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1
Nori, J., S. Kakay et M. Belayneh. « Effect of SiO2 and SiO2/TiO2 hybrid nanoparticles on cementitious materials ». IOP Conference Series : Materials Science and Engineering 1201, no 1 (1 novembre 2021) : 012054. http://dx.doi.org/10.1088/1757-899x/1201/1/012054.
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Abstract In this paper, we report the effect of SiO2 nanoparticle solution on the properties of the neat industry and environmental cements. Moreover, the hybrid SiO2/TiO2 nanoparticles solution impact on the Portland G-class cement. Both destructive and non-destructive tests were used to characterize the properties of the slurries and the cement plugs. Results indicate that the optimum concentration of the nanoparticles improved the elastic, energy absorption, rheological, heat development, and the mechanical load carrying capacity of the cements. The selected optimal nanoparticles concentrations results showed that • the addition of 0.56 % SiO2 by weight of cement (bwoc) increased the uniaxial compressive strength (UCS) of the neat industry cement by 16.7%. • the 0.13% SiO2 bwoc increased the UCS of the neat environmental cement by 50.2%. • the blending of 0.264 %SiO2/0.044% TiO2 bwoc increased the UCS of neat G-class cement by 8.5%. However, by changing the curing temperature and pressure, different results can be achieved.
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Zhang, Jie, Yongsheng Ji, Zhanguo Ma, Jianwei Cheng, Shengnan Xu, Zhishan Xu et Zhongzhe Zhang. « Strengthening Mechanism for the Mechanical Properties of Cement-Based Materials after Internal Nano-SiO2 Production ». Nanomaterials 12, no 22 (17 novembre 2022) : 4047. http://dx.doi.org/10.3390/nano12224047.
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This study focuses on overcoming the agglomeration issue of nano-SiO2 powder in cement, facilitating the strengthening mechanism of cement-based materials. A nano-SiO2 precursor solution (NSPS) was added to cement-based materials to replace nano-SiO2 powder. The influencing laws of the alkalinity and dosage of the NSPS on the mechanical properties of cement were investigated. Further, the strengthening mechanism of the mechanical properties of cement-based materials after internal nano-SiO2 production was analysed. The results show that (1) when the alkalinity of the precursor solution is a weak acid (pH = 6), the compressive strength of cement-based materials after internal nano-SiO2 production is 25%~36% higher than that of pure cement-based materials and 16%~22% higher than that of cement-based materials with silica fume; (2) when the solid content of SiO2 in the current displacement solution is about 0.16% of the cement mass, the compressive strength of the prepared cement-based material is the highest. With the continuous increase in the solid content of SiO2 in the precursor solution, the compressive strength of cement-based materials after internal nano-SiO2 production decreases but is always greater than the compressive strength of the cement-based material mixed with nano-SiO2 micro powder. According to a microstructural analysis, nano-SiO2 particles that precipitate from the precursor solution can facilitate the hydration process of cement and enrich the gel products formed on the cement particle surface. In addition, new network structures among cement particles are formed, and precipitated nano-SiO2 particles fill in the spaces among these cement particles as crystal nuclei to connect the cement particles more tightly and compact the cement-based materials. This reinforces the mechanical properties of cement-based materials.
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Mabeyo, Petro E., et Jun Gu. « Coupled effects of hydrophilic nano silica oxide and anatase nano titanium oxide on strengths of oilwell cement ». Tanzania Journal of Science 47, no 2 (11 mai 2021) : 568–82. http://dx.doi.org/10.4314/tjs.v47i2.13.
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The life of oil wells depends on the stability of cement sheath and bond strength with the formation and casing. Extreme subsurface conditions cause substantial stresses on the cement sheath resulting in a serious impact on well integrity. The recommended API cement for oilwell fails to provide the required durability of the cemented well due to such conditions. Supplementary cementitious materials such as nanoparticles are added to improve the cement for long-lasting zonal isolation. In this study, the compressive and shear bond strengths of oilwell cement containing nano-SiO2 and nano-TiO2 were studied at 80 °C for 3, 7, 14, and 28 days of hydration. The XRD, TG, and DSC were used for the analysis of cement hydration products. The results revealed that both nano-SiO2 and nano-TiO2 increased strength evolution. A ternary system made with 2% nano-SiO2 and 2% nano-TiO2 improved compressive strength by 22.6 and 48.4%, while the shear bond strength increased by 110.6 and 55% at age of 3 days and 28 days, respectively, compared to their corresponding binary systems. Therefore, these results remark the potential of replacing an appropriate proportion of oilwell cement with coupled nano-SiO2 and nano-TiO2 to ensure cement sheath structure durability in the annular and long-lasting zonal isolation.
Keywords: Nano-silica, nano-titanium, compressive strength, shear bond strength, oilwell cement
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Wang, De Zhi, Yin Yan Zhang et Yun Fang Meng. « Properties of Cement Mortars Mixed with SiO2 and CaCO3 Nanoparticles ». Key Engineering Materials 539 (janvier 2013) : 244–48. http://dx.doi.org/10.4028/www.scientific.net/kem.539.244.
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Water requirement of normal consistency, setting time and soundness of cement pastes mixed with SiO2 and CaCO3 nanoparticle and the flexural strength and compressive strength of cement mortars mixed with SiO2 and CaCO3 nanoparticles were experimentally studied. Results indicated that the added nano-SiO2 and nano-CaCO3 with a mass account of 4.0 wt. % decreased the setting time and increased the water requirement of normal consistency, flexural strength and compressive strength. And these nanoscaled mineral admixtures did not have a negative impact on cement soundness. The optimal replacement levels of cement by SiO2 and CaCO3 nanoparticles for producing cement mortar with improved strength were 2.0 and 4.0 wt.% respectively.
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Suprompituk, Wanchart, et Papot Jaroenapibal. « Improvement of Early Compressive Strength in Belite Cement by Incorporating Silica Coated Single-Walled Carbon Nanotubes ». Key Engineering Materials 718 (novembre 2016) : 157–62. http://dx.doi.org/10.4028/www.scientific.net/kem.718.157.
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This work demonstrated the improvement of belite cement compressive strength by incorporating nanosilica coated single-walled carbon nanotubes (SWNTs@SiO2) into the cement paste. The structure and chemical compositions of SWNTs@SiO2 materials were characterized by transmission electron microscopy and energy dispersive X-ray spectroscopy techniques, respectively. Belite cement composites were prepared by mixing belite cement paste with different loadings of SWNTs@SiO2 ranging from 0.02 – 0.1 wt%. In order to measure the early strength of cement composites, the samples were aged for 7 days, and then subjected to compression tests. Effects of uncoated SWNTs and silica coated SWNTs loadings on the compressive strength of belite cement composites were studied. Without pre-coating SWNTs with nanosilica, the SWNTs additives led to large decrease in compressive strength of belite cement composite. Improvements in compressive strength of belite cement are shown in samples that incorporated SWNTs@SiO2 loadings. The coating layer helps enhance bonding strength between reinforced SWNTs and the matrix, as well as promote hydration reactions in the cement paste. The highest increase in the compressive strength of 18.8 % is found in the sample with the minimal SWNTs@SiO2 loading of 0.02%.
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Gu, Yue, Qian Ping Ran, Xin Shu, Cheng Yu, Hong Lei Chang et Kai Lv. « Synthesis of SiO2-PCE Core-Shell Nanoparticles and its Modification Effects on Cement Hydration ». Key Engineering Materials 711 (septembre 2016) : 249–55. http://dx.doi.org/10.4028/www.scientific.net/kem.711.249.
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NanoSiO2 was widely used to modify the property of cementitious materials, however, for nanoparticles used in cement-based materials, key problem is the effective dispersion. The surface modification technology can be introduced to promote dispersion of nanoparticles in aqueous system, especially in cement pore solution, which possess high concentration of ions. In this study, at first, NanoSiO2-polycarboxylate superplasticizer (SiO2-PCE) core-shell nanoparticle was synthesized from silanized polycarboxylate superplasticizer and colloidal nanoSiO2 by the “grafting to” method, then SiO2-PCE was testified by UV-Vis, FTIR, and TGA. Additionally, stability of SiO2-PCE and its effect on cement hydration were investigated. Results shows: SiO2-PCE possess higher stability in saturated calcium hydroxide solution compared to nanoSiO2, and heat development of cement hydration can be regulated by shell structure of SiO2-PCE. The research implied a new approach for nanoSiO2 to optimize cement-based composites.
