Environmental and Construction Engineering: Reality and the Future

Diffraction of shock waves into multistory frame buildings is analyzed by Finite Element Analysis (FEA). The FE model consists of a ten-story superstructure rested on the slab foundation. The trigonometric approximation of the delta function was used to model the application of loads with values for shock durations t = 0.5, 1, and 1.5 s. Analysis of the interaction of shock waves with the building was performed using the software package Abaqus/CAE 6.14. Six columns and four longitudinal axes were selected and the stress values were evaluated in monitoring points distributed in specific positions on the considered columns and longitudinal axes. The dynamic analysis over a time period of 10 s reveals that the arrival of the shock waves results in dangerous stresses first in the foundation before the columns for the different shock durations. Moreover, the analysis also reveals that the columns are not affected by a shock duration smaller than 0.5 s.

Currently, in the construction of buildings and structures, builders use a variety of building materials and products for various functional purposes, including silicate materials. On the territory of Russia, there are a large number of sands with a high content of clay impurities, which makes it difficult to use them in the production of silicate materials. The purpose of the research was to study the properties of autoclave-hardened silicate materials using sands containing clay impurities, as well as the interaction processes in the “lime—sand-clay rock—sand-aggregate—water” system. Based on the conducted studies, it was found that sand-clay rocks containing 20% wt. of clay impurities are widely distributed in Russia and can be used as a component of the raw material mixture to produce silicate composites. The use of such raw materials allows accelerating the synthesis of new things, and as a result, increasing the performance indicators of finished products. To achieve maximum efficiency, the sand-clay rock must be used as a part of an aluminosilicate binder obtained by joint grinding of the initial rock and lime, which will ensure the most uniform distribution of the clay fraction in the raw mixture. The optimal total content of sand-clay rocks in the raw material mixture, which ensures the achievement of maximum strength indicators, is 35–40 wt.%.

It is investigation of separation of the oil–water emulsion by polysulfonamide membranes with a molecular weight cut-off 20 kDa treated with a low-temperature high-frequency capacitive plasma of reduced pressure in an air medium at a voltage Ua = 1.5–7.5 kV and a processing time τ = 1.5–7 min. Round flat filter elements with a diameter of 47 mm are used as membranes. The emulsion with a concentration of 3% (by volume) is prepared on the basis of Devonian oil from the Tumutuk field and distilled water, stabilized with a surfactant of the Kosintol-242 brand. The experiments were carried out on a laboratory ultrafiltration separation unit.Based on the results of studies have shown the increased productivity of the separation of oil–water emulsion for plasma treated membranes at Ua = 1.5 and 3.5 kV 1.5 times, when exposed to plasma at Ua = 7.5 kV and τ = 7 min was an increase in the efficiency of the investigated process of 95.7–99.6%.The methods of dynamic light scattering and dielectric permittivity revealed a decrease in the particle size and stability (in -potential) of the emulsion after its separation by the membrane, while lower values are observed when using a plasma-treated filter element, for which lower values of the dielectric permittivity are also observed.

The most important indicators of molding mixes for 3D construction technologies that determine the quality of products are rheological and technological characteristics, in particular, the preservation of viability (flowability of the mixture), the ability to regulate the thickening and setting time within the required limits, as well as the ability to maintain certain rheological parameters throughout the entire process of their preparation. The use of special molding mixes based on composite gypsum binders (CGB) will reduce the duration of the production cycle and improve the quality of products.The paper presents the results of experimental studies on the rheological characteristics of fast-hardening special molding mixtures based on CGB, including (wt. %): gypsum binder—58% (70% G-5 BII and 30% GVVS-16); cement—20%; waste of wet magnetic separation of ferruginous quartzite (WMS waste)—20%; metakaolin—0.5% and chalk—1.5%, which were studied on a rotary viscometer “RHEOTEST RN 4.1”.The studies confirmed the ability to control the rheological properties of molding mixes on CGB due to the combined functional and rheologically active additives with optimizing their properties for features of different types of forming equipment and tasks.

The article deals with issues related to the mechanical machining of a flat surface of a metal-polymer work piece by flat grinding. The attention paid to the mechanical machining of flat surfaces is due to the use of metal-polymer as structural materials for the manufacture of parts of molds and their repair. The article provides an analysis of materials and types of machining of a combined part consisting of metal-polymer and metal, such as a forming part of a mold for casting plastic products. A brief description of the part is given on the example of the forming part of the mold and the requirements for dimensional accuracy and roughness imposed on it. Based on the analysis of the properties of two materials with different physical and mechanical properties, an analysis of the types of machining, the parameters of accuracy, roughness and deviation of the shape and location of surfaces achieved by them is given. The conclusions on the advisability of using one or another type of processing are presented in a tabular form, which is convenient to use when developing a technological process for manufacturing a combined metal-metal-polymer flat part.

The article considers the damage rate of concrete and its main design parameters using an elastic-plastic model. The main dependencies that determine the operation of the model are given. An example of an approximation is given, which allows us to take into account quite accurately the shape of the curve of the dependence of damage d on deformations ε. The dependences of voltage on deformations are obtained, based on the results of calculations with different values of viscosity, which are compared with the original deformation diagram, which is set as parameters of the material model. An approach is proposed to construct a calculated diagram of concrete deformation under voltage, taking into account the descending branch, based on the concrete parameters presented in regulatory documents, and with a known value of the specific energy of destruction. Based on the analysis of the results of computational studies conducted using various sets of parameters of the nonlinear concrete model, the effect of taking into account the descending branch of the voltage strain diagram, as well as changes in the specific fracture energy and the angle of dilation of concrete on the voltage state of the structure at sufficiently large load values is shown.

The results of the study of the strength characteristics of concrete wall stones are presented. The results were obtained when testing wall stones according to the methodology of the updated state standard for testing the strength of wall materials. Statistical indicators that characterize the stability of the studied characteristics are calculated. Special computer programs are used to perform calculations and statistical data processing. To increase the architectural expressiveness in construction, wall stones with a textured surface are used, as well as colored ones, made of a concrete mixture with pigments or with the use of colored cements. A comparative analysis of the compressive strength of concrete wall stones, unpainted and colored, made of concrete mixtures with pigments, is carried out. For the production of colored stones, pigments of red, yellow and green were used. Recommendations on the organization of the technological process of production aimed at obtaining colored concrete with stable quality indicators are given.

