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Mendes, Thiago Melanda, i Wellington Longuini Repette. "Nano-silica added to Portland cement". Acta Scientiarum. Technology 43 (14.06.2021): e51699. http://dx.doi.org/10.4025/actascitechnol.v43i1.51699.
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For a controlled particle size distribution, nano-silica was added to three different cements. The chemical and mineralogical compositions of the cements were characterized by fluorescence and X-ray diffraction. The granulometric distributions of cements and nano-silicas were obtained by laser granulometry and dynamic lightning scattering. The specific surface area of the raw materials was determined by gas adsorption. The effect of nano-silica and type of cement on rheological behavior was evaluated by rotational rheometry. The mechanical performance was investigated through the compression strength. The microstructural analysis was performed by scanning electron microscopy. The water demand and the consumption of dispersant increases according to the nano-silica content. The reduction in the inter-particle separation, and the agglomeration of nano-silica led to an increase in the viscosity of the suspension. The mechanical performance was directly affected by the specific surface area of the cements. Microstructural analysis showed that nano-silica changed from a layered adsorbed structure, to a porous or agglomerated structure.
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Clarizka, Cynthia, Agus Prasetya i Indra Perdana. "Influence of Calcium/Silica Ratio on the Formation Belite Cement Clinker from Geothermal Sludges". Materials Science Forum 948 (marzec 2019): 249–53. http://dx.doi.org/10.4028/www.scientific.net/msf.948.249.
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Cement industry is seeking alternative raw material and process to reduce the energy consumption and environmental impacts from conventional cement manufacture. This paper describes process of belite cements synthesis. Geothermal sludges, an undesired waste from Dieng Geothermal Power Plant as amorphous silica source and calcium hydroxide were used to form belite cement at elevated temperatures. Experimental results showed that principal phase of belite cement (larnite or β-Ca2SiO4) was formed at temperature as low as 800 °C. Thus, the geothermal silica is shown to be very promising starting material for the low-temperature production of belite cement.
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Wang, Xiao Jun, Xiao Yao Wang, Hong Fei Zhu i Xiao Ye Cong. "The Change of Silica Tetrahedron in Cement-Silica Fume Blends Hydration". Materials Science Forum 743-744 (styczeń 2013): 280–84. http://dx.doi.org/10.4028/www.scientific.net/msf.743-744.280.
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The change of silica tetrahedron in cement-silica fume blends hydration is critical for blended cement application. 29Si solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) investigations on the change of silica tetrahedron, which were Portland cement hydration, silica fume in simulated hydration and cement-silica fume blends hydration, were characterized and compared in this paper. The experimental results revealed that the amorphous silica tetrahedron structure in silica fume changed into Q1 and Q2 silica tetrahedrons, the same as silica-oxide structure of cohesive gel in the hydration of Portland cement. The coexistence of Q1 and Q2 silica tetrahedron in hydration product was beneficial to the strength increase of blend paste with silica fume. The amount of Q2 silica tetrahedron in cement-silica fume blends was higher than that in Portland cement. The pozzolanic reaction of silica fume accelerated the course of the silica tetrahedron in blended paste turning into the stable state of Q2 silica tetrahedron and existing principally in blended paste. That is reason that the physical properties of cement-silica fume blends are better than those of Portland cement.
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Ren, Jie, Zhengxiang Lv, Honghui Wang, Jianmeng Wu i Shunli Zhang. "The Origin of Quartz Cement in the Upper Triassic Second Member of the Xujiahe Formation Sandstones, Western Sichuan Basin, China". Water 13, nr 14 (8.07.2021): 1890. http://dx.doi.org/10.3390/w13141890.
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High-precision in situ δ18O values obtained using secondary ion mass spectrometry (SIMS) for μm-size quartz cement are applied to constrain the origin of the silica in the deep-buried Upper Triassic second member of Xujiahe Formation tight sandstones, western Sichuan Basin, China. Petrographic, cathodoluminescence (CL), and fluid inclusion data from the quartz cements in the Xu2 sandstones indicate three distinct, separate quartz precipitation phases (referred to as Q1, Q2, and Q3). The Q1 quartz cement was formed at temperatures of approximately 56–85 °C and attained the highest δ18O values (ranging from 18.3 to 19.05‰ Vienna Standard Mean Ocean Water (VSMOW)). The Q2 quartz cement was generated at temperatures of approximately 90–125 °C, accompanying the main phase of hydrocarbon fluid inclusions, with the highest Al2O3 content and high δ18O values (ranging from 15 to 17.99‰ VSMOW). The Q3 quartz cement was formed at temperatures of approximately 130–175 °C, with the lowest δ18O values (ranging from 12.79 to 15.47‰ VSMOW). A portion of the Q2 and Q3 quartz cement has a relatively high K2O content. The dissolution of feldspar and volcanic rock fragments was likely the most important source of silica for the Q1 quartz cement. The variations in δ18O(water) and trace element composition from the Q2 quartz cement to the Q3 quartz cement suggest that hydrocarbon emplacement and water-rock interactions greatly altered the chemistry of the pore fluid. Feldspar dissolution by organic acids, clay mineral reactions (illitization and chloritization of smectite), and pressure dissolution were the main sources of silica for the Q2 and Q3 quartz cements, while transformation of the clay minerals in the external shale unit was a limited silica source.
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Grine, Khaled. "Mechanical and Chemical Stabilisation of Carbonatesand". Advanced Materials Research 742 (sierpień 2013): 224–30. http://dx.doi.org/10.4028/www.scientific.net/amr.742.224.
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This paper describe a laboratory investigation into the effects of adding silica sand and/or cement on the behaviour of artificial carbonate sand under shear and compression. Drained shear and compressibility tests have been performed on artificial carbonate sand samples and artificial carbonate sand samples mixed with different proportion by weight of silica sand and/or cement in order to determine the shear stress-strain and compressibility characteristics of the mixed material.The results demonstrate that contraction during shear and compressibility during isotropic compression decrease as the fraction of silica sand and/or cement increases within the artificial carbonate sand.A positive volumetric change (dilation) during shear is more obvious with cemented samples. It also demonstrate how the addition of a combination of silica sand and cement produces the most effective improvement in terms of strength, stiffness, compressibility and crushing.
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Menéndez, Esperanza, Miguel Ángel Sanjuán i Hairon Recino. "Study of Microstructure, Crystallographic Phases and Setting Time Evolution over Time of Portland Cement, Coarse Silica Fume, and Limestone (PC-SF-LS) Ternary Portland Cements". Crystals 13, nr 8 (21.08.2023): 1289. http://dx.doi.org/10.3390/cryst13081289.
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The use of silica fume as a partial replacement for Ordinary Portland Cement provides a wide variety of benefits, such as reduced pressure on natural resources, reduced CO2 footprint, and improved mechanical and durability properties. The formation of more stable crystallographic phases in the hardened cement paste can promote resistance to concrete attacks. However, using coarse silica fume may result in lower expenses and shorter workdays. In this work, coarse silica fume was used as a partial replacement of cement, by weight, at 3%, 5%, and 7%, and it was used as limestone filler at different particle sizes. The size of coarse silica fume used was 238 μm. The microstructural, compositional analysis, and crystalline phase content of mixed cements at different ages were evaluated. The addition of coarse silica fume and limestone promoted pore refinement of the composites and increased the calcium and silica content. The filling effect of fine limestone and coarse silica fume particles, as well as the formation of CSH gel, was found to be the main reason for the densified microstructure. The contributions of combined coarse silica fume and limestone improve the stability of CSH gels and pozzolanic reaction.
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Tobón, J. I., O. Mendoza, O. J. Restrepo, M. V. Borrachero i J. Payá. "Effect of different high surface area silicas on the rheology of cement paste". Materiales de Construcción 70, nr 340 (30.12.2020): 231. http://dx.doi.org/10.3989/mc.2020.15719.
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This work studies the effect of nanosilica (NS) on the rheology of cement paste by comparing it with two high specific surface area silicas: silica fume (SF) and pyrogenic silica (PS). Portland cement pastes were produced with different water-to-cementing material ratios and different solid substitutions of cement by silica. Water demand, setting time, and rheology tests were performed. Results showed that NS and SF decreased plastic viscosity, while PS increased it. Only PS was found to have an effect on yield stress. NS showed the most decreasing effect on viscosity, regardless of its higher water demand. It was concluded that the behavior of pastes containing NS and SF is governed by the “ball-bearing” effect from silica particles, by their agglomeration degree, and their impact on the solid volume fraction. The behavior of pastes containing PS is governed by its ability to absorb a portion of the mixing water.
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Taylor, K. G., i J. H. S. Macquaker. "Diagenetic alterations in a silt- and clay-rich mudstone succession: an example from the Upper Cretaceous Mancos Shale of Utah, USA". Clay Minerals 49, nr 2 (kwiecień 2014): 213–27. http://dx.doi.org/10.1180/claymin.2014.049.2.05.
