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.

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.

Heat-Resistant Composite Materials Based on Secondary Material Resources

2020 ◽  
Vol 299 ◽  
pp. 287-292
Author(s):  
V.D. Tukhareli ◽  
E.E. Gnedash ◽  
A.V. Tukhareli
Keyword(s):  
High Temperature ◽  
Portland Cement ◽  
Bending Strength ◽  
Cement Stone ◽  
Safety Measures ◽  
Fine Grained ◽  
Material Resources ◽  
Heat Resistant ◽  
Production Wastes ◽  
Heat Exchanges

Heat-resistant properties of the cement stone are provided by both high-temperature filler and the modified matrix on the basis of the Portland cement. For production of heat-resistant compositions as high-temperature filler, it is offered to use the secondary and accompanying products of production of carbide of silicon (SiC) and production wastes of the abrasive tools on a ceramic base. Increase in heat-resistant properties of the Portland cement knitting substance is offered to be solved by introduction to the structure of a cement composition of single substituted orthophosphate of calcium. The choice as an additive to the Portland cement a single substituted orthophosphate of calcium (double superphosphate) is proved by questions of safety measures and ecology, when using ortho-phosphoric acid and its salts for giving to cement compositions heat-resistant properties. The multicomponent composition of fine-grained concrete makes it possible to operate effectively the processes of forming the structure of cement stone at all stages of the technology, and to obtain materials with the most diverse set of properties. An introduction to the structure of a composite of 5% of filler of cyclonic dust of carbide of silicon, and a replacement of quartz filler by waste of abrasive production gave the increase of the compressive strength at 12%, bending strength for 36%. The thermal firmness increased by 3 times. An introduction to the structure of heat-resistant composition of single substituted orthophosphate of calcium (double superphosphate) in a number of 0.2% of the mass of cement allowed to increase the thermal firmness of structures to 20 heat exchanges (water, 800 oС).

Extreme Modelling of Concrete Optimal Composition and Content of the Components

2021 ◽  
Vol 887 ◽  
pp. 536-541
Author(s):  
N.P. Lukuttsova ◽  
A.A. Pykin ◽  
S.N. Golovin ◽  
P.A. Artamonov
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Bending Strength ◽  
Cement Content ◽  
Halloysite Nanotubes ◽  
Particle Sizes ◽  
Computing Environment ◽  
Fine Grained ◽  
Fiber Concrete ◽  
Micro Level

The optimal compositions of fine-grained concrete (FGC) with two-level reinforcement with fiber are determined via the extreme modelling of experimental data based on the Scilab engineering and scientific computing environment. At the macro level brass plated fibre of the wave profile FSW LV 15/0.3 made of steel grade 70-85 with the fiber length of 15 mm and the diameter of 0.3 mm was used for reinforcement. At the micro-level the halloysite nanotubes NN-RTE 200 with the particle sizes from 0.05 to 5 microns were applied. Having calculated the models the designed program Extr.sce determined the extrema of the required characteristics of fine-grained concrete Max_z and their coordinates max_x and max_y, corresponding to the contents of the brass plated fiber (x) and halloysite nanotubes additive (y). The graphic dependences of the compressive strength, bending strength and water absorption of fine-grained fiber concrete on the content of brass plated fibre and halloysite nanotubes additive with minimum, average and maximum cement content in it in the form of contour and 3d graphs of the interpolation surface are obtained. Two-level reinforcement of FGC, optimized by the program Extr.sce, proved that fine-grained concrete with 10% of brass plated fibre, 20% of halloysite nanotubes additives, and cement content of 600 kg had the maximum compressive strength of 70.26 MPa. In order to obtain FGC with maximum bending strength (17.43 MPa), there should be 5% of brass plated fibre, 10% of halloysite nanotubes additives, and 600 kg of cement in it. The fine-grained concrete without any reinforcement additives will have the minimum water absorption (3%).

Study Of Structure Formation Of Organic-Mineral Compositions With Fibrous Filler By Electron Microscopy Method

2019 ◽  
pp. 41-47
Keyword(s):  
Electron Microscopy ◽  
Structure Formation ◽  
Mineral Composition ◽  
Bending Strength ◽  
Cement Stone ◽  
Hydrated Cement ◽  
Fibrous Filler ◽  
Organic Mineral ◽  
Microscopy Method ◽  
Mineral Compositions