The article presents studies on the regulation of the surface microrelief of titanium hydride fraction by the method of sorption modification from a solution of titanium sulfate salt under static and dynamic conditions. The results of a scanning electron microscopy study with the removal of Energy-Dispersive X-Ray Spectroscopy Mapping of coatings obtained on titanium hydride fractions are presented. It has been established that the time of sorption interaction affects the structure of the coatings. Under static conditions of sorption interaction of shot with titanium sulfate salts at pH = 0–1, etching processes prevail, as a result of which crater structures and pitting pits are formed. The mechanism of interaction of titanium sulfate salt with the surface of titanium hydride fraction is established. It is shown that under dynamic conditions at pH = 4–5 on the surface of the titanium hydride fraction, a uniform formation of a modification shell occurs with its chemisorption fixation due to interaction with the hydroxo groups of the surface layer. As a result of subsequent thermal drying at a temperature of 180 °C and removal of excess hydrated water, the surface of the titanium hydride fraction is completely covered with an adsorption layer of hydroxotitanil with a pronounced aggregate-like relief and a high degree of adhesion of adsorbed ions due to the incorporation of atoms into the crystal lattice of titanium hydride.

The creation of “smart” materials that can independently respond to changes in structure during operation and take measures to eliminate them is a promising direction for increasing the service life of asphalt concrete pavements. The implementation of the technology of self-healing of asphalt concrete can be ensured through the use of encapsulated modifiers, which are a reducing agent inside a functional capsule. Making capsules with a reducing agent through an aqueous solution of sodium alginate is a simple method for encapsulating modifiers. The encapsulation of reducing agents for asphalt concrete can be carried out by extrusion or by means of an emulsion of a reducing agent, which is fixed dropwise through a solution of calcium salt. It has been shown that alginates are an effective component that makes it possible to implement the technology of encapsulation of modifiers (reducing agent) for self-healing asphalt concrete. The regulation of viscosity by controlling the prescription factors will make it possible to use an alginate solution with the required technological properties for encapsulation, including rate of separation of the emulsion into individual drops. The control of recipe parameters allows in a wide range to control the technological properties of alginate solution and emulsions, as well as the parameters of the resulting capsules with a modifier (reducing agent) for self-healing asphalt concrete.

The article discusses two main issues that need to be addressed in the development of a technological process of abrasive machining of a combined shaping. The first issue is the optimization of the surface grinding process, taking into account technological limitations due to the heterogeneity of the work materials. The second issue is the establishment of functional relationships required for calculating the amount of heat generated during flat grinding. The optimization of machining modes for flat grinding with the periphery of the wheel according to the criterion of the minimum technological cost takes into account the parameter of roughness of the closing joint as the main criterion for the operability of the mold package. The temperature limitations imposed by the heterogeneity of the materials properties, from which the forming mold is made, also takes into account. The research and new approaches to the assignment of technological parameters of abrasive machining, presented in the article, is a great interest to engineers of tool and repair production who use metal-polymer materials in the design of their production facilities that require final machining by flat grinding.

In the production technology of non-autoclaved cellular concrete, there are a number of technological changes, the possibility of intensifying which is possible by inserting chemical and mineral additives-stabilizers of the foam matrix. These additives can simultaneously act as accelerators of hardening and setting, as well as stabilize the foam matrix at the initial stage. For the research, the foam matrix mineralizers—fine-ground sulfates were selected for the purpose of possible intensification of the injection molding technology of cellular concrete. The solution to this problem lies in the assessment of the main mixing parameters, the choice of raw materials, the availability of additives and the overall manufacturability of the production process. The paper clarifies the effect of foam matrix mineralizers together with additives that accelerate setting, and also evaluates the effect of a complex of additives on the main properties of foams: durability, multiplicity and syneresis. The influence of the pH environment on the primary characteristics of foams obtained on the basis of foaming agents of various nature is considered separately. The regularities of the influence of the hydrolysis constants of additive on the multiplicity of the resulting foam were identified; the possibility of changing the pH value of the environment on the stability of the foam matrix and initial syneresis was evaluated. Recommendations on the use of some sulfates together with foam thickeners in the technology of non-autoclaved foam concrete are given.

Based on the analysis of the volume of waste generation in the production halls and the technological calculations performed, a bag filter of the brand with a purification degree of 99.9% was selected. It was found that only 14.5% of metal chips (unpolluted) are involved in recycling. More than 80% of the metal chips that are not involved in the secondary production cycle are unsuitable for remelting in traditional drum furnaces of foundries. It was proposed to install a rotary tilting furnace in the workshops instead of the usual rotating drum furnaces, which will reduce energy consumption, and melt any charge without preliminary preparation. Optimization measures for waste disposal at enterprises are proposed, including the capture of pulverized waste using the FRI-120-km, followed by the inclusion of extracted iron and silicon in the metal charge and the remelting of metal chips in the RTF for the preparation of the metal charge.

An increase in the activity of the cement of Plant 1 was made by changing the granulometric composition of its sludge. The change in the granulometric composition of the sludge of Plant 1 was made due to the coarsening of the grinding, by inserting limestone with a fraction of 0.315–0.2 mm in the amount of 3 and 6% wt. and due to the re-grinding of the sludge during the 0, 5, 10, 30, 60, 90 min in a 1-L mill with a standard range of grinding environment at a humidity of 37%. It was found that with an increase in the fineness of the sludge grinding, a more complete absorption of calcium oxide is observed. The binding rate of free calcium oxide increases slightly up to a mixture with 10 min of re-grinding. Then, at 30 min of re-grinding, the binding rate of calcium oxide increases dramatically. In the clinker from the ground sludge, an increase in the proportion of synthesized alite is observed.The relation between the fineness of the raw mix and the strength of the cement is not linear. There is optimum fineness of grinding at 10 min of the re-grinding, which maximizes the strength of cement at 28 days of hardening in water. An increase in the time of re-grinding more than 10–30 min leads to a decrease in strength.

