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2020

Archives Journal Construction Materials and Products Vol. 3

INCREASING THE EFFICIENCY OF MINERAL POWDER FROM TECHNOGENIC RAW MATERIALS DUE TO ITS HYDROPHOBIZATION

https://doi.org/10.34031/2618-7183-2020-3-4-24-30
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 24-30 p.
Abstract
Abstract: a promising direction in solving the problem of obtaining high-quality asphalt concrete is the use of mineral fillers, including from industrial waste.
The article considers the use of OEMK slag as a mineral powder in the asphalt concrete mix.
The influence of hydrophobization of mineral powder by GF Preparation on moisture absorption and its structuring ability to change the maximum shear stress from the content of mineral powder before and after hydrophobization was studied. It is established that the treatment of the filler provides the necessary hydrophobicity of the mineral material, reduces the bituminous capacity, water saturation, porosity of the asphalt binder, and increases its strength and water resistance. The results of studies of the main characteristics of asphalt concrete on the example of a mixture of type G III of the brand showed that as a result of hydrophobization, the strength, water resistance, water saturation, and swelling of the composite significantly increase.
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NON-PLASTIC RAW MATERIALS FOR THE PRODUCTION OF CONSTRUCTION CERAMICS

https://doi.org/10.34031/2618-7183-2020-3-4-31-38
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 31-38 p.
Abstract
Abstract: research by some scientists shows that the most expensive element in the manufacture of construction ceramics are clay materials, in particular kaolins. They allow getting products with high strength, but at the same time increase significantly the mass refractoriness. In this connection, a significant amount of melt is added or the firing temperature is increased. Of course, this leads to an increase in the cost of products. In Russia, the reserves of these raw materials are insufficient and it is advisable to look for new non-traditional types of raw materials. There is a need to adjust the component composition of ceramic masses and use non-plastic raw materials. An example is natural wollastonites or their analogues in the form of diopside, which are a little-used type of mineral raw material. In the Siberian region, there are several deposits of non-plastic varieties of raw materials for the production of fired construction products. The most famous are the deposits of the Slyudyansky and Sayan districts. The authors present the results of analysis of diopside rocks, where the chemical, mineral compositions and behavior of samples under heating are studied. The absence of alkali and alkaline earth metal oxides in diopsides was determined. The content of iron oxide in the amount of 0.1% indicates the purity of the raw material. More than half of the composition is occupied by silica, which is 53% and 58% in the rocks of the Burutuysky and Sayan deposits, respectively. The basis of the mineral composition of the samples is diopside, with the presence of quartz, calcite, mica and magnesium carbonate. This range of minerals is traditional in many charges of ceramic materials. Therefore, the possibility of using diopside rocks in the production of building ceramic materials is quite high.
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ON INTEGRATED HEATING, VENTILATION AND AIR CONDITIONING SYSTEMS IN ROOMS OF SHOPPING CENTERS

https://doi.org/10.34031/2618-7183-2020-3-4-39-47
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 39-47 p.
Abstract
Abstract: the paper considers a method for creating microclimate parameters in the rooms of shopping centers, sports complexes, etc. The possibility of using a complex system including air heating, ventilation and air conditioning is shown on the example of a shopping hall. To improve the efficiency of the system, it is proposed to replace traditional water heating with air heating, which works by using a gas burner-heat exchanger. For the rooms of a shopping center in the city of Saint Petersburg, the thermal engineering calculation of external fences was performed, and the heat capacity of the heating system was determined. Based on the results of the heat and air balance of the grocery shopping area, the performance of the ventilation and air conditioning system is calculated. An autonomous monoblock unit for air treatment was selected. During the cold period, the unit performs the functions of air heating and ventilation. Air recirculation is provided to save heat energy. The amount of outdoor and recirculating air is calculated. During the warm period, air is cooled and dehumidified by using a compression refrigeration cycle. The proposed integrated system for creating the required parameters of the microclimate allows reducing material costs by using a gas burner-heat exchanger instead of a heat point for water heating, as well as using a cheaper energy source and heat recovery through a heat pump.
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EFFECT OF POROUS STRUCTURE ON SOUND ABSORPTION OF CELLULAR CONCRETE