The article presents the study of processes of structure formation of cement stone and products of hardening of organic-mineral compositions with fibrous filler (shavings) by the electronic scanning microscopy method. It is established that the additive-free cement stone at the age of 28 days has a dense and homogeneous structure, consists of calcium hydro-silicates, Portlandite and calcite - newgrowths characteristic for cement systems. Cellulose fibers, which make up the bulk of the substance of shavings, are sufficiently active, which determines the high adhesion of the hydration products of the cement binder to their surface. It is shown that the introduction of shavings into the organo-mineral composition leads to inhibition of cement hydration processes. Organo-mineral compositions with different shavings content (two compositions) were analyzed. The first composition is characterized by a fairly dense structure, the cement stone consists of globular nanoscale nuclei of hydrosilicates, Portlandite and calcite. The second composition has a loose porous structure, cement stone consists of non-hydrated cement grains, newgrowths are represented by calcite and vaterite. The structure of the contact zone "osprey fiber-cement stone" in the organo-mineral composition of the first composition indicates a good adhesion of the filler surface with the phases of hydrated cement. The use of shavings as a fibrous filler (the first composition) increases the tensile and bending strength, as well as the wear resistance of organo-mineral compositions. The data obtained by scanning electron microscopy are confirmed by the results of studying the processes of structure formation of cement stone by quantitative x-ray phase analysis.

The Research on Preparation of Binding Material and Concrete with Desulphurization Gypsum

2014 ◽  
Vol 697 ◽  
pp. 17-20
Author(s):  
Ping Tan
Keyword(s):  
Environmental Pollution ◽  
Bending Strength ◽  
Experimental Results ◽  
Cement Stone ◽  
Waste Sludge ◽  
Binding Material

The binding material and concrete are prepared by desulphurization gypsum, cement, stone, sand and admixture. The performances of binding material are studied in the paper. The experimental results showed that it is absolutely feasible to prepare binding material by using cement, desulphurization gypsum and superplasticizer after drying and screening of desulphurization gypsum. The binding material was prepared by adding desulphurization gypsum replacing 10 percent cement and superplasticizer. the cement micellae compressive and bending strength of the binding material can meet the standard requirements of P.O42.5 and the binding material’s set time and soundness are up to standard. The concrete was prepared by adding desulphurization gypsum replacing 30 percent cement and superplasticizer. The concrete’s strength is up to standard of the C30 concrete, and its impermeability meets the requirement of P12. To execute the research can not only massively use waste sludge desulphurization gypsum but also solve environmental pollution.

scholarly journals Mechanical Milling-Assisted Spark Plasma Sintering of Fine-Grained W-Ni-Mn Alloy

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1323 ◽  
Author(s):  
Yanlin Pan ◽  
Daoping Xiang ◽  
Ning Wang ◽  
Hui Li ◽  
Zhishuai Fan
Keyword(s):  
Spark Plasma Sintering ◽  
Mechanical Milling ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Interface Fracture ◽  
Composite Powders ◽  
Fine Grained ◽  
Plasma Sintering ◽  
Binding Phase ◽  
Spark Plasma

Fine-grained W-6Ni-4Mn alloys were fabricated by spark plasma sintering (SPS) using mechanical milling W, Ni and Mn composite powders. The relative density of W-6Ni-4Mn alloy increases from 71.56% to 99.60% when it is sintered at a low temperature range of 1000–1200 °C for 3 min. The spark plasma sintering process of the alloy can be divided into three stages, which clarify the densification process of powder compacts. As the sintering temperature increases, the average W grain size increases but remains at less than 7 µm and the distribution of the binding phase is uniform. Transmission electron microscopy (TEM) observation reveals that the W-6Ni-4Mn alloy consists of the tungsten phase and the γ-(Ni, Mn, W) binding phase. As the sintering temperature increases, the Rockwell hardness and bending strength of alloys initially increases and then decreases. The optimum comprehensive hardness and bending strength of the alloy are obtained at 1150 °C. The main fracture mode of the alloys is W/W interface fracture.

Synthesis and Properties of Fe3O4 Ferrofluids with Narrow Particle Size Distribution

2011 ◽  
Vol 694 ◽  
pp. 575-579
Author(s):  
Jian Hui Zhang ◽  
Hai Bo Sun
Keyword(s):  
Magnetic Particles ◽  
Particle Diameter ◽  
Free Form ◽  
Narrow Particle Size Distribution ◽  
Particle Sizes ◽  
Bingham Plastic ◽  
Plastic Fluid ◽  
Form Model ◽  
The Mean ◽  
Inference Theory

Fe3O4 ferrofluids with uniform magnetic particles were prepared via improved chemical coprecipation technique. A narrow distribution of 8.6-10.8 nm particle sizes was obtained from the magnetization curve using the free-form-model based on Bayesian inference theory. The mean particle diameter about 9.8 nm is consistent with the XRD and SEM results. The hydrodynamic properties of ferrofluids were investigated with different applied magnetic field and shear rate. The experimental results show that diluted ferrofluid and concentrated ferrofluid are Newtonian-fluid and Bingham-plastic fluid, respectively.