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Bodnarova, Lenka, Rudolf Hela et Daniel Sedlacek. « Effect of Inorganic SiO2 Nanofibers in High Strength Cementitious Composites ». MATEC Web of Conferences 278 (2019) : 01009. http://dx.doi.org/10.1051/matecconf/201927801009.
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The paper deals with the verification of the effect of the addition of inorganic SiO2 nanofibers to cement composites. In the first stage, a stable suspension of SiO2 nanofibers was prepared in an aqueous medium. It is important to distribute nanofibers so that the nanofibers do not appear in the form of clumps and at the same time do not get damaged during the dispersion process. The ultrasonification process was used for dispersion. The dispersed suspension of SiO2 nanofibers and water was dosed together with the superplasticizing admixtures into the dry components of the cement composite and the components were homogenized. The properties of the cement composite with SiO2 nanofibers have been tested – compressive strength, flexural strength, density. Composites with the addition of SiO2 nanofibers at a dose of 0.008 % by weight of cement exhibited an increased compressive strength of up to 33 % and a 19 % greater flexural strength at doses of 0.016 and 0.032 % of cement weight than the reference sample without nanofibers. The presence of SiO2 nanofibers in the composite was monitored by scanning electron microscopy (SEM).
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Alireza Naji Givi, Suraya Abdul Rashid, Farah Nora A. Aziz et Mohamad Amran Mohd Salleh. « Particle size effect on the permeability properties of nano-SiO2 blended Portland cement concrete ». Journal of Composite Materials 45, no 11 (8 novembre 2010) : 1173–80. http://dx.doi.org/10.1177/0021998310378908.
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In this study, nano-SiO2 has been used as a high reactive pozzolan to develop the microstructure of the interfacial transition zone between the cement paste and the aggregate. Mechanical tests of blended cement-based concretes exposed that in addition of the pozzolanic reactivity of nano-SiO2 (chemical aspect), its particle grading (physical aspect) also revealed considerable influences on the blending effectiveness. It was concluded that the relative permeability reduction (relative to the control concrete made with plain cement) is higher for coarser nano-SiO2 after 90 days of moisture curing. However, finer nano-SiO2 particles showed better effects in early ages. These phenomena can be due to the free spacing between mixture particles that was associated with the global permeability of the blended cement-based concretes. This article presents the results of the effects of particle size ranges involved in nano-SiO2 blended Portland cement on the water permeability of concrete. It is revealed that the favorable results for coarser nano-SiO2 reflect enhanced particle packing formation accompanied by a reduction in porosity and particularly in particle spacing after 90 days.
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Kirgiz, Mehmet Serkan. « Effects of Blended-Cement Paste Chemical Composition Changes on Some Strength Gains of Blended-Mortars ». Scientific World Journal 2014 (2014) : 1–11. http://dx.doi.org/10.1155/2014/625350.
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Effects of chemical compositions changes of blended-cement pastes (BCPCCC) on some strength gains of blended cement mortars (BCMSG) were monitored in order to gain a better understanding for developments of hydration and strength of blended cements. Blended cements (BC) were prepared by blending of 5% gypsum and 6%, 20%, 21%, and 35% marble powder (MP) or 6%, 20%, 21%, and 35% brick powder (BP) for CEMI42.5N cement clinker and grinding these portions in ball mill at 30 (min). Pastes and mortars, containing the MP-BC and the BP-BC and the reference cement (RC) and tap water and standard mortar sand, were also mixed and they were cured within water until testing. Experiments included chemical compositions of pastes and compressive strengths (CS) and flexural strengths (FS) of mortars were determined at 7th-day, 28th-day, and 90th-day according to TS EN 196-2 and TS EN 196-1 present standards. Experimental results indicated that ups and downs of silica oxide (SiO2), sodium oxide (Na2O), and alkali at MP-BCPCC and continuously rising movement of silica oxide (SiO2) at BP-BCPCC positively influenced CS and FS of blended cement mortars (BCM) in comparison with reference mortars (RM) at whole cure days as MP up to 6% or BP up to 35% was blended for cement.
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Wang, Yaying, Wei Wang, Yinuo Zhao, Na Li, Jiale Luo, Asefa Mulugeta Belete et Jiang Ping. « Modification Effect of Nano-Clay on Mechanical Behavior of Composite Geomaterials : Cement, Nano-Silica and Coastal Soft Soil ». Materials 15, no 24 (7 décembre 2022) : 8735. http://dx.doi.org/10.3390/ma15248735.
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To study the modification effect of nano-clay and nano-SiO2 on cement-reinforced coastal soft soil, the effects of the nano-SiO2 and nano-clay on the mechanical properties of cement soil were studied through unconfined compressive and unconsolidated undrained shear tests, and the Duncan–Chang model was used to fit the test results. Results show that adding nano-clay and nano-SiO2 to cement soil improved its compressive and shear strength. The compressive strength and shear strength increased by 18–57% and 3–32%, respectively, with the increase in nano-clay content in a content range of 0–10%. Additionally, nano-clay can enhance the ductility of cement soil. Moreover, nano-clay and nano-SiO2 improve the shear strength by increasing the internal friction angle by 1°–2° and cohesion of 9–25%, and the cement-stabilized coastal soft soil enhanced by nano-SiO2 and nano-clay conforms to the Duncan–Chang model well.
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Rong, Zhidan, Mingyu Zhao et Yali Wang. « Effects of Modified Nano-SiO2 Particles on Properties of High-Performance Cement-Based Composites ». Materials 13, no 3 (1 février 2020) : 646. http://dx.doi.org/10.3390/ma13030646.
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In this research, silane coupling agent was used to modify the surface of nano-SiO2, particles and the effects of modified nano-SiO2 particles on the mechanical properties of high-performance cement-based composites and its mechanism were systematically studied. The results indicated that the optimum modification parameters were a coupling agent content of 10%, reaction temperature of 65 °C, and reaction time of 8 h. Compared with the unmodified nano-SiO2, the modified nano-SiO2 promoted and accelerated the hydration process of cement. The pozzolanic effect, filling effect, and nucleation effect of modified nano-SiO2 made the microstructure of the composite more compact, and thus improved static mechanical properties of cement-based composites.
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Luu Thi, Hong, Long Luong Duc, Cham Trinh Thi, Luan Ta Van et Qui Duong Thanh. « Effects of silicafume and fly ash on properties of alumina cement ». MATEC Web of Conferences 251 (2018) : 01015. http://dx.doi.org/10.1051/matecconf/201825101015.
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Alumina cement which was used in this investigation contains about 56% of Al2O3 in the component. Early compressive strength alumina cement at 1 and 3 days can be achieved of 85% compressive strength value at 28 days. After a long period of hydration, the compressive strength of alumina cement harder decreased due to the releasing process of aluminum hydroxide [Al(OH)3] to the outside environment [1, 4,11]. To improve and maintain the long lasting compressive strength of alumina cement harden, new binders would be created SiO2- Al2O3 and among CaO-SiO2-Al2O3. The new binders would exist sustainably in the cement harden as a result of the chemical reaction between the product of hydrated cement called gel [Al(OH)3] with micro silica (amorphous SiO2) [4]. This report demonstrates the result of the investigation which is about the effect of silica fume and fly ash on alumina cement.
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Raheem, Akeem Ayinde, et Mutiu A. Kareem. « Chemical Composition and Physical Characteristics of Rice Husk Ash Blended Cement ». International Journal of Engineering Research in Africa 32 (septembre 2017) : 25–35. http://dx.doi.org/10.4028/www.scientific.net/jera.32.25.