https://doi.org/10.34031/2618-7183-2020-3-2-5-18
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 5-18 p.
Abstract
The compositions of gas and foam concrete with improved acoustic characteristics were developed. The optimal form of porosity, which contributes to the absorption of sound waves, both in the range of audible frequencies and at infrasonic and ultrasonic frequencies, is revealed. The mathematical model for designing sound-absorbing concrete was improved, taking into account both the porosity of the composite and the influence of the porous aggregate. The laws of synthesis of aerated concrete and foam concrete are established, which consist in optimizing the processes of structure formation due to the use of a polymineral cement-ash binder and blowing agent. The composition of the composite intensifies the process of hydration of the system, which leads to the synthesis of a polymineral heterodisperse matrix with an open porosity of more than 60%. Peculiarities of the influence of the “Portland cement – aluminosilicate – complex of modifiers” system on the rheology of the concrete mixture was identified, which can significantly reduce shear stress and create easily formed cellular concrete mixtures. The increased activity and granulometry of aluminosilicates predetermine an increase in the number of contacts and mechanical adhesion between particles during compaction, strengthening the frame of inter-pore septa. The mechanism of the influence of the composition of the concrete mixture on the microstructure of the composite is estab-lished. The presence of refined aluminosilicates and a complex of additives in the system along with cement contribute to the synthesis of the matrix with open porosity, thereby increasing the sound absorption coefficient.
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INFLUENCE OF ARTIFICIAL CALCIUM HYDROSILICATES ON THE HARDENING PROCESSES AND PROPERTIES OF NON-AUTOCLAVE SILICATE MATERIALS BASED ON UNCONVENTIONAL ALUMINOSILICATE RAW MATERIALS

https://doi.org/10.34031/2618-7183-2020-3-2-19-28
 19-28 p.
Abstract
Оne of the possible ways to improve the properties of building materials is to modify the processes of structure formation, which can be realized through the use of crystalline primers. In this regard, it is urgent to study the effect of artificial calcium hydrosilicates on hardening processes, as well as the properties of non-autoclave silicate materials based on non-traditional aluminosilicate raw materials. Studies have shown that the addition of artificial calcium hydrosilicates (CSH) in an amount of 1-1.5 wt. %, when the content in the mixture of CaO is less than 10 wt. %, effectively increases the strength parameters of products at all stages of heat and moisture treatment from 8 to 16%. The most intense increase in strength is observed during the heat-moisture treatment (TBO) from 3 to 6 hours and is at least 13%, while in samples without the addition of artificial calcium hydrosilicates, the strength increase is 6%. The addition of artificial calcium hydrosilicates intensifies the processes of structure formation, which ensures an increase in crystalline matter, and, due to the fibrous structure, acts as a fiber, which contributes to the nano-reinforcement of the cementing substance formed from neoplasms in the CaO-SiO2(Al2O3)-H2O system based on clay rocks and calcium oxide. Due to the accelerated set of strength, it is possible to reduce the duration of isothermal exposure while maintaining the necessary performance characteristics.
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THE RESEARCH OF MULTILAYER OUTER FENCING INCLUDING MATERIALS USING ASH AND SLAG WASTE OF THERMAL POWER PLANTS

https://doi.org/10.34031/2618-7183-2020-3-2-29-35
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 29-35 p.
Abstract
The most important direction of resource saving in construction is the widespread use of secondary material resources, which are waste products. The use of secondary products of industry as raw materials for the production of various building materials is very important, because it provides production with rich sources of cheap and, often, already prepared raw materials; lead to lower costs for the production of some building materials, and therefore saves capital investments intended for the construction of buildings and structures; release large areas of land and reduce the impact on the environment. The article deals with heat-insulating and structural-heat-insulating materials, with partial replacement of components by ash-slag waste (ASW): lightweight concretes with broken glass and concretes modified with sulfur. Properties of concretes modified with sulfur are investigated: compressive strength, density and thermal conductivity. In accordance with the obtained properties, a comparative characteristics of the received materials with existing building materials was carried out: sulfur modified concrete and lightweight concrete; lightweight concrete using broken glass and claydite-concrete. Thermophysical calculation of multilayer hencing is made. In each of the options, one of the following materials was selected as a structural and heat-insulating material: lightweight concrete using broken glass and sulfur modified concrete. Also, for each type of hencing, the necessary heat-insulating and structural materials were selected. In the economic part, the cost of the raw materials necessary to obtain 1 m3 of the investigated materials and the cost of 1 m3 of multilayer hencing, which includes the investigated concrete, are calculated.
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DESTRUCTION MODEL OF IDEALIZED CONCRETE STRUCTURE BY SAWING

