Effective Fine Concrete Modified with a Highly Dispersed Wollastonite-Based Additive

2021 ◽  
Vol 887 ◽  
pp. 422-427
Author(s):  
E.G. Karpikov ◽  
N.P. Lukuttsova ◽  
T.P. Blagoder ◽  
E.A. Bondarenko
Keyword(s):  
Raw Materials ◽  
Particle Diameter ◽  
Solid Particles ◽  
Average Particle ◽  
Ultrasonic Dispersion ◽  
Fine Grained ◽  
Highly Dispersed ◽  
Surface Active ◽  
Portland Slag Cement ◽  
Polycarboxylate Ether

An effective highly dispersed additive based on the wollastonite Miwoll 05-97 with an average particle diameter of 6.5 microns is obtained. A stable effect of interacting the additive components with Portland slag cement CEM II/A–Ш 42.5H is revealed; it results in improving the strength of fine-grained concrete produced with the raw materials mentioned above. It is established that using water suspension of wollastonite solid particles, highly water-reducing/superplasticizing modifier based on the polycarboxylate ether Master Glenium 430, as a stabilizer of the surface-active substance allows producing an additive with an evener distribution of solid particles in the liquid, and with stable functional properties. A highly dispersed wollastonite-based additive, obtained by ultrasonic dispersion for 10 minutes in the bath-type activator at the frequency of 35 kHz in the aquatic environment with a suspension stabilizer, enables producing the wollastonite-modified fine concrete with a compressive strength of more than 50 MPa, with the 10% additive being 2 times higher than that of the control.

Experimental Investigation of Convective Melting of Granular Packed Bed Under Microgravity

2000 ◽  
Author(s):  
J. Jiang ◽  
Y. Hao ◽  
Y.-X. Tao
Keyword(s):  
Experimental Investigation ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Vertical Direction ◽  
Packed Bed ◽  
Melting Rate ◽  
Control Flow ◽  
Solid Particles ◽  
Average Particle ◽  
Ice Particles

Abstract To improve the understanding of convective melting of packed solid particles in a fluid, an experimental investigation is conducted to study the melting characteristics of a packed bed by unmasking the buoyancy forces due to the density difference between the melt and solid particles. A close-loop apparatus, named the particle-melting-in-flow (PMF) module, is designed to allow a steady state liquid flow under a specified temperature. The module is on board NASA’s KC-135 reduced gravity aircraft for the experiments. In the test module, water is used as the fluid, and ice particles are fed to the test section at the beginning of the test. As the liquid flows though the bed, the solid grains melt. A perforate plate, through which liquid can flow while the ice particles are retained, bounds the downstream of the packed bed. From the digital video images the local packed bed thickness is measured under control flow rate, and the melting rate is determined. The temperature distribution along the horizontal direction and vertical direction is measured using 19 thermocouples. An infrared camera is mounted to record the local temperature variation between liquid and solid. The melting rates are presented as a function of upstream flow velocity, temperature and initial average particle size of the packed bed. It is found that the melting rate is influenced mainly by the ratio of the Reynolds number (Re, based on the initial particle diameter) to the square of the Froud number (Fr), and me Stefan number (Ste). In general, the dimensionless melting rate decreases as Re/Fr2 increases and increases as Ste increases. With the absence of gravity, i.e., Froud number approaches infinity, a maximum melting rate can be achieved for otherwise the same test conditions. The increase in the melting rate with the increase in Stephan number also becomes more pronounced under the zero gravity condition.

Minimum Particle Diameter of the Vanadium/Iron Co-Doped Nano TiO2 Transparent Hydrosol at Room Temperature

2014 ◽  
Vol 989-994 ◽  
pp. 611-614
Author(s):  
Ling Li ◽  
Wen Ming Zhang ◽  
Hua Yan Zhang ◽  
Zi Hao Xu ◽  
Sen Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Raw Materials ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Ferric Nitrate ◽  
Average Particle ◽  
Hydrolysis Method ◽  
Vanadium Iron ◽  
Co Doped

Vanadium/iron co-doped nanoTiO2 transparent hydrosol with an average particle size of 3.8 nm was synthesized by a novel complexation-controlled hydrolysis method at room temperature and atmospheric pressure by using TiCl4, ferric nitrate, ammonium metavanadate, etc. as raw materials. The composition, phase structure, particle size, absorbance spectrum, and photocatalytic performance of samples were characterized by XRD, EDS, nanolaser particle size analyzer, and UV-Vis spectrophotometer. The photocatalytic properties of V/Fe doped TiO2 were studied through degrading acid 3R dye, and the results show that when the content of V/Fe was 0.5%, the degradation rate reached more than 96% under irridation for 60 min.