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An understanding of the nature and scales of diagenetic variability within organic-rich mudstones is critical to the accurate assessment of shale-gas reservoir properties, as well as for elucidating chemical evolution pathways within mudstones. Here we integrate field observations with thin section descriptions (optical and electron optical techniques) and mineralogical data for the Blackhawk Member time-equivalent Mancos Shale in Book Cliffs, Utah, to determine the impacts of early and burial diagenesis on this mudstone succession.The detrital assemblage in the Mancos Shale comprises quartz-silt, feldspar, clay minerals, dolomite and organic matter (TOC of 1 to 2.5%). Biogenic silica is negligible. Field mapping reveals laterally continuous (km scale), ferroan dolomite cemented units up to 0.3 m thick, are present. These cemented units cap both coarsening-upward units (1 to 3 m thick), and stacked successions of coarsening-upward units (5 to 15 m thick). These upward-coarsening sediment packages, capped by dolomite cemented strata, correlate to bedsets and parasequences in updip settings. Pervasive cementation in these dolomite-cemented units is likely to have occurred prior to compaction as a result of bacterially mediated respiratory processes. Cementation at these levels is particularly evident because cement precipitation occurred during breaks in sediment accumulation below marine flooding surfaces. The abundance of dolomite cements highlights the importance of macroscopic-scale diagenetic carbonate mobility in these mudstones.In addition to carbonate-cements, diagenetic alteration and precipitation of quartz and alumina-silicate minerals are also important in these mudstones. Kaolinite is present both in uncompacted test of organisms and as vein fills in septarian concretions. Kaolinite precipitation is interpreted to have occurred prior to significant compaction and indicates that both silicon and aluminium were mobile during early diagenesis. We interpret the abundance of early diagenetic kaolinite cement to be the result of Al-mobilization by organic acids generated during organic matter oxidation reactions, with the Al sourced from poorly crystalline detrital aluminium oxides and clay minerals. There is also indirect evidence for burial diagenetic kaolinitization of feldspar grains. Quartz cement takes the form of quartz overgrowths and microcrystalline quartz crystals. Textures and CL spectra for the quartz microcrystalline cement suggests that recrystallization of biogenic silica (opal-A) was likely to have been an important source for quartz cements, although smectite-to-illite transformation may have contributed some. These mineral phases highlight that microscopic-scale diagenetic mobility of silica is important, even within mudstones lacking obvious sources of biogenic silica and is likely to be an important processes in a wide range of mudstones.
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Argiz, C., E. Reyes i A. Moragues. "Ultrafine portland cement performance". Materiales de Construcción 68, nr 330 (13.04.2018): 157. http://dx.doi.org/10.3989/mc.2018.03317.
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By mixing several binder materials and additions with different degrees of fineness, the packing density of the final product may be improved. In this work, ultrafine cement and silica fume mixes were studied to optimize the properties of cement-based materials. This research was performed in mortars made of two types of cement (ultrafine Portland cement and common Portland cement) and two types of silica fume with different particle-size distributions. Two Portland cement replacement ratios of 4% and 10% of silica fume were selected and added by means of a mechanical blending method. The results revealed that the effect of the finer silica fume mixed with the coarse cement enhances the mechanical properties and pore structure refinement at a later age. This improvement is somewhat lower in the case of ultrafine cement with silica fume.
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Wongkeo, W., W. Thawornson i Arnon Chaipanich. "Microstructure and Characterizations of Portland-Bottom Ash-Silica Fume Cement Pastes". Advanced Materials Research 55-57 (sierpień 2008): 629–32. http://dx.doi.org/10.4028/www.scientific.net/amr.55-57.629.
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This research investigated the microstructure and characterization of Portland-bottom ash-silica fume cement pastes. Bottom ash, a by – product from coal-fired thermal power plants, was obtained from Mae Moh power plant, Lampang, Thailand. It currently exists as waste approximately 1.5 MT per year and has not been put to use. Unlike its counterpart, fly ash, which is recognized as an alternative material used to replace part of Portland cement. Silica fume, a nanomaterial from ferrosilicon industry, is nanoparticle and highly amorphous. It is highly pozzolanic reaction and could improve properties of Portland-bottom ash cement pastes. Thus, this research investigated the effect of silica fume on microstructure and characterization of Portland-bottom ash-silica fume cement pastes. The ratios of bottom ash used to replace Portland cement were 0, 10, 20 and 30 percent by weight and silica fume was added at 5 and 10 percent by weight. Compressive strength test was then carried out. SEM and TGA were used to study the microstructure of Portland-bottom ash-silica fume cement pastes. The results show that, the compressive strength of Portland-Bottom ash-silica fume cement pastes increased with added silica fume at 5 and 10 percent. SEM micrographs show C-S-H gel and silica fume around the cement particle in Portland-bottom ash-silica fume cement pastes which gives a highly dense and less porous microstructure. TGA graphs show Ca(OH)2 decreased with silica fume content.
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Bekem Kara, İlknur, i Ömer Furkan Durmuş. "Effect of nano silica on cement mortars containing micro silica". Challenge Journal of Concrete Research Letters 10, nr 2 (27.06.2019): 42. http://dx.doi.org/10.20528/cjcrl.2019.02.003.
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The use of cement and concrete is becoming increasingly widespread all over the world. However, the high energy consumption required for the production of clinker and the greenhouse gas emissions generated during production negatively affect both the economy and the environment. In the studies conducted for many years, researchers have found that the substitution of various pozzolans with cement provides both technical advantages and environmental benefits. The use of pozzolans in cementitious composites provides advantages such as the improvement of the physical and mechanical properties of the material, the conservation of the environment and the economy in terms of the evaluation of industrial wastes. In recent years, studies on the use of nanoparticles in cementitious composites are positively. In this study, it was aimed to investigate the properties of fresh and hardened cement mortars using micro silica as pozzolan and nano silica as nanoparticle. For this purpose, four different cement pastes and mortars mixtures were prepared by substituting 0%, 1%, 2%, 3% nano SiO2 (silica) cement in mortar mixtures containing 5% micro silica. The effects of the nano silica on the micro silica-containing cement paste on the consistency and setting time were investigated. The mortar mixtures produced were subjected to flexural and compressive strength tests on days 7, 28 and 90th. SEM images of mortar mixtures were taken. As a result, it was found that 2% nano silica admixture of 5% micro silica containing cement admixture affects the flexural and compressive strength positively, whereas 2% nano silica admixture increased the flexural strength by 13% and compressive strength by 7%.
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Kirgiz, Mehmet Serkan. "Chemical Properties of Substituted and Blended Cements". Advanced Materials Research 749 (sierpień 2013): 477–82. http://dx.doi.org/10.4028/www.scientific.net/amr.749.477.
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The aim of the experimental study is to determine chemical properties of substituted and blended cement contained marble and brick powders to provide efficacy for the economical and the environmental aspect. Marble and brick powders, CEM I 42.5N cement and clinker were used as materials in the study. Substituted cements were prepared with the addition of cement for marble or brick powder at the ratios of % 6, 20, 21, 35. Blended cements were mixed the addition of cement clinker for marble or brick powder at the ratios of % 6, 20, 21, 35. And CEM I 42.5N cements were also chosen as Reference cement. Results show that marble and brick powders can prevalently add as substitute or blend materials to cement to prevent it detrimental chemicals like alkali-silica reaction.
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Sutriono, Bantot, Retno Trimurtiningrum i Aditya Rizkiardi. "Pengaruh Silica Fume sebagai Subtitusi Semen terhadap Nilai Resapan dan Kuat Tekan Mortar (Hal. 12-21)". RekaRacana: Jurnal Teknil Sipil 4, nr 4 (29.11.2018): 12. http://dx.doi.org/10.26760/rekaracana.v4i4.12.