https://doi.org/10.34031/2618-7183-2020-3-2-46-54
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 46-54 p.
Abstract
The requirements of modern construction are the strength of building structures, as well as low cost. It is these conditions that provide new technologies that are constantly being improved. The article is devoted to the consideration of cases of a probabilistic approach to solving the problem of theoretical energy consumption for the destruction of concrete of ideal structure.
The processes of concrete deformation and its destruction are studied by building mechanics. Concrete is a multicomponent material, which presents a certain difficulty in the study of crack formation. In operating conditions, the concrete/reinforced concrete structure is affected by the properties of its constituent materials; therefore, one of the most important tasks is the selection of criteria that can comprehensively characterize the basic parameters of concrete. Obtaining the strength characteristics of concrete of operated structures remains an urgent task. The article proposes to consider the ideal structure of concrete. The features of this structure are the symmetry of fracture along two principal planes. The destruction of concrete was carried out by sawing individual strips of concrete. Moreover, to describe the sawing process, the authors proposed a model of a symmetric structure of concrete in which aggregate grains are idealized. They are presented in the form of balls in the body of concrete.
The features of the sawing process are revealed. The analytical dependencies of fracture sawing the ideal structure of concrete are obtained.
Conclusions are drawn about the possibility of using the ideal model for obtaining the strength characteristics of concrete. The analysis of symmetrical ideal concrete compositions with various variables is performed. The significance of the work done lies in the possibility of transferring the research results to real buildings and structures and solving the main tasks that are posed in the study.
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THE INFLUENCE OF SEVERAL TYPES OF RESINS ON THE DYNAMIC MECHANICAL PROPERTIES OF POLYMER MIXTURE BASED ON BUTYL RUBBER

https://doi.org/10.34031/2618-7183-2020-3-2-36-45
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 36-45 p.
Abstract
This work is devoted to the problem of developing vibration-damping polymer materials with high damping properties in a wide temperature range. The study of the effect of modifying additives on the strength, damping, adhesive and cohesive properties of a butyl rubber composite is the aim of this work. The task is to identify the actual temperature, frequency, dynamic and mechanical characteristics of a composite material based on butyl rubber depending on the type and concentration of resins. The key methods for studying this problem is the dynamic mechanical analysis method, aimed at obtaining information about changes in the dynamic properties of polymer materials (bond strength with metal when peeling samples of composites, determining the flow resistance of samples, determining the migration of plasticizer). Due to the established experimental dependences, it was found that the addition of resins (3% by weight) in the composition based on butyl rubber leads to an increase in the damping properties of composite materials, and an increase to (4.25% by weight) leads to their decrease. It was established that the obtained filled mixtures with a high damping peak and good adhesive and strength properties are mixtures with the addition of alkyl phenol-formaldehyde resins.
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NUMERICAL ANALYSIS OF EARTH DAM STRESS-STRAIN STATE UNDER SEISMIC IMPACT CONSIDERING THE WAVE DYNAMICS

https://doi.org/10.34031/2618-7183-2020-3-3-5-20
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 5-20 p.
Abstract
The design, construction and operation of high-rise earth dams in seismic regions, such as the territory of the Republic of Uzbekistan, requires constant improvement of the methods to calculate them under various loads, both of a static nature (gravitational forces, hydrostatic, etc.), and of a dynamic nature, including seismic effects. Emergency situations at such facilities or their partial destruction under any impact can lead to disastrous aftermath. The aim of this study is to develop a mathematical statement and an algorithm for numerical solution to an unsteady-state problem for an earth dam in a plane elastic statement. To verify the proposed methodology and the corresponding complex of applied programs, a solution to the test problem was given (the Lamb’s problem). According to the developed methodology and algorithm based on numerical method of finite differences, the problem of studying the stress-strain state was solved under shear stress on the foundation (in the form of a seismogram) on the example of the high-rise Charvak earth dam located near Tashkent city. The solution is presented in the form of distribution lines of equal displacements, stresses along the dam body, depending on time. The most vulnerable zones of the earth dam under consideration were identified.
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MINERAL WOOL COMPOSITE WITH THE USE OF SAPONITE-CONTAINING MINING INDUSTRY WASTE

https://doi.org/10.34031/2618-7183-2020-3-3-21-27
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 21-27 p.
Abstract
The paper shows the possibility of producing a thermal insulating composite based on basalt fibers and saponite-containing mining waste. A method for manufacturing thermal insulating composites from hydro-mass with different contents of the mixture components is proposed. Basalt fibers were used as a filler, and pre-mechanoactivated saponite-containing material (SCM) was used as a binder. It was found experimentally that depending on the composition of composites, the coefficient of thermal conductivity varies from 0.1109 to 0.1342 W/(m•K), and the compressive strength – from 0.45 to 0.93 MPa. In addition, it was found that thermal modification of composites at temperatures up to 1200°C significantly (up to 3 times) increases the compressive strength of composites, while not affecting the coefficient of thermal conductivity. The experiments to determine the conductivity of the composite “basalt fiber – SСM” depending on its moisture content showed that the obtained composite is characterized by intense and linear increase in the values of conductivity when the humidity of the sample to 12% and further increase in humidity practically does not change the values of the coefficient of thermal conductivity. Comparison of the studied thermal insulation composite with known structural thermal insulation materials in terms of its thermal insulation and strength characteristics showed that it is comparable to gas and foam blocks. It should also be noted that this material is environmentally safe and can withstand high temperatures without collapsing.
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