCM) has been contradictorily reported to be beneficial or detrimental to the flowability of concrete and no general conclusion can be drawn up to now. In order to comprehensively disclose the effects of SCM on the flowability, an experimental study had been carried out to measure the flowability of a total of 100 cement paste samples with different condensed silica fume (CSF) and superfine cement (SFC) contents at a wide range of water/cementitious materials (W/CM) ratios. The results showed that the addition of CSF would decrease the flowability at a relatively high W/CM ratio but increase the flowability at a low W/CM ratio, while the addition of SFC could generally improve the flowability of cement paste. Joint addition of SFC and CSF would not exert any definite effect on flowability at a relatively high W/CM ratio but could improve the flowability at a low W/CM ratio. In-depth analysis showed that these results could be well explained by the theory of water film thickness.

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Soltani, Abolfazl, Amir Tarighat, and Masoud Varmazyari. "Calcined Marl and Condensed Silica Fume as Partial Replacement for Ordinary Portland Cement." International Journal of Civil Engineering 16, no. 11 (February 19, 2018): 1549–59. http://dx.doi.org/10.1007/s40999-018-0289-9.

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Wei, Yufei, Michael J. Solomon, and Ronald G. Larson. "Time-dependent shear rate inhomogeneities and shear bands in a thixotropic yield-stress fluid under transient shear." Soft Matter 15, no. 39 (2019): 7956–67. http://dx.doi.org/10.1039/c9sm00902g.

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Rashed, Ahmed I., and Robert Brady Williamson. "Microstructure of entrained air voids in concrete, Part II." Journal of Materials Research 6, no. 11 (November 1991): 2474–83. http://dx.doi.org/10.1557/jmr.1991.2474.

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The microstructure of air voids in both air-entrained and non air-entrained paste, mortar, and concrete containing silica fume has been studied at different ages (5 min to 60 days) in order to understand how air-entrained voids form in portland cement–silica fume systems. Scanning electron micrographs of air voids are presented for many different ages. The solidification process of portland cement–paste and mortar was frozen at different ages using both a low-temperature scanning electron microscope and freeze drying. During the course of these experiments, it was discovered that air voids can be considered “windows” in the microstructure in which one can observe early hydration features that give insight into the nature of portland-cement systems. A well-developed sheaf of wheat morphology has been observed in concretes incorporating silica fume, and a new interpretation of the microstructure of silica fume concrete is presented.

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Eštoková, Adriana, Martina Kovalcikova, and Alena Luptáková. "Deterioration of Cement Composites with Silica Fume Addition due to Chemical and Biogenic Corrosion Processes." Solid State Phenomena 227 (January 2015): 190–93. http://dx.doi.org/10.4028/www.scientific.net/ssp.227.190.

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The paper is aimed at comparative study of resistance of Portland cement composites with addition of silica fume as durability increasing factor in various aggressive environments (sulphuric acid with pH 4, the medium of activated bacteria and the cultivating medium without bacteria) during 150 days under model laboratory conditions. Experimental studies confirmed: the leaching of silicon ions calculated to 1 g of concrete sample affected with bacteriaAcidithiobacillusthiooxidanswas 2.5 times lower (31.78 mg/g of sample) for concrete sample with silica fume addition comparing to concrete sample of ordinary CEM I Portland cement without any additives (82.98 mg/g of sample). The highest concentration of calcium ions released (60.808 mg/g of sample) was observed for reference sample without silica fume addition placed in the cultivating medium. Silica fume based concrete samples were found to have better performance in terms of calcium ions leaching for all environments and silicon ions leaching.

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Bavithran, BG, VA Nagarajan, and KP Vinod Kumar. "Fire-resistant hydrophobic nanocoated composite partition sheets." Journal of Thermoplastic Composite Materials 32, no. 11 (September 20, 2018): 1467–84. http://dx.doi.org/10.1177/0892705718799814.