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Applications of agricultural by-product as substitute for non-renewable material in cement production are desirable in stimulating socio-economic development. In this study, Rice Husk Ash (RHA) blended cement was produced by replacing 5%, 7%, 11.25%, 15%, 20.25% and 25% by weight of Ordinary Portland Cement (OPC) clinker with RHA. The cement without RHA serves as the control. The chemical compositions of RHA, OPC-clinker and the blended cements were determined using X-ray fluorescence analyzer. The physical characteristics of RHA blended cements that were considered are fineness, soundness, consistency, initial and final setting times and compressive strength at 2, 7, 28, 56 and 90 curing ages. The results showed that RHA is a suitable material for use as a pozzolan as it satisfied the minimum requirement by having the sum of SiO2, Al2O3 and Fe2O3 of more than 70%. Incorporation of RHA led to an increase in the composition of SiO2 and reduction in that of CaO. An increase in RHA content showed a decrease in compressive strength at early ages and slightly increase at a later age (90 days). The blended cement produced with lower levels of RHA replacement conforms to standard specifications specified in BS EN 197-1:2000, NIS 439:2000 and ASTM C 150-02. The minimum Strength Activated Index (SAI) of 75% at the age of 28 days of curing as specified by ASTM C 618 was satisfied by RHA replacement of up to 15%. It was concluded that blended cement with the maximum of 15% RHA content is suitable for use for structural purposes.
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Jiao, You Zhou, Pan Ding et Shuang Li Du. « Research on Mineral Formation Mechanism of Pulverized Coal Combustion Boiler Co-Generating Q-Phase Cement Clinker ». Advanced Materials Research 512-515 (mai 2012) : 1687–91. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.1687.
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Conduct test of 2CaO•Al2O3•SiO2 transformed into Q-phase mineral with analytical reagent CaO, SiO2, Al2O3 and MgO in library high-temperature furnace. And carry out experimental investigation on the mineral formation rule of co-generation Q-phase cement clinker on two-section multiphase reaction test stand simulating pulverized coal combustion boiler based on the test. It was found that: 2CaO•Al2O3•SiO2 may generate Q-phase mineral with hydration activity together with appreciated amount of CaO and MgO; experimental coal sort in reasonable ratio may co-generate cement clinker with main mineral sort of 2CaO•SiO2 and Q-phase mineral. Thermodynamic analysis on mineral formation reaction shows that, in Yanzhou coal co-generating Q-phase cement clinker, the most probably occurring is the direct synthesis reaction of 2CaO•Al2O3•SiO2, followed by 2CaO•SiO2 direct synthesis reaction and the Q-phase indirect synthesis reaction comes last according to chemical composition of clinkers.
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Zhang, Jialu, Cheng Shen et Guangfen Diao. « Application and Microstructure Properties of Nanomaterials in New Concrete Materials ». Journal of Nanomaterials 2022 (29 mai 2022) : 1–10. http://dx.doi.org/10.1155/2022/7396295.
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This article takes the application of nanomaterials in new concrete materials as the research object and explores the defects of nanomaterials in improving the toughness and tensile capacity of traditional concrete by analyzing the effects of nanomaterials on the structure and properties of new concrete. This article takes the application of nano-SiO2 in new concrete materials as an example. Firstly, the experiment of preparing nanoconcrete was carried out, and then, aiming at the experimental results, a detailed analysis and discussion on the effects of nano-SiO2 on the shrinkage, mechanical properties, and microstructure of the new concrete materials were carried out. The research results show that the cement paste with nano-SiO2 is much better in chemical shrinkage than the cement paste without admixture, and the chemical shrinkage value of the cement paste with nano-SiO2 increases significantly in the early setting stage. The chemical shrinkage values are 11.4%, 26.7%, 53.9%, and 94.2%, respectively, according to the amount of nano-SiO2 added. With the extension of the setting period, the growth rate of the shrinkage value of cement paste slows down; nano-SiO2 can improve the compressive capacity and strength of concrete, and with the increase of the amount of compressive strength, the value of compressive strength is also increasing. In the early stage of coagulation, when the nano-SiO2 dosage is 1.6%, the compressive strength of the coagulation for 3 days is 39.02%. With the prolongation of the setting period, the increase in compressive strength continues to increase, but the growth rate slows down; the addition of nano-SiO2 has changed the microstructure of concrete. Nano-SiO2 has high pozzolanic activity, which can promote the hydration process of cement, and because of the small particles, it can fill the voids of concrete, thereby improving its compactness and mechanical strength.
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Francis Thoo, V. W., N. Zainuddin, K. A. Matori et S. A. Abdullah. « Studies on the Potential of Waste Soda Lime Silica Glass in Glass Ionomer Cement Production ». Advances in Materials Science and Engineering 2013 (2013) : 1–6. http://dx.doi.org/10.1155/2013/395012.
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Glass ionomer cements (GIC) are produced through acid base reaction between calcium-fluoroaluminosilicate glass powder and polyacrylic acid (PAA). Soda lime silica glasses (SLS), mainly composed of silica (SiO2), have been utilized in this study as the source of SiO2for synthesis of Ca-fluoroaluminosilicate glass. Therefore, the main objective of this study was to investigate the potential of SLS waste glass in producing GIC. Two glasses, GWX 1 (analytical grade SiO2) and GWX 2 (replacing SiO2with waste SLS), were synthesized and then characterized using X-ray diffraction (XRD) and energy dispersive X-ray (EDX). Synthesized glasses were then used to produce GIC, in which the properties were characterized using Fourier transform infrared spectroscopy (FT-IR) and compressive test (from 1 to 28 days). XRD results showed that amorphous glass was produced by using SLS waste glass (GWX 2), which is similar to glass produced using analytical grade SiO2(GWX 1). Results from FT-IR showed that the setting reaction of GWX 2 cements is slower compared to cement GWX 1. Compressive strengths for GWX 1 cements reached up to 76 MPa at 28 days, whereas GWX 2 cements showed a slightly higher value, which is 80 MPa.
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Li, Yanming, Xiaoyang Guo, Junlan Yang et Ming Li. « Preparation of Nano-SiO2/Carbon Fiber-Reinforced Concrete and Its Influence on the Performance of Oil Well Cement ». International Journal of Polymer Science 2019 (15 septembre 2019) : 1–9. http://dx.doi.org/10.1155/2019/2783018.
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In view of the oilfield well thin oil layer, small gap, and side drilling cementing after perforating and subsequent stimulation caused by the cement ring embrittlement (i.e., secondary channeling), the preparation of nano-SiO2/carbon fiber-reinforced body and its influence on the performance of oil well cement were studied to improve the cement stone and enhance its adaptability to oil well pressure in this study. Carbon fibers were treated by liquid phase oxidation and a coupling agent, and the “grafting to” was used to bond nano-SiO2 and carbon fibers. It was found that the mechanical properties of the enhanced cement stone are far better than those of the blank cement stone. The compressive strength and tensile strength of the enhanced oil well cement stone were increased by 25% and 26%, respectively, compared with those of the blank oil well cement sample; the modulus of elasticity was reduced by 29%. Finally, the enhancement mechanism of SiO2/carbon fiber reinforcement on cement stone was explored by infrared, scanning electron microscopy, and XRD patterns. The deflection effect, pull-out effect, and bridging effect of crack were obtained.
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Bonilla, Ashley, Mónica A. Villaquirán-Caicedo et Ruby Mejía de Gutiérrez. « Novel Alkali-Activated Materials with Photocatalytic and Bactericidal Properties Based on Ceramic Tile Waste ». Coatings 12, no 1 (28 décembre 2021) : 35. http://dx.doi.org/10.3390/coatings12010035.