The paper considers the stress–strain state of the timber-to-timber joint elements on inclined screwed-in rods. Experimental studies of timber-to-timber joints were performed for three types of connections: screws with anchorage details, screws, and threaded rods. The connections are established with the angle of deviation of the connecting element from the normal to the shear plane—45°.It is found that the proposed technical solution for connecting wood elements on screws with anchorage details allows increasing the load-bearing capacity of the joints and reducing their deformability. The threaded rods joint has a greater deformability than the screw joint and a lower load-bearing capacity. The load-bearing capacity of joints with screws with anchorage details and threaded rods increases with increasing cross-section and strength of the connecting element, load-bearing capacity of the joint on screws—with increasing the washer area and anchoring length of the screws into the wood.The destruction of joints with screws with anchorage details and threaded rods comes from crumpling of the wood under the washers (if it is not enough washer area) and rupture of the rod. It is found that the load-bearing capacity and deformability of the joints on the screws increase with increasing anchoring length of the screw.As a result of field experiments, a calculation model is proposed for determining the load-bearing capacity of a timber-to-timber joint on inclined screwed-in rods. The load-bearing capacity of timber-to-timber joints on inclined screwed-in rods is determined from the geometric and mechanical characteristics of the wood and the joints. The calculation model takes into account the resistance of wood under the contact surface of the washer. The results of the calculation according to the developed method are compared with the results of the experiment.

The mathematical model presented in this research allows for the calculation of composite elements with nonlinearly compliant shear bonds by deformations by the step method. The article presents an algorithm based on the theory of calculation of composite bars by A.R. Rzhanitsyn, with specification of the stiffness of shear bonds at each calculation step for each bond depending on the magnitude of the shear force. Using the system of equations, arbitrary expressions are determined that describe the distribution of shear forces at the boundaries of sections, the length of which is taken to be equal to the distance between discrete shear bonds. The system of differential equations of the 2nd order allows one to determine the shear forces in the bonds and the vertical displacements of the beam at each step of loading. The article presents the results of theoretical studies of vertical displacements of a composite wooden beam, consisting of layers connected by bolts; deformation of bonds occurs according to a nonlinear law. To compare the results, a linear calculation was performed with constant values of the stiffness coefficients of the shear bonds. The results show that failure to consider the actual nature of the deformation of the bonds can introduce a significant error in assessing the deformability of composite beams on mechanical bonds.

Dual speed drives (AC2), which are currently widely used in elevator drives of residential constructions, are gradually being replaced by electric drives without speed control with speed governor (VSD)—(electric motor + drive). Asynchronous motors in such drives operate in variable frequency and variable voltage (VVVF) systems. They are often called inverters. Usage of these systems in elevators without an engine-room led to the abandonment of gears, a downsizing of the engine, and an improvement in the quality of movement.This work shows the results of the analysis of the operation of different types of elevators in different buildings. For example, elevators with a lifting capacity of 400 kg and 500 kg were analyzed. The advantages and disadvantages of using adjustable and unregulated drives are shown.The analysis of energy consumption in elevators installed in buildings of different storeys and operating at different intensities has been made. It showed that there is a significant variation in the results for the daily number of cycles and daily energy consumption. However, despite the limited number of test objects, there are certain patterns, which that were also mentioned in this paper. It was found out that the energy consumption in standby mode is usually in the range of 20% to 85%, and the average value is about 70% for residential buildings.

The paper shows the complexity of closed systems for grinding fine powders based on grinding-classifying complexes. The problems of modeling the separation process and predicting the granulometric composition of fine powders are presented. It is shown that the main parameter that determines the operation of the separator of any generation is the efficiency of its operation. Analytical expressions of national and foreign researchers are given, which allow determining the efficiency of the separation process in an air separator. It is indicated that these expressions do not take into account the design features of separation devices, their layout schemes, etc. It is shown that a more complete informative characteristic will be a model for determining the fractional efficiency of particle capture of the developed installation. In this paper, probabilistic dependencies are used to predict the fractional efficiency of the device used. For the proposed apparatus, the full deposition coefficients of the corresponding fractions are obtained. Its high efficiency is shown. The main task of modeling the separation process is to predict the granulometric composition of the finished product. This finished product depends on the composition of the starting material, the design and technological parameters of the machines and mechanisms involved in the separation process. However, at the present time, only previously known systems for separating grinding products are used. Therefore, it is necessary to search for technical and technological solutions aimed at increasing the productivity of grinding complexes. It is proposed to introduce an additional concentrator between the separator and the cyclone in the grinding complex, which will increase the productivity of the complex itself.

The article discusses issues related to the process of controlling the deviation of the shape of complex-profile surfaces of parts. The object of research is the inner ring of a ball bearing support, the subject of research is the possibility of determining the deviation of the raceway shape by a non-contact method. The analysis of the methods of machining the raceway showed the urgency of the problem of ensuring the accuracy of control operations and the need for the development of means and methods of control capable of ensuring sufficient measurement accuracy. The article researches the possibility of using projection control, sets the accuracy limits for determining the deviation from roundness. A mathematical model for the control of the raceway has been obtained, based on the geometric dependences of the individual elements of the inner ring of the support. The experiment made it possible to set the possible obtained control accuracy depending on the values of errors in the measurement process. Analyzing the obtained values, it can be concluded that the mathematical model makes it possible to apply the revealed dependencies to implement the method of projection control of the raceway shape.

The article deals with issues related to the mechanical machining of a flat surface of a metal-polymer workpiece by flat grinding. The article describes an experiment on flat grinding of a workpiece and determines the dependence of surface roughness as the main parameter on the modes of machining, namely, feed and depth of cut. The data collected in the course of the experiment were analyzed and, according to the results of statistical processing of the experimental results, a model of the roughness of a flat metal-polymer surface was developed depending on the modes of abrasive machining. The article presents both a functional model, presented as a function of roughness from the parameters of the depth of cut and feed, and a graphical representation in the form of a surface graph. The graphical roughness model is a great interest for engineers during setting cutting conditions, as it is more visual and simple. Scientists, who research ways to improve the efficiency of the machining process of parts in the design of which a metal-polymer material is used, can use the functional relationship of roughness, this will optimize the technological parameters according to the required optimization criterion.