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Composite partition sheets were prepared by vacuum infusion process using noncombustible glass fiber and waste nylon along with polyester matrix. The waste nylon materials obtained in the form of discarded fishing nets were reinforced in sheets with T90° orientation. They were then coated using two types of fumed silica nanopowders mixed in polyester resin. Two types of coated and corresponding bare hybrid composite samples were examined for their various properties. Appreciable values for mechanical properties were obtained for all the hybrid sheets which are more pronounced for the nanocoated sheets. Furthermore, horizontal flammability tests proved that the fumed silica-coated sheets have better flame-retardant characteristics. With constant heat flux of 50 W/m2, the specimens were investigated for the peak heat release rate (HRR) and fire reaction properties like total oxygen consumed, average specific mass loss rate, total smoke release, and average HRR which gave good results for the nanocoated sheets. Moreover, water-absorbing properties of the hybrid sheets were generally less and it was better in the case of hydrophobic fumed silica-coated samples. These low cost and less weight composite sheets were successfully developed and the results obtained were encouraging, which can be used as partition sheets in the construction of affordable buildings.

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Al-Obaidi, Ahmed, Marwa Al-Mukhtar, Omar Al-Dikhil, and Saeed Hannona. "Comparative Study between Silica Fume and Nano Silica Fume in Improving the Shear Strength and Collapsibility of Highly Gypseous Soil." No.1 27, no. 1 (March 15, 2020): 72–78. http://dx.doi.org/10.25130/tjes.27.1.10.

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Soils with highly gypsum content signify known as soils that exhibit collapsibility and sudden failure when being submerged to wetting. Many of the constructions built on this soil showed cracked and/or collapsed at some parts as these soils immersed or leached with water. The utilization of extremely fine materials, for example, Microscale or Nanoscale, is generally utilized these days. This research compared the use of Silica fume (SF) (micro material) and Nano Silica fume (NSF) (Nanomaterial) to explore the capability of these very fine materials to mend the shear strength and collapsibility properties of highly gypseous soils. The soil as Poorly Graded Sand (SP) was used, with a gypsum amount equal to 62%. A succession of direct shear tests and double odometer tests were carried on dry and submarined specimens of soil at various percentages of SF and NSF. The obtained results indicate that mixing the highly gypseous soils with SF or NSF improved the engineering properties of these soils, especially for the wet condition. The average increment in apparent cohesion when adding SF (5-20) percentage varies between (140-310) % in dry soil and (20-40) % in soaked soil. Same results obtained when mixing the gypseous soils with (1-5) % of NSF. Also, the Nanomaterial provided an improvement of the friction angle in dry and submerged cases respectively. Considering that, the SF gives adverse results upon the friction angle of the soil. The SF and the NSF both condensed the dangers of gypseous soil collapsibility. Consequently, the use of NSF can be assertively suggested to improve the engineering characteristics of highly gypseous soils when compared with SF, where only mixing of 3% of NSF gives the best results.

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Stoian, Elena Valentina, Dan Nicolae Ungureanu, Florin Toma, Alexandru Gabriel Colţa, Daniel Anculescu, Vasile Bratu, and Nicolae Angelescu. "Special Binding for Refractory Concretes." Scientific Bulletin of Valahia University - Materials and Mechanics 17, no. 17 (October 1, 2019): 11–16. http://dx.doi.org/10.2478/bsmm-2019-0012.

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AbstractThe paper shows data related to coexistence of various binding systems, which could be present during the hardening of special concretes. It is taken into account the Ultra Low Aluminous Cement Concretes additivated with different materials (phosphates and mineral ultra dispersed powders - Condensed Silica Fume, Hydrated Alumina etc). In correlation to the pH-value, these substances can favour the forming of new binding systems besides the hydraulic binder (which is not important in this case). The new system is the coagulation binding form. The coagulation binding system has a very important role in the advanced compactness and in the increasing mechanical strengths of concrete structures.

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Chen, J. J., A. K. H. Kwan, P. L. Ng, and L. G. Li. "Packing Density Improvement through Addition of Limestone Fines, Superfine Cement and Condensed Silica Fume." Journal of Materials Science and Chemical Engineering 04, no. 07 (2016): 29–36. http://dx.doi.org/10.4236/msce.2016.47005.

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Liu, Xiao, and Decai Li. "Tuning the magneto-rheological properties of magnetic fluid using hydrophilic fumed silica nanoparticles." Soft Matter 17, no. 35 (2021): 8175–84. http://dx.doi.org/10.1039/d1sm00806d.

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In this work, we study the effect of hydrophilic fumed silica nanoparticles with different mass fractions on the magneto-rheological properties of magnetic fluid, and reveal the mechanism by the coarse-grained molecular dynamics simulation.