Experimental Investigation of Convective Melting of Granular Packed Bed Under Microgravity

2002 ◽  
Vol 124 (3) ◽  
pp. 516-524 ◽  
Author(s):  
J. Jiang ◽  
Y. Hao ◽  
Y.-X. Tao
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Froude Number ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Packed Bed ◽  
Melting Rate ◽  
Solid Particles ◽  
Average Particle ◽  
Stefan Number

To improve the understanding of convective melting of packed solid particles in a fluid, an experimental investigation is conducted to study the melting characteristics of a packed bed by unmasking the buoyancy forces due to the density difference between the melt and solid particles. A close-loop apparatus, named the particle-melting-in-flow (PMF) module, is designed to allow a steady-state liquid flow at a specified temperature. The module is installed onboard NASA’s KC-135 reduced gravity aircraft using ice particles of desired sizes and water as the test media. Experimentally determined melting rates are presented as a function of upstream flow velocity, temperature and initial average particle size of the packed bed. It is found that the melting rate is influenced mainly by the ratio of the Reynolds number (Re, based on the initial particle diameter) to the square of the Froude number (Fr), and the Stefan number (Ste). In general, the dimensionless melting rate decreases as Re/Fr2 increases and increases as Ste increases. With the absence of gravity, i.e., as the Froude number approaches infinity, a maximum melting rate can be achieved. The increase in the melting rate proportional to the Stefan number also becomes more pronounced under the zero gravity condition. The trend of average and local Nusselt number of the melting packed bed under microgravity, as a function of Reynolds number and Prandtl number, is discussed and compared with the case of nonmelting packed bed.

scholarly journals EFFECT OF MICROFILLERS BASED ON NATURAL WOLLASTONITE ON PROPERTIES OF FINE-GRAINED CONCRETE

2020 ◽  
pp. 20-28 ◽  
Author(s):  
E. Karpikov ◽  
N. Lukutcova ◽  
G. Soboleva ◽  
S. Golovin ◽  
Yu. Cherenkova
Keyword(s):  
Anionic Surfactant ◽  
Ball Mill ◽  
Bending Strength ◽  
Particle Diameter ◽  
Cement Stone ◽  
Particle Sizes ◽  
Ultrasonic Dispersion ◽  
Fine Grained ◽  
Amorphous Nature ◽  
Type C

The possibility of obtaining effective highly dispersed additives from natural wollastonite is substantiated and their influence on the properties of fine-grained concrete is investigated. On the basis of wollastonite, a complex micro-filler with particle sizes up to 100 microns was developed, obtained by joint grinding with quartz sand in a 3:1 ratio in a ball mill in the presence of an anionic surfactant naphthalene-formaldehyde type C-3 and a calcium stearate hydrophobizer technical C-17. A suspension of wollastonite with a modal particle diameter of 405 nm was obtained by pre-grinding wollastonite and anionic surfactant in a ball mill, with their further ultrasonic treatment in a bath-type activator. Mathematical models of the dependence of compression and bending strength on the content of the initial components are developed. It is established that the complex microfill leads to an increase in the strength of fine-grained concrete in bending by 2 times, in compression by 1.7 times with its content in the composition of fine-grained concrete in the amount of 10% by weight of cement. Wollastonite suspension increases the bending strength of fine-grained concrete to 3.1 MPa, compression to 57.8 MPa. The results of qualitative x-ray phase analysis showed that the total intensity of diffraction maxima of not fully hydrated alite C3S, belite C2S grains and their aggregates in cement stone with wollastonite decreases by 1.5-2 times compared to the control composition. This is most likely due to the amorphous nature of the wollastonite surface after grinding in a ball mill and ultrasonic dispersion in a bath-type activator. In addition, such particles are the centers of crystallization. Their needle-like shape contributes to the reinforcement of the structure by crystallizing new formations of cement stone.

