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Über dieses Buch

This book gathers the latest advances, innovations, and applications in the field of construction design and management, as presented by researchers and engineers at the International Conference Industrial and Civil Construction 2021, held in Belgorod, Russia, on January 18-19, 2021. It covers highly diverse topics, including building materials, building constructions, structural mechanics and theory of structures, industrial and civil construction, environmental engineering and sustainability. The contributions, which were selected by means of a rigorous international peer-review process, highlight numerous exciting ideas that will spur novel research directions and foster multidisciplinary collaborations.

Inhaltsverzeichnis

Frontmatter

The Choice of Filler in the Formulation of Sol-Silicate Paints

It is proposed to apply thermodynamic criteria when choosing a filler in paint formulations - critical surface tension, Hamaker constant. The values of the critical surface tension of a liquid (ethanol solutions with different water content) at the interface with a solid (different fillers) are calculated. The energy of interaction between the filler particles was estimated by the value of the Hamaker constant. Determined that microcalcite has a higher critical surface tension, compared to other fillers. It is shown that when calcite is used as a filler, the inter particle interaction is enhanced. It was found that the use in sol silicate paints as a filler of calcite contributes to obtaining a higher cohesive strength of coatings due to an increase in the contribution of dispersion forces. Based on the study, the numerical values of the Hamaker constant and the critical value of the surface tension of various fillers were obtained. It allowed makes it possible to choose the optimal type of filler. It has been established that there is a linear relationship between the value of the interaction energy between the filler particles (Hamaker constant) and the tensile strength of the coatings. A mathematical model of cohesive strength is obtained depending on the value of the Hamaker constant.

V. I. Loganina, S. V. Klyuev, Y. B. Mazhitov

Thermokinetic Processes of Hydration of Binders Based on Scrap Concrete

The object of research is the hydration of binders obtained from scrap concrete of destroyed buildings and structures. We used fractions of scrap concrete 0.00–0.16 mm and 0.16–0.315 mm, as x-ray phase analysis of various fractions of scrap concrete showed that these fractions have the highest content of non-hydrated alite and belite particles.As a result of thermokinetic studies, it was found that the highest value of the heat release rate is observed in a binder based on scrap concrete with a specific surface of 964 m2/kg: 2.4 times higher than with a specific surface of 555 m2/kg; 1.3 times higher than with a specific surface of 1255 m2/kg; 1.6 times higher than with a specific surface of 1431 m2/kg. This fact reflects its higher reactivity. The results obtained are consistent with the physical and mechanical characteristics of binders based on scrap concrete in the initial period of hardening and are of practical interest from the point of view of controlling the structural and mechanical properties of concrete mixtures on the developed binders. Thus, with a specific surface area of 964 m2/kg, the best conditions are created for the formation of the primary framework and its further fouling with various calcium crystal hydrates, which provide optimal density and strength. This composite binder composition, with a specific surface area of 964 m2/kg, is characterized as the most energy-efficient.

Ahmed Ahmed Anees Ahmed, R. V. Lesovik

Efficient Construction Composites for Construction in the North and the Arctic

Construction in the North and the Arctic associated with certain features characteristic of the polar territories, with a low level of population density, difficulties in implementing technological methods for the production of building materials and construction, as well as with the requirements for increased protection of construction sites from the harmful effects of the environment. In this regard, the development of effective building composites and methods of protecting structures based on new principles of transdisciplinarity is relevant. The article discusses the problem of improving the technology of new generation composites with increased strength while maintaining high strength indicators to protect against natural environmental influences, as well as the development of a new method for self-healing of concrete structures during operation in the Arctic.Thus, new methods of obtaining porous composites of increased strength and self-healing of concrete structure using internal and external factors are shown. The essence of the method lies, firstly, in creating a high-density and high-strength structure of the material and, secondly, in the introduction of a reactive mineral, which is part of a fine filler (iron sulfide). This combination provides the appearance of ettringite-like iron-containing calcium hydrates in the thickness of the concrete stone during cracking, which occurs with an increase in the volume of solid and condensed phases.

Alexander Tolstoy, Anatoly Gridchin, Evgeny Glagolev, Ruslan Lesovik, Nikolay Shapovalov

Color Control of Portland Cement Clinker by Separate Input of Mineralizers

The color control of Portland cement clinker was regulated by separate insertion of calcium fluoride in the presence of Na2O. Studies were carried out on a raw mixture of pure reagents with a Fe2O3 content equal to 2.93%. The mixture has the following characteristics: KH  =  0.93; AM  =  1.24; SM  =  2.18. Calcium fluoride was inserted as a CaF2 reagent of the “pure” qualification. Na2O was inserted as a “pure” Na2CO3 reagent. The samples were roasted in a laboratory furnace at 1300 °C with an isothermal exposure time of 20 min. The heating speed of the furnace is 10 °C/min. The color change was determined by measuring the brightness coefficient on a reference polished barium sulfate plate using an FB-2 gloss meter. The content of free calcium oxide was determined by the ethyl-glycerate method. It was found that the optimal approach for increasing the clinker whiteness is to insert 1.5% CaF2 separately in the presence of 3.5% Na2O. The amount of 3.5% Na2O is sufficient to bind stoichiometric all aluminum in Na2O∙Al2O3. The binding of Al2O3 to sodium aluminate prevents the formation of calcium aluminoferrites. At the same time, the whiteness of the compound with a mineralizer is 49.5%. In the compound without a mineralizer, it reaches 39%. An increase in the clinker whiteness to the maximum is accompanied by a decrease in the content of free calcium oxide. In the compound without a mineralizer, it is 20.1%. The compound with a mineralizer has a free calcium oxide content of 5.28%.

S. V. Kovalev, D. A. Mishin

Cement Hydratation and Curing Cycles

The paper investigates the heat formation and absorption processes in the cement-water system. The temperature gradient in a cement composition is one of the mainsprings of cement hydration and curing and the formation of final properties of the cement-water system. The differential calorimetric analysis based on measuring the temperature difference between dry and wet cement shows the reciprocal, cyclic heat formation. The observed effects are caused by the processes of dispersion and hydration of cement particles and crystallization of cement hydration products. Three types of harmonic frequencies are detected for the heat formation, viz. 1–3 vibrations per minute, ~12 h, and a several days vibration period. The heat formation-based analysis of phenomena observed in the cement-water system shows self-excited vibrations during the cement hydration and curing. The reaction continues owing to the energy release during hydration of clinker minerals and dispersion of the initial cement particles. The high sensitivity of the differential calorimetry as against the integral methods provides the deeper understanding of the phenomena observed and allows improving the cement potential in the production of a wide range of building materials.

V. A. Lotov, N. P. Gorlenko, Yu. S. Sarkisov, T. S. Shepelenko

Decoration of Non-ferrous Metals

Enamel is a thin glassy coating obtained by high-temperature treatment. Technical enamels are applied to products made of cast iron, steel, aluminum and light metal alloys. The metal-enamel combination successfully combines the molding ability and strength of the metal with the chemical resistance and stability of the glass. The aim of this study is to develop methods for decorating non-ferrous metals. Based on the literature analysis, a composition with similar values of the thermal coefficient of linear expansion (TCLE) of enamel (α = 159·10−7 К−1) and copper (α = 162·10−7 К−1) was selected as enamel for decorating copper. The compositions of glass coatings containing fractions of 0.071 mm and 0.1 mm were modeled. The optimal composition of glass coatings was determined experimentally, which contains 70% of the 0.071 mm fraction and 30% of the 0.1 mm fraction. The TCLE of the glass-enamel stack was determined by the dilatometric method with a measurement accuracy of ±1.5%, the TCLE curve was constructed according to the experimental data. The fusibility of the samples was determined in a laboratory muffle silite furnace SNOL-1.6. The frit was made at a temperature of 1250 °C for 0.5 h. The slip was prepared from each composition according to the classical scheme and applied by dipping.