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Ceramics tile wastes (CWs) were mechanically conditioned for the preparation of alkali-activated hybrid-cements from CW (90 wt.%) and Portland cement (10 wt.%) mixtures using sodium silicate (SS) + NaOH as alkaline activators. Molar ratios of SiO2/Al2O3 (6.3 to 7.7) and Na2O/SiO2 (0.07 to 0.16) were used. The cements were prepared at room temperature (25 °C) and characterized by mechanical and physical properties and microstructure. The optimized cement was used for the preparation of novel photoactivated composite materials by incorporating 5 and 10 wt.% TiO2 (Ti) and ZnO (Z) nanoparticles, and its self-cleaning and bactericidal properties were evaluated by means of the degradation of rhodamine-B (Rh-B) and the growth inhibition of Klebsiella pneumoniae and Pseudomonas aeruginosa bacteria. The results of this study showed that the 100SS-5Z and 50SS:50G-10Ti cements have an effective photocatalytic activity for Rh-B degradation of 98.4% and 76.4%, respectively, after 24 h. Additionally, the 100SS-5Z and 50SS:50G-10Ti cement pastes and their respective mortars were effective in inhibiting the growth of Pseudomonas Aeruginosa and Klebsiella pneumoniae bacterial strains, evidenced by the formation of bacterial inhibition halos around the sample discs. Finally, these results are novel, and open the possibility of using constructions and demolition tile waste in high proportions for the elaboration of new rendering mortar with innovative properties.
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Cheng, Shuiming, Huizhong Zhao, Yu Wang, Jianxiu Wei, Jinfeng Chen, Wei Cai et Han Zhang. « Submicron SiO2 Powder : Characterization and Effects on Properties of Cement-Free Iron Ditch Castables ». Advances in Materials Science and Engineering 2021 (19 août 2021) : 1–8. http://dx.doi.org/10.1155/2021/9385917.
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Submicron materials are those with particle size diameters between 0.1 and 1 μm. Submicron SiO2 generally refers to SiO2 powder with a D90 < 1 μm (D90 refers to the particle size distribution exhibited by the sample and corresponds, in this case, to 90% of the particles not exceeding a diameter of 1 μm). In this study, a new type of cement-free iron ditch castable was prepared using dense corundum and silicon carbide as the primary raw materials with submicron SiO2 powder as the binder. The effects of submicron SiO2 powder content on the bulk density, apparent porosity, linear rate of change, compressive strength, and bending strength were investigated. The mechanism of action of the submicron SiO2 powder was also investigated by analyzing its microstructure and particle size distribution. The results revealed that (1) the submicron SiO2 powder can be used as the sole bonding agent in the preparation of cement-free iron ditch castables; (2) in comparison to traditional castables, the cement-free castable developed in this study demonstrated strong service performance and high-temperature bending strength.
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Li, Shaojie, Ping Shen, Hang Zhou, Shiguo Du, Yuling Zhang et Jun Yan. « Synergistic effects of CNTs/SiO2 composite fillers on mechanical properties of cement composites ». RSC Advances 12, no 42 (2022) : 27253–66. http://dx.doi.org/10.1039/d2ra04127h.
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Wang, Dan, Zhi Geng, Pengkun Hou, Ping Yang, Xin Cheng et Shifeng Huang. « Rhodamine B Removal of TiO2@SiO2 Core-Shell Nanocomposites Coated to Buildings ». Crystals 10, no 2 (31 janvier 2020) : 80. http://dx.doi.org/10.3390/cryst10020080.
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Surface application of photocatalyst in cement-based materials could endow it with photocatalytic properties, however, the weak adhesion between photocatalyst coatings and the substrates may result in poor durability in outdoor environments. In this study, TiO2@SiO2 core-shell nanocomposites with different coating thicknesses were synthesized by varying the experiment parameters. The results indicate that SiO2 coatings accelerated the rhodamine B removal to a certain extent, owing to its high surface area; however, more SiO2 coatings decreased its photocatalytic efficiencies. The cement matrix treated with TiO2@SiO2 core-shell nanocomposites showed good photocatalytic efficiency and durability after harsh weathering processing. A reaction mechanism was revealed by the reaction of TiO2@SiO2 nanocomposites with Ca(OH)2.
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Cheng, Youkun, et Zhenwu Shi. « Experimental Study on Nano-SiO2 Improving Concrete Durability of Bridge Deck Pavement in Cold Regions ». Advances in Civil Engineering 2019 (14 février 2019) : 1–9. http://dx.doi.org/10.1155/2019/5284913.
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In order to reduce early damage of bridge deck pavement concrete in cold regions, a certain content of nano-SiO2 is added into the concrete to enhance its durability. Through tests on four durability indexes, strength, frost resistance, resistance to Cl− ion permeability, and abrasion resistance of concrete with 1% nano-SiO2 content and concrete without nano-SiO2, the ability of nano-SiO2 to improve the concrete durability of bridge deck pavement is evaluated. The results of tests and analysis show that the incorporation of nano-SiO2 greatly improves the four durability indexes. Nano-SiO2 effectively absorbs the calcium hydroxide released early by the hydration of cement, increases the calcium silicate hydrate content, and elevates the interface between the paste and aggregate of the hardened cement, which improves the durability of the concrete.
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Heo, Gwang-Hee, Jong-Gun Park, Ki-Chang Song, Jong-Ho Park, Hyung-Min Jun et Zhongguo John Ma. « Improving the Interfacial Bond Properties of the Carbon Fiber Coated with a Nano-SiO2 Particle in a Cement Paste Matrix ». Advances in Civil Engineering 2020 (29 septembre 2020) : 1–18. http://dx.doi.org/10.1155/2020/8838179.
Texte intégralRésumé :
To improve the interfacial bond properties of the carbon fiber coated with a nano-SiO2 particle in a cement paste matrix, the present study proposed a method of coating nano-SiO2 particles on the surface of the carbon fiber by the chemical reaction of a silane coupling agent (glycidoxypropyltrimethoxysilane, GPTMS) and colloidal nano-SiO2 sol in an alkaline environment. To verify whether a nano-SiO2 particle was effectively modified on the surface of the carbon fiber, the surface morphology, chemical composition, and chemical structure were characterized and analyzed by several techniques such as the scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), and Fourier-transform infrared spectroscopy (FT-IR). Nano-SiO2 particles were entirely covered and uniformly distributed on the surface of the carbon fiber, resulting in the formation of a thin layer of nano-SiO2 particles. A thin layer of nano-SiO2 particles reacted with Ca(OH)2 to form a calcium-silicate-hydrate (C-S-H) gel, which is most helpful to increase the form between the fiber and the matrix. In addition, a pull-out test of the tow carbon fibers was performed to verify the effect of the new surface modification method on the interfacial bond properties of the carbon fiber embedded in the cement paste matrix. The experimental results showed that the frictional bond strength of the carbon fiber coated with a nano-SiO2 particle was significantly increased compared to the plain carbon fiber. These results were expected to improve the interfacial bonding force of hardened cement paste from the formation of the C-S-H gel produced through the chemical reaction of nano-SiO2 particles coated on the surface of the carbon fiber with Ca(OH)2. In particular, it was confirmed that the carbon fiber-reinforced cement paste (CFRCP) specimens coated with a nano-SiO2 particle and silica fume which replaced 10 wt.% of cement by mass showed the highest pull-out resistance performance at 28 days of age. The new surface modification method developed in this study can be very beneficial and helpful in improving the interfacial bond properties of CFRCP.
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Gan, Yanling, Suping Cui, Xiaoyu Ma, Hongxia Guo et Yali Wang. « Preparation of Cu-Al/SiO2 Porous Material and Its Effect on NO Decomposition in a Cement Kiln ». Materials 13, no 1 (30 décembre 2019) : 145. http://dx.doi.org/10.3390/ma13010145.
Texte intégralRésumé :
Nitrogen oxide (NOx) emissions have attracted much attention for increasing concern on the quality of the atmospheric environment. In view of NO decomposition in the cement production process, the preparation of Cu-Al/SiO2 porous material and its effect on NO decomposition were studied, and the denitrification mechanism was proposed in this paper. The NO decomposition performance of the Cu-Al/SiO2 porous material was tested via the experimental setup and infrared spectrometer and micro gas chromatography (GC). The result shows that the Cu-Al/SiO2 porous material with the template of cetyltrimethylammonium bromide (CTAB) had a better NO decomposition rate than materials with other templates when the temperature was above 500 °C, and NO decomposition rate could approach 100% at high temperatures above 750 °C. Structure analysis indicates that the prepared Cu-Al/SiO2 material structure was a mesoporous structure. The X-Ray Diffraction (XRD) and Ultraviolet–visible spectrophotometry (UV–Vis) results of the denitrification product show that the Cu-Al/SiO2 material mainly decomposed to Cu2O and Si2O, and the CuO decomposed to Cu2O and O2 at high temperature. The Cu(I)O was considered as the active phase. The redox process between Cu(II)O and Cu(I)O was thought to be the denitrification mechanism of the Cu-Al/SiO2 porous material.