Deciduous waste from agriculture and urban utilities is a widely available and virtually unclaimed material, especially in Eastern European countries. The objects of research were the leaves of apricot (Prunus armeniaca L.) and horse chestnut (Aésculus hippocastanum L.). It was found that in the range of roasting temperatures of 200–300 °C, the values of the efficiency of purification from zinc ions for modified apricot and chestnut leaves are the greatest. At 300 °C, they are 94% for chestnut leaves and 92% for apricot leaves. High cleaning efficiency is achieved already with the addition of 0.04 g/100 ml, and is 81–84%. When adding 0.08 g/100 ml of the material, the values are 95–96% and do not change with an increase in the amount of the sorbent. In general, 0.06 g/100 ml of the sorbent allows getting 93–95% efficiency, which is very close to the maximum, so under similar experimental conditions, this amount of sorption material can be considered the most rational. It was found that the specific surface area of the studied sorbents increases by 7 times with an increase in the roasting temperature. Microphotographs of the surface of the samples of the original deciduous materials are presented.

In the regulatory documents regulating the design of beam structures, insufficient attention is paid to checking the overall stability of thin-walled beams. Recommendations for testing the stability of single pin-ended beams and rigidly sealed cantilevers are given. There are no recommendations for calculating the stability of continuous multi-span beams. Insufficient attention to the general stability of thin-walled beams can be explained by the fact that the load on the beam structures is transmitted, as a rule, through other beams, decking, etc., that is, additional connections are imposed on the beam, preventing the rotation and lateral displacement of the loaded sections, which positively affects its stability. The specifics of the working conditions of crane beams, namely, the lack of additional connections and the level of load application, negatively affect their stability. The lack of recommendations for checking the overall stability of continuous crane beams leads to an unjustified assignment of geometric cross-section parameters during design, and, as a result, to serious accidents. In this paper, the solution of the equations of stability of a flat bending shape is given by the finite difference method. The derivatives of the deflection and the angle of torsion of the beam are replaced by the central finite differences of the second order. The boundary conditions are written for the extreme and intermediate supports. The use of the finite difference method in solving the stability equations allows obtaining a result for continuous multi-span crane beams, taking into account the level of load application and the influence of neighboring spans on the stability of the most loaded span.

In recent decades, disintegrator mills have become widespread for grinding, activating and mixing building materials. The efficiency of these mills is largely influenced by the design parameters of the working chamber, loading and unloading units, as well as some technological parameters, such as the rotational speed of the rotors. This article discusses a new design of a disintegrator with a unit for preliminary grinding of the material, designed to obtain finer particles of the finished product and increase the uniformity of its granulometric composition. The process of preliminary destruction of material particles is considered within the framework of the inhomogeneous Markov process based on the time variation of the statistical quantity M(t) (mathematical expectation). The result of this work is an analytical dependence that determines the regularity of the change in the size of material particles as a result of the action of the cam mechanism in the central part of the disintegrator grinding chamber. The graphical dependence of the particle size of the material leaving the pre-grinding unit on the particle size supplied to the loading unit is presented. The results of this article can be used in the design of a disintegrator with a preliminary grinding unit, presented in the form of a cam mechanism, as well as in the educational process of bachelors and masters students.

The work is devoted to the study of the stress-deformed state of soils under compression and shear conditions. The results of comparative studies of the stress-strain state of soils under conditions of the impossibility of lateral expansion with the measurement of lateral pressure and single-plane shear on sandy and loess soils of undisturbed structure are presented. It is found that under the conditions of compression, the Coulomb limit equilibrium condition is realized, which is caused by the development of irreversible deformations during compaction due to micro-movements of soil particles. Coulomb’s condition of ultimate equilibrium, as a state of stability, determines the stress state at rest, for the preservation of which the maximum horizontal force is necessary. In the case of compression without the possibility of lateral expansion, this is the compression spacer. The concept of the equality of Coulomb and Mohr conditions, which is accepted in soil mechanics, allows extending them to compare the parameters of the stress state at shear and compression. The developed method with the measurement of lateral pressure makes it possible to apply the Mohr solution to evaluate the strength parameters. This conclusion is confirmed by 850 experiments conducted by the authors of these tests, which give a close convergence in the range of 1.8–2.9%.

Using the coefficients of the hardening intensity, as well as on the basis of calculations using the transport theory equations containing the initial hardening rate and the deceleration coefficient, the analysis of the regulatory and technical requirements established in various countries of the world for the rate of strength gain of cement stone is carried out. It is shown that the kinetic constants of cement hardening in the United States and China mostly correspond to modern ideas about the kinetics of hardening of Portland cement stone. On this basis, the analysis of the hardening kinetics of cements from different countries was carried out. Regulatory and technical requirements for the strength of cements of certain brands in Japan and India require adjustments. The regularities revealed in the analysis of the physical and mechanical properties of cements at different curing times are considered. It is shown that at the age of 28 days, samples of cement stone have more reproducible physical and mechanical parameters than at the age of 1, 3, 7 days. The shorter the hardening time of the samples, the lower their mechanical strength, the greater the coefficient of variation during their testing. It is established that the kinetics of cement hardening in different countries with a correlation coefficient of 0.9 and higher is described by an equation with intensive braking based on the transport theory.

In the construction industry, the development of gypsum materials is one of the priority and promising areas. As world experience shows, the availability of dry building mixes on the market is in demand by the consumer, which leads to the development of the industry and the development of new, improved materials. It is possible to create a competitive and high-quality product by constantly conducting laboratory tests. Dry floor mixtures consisting of natural and technogenic anhydrite have not been sufficiently studied. However, it is known that the technical characteristics of anhydrite binders are on a par with Portland cement and building gypsum, occupying the golden mean between them. At the theoretical level, it can be assumed that using anhydrite binders as the main component of dry mixes, it is possible to achieve a solution with no disadvantages of similar dry building mixes based on lime, cement or gypsum, as well as with improved rheological characteristics.The paper highlights the possibilities of using anhydrite binders based on ground gypsum-anhydrite stone from the Poretsky deposit in dry building mixes for floors. The effective composition of the anhydrite binder was found, particle size distribution of mineral filler was defined, a plasticizer was selected.