N. I. Bondarenko, Z. V. Pavlenko, D. O. Bondarenko

Research of Black Soldier Fly (Hermetia Illucens) Maggots Zoocompost’s Influence on Soil Fertility

At present the soil covering is systematically exposed to adverse factors, which have a negative impact on its fertility. One of the ways of maintaining soil fertility is the application of composts. In this research zoocompost of black soldier fly (Hermetia illucens) maggots was used as a fertility amendment. The zoocompost under study was a loose, slightly moving, fine-grained mass of brown color, with a faint smell of ammonia, with a predominant particle size of 1–3 mm. The main nutrients of the zoo compost are in the form of various humic acid compounds, contain the necessary macro-and microelements, biogenic Ca2+, Mg2+, Fe2O3. the zoocompost is rich in saprophytic microflora useful for soil and plants. It has been determined that such zoocompost can be used as an organic fertilizer, as its parameters meet the requirements of GOST 33830-2016. The carried-out field re-search has demonstrated the positive dynamics of growth and development of cu-cumber fruits, variety «Dalnevostochny 27». The crop yield from one cucumber plant increased from 22.16 to 240.59 g, the yield from a plot from 63.75–692.68 g. The optimal amount of application was considered to be 2 t/ha, added in spring.

E. A. Pendyurin, S. Yu. Rybina, L. M. Smolenskaya

Effects of Sea Surf on Gabion Retaining Walls

The article presents the results of long-term observations of the destruction of a long gabion retaining wall at the base of a high coastal slope, under the influence of frontal sea waves. The destruction scheme is not consistent with the destruction scheme adopted in the normative literature as a result of stability under active soil pressure. The destruction of a stepped vertical wall occurs mainly as a result of the rupture of the metal mesh and the removal of stone material from the structure by the recoiling wave. The increasing strength of storms and the direction of the wind, in turn, are associated with global climate change. Analyzing the situation, the author comes to the conclusion that in the process of operation, the structure, despite its own destruction, made it possible to preserve the coastline and carry out work to strengthen the surface of the slope, subject to landslide and suffusion processes.

L. I. Cherkasova

Effect of Clay Raw Materials on the Formation of the Microstructure of Cellular Concrete for Thermal Insulation Purposes

It is found that using sand and clay rocks of the incomplete stage of mineral formation as raw materials, it is possible to obtain effective autoclave cellular concretes for thermal insulation purposes. Improved rheological properties of the aerated concrete mix and a higher gas-holding capacity in comparison with lime-sand raw materials ensure the formation of a more uniform cellular structure. It is shown that the polymineral composition of raw materials provides the formation of gelled and highly crystallized phases, such as low-base calcium hydrosilicates CSH(B), hydrogranates and tobermorite, including alumina-containing ones, which optimizes the microstructure of the cementitious substance. At the same time, more dense inter-layer partitions than on lime-sand raw materials are formed, which increases the physical, mechanical and operational properties of thermal insulation materials. Increasing the number of phases in the composition of the cementing agent reduces its thermal conductivity. Micropores formed from finely dispersed highly crystallized phases also contribute to improving the thermal protection properties of heat-insulating autoclave cellular concretes on clay raw materials. The compressive strength, depending on the mineral composition of the rock at an average density of 350 kg/m3, increases by 7–23% in comparison with lime-sand materials, and the coefficient of thermal conductivity decreases from 0.09 to 0.075–0.065 W/m·°C.

A. N. Volodchenko, V. G. Klimenko

Effect of Sleet-Proof Reagents on the Cement Stone of Concrete

This research evaluates the effect of single-component sodium chloride solution in comparison with multicomponent commercial sleet-proof reagents (SPR) on the cement stone of side stone concretes of different compositions. Furthermore, it estimates manufacturing technologies: vibration casting - composition №1 - with a water-cement ratio of 0.4 and a strength of up to 70 MPa and №2 – W/C ˃0.4, strength <40 MPa. The composition №3 is manufactured using class B30 vibropress technology. Samples of each composition are saturated with salt solutions – single-component 10% NaCl or multicomponent commercial SPR of 10 or 30% concentration. Multicomponent SPR containing sodium and calcium chlorides has a greater impact on concrete in comparison with single-component salt. However, a higher concentration of the SPR solution may have a less destructive effect on the concrete. The lowest accumulation of chlorides is observed in vibropressed concrete, despite the high value of water absorption of samples. The permeability of concrete made using vibropress technology is higher than that of vibration casting ones, but destructive processes develop much more slowly. Thus, the nature of the pore space, rather than the volume, has a greater influence on their flow.

I. G. Endzhievskaya, R. A. Nazirov, A. S. Endzhievskiy

Eco-Resource Intensity Enhancement of Residential Apartment Buildings via Optimizing Design Solutions

A significant part of design decisions affecting the future maintenance and building environmental safety are made at the initial design stage. Currently, about 80% of design decisions are made by designers and architects at the initial stage of designing civil buildings, and the remaining 20% - by engineers at subsequent stages. With respect to civil buildings (namely, residential from 9 to 20 floors) the influence of various design volumetric-planning and structural parameters on the components quantity for common structural systems is strong enough. In this regard, it is crucial to have tools for quick and reliable quantitative assessment of the environmental safety of a building at the initial stages of the project – the stage of alternative design. The proposed approach will allow to establish quantitative dependencies between design solutions and used construction resources, as well as to carry out express-diagnostics of resource intensity at the pre-project stage. Using the obtained data, this will allow for comparative analysis of potential engineering (volumetric planning and organizational and technological) solutions alternative to the project and analysis primary energy use and carbon impact for the development of conventional residential buildings as well.

N. V. Bakaeva, A. E. Naumov, M. O. Suvorova

Metallurgical Waste Recycling for Transport Construction

Nowadays industrial waste recycling is the key concern for metal industry. Higher steel outputs are accompanied by increased by-products related with steel production. One of large-tonnage by-products of metallurgical production is electric arc furnace dust from arc steel furnaces. The use of metallurgical waste is therefore a promising area of research. The chemical composition of dust from arc steel furnace cleaning has been studied. The micro-structural features of gas cleaning dust have been investigated. Dust formation processes have been understood. The most efficient dust clotting schemes have been selected. It has been demonstrated that it is possible to granulate dust using process water as a liquid-phase binder. It has been established that a disk pelletizer makes it possible to obtain granules up to 5 mm in diameter with sufficient strength for their transportation and further drying. When using a screw extruder it is possible to produce granules of proper cylindrical shape. Heat released from hydration of free CaO being a part of dust and bulk mixing result in screw conveyor jamming and die hole clogging. Bulk dust density has been determined for gas cleaning of arc steel furnaces. Bulk density of granules obtained by two granulation methods has been determined - with the use of a disk petellizer and a screw granulator.