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Pokorný, Jaroslav, Milena Pavlíková, Eva Navrátilová, Pavla Rovnaníková, Zbyšek Pavlík et Robert Černý. « Application of a-SiO2 Rich Additives in Cement Paste ». Applied Mechanics and Materials 749 (avril 2015) : 362–67. http://dx.doi.org/10.4028/www.scientific.net/amm.749.362.
Texte intégralRésumé :
The effect of a-SiO2 of various origin on the properties of cement paste with incorporated different silica containing materials is experimentally studied in the paper. For the applied a-SiO2 materials, basic physical and chemical properties are accessed, together with their chemical composition. Amount of amorphous phase of SiO2 in particular siliceous materials is determined using XRD analysis. Matrix density, bulk density, total open porosity, compressive and bending strength are measured for all developed pastes with incorporated a-SiO2 containing materials, together with initial and final setting time of fresh mixtures. The obtained data give evidence on a high and fast reaction activity of tested siliceous materials which results in a significant improvement of porosity and mechanical strength of a-SiO2 modified cement pastes.
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Ren, Jiaolong, Zedong Zhao, Yinshan Xu, Siyuan Wang, Haiwei Chen, Jiandong Huang, Boxin Xue, Jian Wang, Jingchun Chen et Chengxu Yang. « High-Fluidization, Early Strength Cement Grouting Material Enhanced by Nano-SiO2 : Formula and Mechanisms ». Materials 14, no 20 (16 octobre 2021) : 6144. http://dx.doi.org/10.3390/ma14206144.
Texte intégralRésumé :
Cement grouting material is one of the most important materials in civil construction at present, for seepage prevention, rapid repair, and reinforcement. To achieve the ever-increasing functional requirements of civil infrastructures, cement grouting materials must have the specific performance of high fluidization, early strength, and low shrinkage. In recent years, nanomaterials have been widely used to improve the engineering performance of cement grouting materials. However, the mechanisms of nanomaterials in grouting materials are not clear. Hence, a high-fluidization, early strength cement grouting material, enhanced by nano-SiO2, is developed via the orthogonal experimental method in this study. The mechanisms of nano-SiO2 on the microstructure and hydration products of the HCGA, in the case of different curing ages and nano-SiO2 contents, are analyzed through scanning electron microscopy tests, X-ray diffraction tests, differential scanning calorimetry tests, and Fourier transform infrared spectroscopy tests.
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Wang, Li Feng. « Orthogonal Test and Multi-Element Linear Regression Analysis of Compressive Strength of Nanometer Silicon Cemented Soil ». Advanced Materials Research 317-319 (août 2011) : 34–41. http://dx.doi.org/10.4028/www.scientific.net/amr.317-319.34.
Texte intégralRésumé :
Cement-stabilized soil has been widely used to ground treatment, tracing of foundation pit, water resistance. Additives in cemented soil play an important role in improving its basic properties of cemented soil. In this paper, a new kind of additive, Nanometer Silicon Oxide (SiO2-x), was incorporated into cemented soil. Undrained triaxial compression tests were performed to discuss the reinforced effect of the nanometer silicon on the strength property of the cemented soil. Four main factors that influence the compressive strength of the nanometer silicon cemented soil (NCS) are considered: cement content, nanometer material content, confining pressure, and water\cement ratio. Based on orthogonal tests, the paper analyzed quantitatively the main influence factors of the compression strength of NCS and presented the optimum mix combination. A linear regression model for the compression strength were proposed. Finally, some conclusions have been achieved.
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Peng, Hong, Jun Liu, Qinghu Wang et Yawei Li. « Improvement in Slag Resistance of No-Cement Refractory Castables by Matrix Design ». Ceramics 3, no 1 (11 janvier 2020) : 31–39. http://dx.doi.org/10.3390/ceramics3010004.
Texte intégralRésumé :
The corrosion resistance of spinel containing cement bonded castables has been extensively investigated in the past. However, corrosion of no-cement refractory castables (NCC) has not been widely studied since the use of NCC has been relatively limited up till now. This paper focuses on the slag resistance of NCCs, and the often-used spinel containing low cement castable (LCC) is used as the reference. Three different NCC binders were designed: (i) Al2O3 + MgO (alumina bond), in situ spinel formation; (ii) Al2O3 + SiO2 (microsilica-gel bond), mullite formation; and (iii) Al2O3 + MgO + SiO2 (MgO-SiO2 bond). Slag resistance tests were conducted using the static crucible method with ladle slag. The corrosion mechanisms were studied by means of Scanning Electron Microscopy (SEM/EDS), X-ray Diffraction (XRD), and thermodynamic simulations. The results confirmed that the mineral phases, microstructure, and liquid formation at a high temperature of the refractory materials had a strong impact on the corrosion resistance. The slag resistance was significantly improved when the cement was replaced by the cement-free binders.
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Saliani, Mehdi, Amin Honarbakhsh, Rahele Zhiani, Seyed Mojtaba Movahedifar et Alireza Motavalizadehkakhky. « Investigating the mechanical properties and durability indices of concrete containing Fe3O4/SiO2/GO and GO nanoparticles ». Cement Wapno Beton 26, no 1 (2021) : 67–82. http://dx.doi.org/10.32047/cwb.2021.26.1.7.
Texte intégralRésumé :
Recent research in the construction industry justifi es the partial replacement of cement by nanomaterials. Graphene oxide na-nocomposite is a material that has been recently proposed as a suitable alternative for part of cement in concrete. However, there is no research on the addition of these synthetic compounds to concrete, and little is known about the effect of these materials on the mechanical and durability properties of concrete. Therefore, in this laboratory study, the synthesis of Fe3O4/SiO2/GO and GO nanoparticles was performed and confi rmed with FT-IR, SEM, TEM analyses. These nanoparticles partially replaced cement by 1, 2, 3, and 4 % by mass of the cement, and their effect on mechanical and durability properties of concrete at the ages of 7, 28, and 90-day, were investigated. The results suggest that mixtures in which 2% Fe3O4/ SiO2/GO and 3% GO substituted cement yielded the best results in the mechanical properties tests. Concrete containing Fe3O4/SiO2/GO nanoparticles enhanced compressive strength by 14% and splitting tensile strength by 12% after 28-days of curing. Also, concrete containing 2% Fe3O4/SiO2/GO, had the highest re-sistance to an acidic environment, the lowest permeability, and the highest transient pulse velocity in the ultrasonic test, compared to the specimen containing GO nanoparticles and the control sample.
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Yang, Zhenfa, Qingmei Sui et Lei Jia. « Rapid Analysis of Raw Meal Composition Content Based on NIR Spectroscopy for Cement Raw Material Proportioning Control Process ». Processes 10, no 12 (24 novembre 2022) : 2494. http://dx.doi.org/10.3390/pr10122494.