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ABSTRAKBeton dan mortar banyak digunakan sebagai bahan konstruksi di seluruh dunia. Meningkatnya permintaan beton dan mortar juga meningkatkan permintaan semen di pasar yang berdampak negatif bagi lingkungan. Industri semen menghasilkan sekitar 6 hingga 7 persen dari seluruh CO2 di seluruh dunia. Oleh karena itu, para peneliti mencoba mengembangkan gagasan tentangbeton ramah lingkungan, dengan mengurangi penggunaan semen dengan menggunakan bahan alternatif seperti silica fume. Silica fume adalah bahan pozzolan yang kaya akan silika dan dapat bereaksi kimia dengan kalsium hidroksida, membentuk gel kalsium silikat (CSH) pada beton. Tujuan dari penelitian ini adalah untuk menyelidiki pengaruh silica fume sebagai pengganti parsial semen terhadap nilai resapan dan kekuatan tekan mortar. Persentase silica fume bervariasi 0%, 5%, 10%, 12% dan 15%. Hasil pengujian menunjukkan nilai resapan minimum adalah 3,276% diperoleh campuran dengan 15% silica fume dan kuat tekan maksimum 312,574 kg/cm2 diperoleh campuran dengan 8% silica fume.Kata kunci: silica fume, nilai resapan, kuat tekan, mortar ABSTRACTConcrete and mortar are widely used as contruction materials. The increasing demand of concrete and mortar also increase the demand of cement in the market which has negative impact for environment. The cement industry produced for approximately 6 to 7 percent of all CO2 worldwide. Therefore, the researches try to develop the idea of green concrete with reducing the utilize of cement with using the alternative materials such as silica fume. Silica fume is a pozzolanic material that contain rich of silica and has chemical reaction with calcium hydroxide forming calcium silicate hydrate (C-S-H) gel in concrete.The aimed of this research is to investigate the influence of silica fume as partial replacement of cement on absoption and compressive strength of mortar.The percentage of silica fume were varied from 0%, 5%, 10%, 12% and 15%. The test result showed that the minimum absorption value is 3.276% obtain from the mixture with 15% of silica fume and the maximum compressive strength is 312.574 kg/cm2 obtain from the mixture with 8% of silica fume.Keywords: Silica fume, absorption, compressive strength, mortar
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Gopu, Ganesh Naidu, Sri Durga Vara Prasad M, Swaroop Babu Mylavarpu i S. Ankarao. "Development of Ultra Strength Concrete". Journal of Physics: Conference Series 2070, nr 1 (1.11.2021): 012173. http://dx.doi.org/10.1088/1742-6596/2070/1/012173.
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Abstract Most superior cements delivered today contain materials notwithstanding Portland cement to help accomplish the compressive strength or solidness execution. These materials include fly ash, silica fume and ground-granulated blast furnace slag used discretely or in coalescence. Concurrently, chemical admixtures such as high-range di-hydrogen monoxide-reducers are needed to ascertain that the concrete is facile to convey, place and culminate. For high-strength cements, a blend of mineral and compound admixtures is almost consistently fundamental to guarantee accomplishment of the necessary strength. The Primer investigations have been done on concrete, Fine aggregate and coarse aggregate. The Blend Extent for M200 grade concrete is determined 1: 0.313: 1.463 by following the plan methodology given by ACI Strategy. By keeping up the w/c proportion as 0.25, the multi day Compressive strength, Flexural strength and Split elasticity of cement at 3% of silica fume and 1.5% of conplast have been accomplished as 163.33 N/mm2, 8.4 N/mm2& 9.5 N/mm2 separately. The variety of solidarity of cement with the variety of silica fume is appeared in bar outline. The strength of the concrete might be as yet expanded by decreasing the w/c proportion and expanding the level of silica fume
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Pratiwi, Wieke, Gaos Abdul Karim i Titi Rachmawati. "Local Silica Sand as a Substitute for Standard Ottawa Sand in Testing of Cement Mortar". Materials Science Forum 1000 (lipiec 2020): 220–26. http://dx.doi.org/10.4028/www.scientific.net/msf.1000.220.
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Compressive strength of cement mortar is an important parameter in the quality control of Portland cement. The limitation of Ottawa sand imports has prompted a study on the potential and utilization of local silica sand available in several regions in Indonesia. The purpose of this study was to investigate the potential and possibility of utilizing local silica sand from several regions in Indonesia including Bangka, Belitung, Sidrap (South Sulawesi Province) as a substitute for standard Ottawa sand in cement mortar testing. Evaluation of local silica sands consisted of SEM analysis, characterization of silica sands and testing of cement mortar compressive strength. Silica sands from Bangka, Belitung and Tuban had silica content of more than 90%, while that from Sidrap was more or less 90%. Based on the SEM analysis, characteristic of silica sands, and compressive strength of cement mortar, local silica sand from Sidrap (South Sulawesi Province) has a good potential to be used as a substitute for standard Ottawa sand in testing of cement mortar.
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Bergschmidt, Philipp, Rebecca Dammer, Carmen Zietz, Susanne Finze, Wolfram Mittelmeier i Rainer Bader. "Adhesive strength of total knee endoprostheses to bone cement – analysis of metallic and ceramic femoral components under worst-case conditions". Biomedical Engineering / Biomedizinische Technik 61, nr 3 (1.06.2016): 281–89. http://dx.doi.org/10.1515/bmt-2014-0090.
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Abstract Evaluation of the adhesive strength of femoral components to the bone cement is a relevant parameter for predicting implant safety. In the present experimental study, three types of cemented femoral components (metallic, ceramic and silica/silane-layered ceramic) of the bicondylar Multigen Plus knee system, implanted on composite femora were analysed. A pull-off test with the femoral components was performed after different load and several cementing conditions (four groups and n=3 components of each metallic, ceramic and silica/silane-layered ceramic in each group). Pull-off forces were comparable for the metallic and the silica/silane-layered ceramic femoral components (mean 4769 N and 4298 N) under standard test condition, whereas uncoated ceramic femoral components showed reduced pull-off forces (mean 2322 N). Loading under worst-case conditions led to decreased adhesive strength by loosening of the interface implant and bone cement using uncoated metallic and ceramic femoral components, respectively. Silica/silane-coated ceramic components were stably fixed even under worst-case conditions. Loading under high flexion angles can induce interfacial tensile stress, which could promote early implant loosening. In conclusion, a silica/silane-coating layer on the femoral component increased their adhesive strength to bone cement. Thicker cement mantles (>2 mm) reduce adhesive strength of the femoral component and can increase the risk of cement break-off.
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Meganadhan, Anand, Kavitha Sanjeev i Mahalaxmi Sekar. "Influence of Silica Fumes on Compressive Strength and Wear Properties of Glass Ionomer Cement in Dentistry". Journal of Evolution of Medical and Dental Sciences 10, nr 20 (17.05.2021): 1457–62. http://dx.doi.org/10.14260/jemds/2021/306.
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BACKGROUND Glass ionomer cements (GIC) are an interesting restorative option due to their biocompatibility. However, it has limitations that challenge its survival in oral environment due its porous set matrix influencing the properties of the cement. This study was conducted to evaluate the influence of the addition of varying concentrations of silica fumes (SF) on the properties of GIC by field emission scanning electron microscopy [FESEM] and energy-dispersive spectroscopy [EDX]. The final set matrix of GIC remains porous, compromising the mechanical properties, limiting its extended use clinically. Incorporation of silica fumes, a pozzolan, as an additive in GIC serves as a potential filler by increasing its compressive strength and reducing wear properties. METHODS The cement was divided into 5 groups based on the absence or presence of varying concentrations (0.5, 1, 1.5, 2 %) of silica fumes; conventional glass ionomer group (CG) (I) and 0.5, 1, 1.5, 2 silica fumes incorporated glass ionomer cement (SG) (II, III, IV & V) respectively. Compressive strength and wear resistance were subjected to Universal Testing Machine and Pin on Tribometer respectively. The microstructure and the elemental composition of prepared specimens of all the groups were evaluated using FESEM and EDX. Data obtained was analysed using Statistical Package for the Social Sciences (SPSS) V22.0 (IBM, USA) followed by one-way analysis of variance (ANOVA) and post hoc Tukey test (P < 0.05). RESULTS Except 0.5SG, increased compressive strength and decreased wear of glass ionomer material was observed as the concentration of silica fumes increased. Of all the concentrations, 2SG had significantly increased compressive strength (221.62 ± 22.84 MPa) compared to CG (167.38 ± 36.94 MPa) (P < 0.05). Significantly increased resistance to wear was noted in 2SG (11.80 ± 2.58 µm) compared to CG (20.40 ± 2.07 µm) (P < 0.05). The set matrix of silica fumes modified GIC showed minimal / absence of pores with dispersion of crystalline particles as the concentration of SF increased. EDX revealed similar constitution of minerals but, varied with increased concentration of silica fumes. CONCLUSIONS 2 % silica fumes incorporated glass ionomer cement (2SG) enhanced the properties of conventional glass ionomer cement. KEY WORDS Compressive Strength, EDX, Field Emission Scanning Electron Microscope, Glass Ionomer Cement, Silica Fumes, Pozzolan
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Song, Xinjiang, Haibo Xu, Deqin Zhou, Kai Yao, Feifei Tao, Ping Jiang i Wei Wang. "Mechanical Performance and Microscopic Mechanism of Coastal Cemented Soil Modified by Iron Tailings and Nano Silica". Crystals 11, nr 11 (31.10.2021): 1331. http://dx.doi.org/10.3390/cryst11111331.