Nowadays building material industry as well as other industry branches exercise bigger demand to use powders with high dispersion. Jet mills are used to produce such powders, that’s why development of new jet mill designs, increase of grind efficiency, reduction of specific energy consumption is an important objective. This article provides a mathematic description of the two-phase flow motion at the outlet of the vertical acceleration tube of a jet mill with a plane grinding chamber of torus-shaped form. The part of the acceleration tube above the impact plate is essential for grinding, as the initial particle grind occurs at this very section, in the grind chamber. Moreover, the initial grind defines the size of particles, that are further reground at the mill chamber. As the result of theoretical calculations a formula, that enables to define the height of an acceleration tube from the baffle element at the specified velocity parameters of the two-phase flow. The article also contains the graph, that shows how particle velocity depends on the current (specific) height point (value) of the acceleration tube. This graph shows that particle size strongly affects the way they move in the grind chamber. Using the formula we can calculate the effective propulsion range of particles, depending on theirs’ size, by presuming they have the maximum velocity.

The dependence of the reliability of the reinforced concrete bending section on the statistical characteristics of the strength of its constituent materials—concrete and reinforcement—is considered. It is shown that the reason for the high reliability of the calculated values of the strength of the reinforcement (at least 1 − 1.39·10−9 when the coefficient of variation of strength 4%), it is advisable to limit the reliability requirements of section levels of reliability strength of concrete. To quantify the reliability of the cross-section, the safety factor for concrete is used, showing the amount by which it is possible to increase the estimated time to the reliability section remained at the level of concrete strength. It is found that B30 class concrete and reinforcement steel grade A400 may increase the estimated bending moment by 10% in the range of rebar from 0.5 to 2.5%, when they are used in a reinforced concrete element, in addition, at the number of rebar from 1 to 2% the estimated bending moment may increase by 15%. The use of low-strength concrete in combination with high-strength reinforcement significantly reduces the permissible increase in the design bending moment.

Designers’ attention is drawn to the necessary constructive calculations not only for the strength of multi-storey, multi-layered, and multi-loaded walls, but also for deformations. The article shows peculiar features of deformation-strength properties of mortars in horizontal masonry joints under forceful compression, compared with those in standard mortar samples in standard tests. It is necessary to jointly consider the conditions of equilibrium and deformations, since the work conditions in the masonry of stone and mortar of different types are polar opposite. The stone is vertically compressed by the load and transversely stretched by the mortar that is usually more subjected to deformation, as a result of which its strength in the masonry is significantly lower than the standard compressive strength. The mortar, whose transverse deformations are constrained by less deformable stones, on the contrary, is unevenly compressed both in the vertical and transverse directions, due to which its strength, unlike deformations, increases significantly.

One of the main directions of geotechnical construction is the reconstruction of objects. This type of construction in most cases is associated with the need to strengthen the foundations of the bases. Geotechnicians are particularly concerned about the presence of weak underlying layers at the base, which complicate the reliable operation of the constructed objects. Due to the availability of modern geotechnical technologies, it is possible to minimize their negative impact. When choosing them, the principle of “technical feasibility and economic efficiency” must be observed. The paper considers several geotechnical technologies for strengthening weak bases. The principle of selecting a technically feasible and cost-effective type is considered.

In the construction practice of nuclear facilities, medical institutions and other special structures, special construction concretes are used. Basalt, limonite, serpentinite, chromite, hematite, barite and metal aggregates and others minerals are used as fillers. However, the most effective materials for radiation protection are metal hydrides, in particular titanium hydride. A limiting feature of its use as a filler is its low operating temperature. Increasing the thermal stability of titanium hydride will make it possible to use this material to obtain a new generation of radiation-protective building materials.In this study, the method of magnetron sputtering is used as a method of forming a protective shell on the surface of a TiH2 shot. A technical solution has been developed and optimal conditions have been determined for uniform coating of the titanium hydride shot. One-layer metal protective coatings of copper and titanium, two-layer Ti/Cu and three-layer Cu/Ti/Cu protective coatings on titanium hydride shot were obtained. By scanning electron microscopy was studyes protective coatings structure and their thickness is determined. The use of such coatings will increase the thermal stability of TiH2 shot and, as a consequence, the efficiency of using titanium hydride as a radiation-protective material.

The process of forming new technological methods of construction of buildings and structures, a high degree of industrialization of construction and unification of elements, lead to the study of various principles of forming the spatial structure of the object from flat scans. The authors consider a new transformable architectural and structural system consisting of rod spatial arches, the main elements of the developed system are rods and hinges that connect them at the ends. The latter are made as an analog of bionic mobile communication. Research has shown that on the basis of the resulting arched strezhnevoy system, it is possible to form spaces close to the cylindrical and spherical shape. The variability of forms based on a single set of structures, low-labor-intensive installation process using the principles of self-construction, create prerequisites for new research in the field of improving this type of transformable architectural and structural systems. These issues provide a wide range of tools for solving architectural, structural and technological factors of shaping, which contributes to the development of creative activity.

The trend in the development of modern construction is an increase in the span and number of floors of the structures being built. To solve such problems, it is advisable to use high-strength concretes with a strength class of B60 and higher. To date, the production and use of such concretes has a number of difficulties, both technological and economic in nature (high cost). Therefore, high-strength concrete, in particular in Russia, is experiencing strong competition from metal structures that are inferior to them in terms of fire safety, durability and cost. Increasing the availability and adaptability of high-strength concrete is possible by eliminating the use of standard cement with the transition to composite binders based on it. The paper considers the issue of increasing the efficiency of self-compacting concretes, due to the use of a carbonate additive and fine-dispersed waste from the processing of heavy concrete. It is established that the use of these additives enhances the resistance to delamination and separation of the mixture, the high correlation of filler grains and reduce the friction between the particles of coarse components for maximum yield under the action of gravitational forces to improve the physical, mechanical and operational characteristics of concrete. A method for comparing different strength compositions is proposed, which makes it quite simple and clear to assess the influence of heterogeneous factors under study on the effectiveness of the use of the clinker component.