S. N. Bondarenko, A. N. Bodyakov, M. S. Lebedev

Diffraction of Harmonic S-waves into Frame Buildings

Diffraction of seismic S-waves into multistory frame buildings is analyzed by FEA (Finite Element Analysis). The FE model consists of a ten-story superstructure rested on the slab foundation. Engineering software Abaqus/CAE 6.14 was used to analyze the interaction of seismic shear waves with the building. The explicit dynamic analysis was performed for the following seismic frequencies 0.5; 1 and 2 Hz over a time period of 5 s. Three types of columns were selected (corner- interior - edge) and the stress values were considered in monitoring points distributed over the entire height of the building at the places where these columns connect with the slabs. The analysis reveals that the arrival of the S-waves at small frequencies results in dangerous stresses in the bottom columns, especially in the corner columns, with the decreasing values of these stresses in a direction towards the last floor. Moreover, the analysis also reveals that at higher frequencies the stress magnitudes slightly decrease.

Ali Al Shemali

Filling of Epoxy Polymers with Chemically Precipitated Chalk from Chemical Water Treatment Sludge

The results of the use of chemically precipitated chalk as an active highly dispersed filler in compositions based on epoxy oligomers are presented. Used chemically precipitated chalk (original and hydrophobized), obtained by precipitation, dehydration, drying and classification of sludge from the chemical water treatment plant. To achieve the homogeneity of composites, two methods of preparing the reaction mixture for curing are considered: the introduction of the filler initially into the epoxy oligomer and the introduction of the filler into the amine hardener. Depending on the method of filler introduction and its concentration in the binder (0.5–5.0% of the mass of the epoxy oligomer), the developed formulations can be recommended for obtaining adhesives and coatings, as well as as structural composites. To study the mechanical properties, the method of determining the microhardness was used, which made it possible to evaluate the effect of the size of the filler particles and to carry out a comparative assessment of their effectiveness with small amounts of carbon-containing nanofillers (0.005–0.5%).

R. R. Galeev, R. K. Nizamov, L. A. Abdrakhmanova

Application of Antifreezing Additives in Mortars

Concrete and reinforced concrete are currently used for the construction of buildings and structures. At negative temperatures, the hydration of the binder slows down and the solidification of mortars proceeds quite slowly, and the strength set of mortars and concrete mixtures stops. As a result, to ensure a set of strength in winter conditions, it is necessary to introduce antifreezing chemical additives into the mortars, which contribute to the normal flow of cement hydration processes. In this regard, the urgent task is the correct and rational choice of raw materials, which directly affect the durability and reliability of concrete and reinforced concrete products and structures. Therefore, in the course of research, most of the time is devoted directly to the study and selection of raw materials for the preparation of concretes and mortars. It is impossible to achieve the necessary durability of concrete without introducing chemical additives into its composition. The paper presents a study of antifreezing additives that positively affect the properties and durability of concrete and mortars and work effectively in conditions of negative temperatures. Optimal dosages of the studied additives were determined and the influence of new types of additives on the strength characteristics of concrete and mortars was studied.

J. V. Denisova

On the Issue of Measuring the Strength of Additively Manufactured Concrete

One of the most actual issues in the development of construction printing is the development of sound methods for determining the main properties of additively obtained composites. And this applies not only to special properties, such as printability or shape stability, but also, it would seem, well-studied strength indicators. Most researchers in their works pay attention to the fact that the strength of samples obtained using molds does not correspond to the same indicator in printed structures. In this regard, this paper proposes a method for determining the strength of samples of standard sizes obtained by cutting out of a printed array. The array printing scheme assumes that each sample contains a large number of contact zones of layers, which are a weak point in the system under consideration. This approach allows considering the additively obtained composite as quasi-homogeneous, which makes it possible to simplify the calculation methods of structures and make them safer in operation. The analysis of the obtained results confirms the incorrectness of using standard methods for determining the strength indicators of additively manufactured materials when evaluating their design characteristics; the main direction for improving printing technology is the need to improve adhesion between layers; the expediency of increasing the width and thickness of tracks, which helps to reduce the number of contact zones. The proposed method is simple, accessible and does not require a special laboratory base.

V. S. Lesovik, E. S. Glagolev, M. Yu. Elistratkin, D. S. Podgorniy

Assessment of the Resource of Water Protection Properties of Coatings Cement Concrete External Wall Buildings

The information on the resource of water-protective properties of cement concrete coatings is given. A methodological approach is proposed for assessing the resource of water-protective properties of coatings, which consists in assessing the time to reach the maximum permissible moisture content in the contact plane “coating-concrete of the enclosing structure”. It is revealed that the resource of water-protective properties depends on the initial moisture content of the structure. Bulk hydrophobization of coatings contributes to an increase in the resource of water-protective properties. The influence of the substrate porosity on the service life of the waterproofing properties of coatings is considered. It is shown that with an increase in the surface porosity of the substrate, a decrease in the time of moisture penetration through the coating is observed. The data on the influence of substrate moisture on the resource of waterproof properties and durability of protective and decorative coatings are given.

V. I. Loganina

Molding Properties of Alkali Silicate Compositions

The results of research on compositions based on sodium liquid glass and fillers of mineral and organic origin are presented. Materials that can affect the molding properties and thermal transformations of compositions are used as fillers. It was found that the molding properties of the compositions depend on the mineral composition and content of the filler. It is shown that the greatest increase in the viscosity of the compositions is provided by fine mineral fillers, which limit the influence of free and adsorptive water in the composition of liquid glass. The influence of the dispersion of fillers on the rheological properties of compositions is determined. It was found that an increase in the specific surface area of fillers from 350 to 550 m2/kg can increase the structural strength of molding mixtures by 10–30%. To improve the molding properties of compositions characterized by high porosity, it is proposed to use combined fillers: glass boilerplate and organic filler; broken glass and mineral filler containing a pore-forming component (oil shale, gaize, lignite-bauxite, and refuse ore). The expediency of using fillers with a porous structure is shown. Studies of porous compositions have confirmed the advantages of using combined fillers. It is noted that the use of combined fillers contributes to the porization of liquid-glass compositions at low temperatures.

O. A. Miryuk

Sulfoaluminate Cement and Low-Temperature Roasting Additive from Low Aluminate Raw Materials with a High Content of Silicon Oxide

The preparation of sulfoaluminate clinkers from low-aluminate natural and technogenic raw materials that are substandard for the production of aluminate cement due to the high content of silicon oxide is considered. Raw mixtures for the synthesis of sulfoaluminate clinkers of the most approximate chemical composition from natural raw materials and from technogenic products are calculated. The technological properties, phase compositions of clinkers obtained by sintering, and hydraulic properties of sulfoaluminate clinkers and compositions with their application are compared. The presence of a sulfate component avoids the formation of clinkers in the hydraulically inert gehlenite. The presence of alkaline and other impurity compounds in the used technogenic waste reduces the synthesis temperature of sulfoaluminate clinkers by 130 degrees; changes the phase composition and properties of cement; shifts the effect of sulfation from the aluminate phase to the silicate phase. In clinkers, mainly calcium sulfoaluminate is formed from natural raw materials, and calcium sulfosilicate is formed from technogenic products. It is established that cement stone made of clinker based on natural raw materials has high strength, including in the early stages of hardening. From the considered technogenic waste, it is possible to obtain a sulfoaluminate additive of low-temperature roasting, which increases the strength characteristics of the stone from the binding composition in the early stages of hardening.