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In order to explore the effect of composite materials on the mechanical properties of coastal cement soil, cement soil samples with different iron tailings and nano silica contents were prepared, and unconfined compression and scanning electron microscope tests were carried out. The results show that: (1) The compressive strength of cement soil containing a small amount of iron tailings is improved, and the optimum content of iron tailings is 20%. (2) Nano silica can significantly improve the mechanical properties of iron tailings and cement soil (TCS). When the content of nano silica is 0.5%, 1.5%, and 2.5%, the unconfined compressive strength of nano silica- and iron tailings-modified cement soil (STCS) is 24%, 137%, and 323% higher than TCS, respectively. (3) Nano silica can promote the hydration reaction of cement and promote the cement hydration products to adhere to clay particles to form a relatively stable structure. At the same time, nano silica can fill the pores in TCS and improve the compactness of STCS.
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Sanjuán, Miguel Ángel, Esperanza Menéndez i Hairon Recino. "Mechanical Performance of Portland Cement, Coarse Silica Fume, and Limestone (PC-SF-LS) Ternary Portland Cements". Materials 15, nr 8 (18.04.2022): 2933. http://dx.doi.org/10.3390/ma15082933.
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Ternary Portland cements composed of coarse silica fume (SF), limestone (LS), and Portland cement (PC) can afford some environmental advantages by reducing the clinker content in Portland cements. These cements will help to reduce the clinker factor target from 0.78 to 0.60 by 2050 with the aim to be climate neutral. Silica fume (SF) possesses pozzolanic properties that enhance mechanical strength and durability. By contrast, limestone powder has three main outcomes, i.e., filler, dilution, and chemical effects. The first reduces porosity and refines the microstructure of mortars and concretes. The second decreases the amount of hydration products and increases the porosity; the third one promotes the appearance of carboaluminates and reduces porosity. This paper covers the mechanical properties of Portland cement-limestone-coarse silica fume ternary cements, and its synergetic mechanism. Compressive and flexural strength of mortar at 2, 7, 14 and 28 days was performed. Coarse silica fume has a minor contribution on the nucleation effect compared to ground limestone at early ages. The nucleation and filler effects, at early ages, are less pronounced in coarse and very fine limestone powder. The highest compressive strength at 28 days is reached with the lowest content of coarse silica fume (3%). Mortar mixes made with a high level of limestone presented a delay in the compressive strength development.
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Rahman, Ibadur, Priyanka Singh, Nirendra Dev, Mohammed Arif, Faiz Noor Khan Yusufi, Ameer Azam, M. Masroor Alam i in. "Improvements in the Engineering Properties of Cementitious Composites Using Nano-Sized Cement and Nano-Sized Additives". Materials 15, nr 22 (15.11.2022): 8066. http://dx.doi.org/10.3390/ma15228066.
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The findings of an extensive experimental research study on the usage of nano-sized cement powder and other additives combined to form cement–fine-aggregate matrices are discussed in this work. In the laboratory, dry and wet methods were used to create nano-sized cements. The influence of these nano-sized cements, nano-silica fumes, and nano-fly ash in different proportions was studied to the evaluate the engineering properties of the cement–fine-aggregate matrices concerning normal-sized, commercially available cement. The composites produced with modified cement–fine-aggregate matrices were subjected to microscopic-scale analyses using a petrographic microscope, a Scanning Electron Microscope (SEM), and a Transmission Electron Microscope (TEM). These studies unravelled the placement and behaviour of additives in controlling the engineering properties of the mix. The test results indicated that nano-cement and nano-sized particles improved the engineering properties of the hardened cement matrix. The wet-ground nano-cement showed the best result, 40 MPa 28th-day compressive strength, without mixing any additive compared with ordinary and dry-ground cements. The mix containing 50:50 normal and wet-ground cement exhibited 37.20 MPa 28th-day compressive strength. All other mixes with nano-sized dry cement, silica fume, and fly ash with different permutations and combinations gave better results than the normal-cement–fine-aggregate mix. The petrographic studies and the Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) analyses further validated the above findings. Statistical analyses and techniques such as correlation and stepwise multiple regression analysis were conducted to compose a predictive equation to calculate the 28th-day compressive strength. In addition to these methods, a repeated measures Analysis of Variance (ANOVA) was also implemented to analyse the statistically significant differences among three differently timed strength readings.
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Bach, Quoc Si. "Investigation of Blended Cement Hydration in the Reactive Powder Concrete with Increasing Levels of Silica Fume Addition". Applied Mechanics and Materials 889 (marzec 2019): 304–12. http://dx.doi.org/10.4028/www.scientific.net/amm.889.304.
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Hydration is a chemical reaction in which the major compounds in cement form chemical bonds with water molecules and become hydration products. By the process of hydration Portland cement mixed with sand, gravel and water produces the synthetic rock we call concrete. The Therefore, the concrete properties always accompanies with the hydration degree of cement. This paper presents some experimental test results on how silica fume affects the cement hydration in cement pastes of the Reactive Powder Concrete as increasing levels of silica fume addition with the content from 0% to 30% of cement mass. The hydration process of cement/silica fume paste was followed from the estimation of heat of hydration, rate of heat evolution, of binder pastes obtained by isothermal calorimetry (TAM-Air). In addition, the portlandite content, the hydration degree of pure cement, reaction degree of binder paste as well as reaction degree of silica fume were investigated. The quantitative assessment on these characteristics are due to the simulation of the hydration of Portland cement pastes containing silica fume.
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Lin, Dong, i Zi Yun Wen. "Research on the Efficient Application of Silica Fume in High-Tech Cement-Based Materials". Advanced Materials Research 374-377 (październik 2011): 1537–40. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.1537.
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The comparison experiments are carried out at different silica fume dosage between the silica fume with pre-treatment and the silica fume without pre-treatment. The results show that the pre-treatment of silica fume improved the strength greatly and the silica fume dosage corresponding to the strength peak somewhat moved forward from 0.20 for the cement-based materials with pre-treatment of silica fume to 0.21 for the cement-based materials without pre-treatment of silica fume. The particles distribution experiment results indicate that after the pre-treatment of silica fume, the average particle diameter of silica fume reduced from 2.865μｍto 0.151μｍ. Based on Aim-Goff model, it is concluded that the increase in the compressive strength and flextural strength of cement-based materials with pre-treatment of silica fume, are attributed to the dispersion of silica fume agglomeration and the increase in the packing density of the cement-based materials.
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Erdem, A., GC Akar, A. Erdem i T. Kose. "Effects of Different Surface Treatments on Bond Strength Between Resin Cements and Zirconia Ceramics". Operative Dentistry 39, nr 3 (1.04.2014): E118—E127. http://dx.doi.org/10.2341/12-420-l.
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SUMMARY This study compares the bond strength of resin cement and yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic with different surface conditioning methods. Two hundred presintered Y-TZP ceramic specimens were prepared, sintered (4 × 4 × 4 mm), and randomly assigned to four equal groups as control (C, no conditioning); airborne particle abraded (APA, air abrasion with 11 μm Al2O3); tribochemical silica coating/silane coupling system (TSC, Rocatec, air abrasion with 110 μm Al2O3, 30 μm silica-coated Al2O3 and silane); and laser (L, Er:YAG laser irradiation treated at a power setting of 200 mJ). After specimen preparation, composite resin cylinders were prepared and cemented with resin cements (Clearfil Esthetic, Panavia F 2.0, Rely X-U100, Super Bond C&B, and Multilink Automix) on the ceramic surfaces and kept in an incubator at 37°C for 60 days. All specimens were tested for shear bond strength with a universal testing machine, and fractured surfaces were evaluated by environmental scanning electron microscopy. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U-tests (α=0.05). The bond strengths for C and L groups were not significantly different according to adhesive resin cement. APA and TSC resulted in increased bond strength for Panavia F 2.0 and Rely X-U100 resin cements. Additionally, TSC presented higher bond strength with Multilink Automix. Adhesive fracture between the ceramic and resin cement was the most common failure. Complete cohesive fracture at the ceramic or composite cylinders was not observed. Regardless of the adhesive resin cement used, laser treatment did not improve resin bond strength.
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Sanna, Aimaro, Marco Dri, Xiao Long Wang, Matthew R. Hall i Mercedes Maroto-Valer. "Micro-Silica for High-End Application from Carbon Capture and Storage by Mineralisation". Key Engineering Materials 517 (czerwiec 2012): 737–44. http://dx.doi.org/10.4028/www.scientific.net/kem.517.737.
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Waste silica remaining after the Carbon Capture and Storage by Mineral carbonation (CCSM) could represent a potential pozzolan material for partial replacement in concrete. The objective of this work was the production and testing of cement gel cubes with the residual-silica by-product obtained from the accelerated carbonation of Mg-silicate rocks. The silica produced was characterised in terms of its chemical composition, morphology and LOI. Also, the silica was used as an additive to the cement (CEM I class) in order to assess the effect on (28 days) compressive strength in comparison with a cement control specimen. The influence of different cement replacement percentages (5% and 10wt.% silica) were determined by measuring initial setting times and compressive strength. The compressive strength of the cement specimens with 5 and 10wt.% silica as pozzolan replacement of Portland cement were 3% and 8% higher than the control cubes indicating that the residual silica powder may have pozzolanic properties. However, high LOI and magnesium content might represent a limit in high-end applications and further work is required to identify optimised CCSM conditions able to reduce the impurities in the silica by-product and to establish their potential as a pozzolan.