Studies on the damping of vibrations of closed domes under seismic influence are presented. To ensure the effect of vibration damping, a new tape system is used. The quenching effect is achieved by one-way connections of tape systems. A dynamic analysis of the dome vibrations is carried out. For a comprehensive evaluation of the damping system, numerical experiments were carried out with different locations of the belt vibration dampener and the determination of the most rational version of the belt system for different configurations of domes. The design scheme of the dome was a three-dimensional rod system consisting of rigidly fixed steel pipes of square cross-section. The design was calculated using the finite element method. When conducting a numerical experiment, the method of central differences was used to solve the differential equation of motion. It is shown that with the trapezoidal arrangement of the damper, a significant (more than 50%) decrease in the maximum amplitudes of the dome oscillations is observed. Moreover, for several peak values of displacements, the vibration damping effect reaches 80%. For flat domes, the option of cross-positioning the extinguisher belts is effective. To increase the effective volume of the dome space, it is advisable to use the option of three-point attachment of the extinguisher tapes, while the extinguishing effect increases. With this setup, there is a decrease in the values of the maximum deviations of the nodes by another 4–10%, compared to the cross arrangement. It is shown that belt dampers are an effective means of damping vibrations.

Screw presses are widely used in the production of clay bricks by a soft-mud process. The main drawback of screw presses is a torque transfer by the screw blade to the shaped mass so that the mass moves in a spiral. This significantly reduces the performance of screw presses. The work considered the possibility of increasing the performance of screw presses by increasing the friction force of the shaped mass as it moves along the internal surface of the tube. This is achieved by increasing the force of the normal pressure of the shaped mass on the internal surface of the tube by modifying the geometry of the screw blade so as generatrics are not oriented normally towards the screw axis, but inclined opposite to the direction of motion of the shaped mass from the axis of the screw to the periphery. The results of the study show that the performance of the screw press with a blade having an inclination from the axis of the screw to the periphery of 10–30% higher, than a press with a generatric of the blade normal towards the axis of the screw shaft, for the supply of plastic clay by increasing the forward component of the shaped mass movement in the direction of the longitudinal axis of the screw. Analysis of the results shows that the rational value of the angle of inclination for the generatric of the blade depends on the properties of the moulded mass and this value is 10–20°.

One of the most significant indicators of the construction of houses is the construction period of the structure. In this matter, of course, fully assembled houses are the leaders, but their versatility and individuality are very limited. To add personality to the buildings, frame houses are suitable, the supporting structures of which are made of columns and beams, and the filling can be performed with various materials. Significant for such houses will be the connection of columns with beams with the help of reliable connections. One of the most technologically advanced connecting elements in low-rise buildings made of columns and beams can serve as metal connecting plates. A type of connection using steel plates is proposed. The paper presents a method for constructing a connection model on metal plates, which includes both a sequence of partitioning into a grid of finite elements, and the application of boundary conditions, and modeling the connection of a metal plate with a wooden element. The node simulation was performed in the SCAD software package. Mathematical modeling of the system allowed us to obtain a pattern of stress changes from various parameters, such as the thickness of the plate and the size of the grooves in the wooden elements. According to the results of the calculations, all the stress components were obtained, the analysis of which showed that the load distribution due to the bonding of the plates will be uniform over the entire volume of the connection, which allows us to conclude that this connection will be sufficiently reliable. The analysis of the obtained data allowed us to choose the optimal dimensions of the connecting elements. The calculated data should be confirmed by experimental studies. So, on the basis of the obtained data, a methodology for conducting experimental studies is being developed, and an experiment will be conducted, which will be presented later.

The equilibrium sorption of methylene blue coloring agent on carbon-containing sorption materials has been studied. As an initial sorbent the carbon-containing material, obtained by thermal processing of oil extraction industry waste kieselguhr sludge at temperature 500 ºC in conditions of lack of oxygen, notionally named TKS500, was used. TKS500 was activated by treating it with 30% nitric acid solution and 1 M sodium hydroxide solution. It has been demonstrated that the dye’s sorption isotherms for the initial and for the activated TKS500 samples are of the S-type. In low concentrations range of the dye solution a monolayer is formed. With the further increase of the dye content, after monolayer formation the methylene blue molecules are extended to dimer molecules and the sorption becomes polymolecular, which is shown in the isotherm as a sharp increase of sorption capacity. This is characteristic for both the initial sorption material, and for the material, modified with sodium hydroxide and nitric acid solutions. In the low concentrations range of the dye solution the sorption isotherms for the initial TKS500 and for the TKS500, modified with HNO3 solution, are described with Freundlich model’s equations, and the sorption isotherm for the TKS500, modified with NaOH solution, is described with Temkin model’s equation. It has been determined that the maximum sorption capacity (0.244 mmol/g) is possessed by the carbon-containing sorption material TKS500, activated with the 30% nitric acid solution.

The method of increasing the durability of the hammers is proposed, which allows protecting the surface from rapid wear, and thereby increasing the service life of the working bodies. The results of comparative tests of traditional drill hammers, a pilot model of a rotary-vortex mill with a cylindrical shape and a drill hammer, on the working surface of which a solid surfacing and a mesh of wear-resistant material with certain cell sizes are carried out, are presented. As a result of the analytical study of the calculated scheme of force interaction in the hammer cell, an equation is obtained for determining its geometric dimensions, which allow for the pressing of the crushed material. The graphical dependence of the results of the wear value of the hammers made with surfacing of the working surface with wear-resistant material on the operating time in hours, and traditional hammers without surfacing is presented. It was found that the differences in the amount of wear of the hammers made with solid surfacing and with the cells deposited on the working surface are insignificant, this is due to the fact that the crushed material gets stuck in the cells and thus protects the surface of the hammer at the bottom of the cell from intense wear. In this case, the material contacts the area of the cells deposited with the wear-resistant material, which leads to its abrasion, at a rate equal to continuous surfacing.