T. Ye. Goloviznina, V. M. Konovalov, I. A. Morozova

Transition to the Assessment of the Brickwork Quality in Terms of Compressive Strength Class

One of the widely used materials in the construction industry is brickwork, while it should be noted that its mechanical properties significantly lag behind other structural materials. According to the results of the analysis of emergency situations, brick structures are among the most dangerous from the point of view of accidents. The main causes of accidents are related to the violation of the construction and operation technology, but about 4% of all accidents relate to the imperfection of regulatory documents. An adequate determination of the actual strength is the key to high-quality and efficient operation of materials in the structures of buildings and structures, as reliability is laid down in the design. Based on the analysis of data obtained by various authors over the past 70 years, the search for the limiting coefficient of variation was carried out. For different groups of brickwork, its value was from 2 to 58%, so the average value of 38% was taken as the maximum allowable value for in-series tests. Taking into account the required value of the reserve coefficient, possible classes of brickwork strength were calculated. Switching to strength classes for brickwork will allow: controlling effectively the mechanical strength indicators in standard samples; simplifying the marking of brickwork and reducing the range of design resistances of brickwork.

V. S. Lesovik, Yu. A. Belentsov, A. A. Klementyeva, M. Yu. Elistratkin

Research on the Influence of Gypsum and Anhydrite Stone Impurities on the Properties of the Binder

Gypsum (CaSO4 2H2O) and anhydrite (CaSO4) are the most common sulfate minerals. The predominant part of gypsum and anhydrite is used as raw materials for the production of gypsum binders (construction gypsum) and additives in various types of cements, to a lesser extent–for the production of hard-burnt, high-strength, molding and medical gypsum, sulfuric acid, ammonium sulfate, and paper and for soil gypsuming. In addition, gypsum and anhydrite are used in small quantities as decorative and ornamental materials. In each deposit of natural gypsum, the distinctive features are its composition and structure, which directly affects the production conditions and construction and technical properties of gypsum binders. This paper is aimed at evaluating the influence of various impurities present in gypsum and anhydrite stones on the properties of the binder. In this work, the selected samples for each case were subjected to chemical and mineralogical analysis, passed the roasting stage, and then samples-beams are formed and tested for bending and compression on laboratory equipment. In summary, the conclusion was made about the ability of impurities to influence the indicators of setting time, strength values.

A. F. Buryanov, N. A. Galtseva, I. V. Morozov, E. N. Buldyzhova

The Effect of Natural Climatic Aging on Damage Accumulation Kinetics in the Structure of Epoxy Polymers Under Tensile Loads

The approach is proposed for assessing the “critical” state of polymer materials under the effect of aggressive media. Changes in kinetics of failure accumulation of three compositions of epoxy polymers based on ED-20, Etal-247 and Etal-370 epoxy resins cured by Etal-1440 in 45, 90, 180, 270 and 360 days of natural climatic exposure were analyzed. We have identified changes in the rate of damage accumulation when the total level of failures exceeds 70÷80% of their maximum corresponding to the achievement of maximum tensile stresses. Damage accumulation kinetics was calculated based on the author’s method using methods of fractal analysis of deformation curves for polymer materials samples under tension. This approach involves determining the coordinates of “critical” points of deformation curves for which the fractality index values calculated over the previous short time intervals using the least coverage method, were less than 0.5. High stability of epoxy polymer parameters based on modified Etal-247 resin under the natural climatic factors has been found. After a year of full-scale exposure, for this type of epoxy polymer the “critical” levels of tensile stresses and their corresponding relative elongation are reduced by 11% and 16%. At the same time, for polymers based on ED-20 and Etal-370 epoxy resins, these figures are 1.9 and 2.7 ( $$ \sigma_{crit.}^{70} $$ σ c r i t . 70 ) and 2.7 and 5.1 ( $$ \varepsilon_{crit.}^{70} $$ ε c r i t . 70 ) times reduced, respectively, which indicates a significant damage accumulation.

D. R. Nizin, T. A. Nizina, N. S. Kanaeva, A. I. Gorenkova

Assessment of the Fungus Resistance of Cement Stone with a Biocide with Bacterial Cultures Used in Carbonate Biomineralization

The paper presents the analysis of the influence (joint and separate mutual) of bacterial cultures and an active biocidal component on the bacterio- and fungicidal properties of cement stone. The possibility of functioning of the bacterial microbiota in the conditions of biocorrosion, as well as in the presence of a biocidal additive in the composition of the cement system, was proved. The absence of a negative effect on the development of bacteria S. Pasteurii, B. Megaterium, L. Sphaericus, B. pumilus of 0.5% glutaraldehyde solution was experimentally proved. The fungus resistance of sample cubes modified with the active additive - glutaraldehyde, Aspergillus niger micromycete was determined. The greatest fungicidal effect was achieved using a solution of glutaraldehyde in the composition of a cement stone and a bacterial inoculum in an agar medium. Such a combined combination can be used to impart biostability to cement-based building materials.

U. N. Dukhanina, V. V. Nelyubova, O. I. Drozdov, D. A. Balitsky

Prospects for the Use of Neutron-Shielding Metal Hydride Materials in the Construction of NPP Power Units

A technology has been proposed for increasing the thermal stability of titanium hydride by spraying metallic copper atoms onto its spherical granules. The method of quadrupole magnetron sputtering is used, which is based on low-temperature ion sputtering of a copper target on the surface of a metal hydride substrate. The microstructure of the surface of the modified fraction of titanium hydride is investigated. It is shown that the surface has a granular structure with a grain size of 25–50 nm. In some areas of the surface, grain alignment is observed in a specific direction, indicating a uniform texture of the applied copper surface layer. The metallized copper coating fills in surface defects and creates a shell that prevents thermal diffusion of hydrogen into the environment. The thickness of the deposited metallic copper on the surface of the shot is on average 400 nm. The phase composition of the surface layer of the samples of modified and unmodified hydride fraction is estimated by the method of electron probe analysis. It is shown that as a result of modification, the thermal stability of titanium hydride increases to 700 °C.

R. N. Yastrebinsky, A. A. Karnauhov, A. V. Yastrebinskaya

Experimental Research of the Process Bio-corrosion of Cement Concrete for Inspection of Building Structures

The article presents the results of various tests of cement concretes in the research of the process of their biological corrosion, as one of the factors that reduce the durability of concrete and reinforced concrete building structures during their inspection. During the experimental research, microbiological diagnostics was performed, the results of which revealed the taxometric composition of biofilms. The results of taxometric analysis revealed that the biofilm is formed by spores and vegetative forms of bacteria Bacillus subtilis, Nitrosomonas, Lactobacterium, Desulfovibrio, as well as some forms of actiomycetes and micromycetes. The results of strength tests in the framework of experiments showed that the process of biocorrosion significantly affects the loss of strength of cement concretes. The graphs of changes in the profiles of Ca2+cation concentrations in the liquid phase showed increased values compared to conventional uninfected cement concrete, which is caused by the action of waste products of fungi of the genus Aspergillus niger and bacteria of the genus Bacillus subtilis. The results of measuring the pH level of the medium of concrete samples showed that the action of fungi of the genus Aspergillus niger and bacteria of the genus Bacillus subtilis contributes to an increase in the pH value of the hydrogen index in comparison with uninfected samples.