Texte intégralRésumé :
Due to fast analysis speed, analyzing composition content of cement raw meal utilizing near infrared (NIR) spectroscopy, combined with partial least squares regression (PLS), is a reliable alternative method for the cement industry to obtain qualified cement products. However, it has hardly been studied. The raw materials employed in different cement plants differ, and the spectral absorption intensity in the NIR range of the raw meal component is weaker than organic substances, although there are obvious absorption peaks, which place high demands on the generality of modeling and accuracy of the analytical model. An effective modeling procedure is proposed, which optimizes the quantitative analytical model from several modeling stages, and two groups of samples with different raw material types and origins are collected to validate it. For the samples in the prediction set from Qufu, the root mean square error of prediction (RMSEP) of CaO, SiO2, Al2O3, and Fe2O3 were 0.1910, 0.2307, 0.0921, and 0.0429, respectively; the average prediction errors for CaO, SiO2, Al2O3, and Fe2O3 were 0.171%, 0.193%, 0.069%, and 0.032%, respectively; for the samples in the prediction set from Linyi, the RMSEP of CaO, SiO2, Al2O3, and Fe2O3 were 0.1995, 0.1267, 0.0336 and 0.0242, respectively, the average prediction errors for CaO, SiO2, Al2O3, and Fe2O3 were 0.154%, 0.100%, 0.022%, and 0.018%, respectively. The standard methods for chemical analysis of cement require that the mean measurement error for CaO, SiO2, Al2O3, and Fe2O3 should be within 0.40%, 0.30%, 0.20%, and 0.15%, respectively. It is obvious that the results of both groups of samples fully satisfied the requirements of raw material proportioning control of the production line, demonstrating that the modeling procedure has excellent generality, the models established have high prediction accuracy, and the NIR spectroscopy combined with the proposed modeling procedure is a rapid and accurate alternative approach for the analysis of cement raw meal composition content.
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Sadrmomtazi, Ali, et A. Fasihi. « The Role of Nano-SiO2 Addition in the Mechanical Properties of RHA Composite Cement Mortars ». Advanced Materials Research 346 (septembre 2011) : 18–25. http://dx.doi.org/10.4028/www.scientific.net/amr.346.18.
Texte intégralRésumé :
This paper presents a laboratory study on the properties of rice husk ash (RHA) cement composite mortars incorporating nano-SiO2. Different amounts of nano-SiO2 (0%, 1%, 3% and 5%) were incorporated into the mortars with 20% replacement of RHA. The compressive and flexural strengths of mortars were tested at 7, 28, 60 and 90 days. The water absorption test carried out at 28 days. The drying shrinkage of mortars was measured up to the age of 42 days. Scanning electron microscopy (SEM) observation also conducted to evaluate the effect of nano-SiO2 on microstructure of cement paste containing RHA. Incorporating nano-SiO2 into RHA mortars significantly improved the mechanical strength and water absorption properties of the products. Nano-SiO2 increased the drying shrinkage of RHA mortars. SEM analysis showed that nano-SiO2 improved the microstructure of RHA pastes on dense and compact form.
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Suwan, Teewara, Peerapong Jitsangiam et Prinya Chindaprasirt. « Influence of Nano-Silica Dosage on Properties of Cement Paste Incorporating with High Calcium Fly Ash ». Key Engineering Materials 841 (mai 2020) : 9–13. http://dx.doi.org/10.4028/www.scientific.net/kem.841.9.
Texte intégralRésumé :
Nanotechnology is receiving widespread attention in many industrial sectors, including construction material industry. One of the nano-scale admixtures, which has the potential to enhance the performance of cement and concrete, is known as Nano-silica (n-SiO2). In general, fly ash (FA) is currently used in cement and concrete industry for replacing the consumption of Portland cement (OPC) to reduce its production cost as well as to improve some specific required properties, e.g., workability or low internal heat liberation. However, the strength of hardened Portland cement is normally decreased when a higher amount of fly ash is presented. This research article is therefore pointed on the influence of nano-silica dosage on the properties of cement paste incorporating with high calcium fly ash. Seven different proportions of OPC:FA were prepared viz. 100:0, 80:20, 60:40, 50:50, 40:60, 20:80 and 0:100 by weight. The commercial grade nano-silica (in liquid form) was used as an admixture in those mixes by 0.0, 0.5, 1.0 and 1.5 wt% of the mixing water with a water-to-binder (w/b) ratio of 0.30. The results indicated that the addition of n-SiO2 improved the compressive strength of all mixtures (with and without high calcium FA) as the presence of n-SiO2 can be a source of silica and easily contribute to an additional formation of CSH in the cementing system, confirmed by the results of XRD analysis. The main findings show a potential approach of using n-SiO2 as an admixture for cement and concrete construction.
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Zahalkova, Jana, et Pavla Rovnanikova. « Study of the Effect of Diatomite as a Partial Replacement of Cement in Cement Pastes ». Materials Science Forum 865 (août 2016) : 22–26. http://dx.doi.org/10.4028/www.scientific.net/msf.865.22.
Texte intégralRésumé :
The article is focused on study of the effect of filtering diatomite as a partial replacement of cement in an amount of 5-30%. Diatomite is used in civil engineering especially for its high content of an amorphous SiO2, chemical resistance, high porosity, and good thermal insulating properties. Diatomite can be used as a pozzolanic material due to the high content of amorphous SiO2.Cement was replaced by filtering diatomite in amount of 5, 10, 15, 20, 25 and 30% by weight. Diatomite was characterized by chemical composition, granulometry and pozzolanic activity.The specimens were tested in bulk density, bending strength and compressive strength, hydration process was investigated using thermal analysis, and microstructure was observed by scanning electron microscopy. All results were compared to reference sample.
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Srakaew, N., et Sirirat T. Rattanachan. « Effect of Apatite Wollastonite Glass Ceramic Addition on Brushite Bone Cement Containing Chitosan ». Advanced Materials Research 506 (avril 2012) : 106–9. http://dx.doi.org/10.4028/www.scientific.net/amr.506.106.
Texte intégralRésumé :
Apatite wollastonite glass ceramic (AW-GC) (34.2% SiO2, 44.9% CaO, 16.3%P2O5, 4.6% MgO, 0.5% CaF2) was added into a brushite bone cement, which composed of β-tricalcium phosphate (β-Ca3(PO4)2, β-TCP) and monocalcium phosphate monohydrate (Ca (H2PO4)2H2O, MCPM) in powder phases. Cement was prepared using a 3 β-TCP:2 MCPM in weight ratio. To evaluate the effect of AW-GC on the mechanical strength and degradability of brushite bone cement, the powder phases and 1 wt.% of chitosan dissolved in 5 wt.% of citric acid solution were mixed and soaked in simulated body fluid solution at 37 °C for 1, 3, 5,7 and 14 days, respectively. The compressive strength and setting time of AW-GC added in brushite bone cement were studied and compared with pure brushite cement. The pH values increased with addition of AW-GC. Additionally, the obtained brushite bone cements were characterized by XRD, SEM techniques.
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Shan, Guangcheng, Min Qiao, Jian Chen, Nanxiao Gao, Fei Shen et Qianping Ran. « Novel Slow-Release Defoamers for Concrete Using Porous Nanoparticles as Carriers ». Materials 15, no 22 (12 novembre 2022) : 7993. http://dx.doi.org/10.3390/ma15227993.
Texte intégralRésumé :
Excess large and unstable air bubbles can reduce the compressive strength of hardened concrete, and traditional defoamers always fail because of adsorption and encapsulation on cement with the progress of cement hydration in later stages. It is necessary to develop a novel defoamer that shows a sustained defoaming ability in fresh concrete. A novel slow-release defoamer for concrete using porous nanoparticles as carriers is reported for the first time. The porous nanoparticles/polyether defoamer composite (SiO2-Def) was prepared via sol-gel method. SiO2-Def is a spherical composite nanoparticle with a size range of 160–200 nm and a uniform pore size distribution. SiO2-Def shows a high load rate of about 16.4% and an excellent release under an alkali and salt environment. It has a weak initial defoaming ability but shows a sustained defoaming ability with time, so that it can avoid the failures of defoamers and eliminate harmful bubbles entrained during the processes of pumping and transportation. Moreover, SiO2-Def produced a higher compressive strength of the hardened cement mortars.
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Polonina, Elena, Olaf Lahayne, Josef Eberhardsteiner et Sergey Leonovich. « Nanoindentation of cement stone samples ». E3S Web of Conferences 212 (2020) : 02013. http://dx.doi.org/10.1051/e3sconf/202021202013.