In the paper the questions of technology of binding of silicate materials applying petroleum bituminous rocks (PBR) and waste processing, in particular: optimization of ratios of raw components of a mixture of silicate materials, the development of optimal technological parameters of production of silicate materials, technological aspects of production of these materials. The chemical-mineralogical and structural features of PBR and their processing waste are revealed. The optimal compositions of binders were studied using waste from the processing of PBR as an activating component of lime. The optimal ratio of the mixture of waste from the processing of PBR with lime and the technological parameters that allow to ensure the grade of the lime-sand binder from 400 to 500 are established. As a result, technological processes for the production of binders based on PBR and waste from their processing were justified and developed. Silicate materials based on them have high physical and mechanical properties and meet regulatory requirements. The proposed compositions and conditions for the preparation of these binders have high resistance in operating conditions.

The issue of strengthening weak or overloaded bases is an important task for the development of underground space. This is especially true in the presence of alternating weak layers at the base. The paper considers a case from the geotechnical practice of strengthening the overloaded base of a reinforced concrete foundation plate of a 25-storey residential building under construction. Combined ground piles consisting of Get (type 1) ground concrete piles reinforced along the longitudinal axis with made drill-injection piles using electric discharge technology (EDT piles) are used as buried structures. This method of arrangement of a combined buried reinforced concrete structure is due to the need to increase the load-bearing capacity of the pile on the ground by two times or more.

Due to the increase in the volume of extracted, processed and transported oil and petroleum products, emergency situations are becoming more frequent, accompanied by a spill of oil and petroleum products, which has disastrous consequences for the environment and harms human health. This review summarizes the literature data on the use of components of woody biomass of deciduous and coniferous tree species—foliage and needles as raw materials for the production of sorption materials for the removal of oil and petroleum products from the water surface and from wastewater. Interest in the development of adsorbents originating from renewable natural sources, including multi-tonnage biomass waste, is caused at the world level in solving problems of rational nature management. It is shown that it is possible to increase the hydrophobicity of sorption materials from biomass waste and their sorption capacity by modifying them with acidic chemical reagents, low-pressure high-frequency plasma, and heat treatment. The optimal modification parameters for achieving the highest adsorption parameters in terms of oil capacity and oil adsorption from solid and water surfaces, as well as the mechanisms of processes based on models of sorption isotherms, are given. The future prospects of using leaves and needles of trees as precursor materials for the creation of cost-effective and effective sorbents are noted.

The paper presents the results of assessing the risk of construction companies on the environment. The calculation method is proposed for a step-by-step assessment of the risk component. Failures of technological systems in the structure of fault trees are taken into account. The mechanism of the spread of pollutants to a certain point in space is considered. Principles and norms for regulation of environmental pollution have been developed to determine risk levels. Calculation formulas are given to determine the probability of disease or death in the threshold and thresholdless model. The possibility of using the proposed technique for fire and explosive situations with the release of hazardous substances into the atmosphere on the basis of regulatory documents is shown. The conclusion is made about the applicability of this technique for any models of dispersion in the environment. An assessment of the risk to public health is carried out on the example of harmful emissions of the construction industry enterprise into the air. The advantages of the dynamics of risk for a certain period in comparison with a specific amount of risk are indicated. It is concluded that the averaged probabilistic characteristics of the processes of distribution and dispersion of substances do not reduce the effectiveness of the method and allow it to be used for risk mapping.

An essential role in forming the optimal structure and providing the required properties of foam-concrete mixes and non-autoclaved foam concretes is played by air-entraining surface-active agents. All foaming agents, used in construction technology, are divided into synthetic and protein-based. In contrast to synthetic foaming agents, which are more widely used and advertised, the application of protein-based foaming agents allows preventing the layering of foam cement systems and obtaining a stable foam cement mass. This allows producing low-density porous concretes with high physical–mechanical properties. To obtain protein-based foaming agents various vegetable-based and animal-derived materials are used as raw stuff. A protein-based foaming agent was obtained as a result of alkaline hydrolysis of citric acid microbiological production waste biomass of Aspergillus niger fungus. In the alkaline component composition, in order to reduce production costs of the obtained product, the dust from cement production calcinating kilns’ exhaust gases treatment was used. It has been demonstrated that at adding cement dust the alkaline hydrolysis of Aspergillus niger fungus biomass occurs incompletely. At adding the protein-based foaming agent to the mixing water of gypsum binders, the non-hydrolyzed protein molecules, contained in it, are adsorbed on the surface of gypsum binder’s particles, and demonstrate plasticizing action, thinning up the gypsum paste, increasing its flowability and its setting time. This allows reducing the water-gypsum ratio and improving the physical–mechanical properties of finished gypsum products.

The technical and economic development of Orenburg region, especially its eastern part, is hindered by the shortage of drinking water quality, the widespread processes of pollution, salinization and increased radiation. The regional government has put forward the task of providing the region with drinking water. To solve it, it is proposed to develop and implement new technologies for the region, replenishing water intake reserves by partial accumulation of runoff in floods and protecting water from pollution, salinization and increased radiation, using original barrier technologies. Difficult situation in the economic and drinking water supply of the population has developed in the south-east of the region in the settlement Svetly and in the city Yasny. Water supply here is carried out at the expense of the waters of the Kumak reservoir, where the water does not meet the drinking quality. By draining these volumes of water with the planned underground water intake near the Kumak reservoir, it is possible to provide the population of the settlement Svetly and city Yasny with water of good quality. It is possible to protect the water intake from pollution by creating a complex barrier structure, the effectiveness of which is proved experimentally.