S. V. Fedosov, V. Eu. Roumyantseva, S. A. Loginova, I. N. Goglev

Use of Chalk-Marl Rocks as a Base for Designing Pile Foundations

This paper presents the most common physical and mechanical properties of chalk, which are necessary for calculating the foundations of buildings and structures, in particular pile foundations, by limit states and recommendations for choosing the type of foundations. Special (specific) properties of chalk as an residual soil (its fragmentation, non-uniformity, presence of large inclusions) create significant difficulties in studying its physical and mechanical properties in the process of engineering and geological surveys, as laboratory equipment available in survey organizations for determining the physical and mechanical properties of soils is of little use for determining the strength and deformative properties of chalk. This fact, unfortunately, contributes to the fact that the physical and mechanical properties of chalk rocks are calculated indirectly (by static and dynamic sounding, etc.), which invariably leads to miscalculations in the assessment of its properties. This, in the end, leads to the fact that the data available after engineering surveys on the characteristics of chalk are used to obtain results, in particular for calculating foundations and bases by limit states, which further contributes to large errors in the obtained values.

S. A. Gubarev, T. G. Kalachuk

Special-Purpose Polymer Composite Material Based on Thermoplastic Polymer and Modified Aerosil

Every year, the humankind has been developing, improving and modifying the material qualities and properties. This is because science is not static, and each day scientists seek to learn something new and previously unknown. Polymer composite materials find their use in all areas of human life. It is not surprising that the use of such materials in outer space under conditions of high radiation and electromagnetic radiation is no exception. The development of special-purpose composite materials is a highly important engineering and technological challenge of the XXI century. The most common and effective method of improving the properties of a composition is the introduction of modifying additives into its composition, which are most often fillers. It is established that the composite polymer construction materials based on thermoplastic polymer and modified with aerosil, possess a set of properties sufficient for operation not only in nuclear plants but also in space. The introduction of modified aerosil into the polyimide matrix makes it possible to create a polymer composite material with the necessary complex of physical, mechanical and strength properties that will withstand the specified loads.

N. V. Klyuchnikova, M. A. Klepikova, L. V. Denisova, D. S. Matvienko

Effect of Mineral Filler Modification on the Intensity of Bitumen Aging

Changes in the properties of bitumen under the influence of high temperatures of preparation and transportation of the asphalt mixture leads to a significant decrease in the quality of the asphalt pavement. Studies on this problem have given rather contradictory opinions about the effect of various mineral materials on the bitumen aging and on the properties of asphalt concrete. The paper presents the results of research on the effect of mineral filler hydrophobized with GF-1 specimen on the intensity of bitumen aging at the technological temperature by changing the parameters of penetration, softening point, and cohesion of asphalt binders. It was found that all the studied characteristics of samples prepared on hydrophobized mineral filler change significantly less than on the original filler. This indicates a slowdown in the aging rate of bitumen in the composite with hydrophobized mineral filler. It is shown that an increase in the resistance of bitumen to aging during preparation when using a modified mineral filler is accompanied by an improvement in the structuring of bitumen with filler. Slowing down aging can also be associated with a more uniform distribution of the binder over the surface of the hydrophobized mineral filler, an increase in the interface between them, and the formation of more bonds.

V. V. Yadykina, E. V. Kuznetsova, M. S. Lebedev

Dependence of the Quality of the Foam Concrete Mixture on Its Mixing Modes

In order to make a foam concrete mixture, based on the analysis of a priori information, a single-stage technology was used. During the preparation of the mixture, a laboratory turbulent three-bladed mixer with a conical part and reflective partitions was used. A mixer was used to ensure the slurry process of particles in the mixing mass. The authors considered the features that need to be paid attention to in the process of mixing such dispersed systems as “solid phase – liquid”. Such systems are characterized by high particle deposition rates. This condition can also be used for foam concrete mixtures. Experiments were conducted on the effect of the activator rotation speed on the homogeneity of mixing of the foam concrete mixture. The distributions of suspended particle concentrations over the radius and height of the mixer are considered. The dependences of the structural homogeneity of the mixture on the speed of rotation of the activator and the time component of the mixing process are analyzed. It was found that the rise of particles and increased power consumption is affected by changing the height of the agitator installation above the bottom, namely, its reduction. It is established that the efficiency of the designed mixers depends to a greater extent on the requirements for the indicator of uniformity of the concentration distribution in the foam concrete mixture. The higher the requirements for the uniformity indicator, the more power increases. An excessive reduction in the requirements for the degree of uniformity of the foam concrete mass may contribute to the deposition of some of the solid phase on the bottom of the mixer, which will lead to heterogeneity of the mixture.

L. R. Mailyan, S. A. Stel’makh, E. M. Shcherban’, K. E. Tkacheva

Lead Oxides as Fillers of Composite Materials for Protection Against Ionizing Radiation Based on Building Gypsum

Based on experimental and theoretical data, the possibility of using lead oxides in the production of radiation-protective materials based on building gypsum was established. The influence of lead oxides of various compositions, such as β-PbO, β-Pb3O4, and α-PbO2, on the physical, mechanical, and radiation-protective properties of gypsum composites was studied. It is established that the physical and mechanical characteristics of composite materials significantly depend on their structure, which in turn depends on the composition of lead oxide. The material based on BG and β-Pb3O4 consists of large gypsum crystals with a layered-batch structure. In contrast, the material based on BG and α-PbO2 is represented by elongated thin prismatic gypsum crystals wrapped in a fine-crystalline mass of filler. No new compounds were found in the construction gypsum lead oxides system, which indicates a weak interaction between the filler and the binder. A composite finishing material for biological protection against ionizing radiation with a linear attenuation coefficient of 1.76–2.11 cm−1 was obtained on the basis of building gypsum and lead oxides. Composites based on BG and β-Pb3O4 have higher strength characteristics than those based on other lead oxides, which is due to their high dispersion and the presence of lead atoms in different degrees of oxidation. Compositions of composite materials are proposed.

V. G. Klimenko, A. N. Volodchenko, R. V. Sidelnikov

Utilization of Drilling Waste in the Production of Construction Materials

A technology for the disposal of drilling waste is proposed that provides an inexpensive, environmentally friendly construction material that meets the required physical and mechanical characteristics and has protective properties against ionizing radiation. The results of research on determining the physical and mechanical properties of composite materials are presented. Studies were carried out for different contents of drilling sludge in the raw material mixture. It is shown that when the content of drilling sludge in the aggregate is 50%, the highest values of the compressive strength of samples are provided. These results correlate with data on the value of the attenuation coefficient of the ionizing radiation dose rate, which makes it possible to consider the ratio sand: drilling sludge  =  50: 50 as the optimal composition of a composite material with increased mechanical strength and the ability to attenuate the ionizing radiation dose rate. The results of the study showed that the proposed compositions of composite materials are able to withstand long-term radiation exposure without significant deterioration of construction and technical properties. The proposed method of disposal of drilling waste increases environmental protection, improves the environmental situation and at the same time allows using cheap components to obtain building material for lining rooms with sources of ionizing radiation, for the construction of storage facilities for low-level radioactive waste.