Texte intégralRésumé :
The preliminary results of the studied cement samples were obtained by the nanoindentation method. It was revealed that the elastic modulus M increases in samples that contain a complex additive containing nanosized particles. The effect is also observed with the introduction of an additive containing only one type of nanoparticles (nanosilica sol SiO2 or carbon nanomaterial MCNT). The selection of the parameters of the nanoindentation method, which ensured the obtaining of the final consistent results, was performed. These results are presented by histograms of the distribution of nanoindentation points in modulus of elasticity M and hardness H and distributions in M and H in the horizontal XY plane perpendicular to the motion of the nanoindentor. The results obtained indicate that there is a change in the nanostructure of the C – S – H gel, which is compared with an increase in strength, Young’s moduli and shear, upon the introduction of SiO2 nanoparticles and MCNT nanoparticles.
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Shvedova, M. A., O. V. Artamonova et A. Yu Rakityanskaya. « Nanoand micro-modification of cement stone with complex additives based on SiO2 ». Вестник гражданских инженеров 18, no 6 (2021) : 105–14. http://dx.doi.org/10.23968/1999-5571-2021-18-6-105-114.
Texte intégralRésumé :
The research considers the features of the influence of nano-, ultra- and micro-additives based on SiO2 on the processes of hydration, setting, structure formation and strength gain of cement hardening systems. There was used a complex nano-scale additive based on silicon dioxide, sodium liquid glass and metakaolin. It is established that the additives used accelerate the processes of setting and hydration of cement hardening systems. The start time of setting of all modified cement systems is 210 minutes with the corresponding values of plastic strength of 577-582 kPa. Concurrently, the cement system, modified with a complex nano-scale additive based on silicon oxide after 28 days of hardening is characterized with the highest value of the hydration degree (93 %), as well as it has the high strength indicators throughout the entire hardening time (65 and 93 MPa on the 1-st and 28-th day, respectively), which is due to the formation of low- and high-base calcium hydro-silicates of various morphologies capable of forming a dense, amorphous-crystalline structure.
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Maagi, Mtaki Thomas, et Gu Jun. « Application of nanoparticles for strengthening wellbore cement-formation bonding ». Oil & ; Gas Science and Technology – Revue d’IFP Energies nouvelles 75 (2020) : 64. http://dx.doi.org/10.2516/ogst/2020052.
Texte intégralRésumé :
This study evaluates the wellbore shear bond strength of oil-well cement pastes containing nano-SiO2 and nano-TiO2 particles with an average of 20 ± 5 nm particle sizes. The nanoparticles were selected by weight of cement at proportions equivalent to 1, 2, 3 and 4%. The findings demonstrated that nanoparticles significantly increased the shear bond strength, and the strength increase was dependent on the nanoparticle types, dosage and curing period of the specimens. Due to effective pozzolanic activity, nano-SiO2 provided higher shear bond strength compared to nano-TiO2. The specimens containing 3% nano-SiO2 cured for 28 days displayed the utmost shear bond strength results (0.553 MPa). The optimal replacement dosage was 3% for all nanoparticles. The particle type did not affect the optimum nanoparticles replacement content. To examine the influence of nanoparticles on cement-formation bonding, a Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and thermogravimetric technique were used.
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Procházka, Lukáš, et Jana Boháčová. « The Role of Alkalis in Hydraulic Mixtures ». Materials Science Forum 955 (mai 2019) : 62–67. http://dx.doi.org/10.4028/www.scientific.net/msf.955.62.
Texte intégralRésumé :
Alkali substances are present in cements used as a binder in concrete only in a minimum content. The most known process that alkali causes is the alkali-silica reaction. In this reaction, the alkali contained in the cement or supplied from the outside with an inappropriately selected aggregate containing amorphous SiO2. This reaction results in the development of hydration products, resulting in an increase in the volume of the original components, which can cause a breakage of the concrete structure and subsequent disintegration. The range of alkali-silica reaction can be reduced by the use of a suitable aggregate or the use of Type II admixtures which are characterized by pozzolanic or latently hydraulic activity. These admixtures react with alkali and then no longer react with the amorphous SiO2 contained in the aggregate. Alkalis also affect other properties of concrete such as basic physical-mechanical properties, frost resistance and pH.In the experimental part the pH values were compared between mixtures of Portland cement and alkaline activated blast furnace slag using slag aggregate from the heap Koněv.
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Wang, Gang, Hua Tan, Chunjing Lu et Ao Sun. « Effect of core–shell nanocomposites on the mechanical properties and rheological behaviors of cement pastes ». RSC Advances 12, no 14 (2022) : 8310–16. http://dx.doi.org/10.1039/d1ra09283a.
Texte intégralRésumé :
The core–shell structure endowed the SiO2/PEGMA nanocomposite with multiple functions, which could not only significantly improve the cement hydration and densify the microstructure, but also efficiently enhance the fluidity of the cement pastes.
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Zozulynets, V., et O. Kovalchuk. « Prospects of development of acid–resistant hybrid cements on the basis of alkaline–activated binders ». Ways to Improve Construction Efficiency 1, no 50 (11 novembre 2022) : 15–21. http://dx.doi.org/10.32347/2707-501x.2022.50(1).15-21.
Texte intégralRésumé :
Quite often during operation, construction products and structures are exposed to aggressive environments, which leads to a decrease in their physical and mechanical characteristics and durability in general.
To date, there is a wide range of options for eliminating the effects of structural failure, and new recommendations are being developed to prevent destructive processes that take place in the body of artificial cement stone. The issue of improving the acid resistance of building materials is no exception. Unfortunately, the existing acid–resistant materials, although characterized by high resistance to operation in acidic environments, but under the influence of water and with the change of environment to neutral or alkaline, they are also destroyed. This applies directly to acid–resistant materials based on liquid glass.
An analysis of existing research has confirmed the effectiveness of using alkaline–activated binder systems as a basis for acid–resistant cements especially when comparing them with Portland cement. This is primarily due to the difference in the phase composition of their cement stone, which is characterized by the absence of highly basic hydrosilicates of calcium, etringite, free lime and the presence of alkaline and alkaline earth hydrosilicate and hydroaluminosilicate neoplasms. The latter, as research experience has shown, provide improved performance properties of materials based on alkaline–activated binders. They are also characterized by increased acid resistance. Thus, the main task of research is to determine the optimal ratio in the cement stone of the hybrid composition of the phases of the systems систем СaO – SiO2 – H2O; Na2O – CaO – Al2O3 – SiO2 – H2O and Na2O – Al2O3 – SiO2 – H2O, which will provide both hydrating properties of the binder and high acid resistance.
The concept that clearly reflects the prospects of research is to consider the main factors influencing the formation of acid–resistant phases: "composition – properties – structure – technology". To study the physicochemical conditions of synthesis it is necessary to study model systems of different compositions of R2O – CaO – Al2O3 – SiO2 – H2O, as well as study of technological factors such as component composition, cooking conditions, curing conditions. As a raw material base, it is advisable to use man–made products of industrial production, which are generally represented by slag, ash, etc.
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Mawardi, Mawardi, Illyas Md Isa, Alizar Ulianas, Edtri Sintiara, Fadhlurrahman Mawardi et Rizky Zalmi Putra. « The Fabrication of Portland Composite Cement Based on Pozzolan Napa Soil ». Materials 14, no 13 (29 juin 2021) : 3638. http://dx.doi.org/10.3390/ma14133638.
Texte intégralRésumé :
The objective of this study is to investigate Napa soil’s potential as an alternative additive in producing Portland composite cement. The Napa soil of Tanah Datar district, West Sumatra, Indonesia is a natural material which contains SiO2 and Al2O3 as its major components. The parameters used were the fineness of the cement particles, the amount left on a 45 μm sieve, the setting time, normal consistency, loss on ignition, insoluble parts, compressive strength and chemical composition. The composition of Napa soils (% w/w) used as variables include 4, 8, 12 and 16%. Furthermore, 8% pozzolan was used as a control in this research. The results showed that the compressive strength of Napa soil cement which contained 4% Napa soil was much better compared to that of the control on the 7th and 20th day. Furthermore, all the analyzed Napa soil cements met the standard of cement as stipulated in Indonesian National Standard, SNI 7064, 2016.