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Sanytsky, Myroslav, Tetiana Kropyvnytska i Roman Kotiv. "Modified Plasters for Restoration and Finishing Works". Advanced Materials Research 923 (kwiecień 2014): 42–47. http://dx.doi.org/10.4028/www.scientific.net/amr.923.42.
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The paper is devoted to the research and development of modified plasters for restoration and finishing works based on decorative multicomponent cements containing white Portland cement and supplementary cementitious materials (silica fume, metakaolin and fine ground limestone). This cements are similar to Roman cement by their chemical composition. The use of optimal granulometry of decorative multicomponent cements provide directed formation of microstructure of the cement matrix with the formation of stable hydration products. Compositions of modified plasters by the criterions of workability and compressive strength were designed. Physico-chemical modification of plaster by complex air-entraining admixture allows to obtain high-quality modified plasters with improved quality parameters.
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Bahadori, Hadi, i Payam Hosseini. "REDUCTION OF CEMENT CONSUMPTION BY THE AID OF SILICA NANO-PARTICLES (INVESTIGATION ON CONCRETE PROPERTIES)". Journal of Civil Engineering and Management 18, nr 3 (29.06.2012): 416–25. http://dx.doi.org/10.3846/13923730.2012.698912.
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In this study, effects of replacing cement with colloidal amorphous silica nano-particles have been experimentally investigated on the physical and mechanical properties, durability and microstructure of concrete. Experimental results include workability, fresh concrete density, and hardened concrete properties like compressive strength at different ages of 3, 7, and 28-days, and also 28-days splitting tensile strength. Furthermore, influence of silica nano-particles on durability and microstructure of concrete for 28-days specimens was tested by conducting water absorption test, Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Analysis (EDAX), respectively. In order to study the effect of replacement of cement with silica nano-particles, specimens with 10%, 20%, and 30% cement reduction, and addition of 1%, 2%, and 3% silica nano-particles with respect to witness specimen were fabricated. Experimental results revealed that 20% reduction of cement combining 2% silica nano-particles and also 10% cement reduction combined with 1% silica nano-particles enhance the microstructure of concrete, despite unnoticeable compressive and tensile strength loss. By remarkable reduction of cement consumption and addition of silica nano-particles, strength almost remains constant and consequently decreasing the cement content will become possible. Also, in all specimens, increase in nano-particles content and decrease in cement usage contributed to workability loss. Therefore, applying super-plasticizers seems indispensible while using silica nano-particles. On the other side, according to water absorption test, concretes containing nanoparticles showed more appropriate durability.
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Wongkeo, Watcharapong, Pailyn Thongsanitgarn i Arnon Chaipanich. "Compressive Strength of Binary and Ternary Blended Cement Mortars Containing Fly Ash and Silica Fume under Autoclaved Curing". Advanced Materials Research 343-344 (wrzesień 2011): 316–21. http://dx.doi.org/10.4028/www.scientific.net/amr.343-344.316.
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Cement industry is a one of the major sources of environmental pollution therefore the reduction of cement demand should be improved. Fly ash and silica fume is a by-product of industries and it should be reused to reduce the waste pollution. Thus, this study investigated the use of fly ash and silica fume as a cement replacement in binary and ternary blended cements on compressive strength and physical properties of mortar. Autoclaved curing at 130 °C and 20 psi of pressure for 9 h was used in this study. The results show that the compressive strength of binary blended cement mortar with FA tends to decrease with increased FA replacement and shows compressive strength lower than PC control. However, compressive strength of binary blended cement mortar with SF was improved and shows compressive strength higher than that of PC control. The compressive strength of ternary blended cement mortar was higher than binary blended cement at the same level replacement and it increases with increased SF replacement. Moreover, ternary blended cement mortar containing 10%SF by weight contribute in giving compressive strength higher than PC control. The incorporation of FA with SF can enhance workability of blended cement mortar containing only SF replacement.
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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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Zajac, Maciej, Jan Skocek, Jørgen Skibsted i Mohsen Ben Haha. "CO2 mineralization of demolished concrete wastes into a supplementary cementitious material – a new CCU approach for the cement industry". RILEM Technical Letters 6 (15.07.2021): 53–60. http://dx.doi.org/10.21809/rilemtechlett.2021.141.
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This contribution discusses the carbon capture and utilization (CCU) approach based on CO2 mineralization of cement paste from recycled concrete as new approach to capture CO2 and significantly contribute to the reduction in CO2 emissions associated with cement production. The current literature suggests that all CO2 released from the decomposition of limestone during clinker production can be sequestered by carbonation of the end-of-life cement paste. This carbonation can be achieved in a few hours at ambient temperature and pressure and with a relatively low CO2 concentration (< 10 %) in the gas. The carbonation of cement paste produces calcite and an amorphous alumina-silica gel, the latter being a pozzolanic material that can be utilized as a supplementary cementitious material. The pozzolanic reaction of the alumina-silica gel is very rapid as a result of its high specific surface and amorphous structure. Thus, composite cements containing carbonated cement paste are characterized by a rapid strength gain. The successful implementation of this CCU approach relies also on improved concrete recycling techniques and methods currently under development to separate out the cement paste fines and such. Full concrete recycling will further improve the circular utilization of cement and concrete by using recycled aggregates instead of natural deposits of aggregates. Although the feasibility of the process has already been demonstrated at the industrial scale, there are still several open questions related to optimum carbonation conditions and the performance of carbonated material in novel composite cements.
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Abdulridha, Ali, Saif S. AlQuzweeni, Rasha S. AlKizwini, Zahra A. Saleh i K. S. Hashem. "Evaluating the Durability of Green Cement Mortar Using Ultrasonic Pulse Velocity". IOP Conference Series: Earth and Environmental Science 877, nr 1 (1.11.2021): 012049. http://dx.doi.org/10.1088/1755-1315/877/1/012049.
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Abstract Various experimental studies have highlighted the negative consequences of Portland cement on health and the environment, such as toxic emissions and alkaline sewage. The development of environmentally acceptable substitutes for cement is thus one of the objectives of current investigations. The proposed environmental alternatives to cement, nevertheless, might have detrimental impacts on the concrete’s characteristics. This investigation intends to study the suitability as alternatives to cement in cement mortar, using industrial wastes like silica fume and cement kiln dust. As a replacement for cement, the cement mortars developed in this research continue from 0% to 60% silica fume and cement kiln dust. Ultrasonic pulse velocity tests at 1 to 4 weeks of age were conducted on hardened specimens. The findings showed that a low reduction in the pulse velocity resulted from high proportions of silica fume and cement kiln dust replacements, whereas an improvement in the characteristics of the mortars with low replacement ratios. Using low kiln dust and silica fume of 20 to 40%, the durability of mortars may increase.
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Chun, Booki, Wonsik Shin, Yun Sik Jang i Doo-Yeol Yoo. "Tensile Performance Analysis of Ultra-Rapid-Hardening Fiber-Reinforced Concrete Based on Cement Kiln Dust Content". Journal of the Korean Society of Hazard Mitigation 20, nr 5 (31.10.2020): 217–23. http://dx.doi.org/10.9798/kosham.2020.20.5.217.
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In this study, the effects of cement kiln dust and silica fume on the tensile performance of fiber-reinforced concrete mixtures comprising special materials and polyethylene fiber for the reinforcement of facilities were analyzed. For the purpose of repair, ultra-rapid-hardening cement with high C3A content was employed, and the cement was replaced with supplementary cementitious materials such as granulated ground blast furnace slag, limestone powder, cement kiln dust, and silica fume. Cement kiln dust was incorporated at 10%, 15%, 20%, 30%, 40%, and 50% weight of cement, and silica fume was incorporated at 20% and 40% weight of cement. Four hours after specimen fabrication, a direct tensile test was conducted. The obtained experimental results indicate that the tensile performance (including tensile strength, strain capacity, and energy dissipation capacity) is found to be significantly high when the content of silica fume is 20% and that of cement kiln dust is 15%.
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Assi, Amel. "EXPERIMENTAL STUDY OF MICRO SILICA BEHAVIOR AND ITS EFFECT ON IRAQI CEMENT PERFORMANCE BY USING X-RAY FLUORESCENCE ANALYSIS". Iraqi Geological Journal 53, nr 2E (30.11.2020): 62–73. http://dx.doi.org/10.46717/igj.53.2e.5ms-2020-11-27.