Yu. E. Tokach, Yu. K. Rubanov, O. S. Vyrodov, A. N. Popova

The Role and Significance of Electric and Surface Properties of Mineral Filler in Increasing the Frost Resistance of Powder Concretes

The influence of mineral fillers with positively and negatively charged electric and surface properties on the frost resistance of powder concretes is studied. The authors put forward a hypothesis that in the processes of hydration and corrosion, where water molecules always participate, an important role is played by the electric and surface properties of the solid phase, which make up the binding system. Concretes where the charge on the surface of the pores and capillaries is strongly shifted to the negative area will be subject to a deeper saturation of the material with water and, consequently, will have less frost resistance. Tests for frost resistance were carried out according to GOST 10060-2012 (clause 5.1), according to the first basic method. It was found that the lowest frost resistance is found in samples of powdered concrete with 30% ground quartz sand, compared with powdered concrete with 30% ground marble and fine-grained concrete C:S  =  1:3. The results confirmed hypothesis contained in this work. This is evidenced by the results of changes in the mass of samples during tests for frost resistance. It is proposed to use the obtained data as a theoretical basis for selecting rational compositions of high-frost-resistant concretes, both fine-grained and powdered.

Sh. M. Rakhimbayev, N. M. Tolypina, A. A. Kosinova, E. N. Khakhaleva

Strengthening of the Adhesive Joint in the Production of Glued Beams

Wood is widely used in construction for the production of walls, partitions, floor structures and roofs. Since wood is an anisotropic material, its physical and mechanical properties depend on many factors, including the presence of defects in the form of knots and cracks. To ensure the stability of the properties of the structure, they are made by layer-by-layer gluing of wooden blanks with removed defects. Based on the conducted research, it was found that the strength of the adhesive joint is limited by the strength of the wood to cleave along the fibers, especially for spruce species. To strengthen the deeper layers of wood, it is proposed to prick the glued surfaces. Through the holes, the glue gets into deeper layers and spreads over the tracheal cells, making them more durable. The experiments showed that the strength of the joint with impaled wood is 27% higher compared to wood without impaling.

S. I. Ovsyannikov, A. A. Suska, D. A. Levkin, O. L. Rudenko

Composite Binders and Dry Building Mixes for 3D Additive Technologies

Currently, there are many revolutionary technologies in construction, among which a significant place is occupied by construction 3D printing. It attracts an increasing number of researchers and entrepreneurs. However, the creation of effective compositions for this technology is still an urgent issue, as these mixtures must have a number of required characteristics: high plasticity during extrusion and low fluidity after laying the mixture, as well as a high setting speed. The results of research on the preparation of composite binders based on Portland cement using a superplasticizer and a hardening accelerator are presented. To reduce the energy intensity and cost of production, wet magnetic separation dropouts of metallurgical production were added to the compositions. Optimal dosages of the accelerator additive and superplasticizer when used together were established. A comprehensive study of the samples was performed using x-ray phase analysis and electron microscopy. A two-factor mathematical model of the obtained composite binders is proposed using regression equations and the optimal composition is selected for construction 3D printing. Energy-efficient, cost-effective compositions were obtained that have the required characteristics for workability in 3D printing, as well as a high speed of setting and hardening with guaranteed strength characteristics. A technological solution for the introduction of hardening accelerators directly during extrusion is proposed.

E. S. Glagolev, V. S. Lesovik, L. H. Zagorodnyuk, D. S. Podgornyi

Effective Road-Impregnating Materials

The country’s transport infrastructure is an important factor in its economic development. However, often roads do not meet the operational requirements, there is: peeling, painting with loss of thickness of the coating layer, the formation of a grid of cracks, ruts. In this regard, research in the field of preventive measures to maintain and preserve asphalt concrete pavements in working condition is relevant. In the presented research, the author’s methodology for evaluating the effectiveness of road-impregnating compounds as preventive measures to preserve the operational condition of road surfaces is proposed. Based on the proposed method, samples of developed impregnating materials based on polar (water) and non-polar (nephras) solvents are tested. It is established that road-impregnating materials based on non-polar solvents with high penetrating power contribute to the destruction of the upper layer of asphalt concrete pavement by weakening the cohesive-adhesive bonds at the division “bituminous binder – stone material”. While the impregnating material, based on a polar solvent, forms an elastic protective layer of bituminous binder, reinforced with a complex of rheological additives. The paper experimentally confirmed the effectiveness of the use of road-impregnating materials. A method for evaluating their effectiveness and cooking technology is proposed.

E. A. Lukash, E. A. Vlasova, E. V. Kharlamov, A. V. Kurlykina

Stability of a Multistoried Building on a Ground Base Described by a Bilinear Model

The paper uses computer programs based on the finite element method to study the problems of loss of stability and collapse of multistoried buildings located on weak soils with elastic-plastic properties. Such properties, in particular, can be shown by clay rocks, which are often found on construction sites and in conditions of overload and excessive moisture behave as perfectly plastic materials. A characteristic feature of these soils is the loss of bearing capacity, which is accompanied by a sharp decrease in the modulus of deformation. The problem is solved in a non-linear formulation using a bilinear model of the ground base that best corresponds to the analyzed computational situation. From the point of view of construction mechanics, the critical state of the “ground base – structure” system is considered as an indifferent state. In this situation, with small external forces, an unlimited growth of deformations is observed. From this point of view, the use of numerical research methods is very effective. To solve this problem, the perturbation theory is used in combination with the method of successive loadings. A multistoried building on a slab foundation is considered. A weak wind effect is used as a disturbance. Stepwise increase in the vertical load allows determining the critical reactive pressure in the base. Based on the results obtained, a variant of strengthening the foundation is proposed.

A. I. Oleynik, K. M. Akhmedov, V. V. Shamov

Compounding Features of Special Molding Mixes for 3D Printing Technology

World experience shows that to ensure the speed of building construction and minimize labor costs, the technology of layer-by-layer synthesis (3D printing or three-dimensional extrusion) will develop rapidly in the next decade. In modern Russian conditions, 3D printing is ideal for mass and individual construction of low-rise houses and cottages. The main idea of construction printing is to create a finished product or structure with a single device. For a stable technological process of construction of low-rise buildings by layer-by-layer synthesis, special fast-hardening molding mixes are offered, including clinker minerals, gypsum binders, mineral and organic additives, as well as fine aggregate. The joint insertion of gypsum binders of α - and β - modification (G-5BII and GVVS-16) into the composition of CGB contributes to the early structure formation of stone on CGB. The insertion of modifying additives into its composition - the hyperplasticizer MARP SU 84, the thickener MARF (Forbocrete 9010) and the hydrophobic rheological additive MAPF №T 10 can significantly reduce the water demand of the binder by 28…56%) and improve plasticity, while the compressive strength increases by 2 times in 2 h, by 1.7 times in 1 day, and by 1.5 times in 7 days. Developed for 3D additive technologies, molding mixtures based on CGB and quartz sand quickly harden and gain strength, providing concrete compressive strength class B3.5 in the early stages of hardening (1 day), and at the age of 7 days – B7.5.

E. S. Glagolev, N. V. Chernysheva, V. S. Lesovik, E. N. Lesnichenko

Research of Chernozemic Soil Roads’ Dusting Surfaces Fixation Method

Dust is presented with a mixture of organic and mineral impurities, contained in the outdoor air and varying in chemical composition. Its high content reduces road visibility, thus increasing the accident risk and slowing down the traffic speed. Accumulation of explosive or combustible materials' dust in the air can cause explosions or fires. In this research we have used the chemical agent «Bespylin», which appears as a sticky biopolymer emulsion, for dusting surfaces fixation. To study the dust loss an experimental plant was designed and assembled, which consisted of a wind tunnel, with wind speed varying in the range 4–10 m/s, a return pump and an electric motor. The dust loss was evaluated after one day, one week and one month. The dust loss was determined by calculation, i.e. by the difference in weight of the material under study. It has been determined that after applying the agent on the dusting surface, a stable crust is formed, which prevents the dust loss. The agent can be used in amount of 250–300 ml/m2 at the minimum concentration 1:3. It has been also determined that this method of dusting surface fixation has no adverse effects on the condition of green cover.

