English English

Archives

ANALYSIS OF THE INFLUENCE OF THE QUALITATIVE COMPOSITION OF THE ASPHALT-CONCRETE MIXTURE ON THE MAIN PERFORMANCE CHARACTERISTICS OF ASPHALTIC CONCRETE PAVEMENT

https://doi.org/10.34031/2618-7183-2019-2-1-17-23
 17-23 p.
Abstract
The paper presents an analysis of information quality assurance of production of asphalt concrete mixtures, as well as the study of the relationship of the qualitative composition of asphalt concrete mixtures and physical and mechanical characteristics of asphalt concrete pavement. The study of the main characteristics was carried out on the example of asphalt concrete type B and grade I and crushed-mastic asphalt concrete – SchMA-20. It is established that the deviation of asphalt mixtures in composition from the required values leads to their under-compaction in the pavement. It is also established that increasing the number of inconsistencies in the asphalt concrete mixture leads to an increase of physical-mechanical characteristics that differ from the requirements of GOST 9128-2013 and GOST 31015-2002 respectively. As an information base for the assessment of the influence of granulometry of the mineral part of asphalt concrete, as well as the amount of bitumen on the main characteristics of asphalt concrete, the data of the current ACP of Belgorod region were used. Analysis of the particle size distribution was carried out using a laser analyzer of asphalt ABA7/35B. The obtained data became the basis for a further study of the influence of various parameters on the properties of asphalt mixes, as well as improving the efficiency of the asphalt mix production management system.
PDF

ANALYSIS OF THE FACTORS INFLUENCING THE CHOICE OF INSULATION SYSTEMS OF EDUCATIONAL INSTITUTIONS

https://doi.org/10.34031/2618-7183-2019-2-1-24-31
,
 24-31 p.
Abstract
The article raises the problem of improving the energy efficiency of buildings in operation with a constant increase in energy prices, which is now becoming increasingly important. The analysis of the design deci-sions of the buildings of educational institutions of Donetsk region was carried out; the main typical series of the region were highlighted and given. The issues and the factors affecting the heat and moisture characteristics of enclosing structures of educational institutions were discussed. The values of resistance to heat transfer for the most common standard series of secondary schools are given. The modeling of temperature fields of nodes of public buildings of standard series was made. The most unfavorable design solutions of serial buildings were identified by the following factors: the temperature of the inner surface of the outer enclosures and the temperature difference between the average temperature at the surface and the air temperature in the room. Possible ways of thermo-modernization of such buildings with consideration of the requirements for temperature and breathability are considered. The influence of heat-conducting inclusions on the heat-moisture regime of external enclosing structures during partial and full thermal modernization is estimated. The analysis of various methods and ways of warming the buildings of educational institutions are performed. The advantages and disadvantages of the proposed options from an economic point of view are indicated, as well as on the basis of the requirements of fire regulations.
PDF

INVESTIGATION OF THE STRESS CONDITION OF RIVETED JOINTS BY FINITE ELEMENT METHOD

https://doi.org/10.34031/2618-7183-2019-2-1-32-36
, ,
 32-36 p.
Abstract
Traditional methods of calculation of rivet joints are based on very approximate methods of determining the forces arising in the connection. This leads to serious inaccuracies in the determination of stresses. In addi-tion, this approach makes it impossible to calculate equivalent stresses and obtain a complete picture of the stress-strain state of the joint. All this leads to the need to increase the factor of safety and, as a consequence, increase the number or diameter of rivets, which leads to an increase in the weight of the structure and its rise in price. The proposed method of calculating the connection by the finite element method allows to determine the stresses in all elements of the connection very accurately. This makes it possible to obtain a reliable picture of the stress-strain state of all elements of the compound. As a result, it is possible to reduce the complexity of the compound and its mass by reducing the number of rivets. The finite element method should be used to calculate critical compounds with complex operating conditions. The example of calculation of such connection is considered.
PDF

TRUSS DESIGN CALCULATION

https://doi.org/10.34031/2618-7183-2019-2-1-37-44
, ,
 37-44 p.
Abstract
The completeness of the truss design calculation is its configuration and dimensions when specifying the type of loading, material characteristics and directive dimensions. The problem of equilibrium stability with an unknown location of compressed rods hindered the optimization of the topology and geometry of the truss. The proposed variational method of truss synthesis is based on the principle of possible operation and generalization of the variational principles of Lagrange and Castigliano by expanding the functional space of geometric parameters. The solution of a physically linear isoperimetric problem for a given volume of the truss material allowed to establish its quasi-equal stress, which became the design criterion for the formulation of the geometry optimization problem. Its condition is the stationarity of the functional with respect to variable geometric parameters for a given flexibility of compressed rods. The iterative procedure, caused by a change in the initially accepted signs of longitudinal forces, is based both on their direct adjustment and on the change in the flexibility of individual rods. The global minimum of potential strain energy of the optimal truss is accompanied by a global minimum of material consumption. The proposed software allows to conduct automated design calculation of the truss. An example of designing a mechanical truss is considered.
PDF