The Effect of Preliminary Mechanical Activation on the Structure and Mechanical Properties of Ni3Al+B Material Obtained by SPS

2017 ◽  
Vol 743 ◽  
pp. 19-24 ◽  
Author(s):  
Lilia I. Shevtsova ◽  
Anatoliy A. Bataev ◽  
Vyacheslav I. Mali ◽  
Maksim A. Esikov ◽  
Veronika V. Sun Shin Yan ◽  
...  
Keyword(s):  
Mechanical Activation ◽  
Bending Strength ◽  
Stoichiometric Composition ◽  
Initial Mixture ◽  
Optical Microscope ◽  
Fine Grained ◽  
Plasma Sintering ◽  
Fine Grained Structure ◽  
Spark Plasma ◽  
Almost All

In the present study, a mixture of powders (87.9 at.% Ni, 12 at.% Al, 0.1 at.% B) was used as the initial material to produce sintered Ni3Al + B alloy. Spark Plasma Sintering (SPS) method was used to compact the powder. The powder mixtures were previously prepared in two ways: mixing the initial powders in a mortar (М1) and mechanical activation (М2). The microstructure was observed using optical microscope (OM). The addition of small amount of boron to the initial mixture of nickel and aluminum improves the density of the sintered Ni3Al intermetallic compound (98.8%). The results of density, bending and microhardness tests showed, that the provisional three-minute mechanical activation improves almost all properties of the sintered material. The compact obtained by SPS by M2 contributes to the formation of a homogeneous fine-grained structure of the material. It leads to further increase in flexural bending strength up to 2200 MPa. This value is almost 8 times the strength of the intermetallic Ni3Al stoichiometric composition obtained by SPS.

Effects of Particle Size and Method of Milling on Determination of Morphine in Papaver somniferum L. Straw

1982 ◽  
Vol 65 (3) ◽  
pp. 651-654
Author(s):  
Beatriz Ferreira Engelke ◽  
Phillip G Vincent
Keyword(s):  
Particle Size ◽  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Reproducibility Of Results ◽  
Ball Mill ◽  
Papaver Somniferum ◽  
Particle Sizes ◽  
Morphine Content

Abstract Different particle sizes of blade- and ball-milled poppy straw were separated and analyzed for morphine by high pressure liquid chromatography. Morphine content varied up to 70% among the different size particles. This may account for discrepancies observed in percentages of morphine found among random aliquots. Homogenizing a carefully quartered sample of blade-milled straw by further pulverization in a percussion ball mill 2 min and taking a quartered aliquot for morphine analysis improved the reproducibility of results.

scholarly journals Mechanical properties of microwave sintered Si3N4-based ceramics

2002 ◽  
Vol 34 (3) ◽  
pp. 223-229 ◽  
Author(s):  
O.I. Getman ◽  
V.V. Holoptsev ◽  
V.V. Panichkina ◽  
I.V. Plotnikov ◽  
V.K. Soolshenko
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Normal Pressure ◽  
Ceramic Materials ◽  
Particle Sizes ◽  
Phase Measurements ◽  
Ceramic Samples ◽  
Mean Size ◽  
The Mean

The mechanical properties and microstructure formation processes in Si3N4+3% AI2O3+5% Y2O3(Yb2O3) ceramic compacts sintered under microwave heating (MWH) and under traditional heating (TH) were investigated. The initial ceramic materials were powder blends of silicon nitride with oxides. The mean powder particle sizes were 0.5-1.0 mim. The content of alfa-phase in the Si3N4 powder was more than 95 %. The samples were sintered at 1800BC in nitrogen at normal pressure, the heating rate in all experiments was 60BC/min. The Vickers hardness (HV), fracture toughness (K1C) and bending strength (on) were determined. The microstructures of fracture surfaces of samples were studied by SEM. Quantitative microstructure analysis was carried out. It was shown that the values of HV and Kic of ceramic samples sintered under MWH at 1800BC rose steadily with the sintering time. This caused an increase in density, which reached maximum as fast as after 30 min of the MWH sintering; the mass loss at that time amounted to 3-4 %. The porosity of sintered samples with an addition of yttria was less than 1 %, that of ytterbia was greater, 2.4 %. For similar values of relative density, the hardness and fracture toughness of ceramic samples produced under MWH were higher as compared with those of samples sintered under TH. The microstructure of samples had the form of elongated grains in a matrix of polyhedral grains of the beta-Si3N4 phase. Measurements showed the mean size of grains in samples produced by MWH to be greater that in samples produced by TH. A larger number of elongated grains were formed. It was concluded that for sintering under MWH of Si3N4-based ceramics the growth of elongated beta-Si3N4 grains and formation of a "reinforced" microstructure were promoted and thereby improved the mechanical properties of such ceramics.

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