This article explores blending equipment and reveals advantages and disadvantages of blenders for production of dry building mixes. This analysis results in highlighting a pneumatic blender as one of the most challenging and poorly explored blenders to blend dry mixes. Such blenders fully comply with ecological and production regulations, do not deal any harm to employee’s health, and its technical characteristics are in no way worse than those of mechanical blenders. After examining challenging directions of their improvement we offer a new design of such a pneumatic blender, which aims to enhance the quality of final product through increasing product uniformity by intensifying the blending process. Its main concept is based on blending dry building mixes in air turbulence flow. Additionally, this article deals with the method of calculation design and technological parameters of such a pneumatic blender. A graphical comparison of experimental and theoretical dependences of the coefficient of inhomogeneity on time is presented. Main parameters, that define blender’s geometric and utility features, are pressure, gas consumption, material lifting range. The results of this article can be used in the design of pneumatic mixers for mixing dry building mixtures, as well as in the educational process of bachelors and masters.

In modern Russian standards, the calculation of the strength of the wall of a beam, welded or rolled, not reinforced with webbing, under the action of local stress in the places where the load is applied to the upper sole is made according to the formula of the centrally compressed element. It is assumed that the extreme values of local stresses in the wall act at a distance of 2–3 thicknesses of the beam flanges and are distributed evenly. Finite element calculations show that stress concentrations and significant non-linearity of the distribution are observed near the places where loads are applied in the beam walls. The paper presents the results of finite element modeling of the overlap beam grillage, where special attention is paid to the support zones of beams with a floor-by-floor scheme of co-extension. The results of calculations are presented, which show the zones of nonlinear stress distribution, as well as their values. The obtained stress values in the finite element model are compared with the values obtained by the standard calculation.

The paper considers the use of local quartz sand for cleaning the surface natural waters of drinking water supply. The Department of “Water Supply, Water Disposal and Hydro-technical construction” of the KG UCTA named after N. Isanov for two years conducted a study on the use of cheap local raw materials for the filter loading of fine water filters. Sand from Kyrgyz deposits was used as a loading.The aim of the experiments was to consider the physical picture of the process of water clarification by filtration and the factors characterizing it, to study the features of the filter layers in terms of the loading height and depending on the grain diameter, as well as to determine the parameters of technological modeling for subsequent optimization of the process. The results obtained on the “short” columns were tested on a pilot plant, which is a conventional column with a full height of the filter load, calculated on the basis of technological modeling data. The operating conditions of the pilot plant generally corresponded to the operating conditions of the process simulation plant.The task is to create a simple and affordable device for use in national conditions, in which it would be possible to use a filter load from a natural non-toxic material for the human body, which does not have high operational qualities, for a sufficiently long time to purify drinking water.All technological schemes for the treatment of drinking water quality from surface sources using a rapid non-pressure filter are several times cheaper than similar schemes with filter loads from the Russian Federation.

The actively developing world is developing more and more new territories that were previously economically unattractive. Often, such areas have features in the form of weak foundations that are beginning to be built up. Ensuring the reliability and durability of the foundations of the embankments of urban main roads is an important geotechnical task. To ensure the smooth movement of urban transport, the issues of increasing their load-bearing capacity and stability are relevant. The modern geotechnical industry has various technologies and materials that can solve this problem. To do this, they can use methods of reinforcing the soil embankment, strengthening the base with a pile field of reinforced concrete piles, crushed stone piles, or use combined methods. Each of the methods increases either stability or load-bearing capacity, so it is more expedient to use combined methods based on technical and economic analysis, which give a win in several positions at once.

This paper discusses ladder for overhead power line supports, and those that can be part of machinery and equipment. The design and installation of the ladder should be subject to the same requirements as the machine for which it is intended, including special circumstances such as adverse atmospheric conditions, vibrations. Selected types of structures are made of metal and have removable lower steps. All ladder and its elements must be sufficiently rigid and firm to support the structure to ensure the safety of users under normal operating conditions. There is no test method for removable steps in existing standards. The established safety requirements must be controlled by calculation and/or testing, which must be carried out in accordance with the procedure described in Sect. 5 of GOST R ISO 14122-4-2019. The purpose of this work is to develop safety criteria for the operation of vertical ladders with removable steps. Tests for static characteristics were carried out under normal climatic conditions on a stand for testing personal protective equipment against falls from a height. The tests were carried out on a vertical ladder to solve this problem, the test method was adjusted and approved to eliminate the error due to the technological bias set by the manufacturer.

Biotechnology is a promising area of science that studies the possibilities of using living organisms, systems or products of their vital activity to solve technological problems. The larvae of the fly Hermetia illucens are effectively used for the bioconversion of organic waste, providing a reduction in the load on natural ecosystems and economic feasibility. An increase in the bioconversion of organic substrates using the Hermetia illucens fly contributes to an increase in the amount of insect biomass that requires effective areas of larvae application to solve the problems of creating waste-free circulation. The larvae can be a promising raw material for use in the production of feed. The protein composition of the larvae contains a large amount of amino acids, the composition of which is similar in many ways to fish and soy proteins, due to which in many studies there are good results have achieved when feeding fish and poultry with the larvae. This type of insect also has a good tolerance for mycotoxins, which allows them to thrive on substrates consisting of various wastes. The pathogenic environment has led to the development of the ability to produce antibacterial peptides for protective purposes in the insects, which can be used in medicine and agriculture. The composition of the fat fraction is represented by various fatty acids, such as lauric, oleic, stearic, etc., which makes it possible to consider it as an alternative to industrial cosmetic oils.

A special feature of road pavement with a concrete pavement is the presence of deformation joints. Over time, vertical displacements are observed in the compression joints, leading to the formation of faulting, which impairs the comfort and safety of movement on such pavements. This paper examines the reasons for the occurrence of faulting on concrete pavements. In order to develop a mechanical and empirical model for predicting faulting, full-scale surveys of existing concrete pavements were performed. The surveys allowed obtaining data on the actual values of the faulting in various conditions by climate and traffic composition. Based on the statistical analysis of the data and theoretical assumptions, a cumulative mechanical-empirical model was developed for predicting faulting over time, taking into account changes in the parameters of traffic intensity, as well as seasonal changes in climate parameters. The basis of the mechanical-empirical model for predicting faulting is proposed to use the energy spent on the deformation of the structure in the area of the transverse compression joint. The proposed mechanical-empirical model allows determining the size of the faulting in any period of time, depending on the design features of the road pavement, for example, such as the base material, the distance between the compression joints, the presence of bowel bar connections.