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Xu, Guoliang, Xiangxue Zhu, Xiujie Li, Sujuan Xie, Shenglin Liu, and Longya Xu. "Synthesis of pure silica ITQ-13 zeolite using fumed silica as silica source." Microporous and Mesoporous Materials 129, no. 1-2 (April 2010): 278–84. http://dx.doi.org/10.1016/j.micromeso.2009.10.005.

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M. Ahmed, Nivin, Walaa M. Abd El-Gawad, Elham A. Youssef, and Eglal M. Souaya. "Employment of new modified ferrite pigments in anticorrosive alkyd-based paints." Pigment & Resin Technology 43, no. 4 (July 1, 2014): 201–11. http://dx.doi.org/10.1108/prt-10-2013-0106.

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Purpose – The purpose of this work is to prepare new core-shell pigments based on silca fume waste as core and ferrite pigments in the shell. Silica fume is a byproduct of the smelting process in the ferrosilicon industry. The reduction of high-purity quartz to silicon at temperatures up to 2,000°C produces SiO2 vapours which then oxidize and condense at low-temperature zones to tonnage amounts of tiny particles consisting of non-crystalline silica that is collected and sold rather than being land-filled because nowadays there is increasing environmental concern with regard to excessive volumes of solid waste hazards accumulation. Silica has no direct effect in protecting metals from corrosion, but on precipitating an effective anticorrosive pigment like ferrite on its surface with low concentrations, this can bring out new core-shell pigment with good anticorrosive performance and low cost. The new pigments will be constructed on a waste silica fume core comprising 80-85 per cent of its chemical structure and the ferrite shell that will be only about 20-15 per cent. These pigments are represented as efficient, economically feasible and eco-friendly. Design/methodology/approach – The different ferrites and ferrites/SiO2 pigments were characterized using different analytical and spectro-photometric techniques, such as X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray and transmission electron microscopy (TEM). Evaluation of these pigments was done using international standard testing methods american standard testing methods (ASTM). After evaluation, the pigments were incorporated in solvent-based paint formulations based on medium oil-modified soya-bean-dehydrated castor oil alkyd resin. The physico-mechanical properties of dry films and their corrosion properties using accelerated laboratory test in 3.5 per cent sodium chloride for 28 days were determined. Findings – The results of this work revealed that ferrite/SiO2 core-shell pigments were close in their performance to that of the ferrite pigments in protection of steel, and at the same time, they verified good physico-mechanical properties. Practical implications – As silica fume has a large array of uses, these pigments can be applied in various industries such as painting, wooding coating, anti-corruption coating, powder coating, architectural paint and waterproof paints. Originality/value – Ferrite, ferrite/SiO2 are environmentally friendly pigments which can impart high anticorrosive behaviour to paint films with concomitant cost savings.

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Bílek, Vlastimil, David Pytlík, and Marketa Bambuchova. "High Performance Concrete with Ternary Binders." Key Engineering Materials 761 (January 2018): 120–23. http://dx.doi.org/10.4028/www.scientific.net/kem.761.120.

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Use a ternary binder for production of a high performance concrete with a compressive strengths between 120 and 170 MPa is presented. The water to binder ratio of the concrete is 0.225 and the binder is composed of Ordinary Portland Cement (OPC), condensed silica fume (CSF), ground limestone (L), fly ash (FA) and metakaoline (MK). The dosage of (M + CSF) is kept at a constant level for a better workability of fresh concrete. Different workability, flexural and compressive strengths were obtained for concretes with a constant cement and a metakaoline dosage, and for a constant dosage (FA + L) but a different ratio FA / L. An optimum composition was found and concretes for other tests were designed using this composition.

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Takigawa, Mizuki, Hiromitsu Koyama, Yoshiki Uno, and Shigeyuki Date. "Effects of Silica Fume Addition on Properties of Fresh Mortar." Materials Science Forum 1023 (March 2021): 127–34. http://dx.doi.org/10.4028/www.scientific.net/msf.1023.127.