The Preparation of TiO2 Film Loaded on Fiberglass Mesh and the Experimental Study on Its Photocatalytic Properties

2010 ◽  
Vol 150-151 ◽  
pp. 1421-1424 ◽  
Author(s):  
Man Wang ◽  
Wei Chen ◽  
Cheng Liu
Keyword(s):  
Humic Acid ◽  
Acid Solution ◽  
Photocatalytic Oxidation ◽  
Degradation Rate ◽  
Sol Gel ◽  
Particle Diameter ◽  
High Photocatalytic Activity ◽  
Solid Particles ◽  
Raw Material ◽  
Average Particle

The TiO2 film loaded on fiberglass mesh was prepared by sol-gel method using butyl titanate as raw material, and the catalyst was characterized by scanning electron microscopy (SEM) and X-ray diffraction(XRD).The catalyst surface of loaded TiO2 can obviously observe solid particles and agglomeration to some extent, the crystalline phase was anatase, and no rutile was observed, the average particle diameter of TiO2 was 40nm,Under the ultraviolet light UV-C irradiation, the photocatalytic oxidation experiments of humic acid solution was conducted. The results showed that the prepared photocatalyst has a high photocatalytic activity, the UV254 degradation rate of humic acid solution in 60min reached 96.9%, but the degradation rate of TOC is only 57.3%, indicating that the organisms in humic acid can not be completely mineralized in photocatalytic oxidation process.

Minimum Particle Diameter of the Sulfur-Doped Nano-TiO2 Transparent Hydrosol at Room Temperature

2014 ◽  
Vol 587-589 ◽  
pp. 788-791
Author(s):  
Ling Li ◽  
Hua Yan Zhang ◽  
Xiao Wei Li ◽  
Zi Hao Xu ◽  
Sen Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Photocatalytic Performance ◽  
Raw Materials ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Synthesis Process ◽  
Average Particle ◽  
Hydrolysis Method ◽  
Particle Size Analyzer

Sulfur-doped nanoTiO2transparent hydrosol with an average particle size of 3.8 nm was synthesized by a novel complexation-controlled hydrolysis method at room temperature and atmospheric pressure by using TiCl4, thiourea, organic carboxylic acid, NH3H2O, D-sorbitol etc. as raw materials. The composition, phase structure, particle size, absorbance spectrum, and photocatalytic performance of samples were characterized by XRD, nanolaser particle size analyzer, ultraviolet-visible spectrophotometer. In addition, the influence of reaction conditions in the synthesis process was also studied. The results indicate that when nanoparticle doped with 0.5% S, and the reflux time was 15 min, the photocatalytic performance of sulfur-doped TiO2hydrosol was best.

Fine-Grained High-Strength Concrete

2019 ◽  
Vol 945 ◽  
pp. 131-135 ◽  
Author(s):  
N.P. Lukutsova ◽  
G.N. Soboleva ◽  
S.N. Golovin ◽  
E.V. Chivikova ◽  
E.V. Ogloblina
Keyword(s):  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Ultrasonic Dispersion ◽  
Positive Role ◽  
Strength Concrete ◽  
Fine Grained ◽  
Mineral Components ◽  
Surface Active

The factors determining the production of fine-grained high-strength concrete are considered. The effect of micro-and complex nanodisperse additives based on natural mineral components, as well as the packing density of the quartz aggregate, on the strength parameters of fine-grained concrete is studied. The compositions of the fine-grained concrete modified by micro-and complex nanodisperse additives have been developed. The dependence of the fine concrete strength on the ratio of the mineral component and the stabilizer in the nanodisperse additive and the time of ultrasonic dispersion and additive storage is analyzed. The stabilization mechanisms of water dispersions of complex nanodisperse additives by various surface active modifiers are considered. The positive role of ultrasonic dispersion in obtaining nanodispersed additives is shown. The application efficiency of the micro-filler improving the density and strength of fine-grained concrete is revealed. The structure of fine-grained concrete is studied. It has been established by scanning electron microscopy that the introduction of the micro-and nanodispersed additives in the concrete leads to a less defective crystalline structure of the material.