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The cement slurry is a mixture of cement, water and additives which is established at the surface for injecting inside hole. The compressive strength is considered the most important properties of slurry for testing the slurry reliability and is the ability of slurry to resist deformation and formation fluids. Compressive strength is governed by the sort of raw materials that include additives, cement structure, and exposure circumstances. In this work, we use micro silica like pozzolanic materials. Silica fume is very fine noncrystalline substantial. Silica fume can be utilized like material for supplemental cementations for increasing the compressive strength and durability of cement. Silica fume has very fine particles size less than 1 micron and by an average of about 0.1 microns, about 100 times slighter than particles of cement. We are adding 0%, 5%, 10%, 15%, 20% and 25% micro silica by wt. of cement. The results showed that adding micro silica enhance the performance of Iraqi cement but also leads to a slight decrease in thickening time. To avoid this problem, super plasticizer is used to make the process of cement pumping more easily, in other words, increase thickening time and increase compressive strength. The experimental work showed that adding micro silica leads to reduce free water and this property is very important through horizontal drilling. X-ray fluorescence technique delivers beneficial elemental information about the chemical structure of Iraqi cement to help us use it without causing damage through the cementing job. In this paper, some outlines of the XRF device and its main applications are presented. By using X-ray fluorescence analysis, we detect the problem of Iraqi cement and solve it in this paper to use it at cementing jobs in the Iraqi field instead of using imported cement.
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Al Thaher, Yazan, Hadil Faris Alotaibi, Lirong Yang i Polina Prokopovich. "PMMA bone cement containing long releasing silica-based chlorhexidine nanocarriers". PLOS ONE 16, nr 9 (29.09.2021): e0257947. http://dx.doi.org/10.1371/journal.pone.0257947.
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Prosthetic joint infections (PJI) are still an extremely concerning eventuality after joint replacement surgery; growing antibiotic resistance is also limiting the prophylactic and treatment options. Chlorhexidine (a widely used topical non-antibiotic antimicrobial compound) coatings on silica nanoparticles capable of prolonged drug release have been successfully developed and characterised. Such nanocarriers were incorporated into commercial formulation PMMA bone cement (Cemex), without adversely affecting the mechanical performance. Moreover, the bone cement containing the developed nanocarriers showed superior antimicrobial activity against different bacterial species encountered in PJI, including clinical isolates already resistant to gentamicin. Cytocompatibility tests also showed non inferior performance of the bone cements containing chlorhexidine releasing silica nanocarriers to the equivalent commercial formulation.
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Hendrawati, Nanik, Endah Dwi Rahmayanti i Evi Dyah Priapnasar. "Study Pembuatan Durable Cement dengan Penambahan Pozzolan Silica Fume". Jurnal Teknik Kimia dan Lingkungan 2, nr 1 (29.04.2018): 31. http://dx.doi.org/10.33795/jtkl.v2i1.68.
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Selama ini silica fume dikenal sebagai bahan campuran pembuatan beton karena dapat meningkatkan kuat tekan beton, menurunkan permeabilitas beton dan memiliki ketahanan sulfat yang tinggi. Dalam penelitian ini mencoba mengaplikasikan silica fume pada pembuatan durable cement. Silica fume dijadikan sebagai bahan pozzolan karena didalamnya mengandung silica tinggi yang bersifat reaktif agar dapat meningkatkan ketahanan terhadap sulfat. Bahan pozzolan ini dapat bereaksi dengan Ca(OH)2 pada suhu biasa untuk membentuk senyawa bersifat semen. Pada penelitian ini silica fume divariasikan mulai dari 0; 7,5; 15; 22,5; 30; 37,5%. Durable cement ini akan diuji ketahanan sulfatnya dengan menggunakan metode pengujian kuat tekan. Hasil percobaan menunjukkan terjadinya penururan nilai kuat tekan sampel pada umur 7 dan 28 hari jika dibandingkan dengan blanko. Hal ini disebabkan lambatnya reaksi pozzolan (silica fume). Namun proses peningkatan kuat tekannya akan terus berlanjut hingga setelah umur 360 hari. Jika dibandingkan dengan Standar Nasional Indonesia (15-0302-2004) semen PPC tipe IP-K, hasil sampel durable cement masih memenuhi standar untuk variabel dengan penambahan silica fume antara 7,5% sampai 22,5%. Silica fume is known as a mixture of concrete manufacturing since it can increase the compressive strength of concrete, decrease the permeability of concrete and have a high resistance to sulfates. In this research, try applying silica fume to make durable cement. Silica fume is converted to pozzolan because it contains highly reactive silica to increase sulfate resistance. This pozzolan material can react with Ca (OH)2 at a room temperature to form a cement compound. In this study, silica fume was varied from 0; 7.5; 15; 22.5; 30; 37.5%. The durable cement will be tested for its resistance to sulfates by using a compression resistance test method. The results showed that the compressive strength of the sample was decreased at 7 and 28 days compared to the blanks. This is due to the slow reaction of pozzolan (silica fume). But the process of increasing the resistance to compression will continue until after 360 days. Compared with Indonesia cement national standard (15-0302-2004) of PPC type IP-K, the durable cement sample still meets the standard for variables with the addition of silica fume between 7.5% and 22.5%.
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Schneider, Martin, Siegfried Auer i Andreas Buchegger. "Examination of the Alkali Silica Reaction on Existing Roads with Use of Cements with Different Alkali Equivalent". Key Engineering Materials 711 (wrzesień 2016): 950–57. http://dx.doi.org/10.4028/www.scientific.net/kem.711.950.
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In the paper two existing roads in Austria were examined on the focus of alkali silica reaction of concrete. The two roads have different ages. One is more than 50 years old one is round about 20 years old. The exposition was ordinary highway and countryside highway in the mountains. As next the examination takes the stones from the origin and uses different types of cement to examine the background of the alkali silica guidelines for performance tests of alkali silica reaction. The results are very interesting because most of the performance tests are use test cements with ordinary alkali equivalent. Often the used stones not meet the maximum value of loss of mass under the condition of alkali-load. By using alkali reduced cement the results are less than the maximum value of loss of mass under the condition of alkali-load. One of the targets of the examination was the determination of good load conditions for examination of the alkali silica reaction of stones for use in concrete for road structures. The final paper shows all the examinations and the results between the compared cements and the compared test procedures.
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Eskitaşçıoğlu, Murat, Derya Toprak Gündüz, Zelal Seyfioğlu Polat, Emine Göncü Başaran i Emrah Ayna. "Effects of different surface treatments on the compression-shear strength of CAD-CAM zirconia posts". International Dental Research 12, nr 2 (31.08.2022): 55–61. http://dx.doi.org/10.5577/intdentres.2022.vol12.no2.a3.
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Aim: Post systems are crucial for the treatment of endodontically treated teeth with excessive crown destruction. Currently, increase in esthetic demands has increased the use of tooth-colored post systems. The aim of this study was to evaluate compression-shear strength after the application of different resin cements and different surface treatments to zirconia post-cores produced by the CAD-CAM milling technique. Methodology: One hundred twenty crown parts of maxillary central incisors were cut using a 2-mm enamel–cement joint using a water-cooled diamond bur in an air turbine handpiece at 300,000 rpm. Root canals with the same diameter were prepared using Gates-Glidden drills and Snowpost system drills. According to the enlarged canal, zirconia posts were prepared by the CAD-CAM copy-milling technique, and the zirconia post surfaces were roughened by different techniques (hydrofluoric acid, Al2O3 partial abrasion, CoJet silica coating). The roughened posts were cemented to the tooth canal using three resin cements: 10-Methacryloyloxydecyl dihydrogen phosphate (MDP)-containing cement, Bis-GMA-based resin, and resin-based adhesive. As the control group, the zirconia post surfaces with no application were fixed using three resin cements. The specimens were set down into 25x25x25 mm fabricated blocks with acrylic resin materials. Compression-shear strength tests of the prepared samples were conducted on the Instron Testing Machine by using appropriate equipment. Results: In summary, the combination of roughening techniques such as Al2O3 partial etching and CoJet silica coating using cement-containing MDP rendered the highest compression-shear strength. Conclusion: This in vitro study proposes the cementation of zirconia post-cores etched by Cojet silica coating and Al2O3 particles using MDP-containing resin cement. How to cite this article: Eskitaşçıoğlu M, Toprak Gündüz D, Seyfioğlu Polat Z, Göncü Başaran E, Ayna E. Effects of different surface treatments on the compression-shear strength of CAD-CAM zirconia posts. Int Dent Res 2022;12(2):55-61. https://doi.org/10.5577/intdentres.2022.vol12.no2.a3 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.
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Prasetyo, Arnoldus Meidio Adi, i Ade Lisantono. "COMPRESSIVE AND SHEAR BOND STRENGTH OF OIL WELL CEMENT WITH CALCIUM CARBONATE AND SILICA FUME". Jurnal Teknik Sipil 13, nr 4 (10.02.2017): 255. http://dx.doi.org/10.24002/jts.v13i4.933.