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Cho, S. B., Sang Bae Kim, Keon Joon Cho, Ill Yong Kim, Chikara Ohtsuki et Masanobu Kamitakahara. « In Vitro Aging Test for Bioactive PMMA-Based Bone Cement Using Simulated Body Fluid ». Key Engineering Materials 284-286 (avril 2005) : 153–56. http://dx.doi.org/10.4028/www.scientific.net/kem.284-286.153.
Texte intégralRésumé :
Novel PMMA-based bone cement using bioactive sol-gel derived CaO-SiO2 powder in order to induce bioactivity as well as to increase its mechanical property. The novel PMMA-based bone cements formed apatite on their surfaces in Simulated Body Fluid(SBF). In the present study, a change in mechanical property of the cement was evaluated using SBF. Before soaking in SBF, its compressive strength showed 80.6±2.1MPa. After soaking in SBF for 2 weeks, 8weeks and 9 weeks, its compressive strength were changed to 83.6±1.6MPa, 87.3±2.4MPa and 85.6±1.8MPa, respectively. It is clear that from the above result, there is no decrease in its compressive strength within 9 weeks soaking in SBF. That it hardly decreases in compressive strength of 7P3S bone cement in SBF is due to the relative small amount of gel powder or its spherical shape and monosize. Therefore, the newly developed PMMA-based cement can bond to the living bone and also be effectively used as bioactive bone cement without decrease in mechanical property.
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Elahi, Kamar, et 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 (8 février 2021) : 45–48. http://dx.doi.org/10.29121/ijetmr.v8.i1.2021.860.
Texte intégralRésumé :
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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Potapov, Vadim, Yuriy Efimenko, Roman Fediuk, Denis Gorev, Andrey Kozin et Yury Liseitsev. « Modification of Cement Composites with Hydrothermal Nano-SiO2 ». Journal of Materials in Civil Engineering 33, no 12 (décembre 2021) : 04021339. http://dx.doi.org/10.1061/(asce)mt.1943-5533.0003964.
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Jo, Byung-Wan, Chang-Hyun Kim, Ghi-ho Tae et Jong-Bin Park. « Characteristics of cement mortar with nano-SiO2 particles ». Construction and Building Materials 21, no 6 (juin 2007) : 1351–55. http://dx.doi.org/10.1016/j.conbuildmat.2005.12.020.
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TORICHIGAI, Takeshi, Kosuke YOKOZEKI, Minoru MORIOKA et Kenji YAMAMOTO. « REDUCTION OF THE ENVIRONMENTAL IMPACT USING CARBONATED CEMENTITIOUS MATERIALS WITH ^|^gamma;-2CaO・SiO2 ». Cement Science and Concrete Technology 63, no 1 (2009) : 161–67. http://dx.doi.org/10.14250/cement.63.161.
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Niazi, Fayez Hussain, Norhayati Luddin, Masitah Hayati Harun, Arshad Hasan, Thirumulu Ponnuraj Kannan, Suharni Mohamad et Amer Mahmood. « Dentin–Pulp Complex Response in Molars of Rats after Occlusal and Cervical Restorations with Conventional Glass Ionomer Cement and Nano-Hydroxyapatite Silica Glass Ionomer Cement ». Applied Sciences 13, no 5 (1 mars 2023) : 3156. http://dx.doi.org/10.3390/app13053156.
Texte intégralRésumé :
The purpose of this in vivo study was to evaluate and compare the dentin–pulp complex response following occlusal and cervical restorations in rat molars restored with nano-hydroxyapatite silica glass ionomer cement (nano-HA-SiO2-GIC) and conventional glass ionomer cement (c-GIC). In total, 64 maxillary first molars of 32 male Wistar rats were restored using Fuji IX (c-GIC) and nano-HA-SiO2-GIC using a split-mouth design. Half of them were reserved for the occlusal type of restoration while the other half was for cervical restorations. After one week and one month, rats were euthanized and were stained with hematoxylin and eosin, Masson’s trichrome, and Brown and Brenn techniques for histological examination. Parameters such as disorganization of the pulp tissue, inflammatory cell infiltration, detection of bacteria, and tertiary dentin deposition were measured for each group. One week after sacrifice, the odontoblastic layer was disrupted, and moderate inflammation in the pulp area close to the cut dentin was observed in both types of restorations. Nano-HA-SiO2-GIC showed significantly superior properties when assessed based on tertiary dentin formation as compared to c-GIC. One month after sacrifice, there was no evidence of disruptions of the odontoblast layer, which exhibited a normal palisade appearance in both groups. In terms of inflammation, the pulp tissue recovered in almost all cases except one of c-GIC, but a few cases of the nano-HA-SiO2-GIC group still displayed mild-to-moderate inflammatory reactions, especially of the occlusal type. Both c-GIC and nano-HA-SiO2-GIC exhibited favorable responses in terms of biocompatibility. Nano-HA-SiO2-GIC exerted more inflammation but encouraged better tertiary dentin formation compared to c-GIC.
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Wu, Xi, Xing-Lang Fan et Jin-Feng Wang. « Temperature Sensitivity of Mechanical Properties of Cement Asphalt Mortar with Nanoparticles ». Advances in Civil Engineering 2020 (31 janvier 2020) : 1–14. http://dx.doi.org/10.1155/2020/3109612.
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Cement asphalt mortar (CAM) in high-speed lines is subjected to varying environmental conditions, which lead to the deterioration of CAM. The nanoparticles of nano-SiO2 and nano-TiO2 are added to improve the performance of CAM, and the temperature sensitivity of CAM with nanoparticles is primarily studied in this paper. The flexural strength and compressive strength of CAM with and without nano-SiO2 and nano-TiO2 were measured and compared to study the effect of nanoparticles on the performance of CAM subjected to different temperatures. Temperature sensitivity factors of flexural and compressive strength based on Arrhenius model were proposed to evaluate the temperature dependence of CAM by nanoparticles. Furthermore, the microstructure of hardened CAM was studied using scan electronic microscope (SEM) to investigate the mechanism of temperature sensitivity of CAM with and without nanoparticles. The results indicated that the flexural and compressive strength of CAM with and without nanoparticles decreased with the increasing temperature; however, the decreasing rate of strength with temperature was different in CAM with and without nanoparticles. The reduction in the decreasing rate of strength was obtained by using nano-SiO2 rather than nano-TiO2 in CAM. Based on the SEM results, the free asphalt was seen to be greatly reduced in the CAM with nano-SiO2, suggesting a positive effect of nano-SiO2 on the mitigation of temperature sensitivity of CAM.
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Windarti, Tri, Widjijono Widjijono et Nuryono Nuryono. « Deposition of Hydroxyapatite on Silica Made from Rice Husk Ash to Produce the Powder Component of Calcium Phosphate Cement ». Indonesian Journal of Chemistry 21, no 3 (16 décembre 2020) : 588. http://dx.doi.org/10.22146/ijc.57900.
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Hydroxyapatite (HA) has been deposited on silica (SiO2) particles to produce HA-SiO2 composite that will be used as the powder component of calcium phosphate cement. HA was expected to be on the composite surface to maintain its bioactivity. SiO2 was made by the sol-gel method, in which silicate solution was extracted from rice husk ash with NaOH solution. Deposition of HA on SiO2 was carried out by wet chemical deposition method at various Ca/Si molar ratio (in a range of 5–25) followed by calcination at 600 °C for 2 h. Results showed that HA was successfully deposited on SiO2 particles. The cell parameters of the HA crystals were slightly distorted by the presence of SiO2 and HA in the composite had a bigger cell volume than pure HA. The crystallite size of HA in the composites increased with the increase of the Ca/Si ratio but the values were smaller than pure HA. SiO2 acted as a morphology directing agent. At low Ca/Si ratio, the HA-SiO2 particles were in a form of short rod-like particles with sizes of < 50 nm, while at high Ca/Si ratio, a mixture of short and long rod-like particles with the size of < 100 nm was obtained. The zeta potential of composites was almost similar to pure HA. These properties indicated that HA-SiO2 composites support the bioactivity of injectable calcium phosphate cement.