VITREOUS PROTECTIVE AND DECORATIVE COVERINGS ON WOOD PARTICLE BOARD

https://doi.org/10.34031/2618-7183-2018-1-4-4-12
, , , ,
 4-12 p.
Abstract
Scientific and technological bases of receiving vitreous coverings on wood with use of a torch of low-temperature plasma are developed. Before plasma dusting of glass powders by grain structure 60-120mkm, the special protective coating protecting chipboard from destruction at high-temperature influence of a plasma stream on a front surface of the wood particle board (WPB) was applied. The structure of an intermediate protective coating including mix of a fine-grained glass powder and liquid glass is developed. Preliminary drawing an intermediate protective layer provides several consecutive technological operations.
For receiving vitreous coverings fight of colored and colourless glass are used which was previously ground in spherical porcelain mills. Optimum process parameters of plasma dusting of glass powder on the front surface of chipboard are developed. Optimum parameters of plasma melting is: current - 800A; operating voltage – 30B, a consumption of plasma-forming gas of argon 2m3/h.
Operational and aesthetic-consumer properties of vitreous protective and decorative coverings are investigated. It is established that vitreous protective and decorative coverings have the high durability of coupling with an intermediate protective layer. The received vitreous protective and decorative coverings on the basis of colored and colourless glass have the high water resistance, acid resistance, alkali resistance, as well as microhardness and high aesthetic performance.
The technology is recommended for widespread industrial introduction.
PDF

OPTIMIZATION OF RAW MIX COMPOSITION OF SEREBRYANSKY CEMENT PLANT

https://doi.org/10.34031/2618-7183-2018-1-4-13-20
, ,
 13-20 p.
Abstract
Now a top trend of technical development in the cement industry of Russia, is optimization of all technological repartitions of production. Obtaining the quality portlandtsement is multiple-factor process. It is influenced not only by the physical and chemical transformations of raw materials occurring during the firing of cement clinker, but also what will be the composition of the raw mixture and whether this mixture is prepared qualitatively. Work consists in a research and selection of an optimum compounding of raw mix, with the purpose to receive cement with high rates of quality. This direction will allow: first, to expand a source of raw materials, to process raw materials which go to dumps because in it is mute a large amount of quartz and impurity connections contains; secondly, to make small reconstruction of the line of preparation of raw mix. At the moment, the plant works on mixed mixtures of aluminosilicate raw materials, i.e. two types of aluminosilicate raw materials which are previously mixed in certain ratios therefore it affects on the accuracy of dispensing of components are used. Accuracy of dispensing of modern batchers, a component ± (1 … 2) %, is often insufficient. In this regard, the new option of optimum composition of mix is offered and investigated. This option of a "clean" mixing of components, will allow to improve process of mixing of initial raw materials, to operate process of drawing up proportions of mixes in a supply line of materials. And also it will allow to eliminate long-term deviations, guaranteeing the solution of problems at the earliest stage of their emergence. Receiving a qualitative ready-made product, reduction of costs for energy resources and cost efficiency of the proposed solution is result of this work.
PDF

INFLUENCE OF SiO2 CRYSTAL STRUCTURE ON THE THERMAL CYCLE OF POLYMER COMPOSITES

https://doi.org/10.34031/2618-7183-2018-1-4-21-29
,
 21-29 p.
Abstract
Polymer composites are widely used in the space industry for the manufacture of spacecraft, satellite panels, antennas, thermostatically controlled coatings, etc. In space, they are subjected to harsh environmental con-ditions, such as ultraviolet, deep vacuum, atomic oxygen, charged particles, anthropogenic debris, micrometeoids, electromagnetic radiation and thermal cycles that cause severe degradation of the material. One of the most important environmental effects of materials based on polymers is the thermal cycle, in which the composite undergoes a large temperature difference from -170˚C to + 200˚C. The paper presents an assessment of the use of composites based on a polyalkane-rich matrix and a filler in the form of an SiO2 amorphous and crystalline structure under thermal cycling conditions. The data on the change in tensile strength, modulus of elasticity in tension and relative elongation in tension of materials after several cycles of a sharp differential temperature (from -190 to +200°C) are presented. The thermal cycle was repeated 5, 10 and 20 times. It is shown that the sample polyalkanimide has a large value of tensile strength and elastic modulus compared with highly filled composites.However, during thermal cycling there is a significant decrease in these parameters.For a highly filled composite sample with 65% crystalline SiO2 content, the decrease in tensile strength and elastic modulus after thermal cycling is insignificant and is within the measurement error. A composite with amorphous SiO2 is more susceptible to a change in mechanical properties after thermal cycling in comparison with a composite containing crystalline SiO2.
PDF