L. M. Smolenskaya, E. A. Pendyurin, S. Yu. Rybina, M. M. Latypova

Composite Material Based on Polyvinyl Chloride and Methylcellulose Fibers with Improved Performance and Environmental Characteristics

The article presents data on obtaining a polymer composite material based on polyvinyl chloride and methylcellulose fibers, testing it for Flexural strength and impact strength, and evaluating the Toxicological properties of this material for the survival of Daphnia moina due to the presence of a toxic stabilizer in the material. The samples were obtained by mixing the components in a mixer and then hot pressing. The samples were obtained considering the mass and volume fraction of the components. The optimal matrix-filler ratio was determined based on the obtained experimental characteristics. It was 10% of the volume of methylcellulose from the content of polyvinyl chloride. It is shown that the resulting polymer composite material has increased strength characteristics, such as Flexural strength and impact strength, and does not exhibit toxic properties in certain ratios of methylcellulose and polyvinyl chloride. Electron microscopic analysis of the surface state of the samples was performed, which confirms the above conclusion.

L. N. Naumova, N. A. Kristalova, E. V. Burmakina, A. N. Ryzhkova

Purification of Model Waters from the CONGO Red Dye with Organomineral Sorption Material Based on Sludge Waste

The food industry generates a lot of large-capacity sludge waste that requires recycling. The paper presents the results of a study on sorption treatment of model waters containing the Congo red dye using sorption materials based on diatomite-containing sludge formed in the brewing industry and carbonate sludge formed in the sugar industry. It was found that when using sorbents separately, the most effective is heat-treated at 450 °C diatomite-containing sludge (DS450), the optimal time of interaction of the sorbent with the solution is 20 min. The sorption material based on thermally modified carbonate sludge (TCS) showed the lowest cleaning efficiency under the conditions of this experiment. It is shown that combining TCS to DS450 in a ratio of 1:9 significantly increases the cleaning efficiency. When the TCS content in the mixture increases, the efficiency decreases. At the same time, using DS450 and TCS separately gives a lower cleaning effect, 93% and 41%, respectively, while a mixture containing 10% TCS allows achieving 98% efficiency. The identified effect requires further study.

Zh. A. Sapronova, I. V. Starostina, I. V. Bomba

Impact of Technological Parameters of Vibration on the Integral Characteristics of Vibrocentrifugal Concrete

For the best compaction of the concrete mix, it is appropriate to use the method of centrifugation together with vibration. This mode is appropriately called vibrocentrifugal. In the process of vibrocentrifugation, vibration can also be considered as a method for diluting the concrete mixture at the stages of its dispersal under the influence of centrifugal forces. Under the proposed experimental setup to generate vibrocentrifugal items with variational structure and method of their production was allocated to the process parameters that have the most significant influence on the characteristics of vibrocentrifugal concrete and constructions. In the experiments, the following technological factors varied: the height and length of the technological projections of the clamps, the step between them, and the vibration mode. The problem of evaluating the influence of these factors on the integral (general, cross-section averaged) characteristics of concrete was investigated. The results of experimental studies of the integral characteristics of vibrocentrifugated concrete are analyzed. The most effective will be the use of clamps with a height of technological projections of 5 mm, a length of 20 mm and a step between them of 30 mm, the vibration mode is alternating. At combinations of technological parameters of vibrating vibrocentrifugal concretes have better values of integral characteristics.

L. R. Mailyan, S. A. Stel’makh, E. M. Shcherban’, A. K. Sysoev

Analysis of the Methods of the Connection Calculation

In the present research work the compression analysis of the method of calculating joint connections made of roll-welded profiles, specified in the “Guide on structural steel design (for Construction Standards and Regulations II-23-81*)” (hereafter - SNiP), was performed. According to item 15.16. of the guide [1], two types of joints, F and Fr, were chosen as the study object. During the research several combinations of the construction of such joint types were accepted and modelled with the help of the software solution IDEA StatiCa which does calculations based on the component-based finite element method (hereafter - CBFEM). The obtained results from the software solution were checked against the results calculated by the procedure described in the guide. It was established that during the compression calculation of the connections, the load-carrying capacity of the joint is reduced by the receiving gusset, which is disregarded in SNiP. The research was conducted with the help of the CBFEM used by the software solution IDEA StatiCa.

O. S. Chernyavskiy, D. E. Pashkov

Research of Fiberglass Polymer Concrete Switch Bars on Endurance Under Cyclic Loading

The purpose of this work is to identify to assess comprehensively the strength and endurance of fiberglass polymer concrete (FPC) elements at bending. To research the degree of influence of the reinforcement coefficient and controlled loading on the value of the destructive bending moment of fiberglass polymer concrete, the method of planning an experiment with the construction of an orthogonal central composite plan of the second order was used. It is proved that the percentage of reinforcement of prestressed beams and the degree of controlled stress significantly affect the load-bearing capacity of bars, the second factor is the most significant. The change in deformations along the height of the cross-section of beams confirms the acceptability of the flat cross-section hypothesis for fiberglass polymer concrete bending elements. It was found that the neutral axis gradually rises with increasing reinforcement coefficient and the degree of controlled stress, reducing the value of the relative compressed zone of polymer concrete. The nature of the destruction is basically the same, the destruction occurred in the compressed zone of polymer concrete in the area of pure bending. The values of the ultimate endurance for fiberglass polymer concrete elements are obtained for the cycle asymmetry coefficient ρ = 0.3 and for different degrees of pre-stress of fiberglass reinforcement. A theoretical analysis of the resistance of fiberglass polymer concrete elements to cyclic loads using a structural diagram is presented. The results of experiments and obtained theoretical dependences are compared.

B. A. Bondarev, A. A. Kosta, A. Y. Sychev

Tensile Deformations of “Mild” Reinforcing Steels for Reinforced Concrete Structures

Reinforced concrete structures are widely used in all areas of modern construction, which is explained by their durability, the possibility of using local building materials, low consumption of steel, and a variety of forms. The increasing requirements for ensuring the reliability of reinforced concrete structures makes it necessary to improve the calculation of bent elements. The main difficulty of the calculation is that “mild” steels, like all real structural materials, are deformed under force loading non-equilibrium and non-linear, while the desired physical relationship “stress – deformation” is usually reflected by analytical dependencies of high degrees (5 and higher). The authors consider the nature of the “stress – deformation” curves taking into account the heterogeneity of the physical properties of various steel components, the elastic limits on the tensile curve, the nature of steel deformation, the transition sections of the experimental tensile curves of reinforcing bars from the elastic limits and proportionality to the yield point determined by the results of experimental data from various devices, and the expression of the secant modulus of deformation of mild” steels is developed, which allows not only to calculate accurately reinforced concrete bending elements, but it also allows getting the elastic coefficients of individual sections of reinforcing steel when they are stretched.