Effective Fine-Grained Concrete with High-Dispersed Additive Based on the Natural Mineral Wollastonite

2019 ◽  
Vol 945 ◽  
pp. 85-90 ◽  
Author(s):  
E.G. Karpikov ◽  
N.P. Lukutsova ◽  
E.A. Bondarenko ◽  
V.V. Klyonov ◽  
A.E. Zajcev
Keyword(s):  
Raw Materials ◽  
Selective Adsorption ◽  
Aggregate Stability ◽  
Rheological Parameters ◽  
Ultrasonic Dispersion ◽  
Natural Mineral ◽  
Fine Grained ◽  
Deformation Properties ◽  
Strength And Deformation ◽  
Micro Fillers

Micro-fillers based on natural mineral wollastonite, modifying fine-grained concrete and improving its physical and mechanical characteristics, are developed and studied. The influence of the most common stabilizers on the aggregate stability of wollastonite-based microdispersed systems in the aquatic dispersion environment is considered. The optimal parameters, ensuring the production of micro-fillers in the form of stable suspensions, are developed. The application efficiency of the wollastonite-based filler due to its micro-reinforcing properties is revealed. These properties are specified by the formation of needle-shaped crystals by the ultrasonic dispersion in the aquatic environment, chemically related to cement-containing raw materials and contributing to the active selective adsorption of the binder hydration products. It has a significant influence on the rheological parameters of cement composites, on structure formation, as well as on their strength and deformation properties.

Preparation of Silica Nanoparticles Using Silica-Rich Filtrate from Potassium-Rich Rock

2010 ◽  
Vol 160-162 ◽  
pp. 1372-1377
Author(s):  
Cong Cong Yin ◽  
Hong Bin Qi ◽  
Xiao Chao Chen ◽  
Zhi Hui Wang
Keyword(s):  
Silica Nanoparticles ◽  
Raw Materials ◽  
Average Particle Size ◽  
Chemical Precipitation ◽  
Precipitation Process ◽  
Average Particle ◽  
Dispersion Method ◽  
Ultrasonic Dispersion ◽  
Uniform Size ◽  
Size Of Particles

The silicon-rich filtrate which was obtained from the desilication solution of potassium-rich rock was used as raw materials to prepare nanometer sillica and ultrasonic dispersion method was applied to the chemical precipitation process. A detailed study was carried out on the effect of filtrate concentration, surfactant dosage, reaction temperature, calcinations temperature, ultrasonic dispersion on size of silica nanoparticles. The basic properties and size of particles were characterized by means of FE-SEM, TEM, XRD, TGA and FTIR. The results obtained in the study indicated that monodisperse and uniform-size silica nanoparticles were prepared using ultrasonication by chemical precipitation process and the average particle size was 50 nm.

Effective Highly Dispersed Additive for Concretes on the Basis of Natural Mineral Raw Materials

2020 ◽  
Vol 992 ◽  
pp. 168-172
Author(s):  
E.G. Karpikov ◽  
N.P. Lukuttsova ◽  
E.A. Bondarenko
Keyword(s):  
Compressive Strength ◽  
Bending Strength ◽  
Raw Materials ◽  
Chemical Activation ◽  
Raw Material ◽  
Experiment Planning ◽  
Water Medium ◽  
Natural Mineral ◽  
Fine Grained ◽  
Highly Dispersed

The composition of a highly dispersed additive for concrete based on the natural mineral raw material wollastonite is developed. The properties of the modified fine-grained concrete (FGC) are studied. The three-factor experiment planning made it possible to obtain mathematical dependences of the bending and compressive strength after 3 and 28 days of hardening, density, and water-cement ratio of the fine-grained concrete on such factors as the content of anionic surfactant of naphthalene-formaldehyde type in the composition of the raw material wollastonite being an activator of mechanic-chemical processing, the suspension stabilizer of the pre-activated material, and the content of S-3+wollastonite in powder after mechanic-chemical activation in the suspension. The dependence nomograms are built. The optimal strength parameters of the modified fine-grained concrete with the content of a highly dispersed additive of 5% by weight of cement in its composition, and the wollastonite concentration of 3 g/l in the water medium of the suspension stabilizer S-3 are ascertained. The developed highly dispersed additive allows obtaining fine-grained concrete with the bending strength of 3.1 MPa and the compressive strength of 57.8 MPa.

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