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In recent years, concrete structures have tended to be taller and larger than before. With that trend, concrete as a material has diversified, and various kinds have been developed to meet differing quality requirements. In particular, the need for high-strength concrete is increasing. In general, high-strength concrete has a low water-binder ratio, so its workability is inferior to general concrete. Including admixtures such as silica fume is one way to remedy this problem. Previous studies have discussed the quality and hardening characteristics achievable using silica fume. Nevertheless, expected increasing demand for high-strength concrete dictates the need to understand not only its properties when fresh, but also to have an accurate picture of its vibration compaction properties on construction sites. In this study, the effect of adding silica fume on the workability of mortar was investigated by evaluating its fresh properties, plastic viscosity, and vibration propagation characteristics. Changes to mortar’s fresh properties due to pressure were also investigated to clarify its behavior in pumping environments. The study confirmed that the addition of silica fume decreases plastic viscosity and increases vibration propagation characteristics, and that increased plastic viscosity due to pressurization can be reduced.

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Nan, Xue Li, Jian Rui Ji, Rong Yang Li, Yi Wang, Hao Chen, and Wei Bing Tang. "Influence of Glass Powder on Rheological Properties of Ultra-High Performance Concrete Paste." Materials Science Forum 1036 (June 29, 2021): 419–31. http://dx.doi.org/10.4028/www.scientific.net/msf.1036.419.

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Replacing cement and silica fume with glass powder to prepare ultra-high performance concrete (UHPC) is beneficial to solve the ecological problem in the field of civil engineering, but the technologies of preparation, transportation, pumping, and hardening of UHPC mainly relate to its rheological property. Therefore, this paper studied the influence of glass powder on the rheological properties of UHPC paste by performing the flow and the rheological test. Experimental results showed that when the cement and silica fume partially replaced by glass powder, the UHPC paste appears shear thickening, yield stress, plastic viscosity, and area of hysteresis loop decrease. This means that mixing glass powder can somehow inhibit the problems of segregation and bleeding of UHPC during pumping. In this manner, the dosage of the superplasticizer in UHPC is appropriately reduced, the filling capacity of UHPC during pouring is improved, and the energy required for UHPC in the pumping process is weakened. Compared with replacing cement, replacing silica fume with glass powder significantly increases the shear thickening and fluidity of UHPC paste, and at the same, reduces its yield stress and plastic viscosity. This indicates that the construction performance of UHPC is greatly improved with the replacement of silica fume. The fluidity and yield stress of UHPC paste satisfy the quadratic polynomial function relationship, and the replacement of cement and silica fume with glass powder should be less than 33% and 50%, respectively. Under this condition, the rheological properties of the UHPC paste are greatly improved and result in little negative impact on the mechanical properties of UHPC.

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Chen, J. J., P. L. Ng, L. G. Li, and A. K. H. Kwan. "Production of High-performance Concrete by Addition of Fly Ash Microsphere and Condensed Silica Fume." Procedia Engineering 172 (2017): 165–71. http://dx.doi.org/10.1016/j.proeng.2017.02.045.

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J. Chen, J. "Effects of Pulverized Fuel Ash and Condensed Silica Fume on Heat Generation of Curing Concrete." International Journal of Materials Science and Applications 5, no. 6 (2016): 271. http://dx.doi.org/10.11648/j.ijmsa.20160506.16.

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Bhaskar, M., P. Srinivasa Rao, and B. L. P. Swami. "Strength Properties of Fibre Reinforced High Performance Concrete Blended with Metakolin and Condensed Silica Fume." IOSR Journal of Mechanical and Civil Engineering 16, no. 053 (December 2016): 99–105. http://dx.doi.org/10.9790/1684-160530199105.

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Abadjiev, P., K. Panayotov, and S. I. Petrov. "Influence of condensed silica fume as admixture to concrete on the bond to the reinforcement." Construction and Building Materials 7, no. 1 (March 1993): 41–44. http://dx.doi.org/10.1016/0950-0618(93)90023-6.

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MITANI, Yoshio, Takanori TESHIMA, Yasuo YOSHIDA, and Noboru YAMAZOE. "Dispersibility of Fumed Silica in Simple Media." Journal of the Ceramic Society of Japan 101, no. 1174 (1993): 707–12. http://dx.doi.org/10.2109/jcersj.101.707.

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Yziquel, F., P. J. Carreau, and P. A. Tanguy. "Non-linear viscoelastic behavior of fumed silica suspensions." Rheologica Acta 38, no. 1 (May 11, 1999): 14–25. http://dx.doi.org/10.1007/s003970050152.

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Journal articles on the topic 'Fumees de silice condensees'

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