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One of the critical factors of cementing process in oil drilling of off-shore-project is designing the cement slurry. For this reason, the slurry properties which have been classified by American Petroleum Institute (API) should be changed so it will match with the requirement of reservoir condition. Changing the slurry properties can be done by adding the additive material into the cement slurry such as Calcium Carbonate and Silica Fume. The research objective is to study the effect of calcium carbonate and silica fume to the compressive and shear bond strength of oil well cement. Fourty five cylinder specimens with the size of (75 x 150) mm were made for compressive strength testing and fourty five cylinder specimens with the size of (25.4 x 50.8) mm were made for shear bond strength testing. Five variants of the specimen were made in this study. The variant were cement slurry with (0% Calcium Carbonate + 0 % Silica Fume) as a reference specimen; (5% Calcium Carbonate + 5 % Silica Fume); (10% Calcium Carbonate + 10 % Silica Fume); (15% Calcium Carbonate + 15 % Silica Fume); (20% Calcium Carbonate + 20 % Silica Fume). The oil well cement specimens were tested in 7, 14, and 28 days. The experimental results show that the compressive strength of oil well cement will decrease when it is added with calcium carbonate and silica fume. The shear bond strength of the oil well cement increases for the specimen with 5 % Calcium Carbonate + 5 % Silica Fume. However, the shear bond strength will decrease when content of the Calcium Carbonate + Silica Fume more than 5 %. Based on the result of this research, the optimum amount of calcium carbonate and silica fume that can be use is 5%, because with 5% of calcium carbonate and 5% of silica fume, the reducing of compressive strength is the smallest and the shear bond strength is increased compare to the others specimen with 10%, 15%, and 20% calcium carbonate and silica fume.
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Srinivas, Bangaru Sai, i K. V. V. Rama Raju. "Strength Evaluation and Durability on Addition of Nanosilica in M30 Grade Concrete". International Journal for Research in Applied Science and Engineering Technology 10, nr 2 (28.02.2022): 1430–37. http://dx.doi.org/10.22214/ijraset.2022.40537.
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Abstract: Nano technology plays a very vital role in all the areas of research. The incorporation of nano materials in concrete offers many advantages and improves the workability, the strength and durability properties of concrete. In this study an attempt has been made to carry out an experimental investigation on concrete in which cement was replaced with nano sized cement. Nano-silica has a unique advantage in the potential pozzolanic-reaction with cement hydration products over other nanoparticles. Addition of Nano-silica is known to redefine pore size and distribution which would alter the durability of the concrete. Ordinary Portland cement of 53 grade was ground in a ball grinding mill to produce nano cement. . Nano technology is an emerging field of interest for civil engineering utility. A few of the nano substances presently used in concrete, nano-silica very own greater pozzolanic nature. It has the functionality to react with the unfastened lime inside the route of the cement hydration and bureaucracy extra C-S-H gel giving strength, impermeability and durability to concrete. Present paper investigates the effects of addition of nano silica in normal strength of concrete. The present research deals with Partial alternative cement through nano silica powder as partial replacements in concrete at associate with various materials like OPC53 grade cement, fine aggregate, coarse aggregate to check their suitability for making concrete. The mix proportions of concrete were modified as micro silica (5%, 7.5%, 10%, 15%) and nano silica (1%, 1.5%, 2%, 2.5%) as partial replacement of cement. The cubes were cast by replacing Specimens were cast as per mix design and the tests are conducted after proper curing, the tests are compressive strength of cubes (150mm x 150mm x 150mm) and split tensile strength of cylinders (150mm x 300mm). The results had been compared with the outcomes of concrete specimens with 0% of nano silica. Keywords: M30 grade, nano silica, Nano technology,pozzolanic-reaction
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Skripkiūnas, Gintautas, Žymantas Rudžionis i Vitoldas Vaitkevičius. "COMPLEX ADMIXTURES FOR HIGH-STRENGTH CONCRETE". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 8, nr 4 (31.12.2002): 276–80. http://dx.doi.org/10.3846/13923730.2002.10531288.
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The influence of naphthalene formaldehyde superplasticizers (NFS), lignosulfonate plasticizers (LSP) and silica fume on cement paste properties and complex usage of these admixtures for high-strength concrete production are investigated in this research. These admixtures influence the cement hydration products morphology and properties of hardened cement paste. The degree of cement hydration and Ca(OH)2 content in hardened cement paste were determined for analysis of cement hydration process with admixtures. Mechanical properties and porosity of hardened cement paste with the admixtures were tested. Optimal dosages of plasticizing admixtures and silica fume were estimated and the most efficient method of silica fume adding to concrete mixture was proposed. The results of investigation have been used for high-strength concrete production.
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Sinulingga, Karya, Harry Agusnar, Zakaria Mohd Amin i Basuki Wirjosentono. "The Effect of Three Different Types of Rice Husk Ash as Ad Mixture for Ordinary Portland Cement". Applied Mechanics and Materials 679 (październik 2014): 228–36. http://dx.doi.org/10.4028/www.scientific.net/amm.679.228.
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The effect of three different types of rice husk ash which distinguish by color, pink, grey and white ashes were used as admixture to ordinary Portland cement paste was studied. Six batches of cement paste was prepared by adding 0-50 wt % RHA. The chemical and mineralogical characteristics of RHA were first analyzed. The characteristic of cement paste was investigated using IR, TGA and XRD. Hydration temperature also recorded. Chemical analysis shows higher amount of silica in RHA which is in range of 95-98wt. %. XRD and IR confirmed the white RHA is amorphous silica. The optimum amount of RHA addition was 10 wt. % which produced comparable properties with cement paste control. Based on Calorimetery Studied, IR, TG and hydration temperature results, white silica was found the most reactive silica but plays limited role as admixture in OPC paste.Keywords: rice husk ash, ordinary Portland cement, cement paste, hydration temperature
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Rai, Sarita, i Shivani Tiwari. "Nano Silica in Cement Hydration". Materials Today: Proceedings 5, nr 3 (2018): 9196–202. http://dx.doi.org/10.1016/j.matpr.2017.10.044.
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Ma, Li Guo, i Yun Sheng Zhang. "Study on the Effect of Fly Ash or Silica Fume to Hydration Heat of Cement". Advanced Materials Research 250-253 (maj 2011): 4001–4. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.4001.
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The hydration heat evolution process is studied on the pure cement paste, the cement- fly ash binary system and the cement- silica fume binary system with water binder ratio(w/b) of 0.53, 0.35 and 0.23 by using isothermal calorimeter(TAM Air). The fly ash replacement in the cement-fly ash binary system is 10%, 30% and 50% respectively. The silica fume replacement in cement-silica fume binary system is 4%, 8% and 12% respectively. The experiments results indicate that w/b had great impact on the hydration heat evolution and the hydration heat decrease with the decrease in w/b. The addition of fly ash greatly decrease the exothermic rate and total hydration heat. The addition of silica fume shortens dormant period and increases the peak exothermic rate, but reduces the total hydration heat.
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Li, Qiang, Jie Chen, Qian Shi i Shihao Zhao. "Macroscopic and Microscopic Mechanisms of Cement-Stabilized Soft Clay Mixed with Seawater by Adding Ultrafine Silica Fume". Advances in Materials Science and Engineering 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/810652.
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The strength of the cement-stabilized soil can be improved by the use of seawater. Compressive strength test results show that the strength of cement-stabilized soil mixed with seawater is 50% greater than that mixed with freshwater at the 90th day. However, the application is limited because the expansion of the cement-stabilized soil mixed with seawater increases significantly. A kind of ultrafine silica fume was added into the cement-stabilized soil to inhibit swelling of the cement-stabilized soil with seawater. The expansion of cement-stabilized soil mixed with seawater by adding ultrafine silica fume is close to that of cement-stabilized soil mixed with freshwater. With the addition of ultrafine silica fume, the unconfined compressive strength increases by close to 6.5% compared with seawater alone at the 90th day. The mechanisms of adding ultrafine silica fume into the cement-stabilized soil mixed with seawater are revealed by several physical and chemical characterization parameters, such as specific gravity, unbound water content, surface morphology seen with SEM, and crystal products by X-ray diffraction tests. The results show that the crystal growth is an important factor, affecting the strength and expansion of cement-stabilized soil mixed with seawater.
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Mohamed, Osama Ahmed, Waddah Al Hawat i Omar Fawwaz Najm. "Durability of Sustainable Self-Consolidating Concrete". Key Engineering Materials 765 (marzec 2018): 285–89. http://dx.doi.org/10.4028/www.scientific.net/kem.765.285.