STUDY OF THE EFFECT OF PARTICULATE ADDITIVES ON THE SETTING TIME AND MICROSTRUCTURE OF HIGH-ALUMINA CEMENT

https://doi.org/10.34031/2618-7183-2018-1-4-30-37
, , , ,
 30-37 p.
Abstract
The paper is devoted to a full-scale study of corundum modifying dispersed additives (reactive, tabular, dispersing alumina) and artificial ceramic binder, their impact on high-alumina cement microstructure and setting time. Artificial ceramic binders are characterized by similar chemical, phase and grain composition with modifying corundum additives and characterized by the presence of particles less than 100 nm (up to 0.5%). The studied materials are finely dispersed polyfractional systems from 0.1 to 13 μm with a prevailing grading fraction of 2-10 μm. In this case, dispersing and reactive alumina are more coarse. Using the microscopy method it was established that the corundum additives increase packing density of high-alumina cement samples, especially with artificial ceramic binder addition. Studies of dispersed additives effect on the setting time of cement was conducted. It is established that the adding of artificial ceramic binder or dispersing alumina at 0.5% is speeding up the initial setting, but a further increasing of the additive content does not affect this indicator. The maximum reduction of setting time is caused by the introduction of 5% tabular alumina.
PDF

STRUCTURE FORMATION IN ALKALI ACTIVATED ALUMINOSILICATE BINDING SYSTEMS USING NATURAL RAW MATERIALS WITH DIFFERENT CRYSTALLINITY DEGREE

https://doi.org/10.34031/2618-7183-2018-1-4-38-43
, , ,
 38-43 p.
Abstract
The efficiency of traditional raw materials using as well as expanding of potential uses for non-conventional and alternative raw materials with different origin is the tasks exiting interest among material scientists and manufacture stuff. Investigation of the above is oriented on solution of such scientific problem as more deep understanding of structure and features of material. The results obtained also allow solution of some technological, technical and economical tasks.
Greatly, it is actual when using of new types of raw materials as well as when synthesis of new composites. Concerning the construction material science field, the classic problem is the looking for ways to study the reactivity of raw components under different conditions, its control and, generally, its increasing to produce higher performance materials.
Among the popular and widely-used construction materials are alkali-activated binders and relevant composites.
In this study the results of granulometric analysis of suspension based on alkali-activated aluminosilicate with different crystallinity degree are presented. It was found, when treatment of aluminosilicate grain by alkali activator leads to the grain solubilizing (but differently depending on crystallinity degree of aluminosilicate) and formation of alkali-aluminosilicate gel that reacts with unreacted part of the grain according to structure affinity principle. It was also determined the crystallinity degree of aluminosilicate component is inversely proportional to its solubility in highly-alkali environment. The model of structure formation for geopolymer system under alkali effect is offered.
PDF

STUDY OF PHYSICAL-MECHANICAL PROPERTIES OF ASPHALT-CONCRETE SPECIMENS ON ACTIVATED MINERAL POWDERS OF VARIOUS COMPOSITIONS

https://doi.org/10.34031/2618-7183-2018-1-4-44-50
, ,
 44-50 p.
Abstract
The article presents the results of testing asphalt samples based on activated mineral powder from silica-containing raw materials. Activated filler was obtained by joint grinding of waste wet magnetic separation (WMS) of ferruginous quartzites of the Kursk Magnetic Anomaly in a spherical planetary mill in the presence of surfactants (stearic acid, adhesive additive Amdor-10) and bitumen. First of all, it should be noted that the use of activated mineral powder in the composition of asphalt concrete mixture led to an increase in the packing density of the composite. This was reflected not only in the technological process, but also contributed to the decrease in the porosity of the mineral core. It was found that the use of surfactants in the process of grinding mineral powder made it possible to increase the strength of asphalt concrete samples. However, the change in the crack resistance and shear resistance of asphalt concrete specimens, determined from the ratio of the corresponding compressive strengths, did not occur (table). This is due to the fact that there has been a proportional change in all the strength characteristics at different temperatures. Analysis of the physical-mechanical characteristics of the properties of asphalt concrete led to the conclusion that it was possible to use activated mineral powder from waste WMS as a component of asphalt concrete mixtures.
PDF