O. M. Donchenko, L. A. Suleymanova, V. I. Rimshin, I. S. Ryabchevskiy

Research on Properties of Pressed Silicate Materials of Non-autoclave Hardening with the Addition of Synthetic Tobermorite-Like Calcium Hydrosilicates

At the present stage of development of construction materials science, the tasks of producing high-performance construction composites of a new generation, including those using natural and technogenic raw materials, are of particular relevance. To a greater extent, these requirements are met by wall silicate materials. Currently, the raw material base for the production of silicate materials is not expanding, and the use of quartz sand in the technology determines the high energy intensity of the synthesis of new formations in the CaO-SiO2-H2O system, as well as the production process as a whole. In the production of wall silicate materials using non-autoclave technology, instead of quartz sand, it is possible to use clay rocks of an incomplete stage as the main component. The question of study of influence of synthetic tobermorite-like calcium hydrosilicates (STCH) on synthesis system CaO–AI2O3–SiO2–H2O and properties of extruded silicate materials of non-autoclave hardening using clay rocks of unfinished stage of formation is relevant. In the course of research, the nature of the influence of synthetic tobermorite-like calcium hydrosilicates (STCH) on the physical and mechanical properties of non-autoclaved silicate composites based on unconventional aluminosilicate raw materials represented by clay rocks of the incomplete stage of mineral formation was established. The rational content of the STCH additive is 1 wt.%, and with an increase in the percentage, the strength characteristics of finished products decrease.

A. A. Volodchenko

Effect of Cubic and Orthorhombic Crystal Systems of Tricalcium Aluminate to Form Ettringite in the Presence of Dihydrate Calcium Sulfate

Hydration of clinker minerals plays an important role in the formation of a strong cement stone. Depending on the composition, quantity, shape, size, and structural defects of the formed crystallohydrates, the physical and technical properties of the hardened cement stone are determined. The most chemically active mineral in Portland cement clinker is tricalcium aluminate (3CaO·Al2O3), which also reacts easily and forms solid solutions with R2O. In turn, alkaline solid solutions affect the solubility of tricalcium aluminate in water and the further formation of crystallohydrates. The effect of alkaline solid solutions of tricalcium aluminate on the formation of ettringite (3CaO·Al2O3·3CaSO4·32H2O) during hydration was studied. It is established that the rates of hydration of cubic and orthorhombic crystal systems of tricalcium aluminate are different, and when they interact with dihydrate calcium sulfate, different hydration products are formed. Thus, the orthorhombic crystal system 3CaO·Al2O3 (C3A) with CaSO4·2H2O in water promotes the formation of calcium aluminate sulfate hydrate (3CaO·Al2O3·CaSO4·12H2O), which then formed calcium aluminate trisulfate hydrate (3CaO·Al2O3·3CaSO4·32H2O). A cubic system of C3A with CaSO4·2H2O in water, on the contrary, first forms a calcium aluminate trisulfate hydrate, which is eventually converted to calcium aluminate sulfate hydrate.

A. O. Erygina, D. A. Mishin

Prospects for Construction of Monolithic Cement-Concrete Transport Infrastructure Facilities in the Siberian Region

Today, one of the priority tasks of road construction in the Russian Federation is to improve road safety and increase the quality and service life of road surfaces. The climate of the Siberian Federal district, selected as a construction area, is characterized as sharply continental, with hot summers, harsh winters, and a sharp drop in daily temperatures. Therefore, improving the quality of road surfaces and their durability is an urgent problem both in the short and long term. In this paper, we analyzed the effectiveness of testing the technology of laying monolithic transport infrastructure objects using a concrete paver and their operation in the city of Krasnoyarsk. As the object of research, we selected road drainage trays made in 2015 using the Power Curber 5700-C concrete paver, located at a transport interchange near the village of Badalyk in the Krasnoyarsk territory. The results of the survey showed that the identified defects do not affect the operational suitability of the elements. However, when studying the possibilities of using cement concrete coatings in the city of Krasnoyarsk, it turned out that the issues of manufacturing technology and selection of concrete mix compositions taking into account local conditions were not sufficiently developed.

I. G. Endzhievskaya, A. A. Yakshina, R. T. Emelyanov, M. L. Berseneva

Combined Method of Water Treatment for Sealing Gypsum Systems and Materials Based on Them

The paper considers technologies for producing gypsum binders sealed with water that has passed through microwave (ultra - high-frequency) radiation, a permanent magnet field, and a combined processing method. Methods of mixing water treatment for gypsum binders are proposed, which provide high strength of gypsum systems, the introduction of substances of various concentrations improves the conductive properties of systems, reduces electrical resistance and increases electrical conductivity. The introduction of iron oxides of various degrees of oxidation contributes to the production of composite materials with a mixed type of conductivity. This paper uses the method of introducing low concentrations of iron chloride into the mixing water and treating the solutions with a microwave field and a magnetic field at different stages of the hardening process of a gypsum system based on iron oxides, which allows you to adjust the properties of the resulting gypsum matrix when using it. Methods of processing binders encapsulated in a gypsum matrix are analyzed, which in the future will make it possible to obtain structural composites with mixed electron-ion conductivity, which have high strength and controlled conductivity, in contrast to conventional gypsum systems used for the repair of construction objects.

S. N. Lapteva, V. I. Pavlenko

Sorption Extraction of Zn2+ Ions from Aqueous Environment with Zoo Compost of Black Soldier Fly

The paper presents the results of experimental studies to determine the possibility of sorption extraction of zinc ions (Zn2+) from aqueous environment using the zoo compost of the Black soldier fly (Hermetia illucens). The indicators of zoo compost on the content of biogenic elements in it are given. The adsorption of zinc ions was studied on model solutions using a static method at a temperature of 20 °C and a sorption interaction time of 24 h. The concentration of Zn2+ ions in the initial and purified solutions was determined photocolorimetrically at a wavelength of ƛ = 213.8 nm. The obtained values of the concentrations of zinc ions in solutions before and after the adsorption process were used to determine the sorption capacity of the material (A). It was found that the maximum sorption capacity of the zoo compost for zinc ions is 0.149 mmol/g. To determine the mechanism of the process, the resulting adsorption isotherm was processed using the Langmuir, Freundlich, and Dubinin-Radushkevich models. It is established that the adsorption process is well described by the Langmuir isotherm, which indicates the course of monomolecular adsorption. The necessary constants and thermodynamic parameters are calculated. The Gibbs energy of the adsorption process is determined, the negative value of which indicates the spontaneous flow of the process.

S. V. Sverguzova, I. V. Bomba, E. A. Pendyurin

Porous Magnesia Compositions with Various Fillers

The paper presents the results of studies of magnesia compositions of porous structure. The possibility of pore formation in the structure of magnesia materials by various technological methods is shown. It was found that the high adhesive capacity of magnesia binders allows the use of fillers of various origins in compositions. The characteristics of magnesia compositions containing an ash microsphere, expanded polystyrene, expanded granules based on liquid glass, and porous magnesia granules are determined. A combination of porization methods is proposed for the formation of low-density magnesia compositions. A comparative analysis of the mechanical and thermal properties of porous magnesia compositions of various preparations is carried out. The advantages of complex porization of magnesia compositions due to a combination of mechanisms of foaming, gas formation and insertion of fillers of a porous structure are revealed. Magnesia compositions containing integral fillers of various shapes and origins are proposed. Multi-component compositions are characterized by a density of 540 kg/m3 and a compressive strength of 4.1 MPa. The impact of the method of preparing the molding mixture on the strength of porous structures is established. Porous raw materials were developed to produce granulated magnesia aggregate based on caustic magnesite and wood particles. Magnesia aggregate granules are used to obtain granular-cellular and coarse-pore structure of compositions.

O. A. Miryuk

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