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Supplementary cementitious materials such as fly ash, silica fume and ground granulated blast furnace slag (GGBS) have been used widely to partially replace cement in producing self-consolidating concrete (SCC). The production of cement is associated with emission of significant amounts of CO2 and increases the human footprint on the environment. Fly ash, silica fume, and GGBS are recycled industrial by-products that also impart favorable fresh and hardened properties on concrete. This study aims to assess the effect of the amounts of fly ash and silica fume on strength and chloride penetration resistance of concrete. Rapid Chloride Penetration Test (RCPT) was used to assess the ability of SCC to resist ingress of chlorides into concrete. SCC mixes with different dosages of fly ash and silica fume were developed and tested at different curing ages. Test results showed that replacing 20% of cement with fly ash produced the highest compressive strength of 67.96 MPa among all fly ash-cement binary mixes. Results also showed that replacing15% of cement with silica fume produced the highest compressive strength of 95.3 MPa among fly ash-cement binary mixes. Using fly ash and silica fume consistently increased the concrete resistance to chloride penetration at the early ages. Silica fume at all dosages results in low or very low levels of chloride penetration at all curing ages of concrete.
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OSAWA, Norihisa, Go IGARASHI, Kazuo YAMADA i Tomoya NISHIWAKI. "FUNDAMENTAL STUDY ON THE MECHANISM OF EXPANSION GENERATION BY ALKALI-SILICA GEL FROM ALKALI-SILICA REACTION". Cement Science and Concrete Technology 71, nr 1 (2017): 272–79. http://dx.doi.org/10.14250/cement.71.272.
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Zhong, Weiguang, Dan Wang, Congcong Jiang, Xiaolei Lu, Lina Zhang i Xin Cheng. "Study on Visible Light Catalysis of Graphite Carbon Nitride-Silica Composite Material and Its Surface Treatment of Cement". Crystals 10, nr 6 (7.06.2020): 490. http://dx.doi.org/10.3390/cryst10060490.
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Cement-based composite is one of the essential building materials that has been widely used in infrastructure and facilities. During the service of cement-based materials, the performance of cement-based materials will be affected after the cement surface is exposed to pollutants. Not only can the surface of cement treated with a photocatalyst degrade pollutants, but it can also protect the cement-based materials from being destroyed. In this study, graphite carbon nitride-silica composite materials were synthesized by thermal polymerization using nanosilica and urea as raw materials. The effect of nanosilica content and specific surface area were investigated with the optimal condition attained to be 0.15 g and 300 m2/g, respectively. An X-ray diffractometer, thermogravimetric analyzer, scanning electron microscope, a Brunauer–Emmett–Teller (BET) specific surface area analyzer and ultraviolet-visible spectrophotometer were utilized for the characterization of as-prepared graphite carbon nitride-silica composite materials. Subsequently, the surface of cement-based materials was treated with graphite carbon nitride-silica composite materials by the one-sided immersion and brushing methods for the study of photocatalytic performance. By comparing the degradation effect of Rhodamine B, it was found that the painting method is more suitable for the surface treatment of cement. In addition, through the reaction of calcium hydroxide and graphite carbon nitride-silica composite materials, it was found that the combination of graphite carbon nitride-silica composite materials and cement is through C-S-H gel.
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Luswata, G. N., D. Onyancha i J. N. Thuo. "Investigation of Performance of Nano Silica Cement Additive on Sulphate Attack In Geothermal Wells". AFRICAN JOURNAL OF APPLIED RESEARCH 9, nr 1 (29.03.2023): 1–19. http://dx.doi.org/10.26437/ajar.v9i1.518.
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Purpose: This research was intended to evaluate Nano silica as an additive to improve the sulphate resistance of cement used in geothermal wells.
Design/ Methodology/ Approach: Sulphate resistance was determined by measuring the longitudinal change in cement cube specimens that were cured in sodium sulphate solution for 21 days. Cube specimens with varied concentrations of Nano silica (0%, 0.3%, 0.6%, 0.9% and 1.2%) were used in the study. Five separate solutions were maintained at 23℃, 40℃, 65℃, 70℃ and 80℃ for 21 days. Final length measurements were taken and compared as a percentage of initial length measurements.
Findings: Beyond 65℃, the sulphate resistance of cement improved for each percentage concentration of Nano silica replacement. Control specimens with 0% Nano silica had the most inferior performance at all temperatures. Higher concentrations of 1.2% and 0.6% Nano silica replacement gave the most resistance between 23℃ and 65℃. A lower concentration of 0.3% proved more suitable between 65℃ and 80℃.
Research limitation: The results of the experiment indicate performance in low-temperature geothermal wells.
Practical implications: The application of this additive can improve the durability and strength of the cement, reducing the potential for degradation due to exposure to sulphates. This can lead to a longer lifespan of the geothermal well, reducing maintenance costs and increasing its overall efficiency.
Social implications: Improved cement designs that create longer-lasting cement sheaths can be developed from this research, thereby fostering geothermal energy development. The option to replace certain volumes of cement with Nano silica contributes to a reduction of the carbon footprint by minimising the demand for, and therefore the production of cement.
Originality/ Value/ Novelty: Previous research that tested cement at high temperatures analysed mechanical resistance. This research examined the sulphate resistance of cement at high temperatures.
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Mohd Ibrahim, Mohd Yusak, Putra Jaya Ramadhansyah, Hainin Mohd Rosli, Mohd Haziman Wan Ibrahim i M. N. Fadzli. "Utilization of Nano Silica as Cement Paste in Mortar and Porous Concrete Pavement". Advanced Materials Research 1113 (lipiec 2015): 135–39. http://dx.doi.org/10.4028/www.scientific.net/amr.1113.135.
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The high percentage of porosity in porous concrete pavement tends to decrease its strength. In concrete industry, nano silica is one of the most popular materials that will improve the properties of cementitious materials. This paper, prepared to review the effect of nano silica in cement paste and mortar related to porous concrete pavement. It was found that, by incorporating nano silica with the right composition in cement paste and mortar, it will improve their mechanical properties. By incorporating nano silica in the mixture, it can be predicted that the strengthening effect of nano silica would be further enhanced in porous concrete because the nano silica improve not only the cement paste, but also the interface between paste and aggregate.
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Mirzababaei, Mehdi, Jafar Karimiazar, Ebrahim Sharifi Teshnizi, Reza Arjmandzadeh i Sayed Hessam Bahmani. "Effect of Nano-Additives on the Strength and Durability Characteristics of Marl". Minerals 11, nr 10 (12.10.2021): 1119. http://dx.doi.org/10.3390/min11101119.
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Low bearing capacity soils may pose serious construction concerns such as reduced bearing capacity and excessive hydro-associated volume changes. Proper soil remediation techniques must be planned and implemented before commencing any construction on low bearing capacity soils. Environmentally friendly soil stabilizers are gradually replacing traditional soil stabilizers with high carbon dioxide emissions such as lime and cement. This study investigated the use of an alternative pozzolanic mix of nano-additives (i.e., nano-silica and nano-alumina) and cement to reduce the usage of cement for achieving competent soil stabilization outcomes. A series of unconfined compressive strength (UCS), direct shear, and durability tests were conducted on marl specimens cured for 1, 7, and 28 days stabilized with nano-additives (0.1~1.5%), 3% cement, and combined 3% cement and nano-additives. The UCS and shear strength of stabilized marl increased with nano-additives up to a threshold nano-additive content of 1% which was further intensified with curing time. Nano-additive treated cemented marl specimens showed long durability under the water, while the cemented marl decomposed early. The microfabric inspection of stabilized marl specimens showed significant growth of calcium silicate hydrate (CSH) products within the micro fabric of nano-silica treated marl with reduced pore-spaces within aggregated particles. The results confirmed that nano-additives can replace cement partially to achieve multi-fold improvement in the strength characteristics of the marl.
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Janavičius, Eugenijus, Mindaugas Daukšys, Gintautas Skripkiūnas, Džigita Nagrockienė i Ala Daugėlienė. "THE EFFECT OF CEMENT MODIFICATION ON THE RHEOLOGICAL PROPERTIES OF CEMENT PASTE". Journal of Civil Engineering and Management 19, Supplement_1 (9.01.2014): S125—S130. http://dx.doi.org/10.3846/13923730.2013.851111.
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Experimental tests have determined the effect of slag, opoka (silica-calcite sedimentary rock), silica fume (SiO2) suspension, dolomite dust and sodium silicate solution (NaSS) together with the polycarboxylatether based plasticizing admixture on the yield stress and viscosity of Portland cement paste the rheological properties of which have been defined applying a rotational viscometer with co-axial cylinders. The tests have revealed that slag, opoka, silica fume suspension and dolomite dust added to cement paste by replacing 10% of Portland cement (by weight) have an effect on the yield stress and viscosity of the paste subject to the form and fineness of additive particles. When 10wt% of Portland cement is replaced with slag cement, the yield stress of Portland cement paste reduces by about 25.9%, and viscosity increases by about 3.5 times compared with the yield stress and viscosity of reference cement paste. The yield stress of Portland cement paste with 0.5% NaSS admixture increases insignificantly, and viscosity grows approximately twice compared with reference cement paste. The tests have also showed that the modifying admixtures of Portland cement paste enable to control the rheological properties of cement paste.