The use of polymer-bitumen binders as part of an asphalt concrete mixture allows to improve the quality of road surfaces. The most commonly used polymer is styrene and butadiene copolymer, however, it does not provide sufficient durability of asphalt concrete and has a high cost. There is a positive experience in solving these problems through the use of polymer composites filled with fine powders. One of the promising polymer fillers is shungite. The purpose of this work was to study the effect of shungite from various deposits of Karelia on the structure and properties of polymer-bitumen binder. It was found that the introduction of shungite in the amount of 5 wt.% changes the physico-chemical characteristics of polymer-bitumen binders: the viscosity and softening temperature increase markedly, the temperature of brittleness, as well as extensibility and elasticity change to a lesser extent. Changes in these properties indicate the structuring of the binder by finely dispersed shungite. This phenomenon may be associated with the transfer of bitumen from a volumetric to a structured state due to its interaction with the surface of the shungite powder, as well as due to the diffusion of low-molecular components of the binder into the pores of the filler. Moreover, shungite samples from different deposits do not affect the studied characteristics in the same way. The explanation for this may lie in the different content of active adsorption centers on the surface of shungite, which is in a linear relationship with the main characteristics of the polymer-bitumen binder modified with shungite.

New requirements for the operational reliability of roads make the utilization of polymer-modified bitumen (PMB) more common in road construction. The application of polymer-modified bitumen based on traditional technology for the production of asphalt mixtures is associated with technological and economic difficulties and does not provide proper adhesion to the mixture’s mineral components. In addition, the method of producing a binder over a long time at high process temperatures leads to increased aging, which significantly reduces the service life of the material in the pavement. This paper presents the results of studies on the effect of polymer–bitumen concentrate (PBC) consisting of styrene–butadiene–styrene, plasticizer, and surfactant on the bitumen characteristics. It has been established that the use of PBC in the bitumen binder leads to an increase in the temperature range of plasticity, softening temperature, elasticity, and cohesive strength with a decrease in the viscosity of the modified bitumen. With a complex modifier rational content of 8% by weight of bitumen, the temperature range of plasticity is 79 °C, and elasticity is 82%, which exceeds the parameters of the factory PMB-60 based on SBS polymer. Tests of binders using the Superpave method allow classifying the modified binder to the PG 64-28, which shows an increase in the temperature range of viscoelastic properties by 6 °C compared with the binder produced by traditional methods. Thus, the expediency of using a complex additive containing a polymer and surface-active substances (surfactants) that can be distributed in bitumen without the use of a colloid agitator and plasticizer has been proven to improve the quality of an organic binder.

The field of additive manufacturing (AM) of various materials is rapidly developing. At the stage of designing and growing products and for the quality control of finished parts, non-destructive methods of analysis, in particular X-ray computed tomography (CT), are in demand. In addition to the advantages of non-destructive imaging of a wide range of materials in three dimensions, modern CT scanners offer a high contrast and high spatial resolution to provide digital information about their three-dimensional geometry and properties. Within the framework of this article, CT was used to follow the structural evolution of a TiNi–TiB2 metal–ceramic composite obtained by direct laser deposition. The relationship has been established between the additive method of production (layered direct laser deposition) and the formed layered structure of the product in the direction of growth. The porosity of the sample was calculated for each scan direction, and the average for the sample was 1.96%. The matrix of the TiNi–TiB2 composite is characterized by the presence of pores of various sizes, shapes and locations. Spherical voids prevail, but keyhole pores are also found. The heterogeneity of the structure was revealed in the form of clearly traced boundaries of the print layers, as well as differences in the density of the inner and outer regions of the composite.

—We discuss the results obtained when performing a test acoustic-hydrological experiment in August 2022 at a marine test site from the coast of Sakhalin Island to Kita-Yamato Bank in the Sea of Japan. The methodology of preliminary studies in the water area intended for studying climatic variability of temperature regimes of the aquatic environment based on numerical modeling using the RAY computational program and the NEMO ocean hydrodynamic circulation model is presented. One of the main results is the average temperature of the marine environment calculated with high accuracy on the axis of the underwater sound channel in the Sea of Japan on the 1000-kilometer acoustic trace at the crossing of the vortex system. The shape of the measuring system and the technical and computational means and methods described in the article can be used as a basis for the organization of high-precision operational monitoring of thermodynamic processes in extended sea areas.

The physicochemical modification of the filler allows changing the hydrophilic–hydrophobic properties and effectively influencing the processes occurring at the filler–binder interface, on which the physicomechanical characteristics of composites largely depend. The paper presents studies related to the modification of limestone-based filler effect on the degree of its hydrophobicity and wetting with liquids of different polarity, establishing the relationship between the characteristics of hydrophobized mineral powders and the adsorption capacity in relation to water. Using mechanochemical processing with hydrophobic components GF-1 and GF-2, it was possible to obtain fillers with a sufficiently high content of hydrophobic particles (58.2% and 85.9%, respectively). It was found that the results of the contact angle (123.6° and 114.5°, respectively) and the degree of hydrophobicity do not quite correlate with each other. It was noticed that the contact angle on the powder modified with GF-1 decreases with time. Studies of the powders’ thermal effects wetting of different polarity liquids via microcalorimetry allows us to establish that with an increase in the filler hydrophobicity degree, the integral heat of immersion decreases due to a significant decrease in the probability of chemical interactions between water and powder due to the adsorption of applied surfactants molecules on the limestone active centers. The revealed endothermic effects indicate the occurrence of physical interactions due to non-polar dispersion forces. Differences in the nature of heat release and heat absorption in modified fillers indicate significant differences in the composition and mechanism of action of the used surfactants, which affected the efficiency of hydrophobization. At the same time, a linear dependence of the moisture absorption and moisture indicators, determined by independent experiments, on the degree of hydrophobicity was established.

—The results of studies of the features of the formation of pulse characteristics on the axis of an underwater sound channel in waveguides with different hydrological and bathymetric conditions of the Sea of Japan and the Sea of Okhotsk are discussed. The results of model calculations and experiments characterizing the regularities of propagation of low-frequency pulse signals in complex waveguides including shelf and deep sea for hundreds of kilometers are presented. It is shown that one of the main effects that determines long-range sound propagation in complex waveguides including the shelf and deep sea is the acoustic “landslide” effect. It is also shown that numerical modeling of the process of signal propagation from the shelf to the deep sea on acoustic traces in the Sea of Japan and the Sea of Okhotsk using the RAY program provides good convergence of the calculated and experimentally obtained impulse characteristics.

This paper studies the feasibility of fabricating pseudo-alloys based on a W-Cu system through vacuum sintering of spherical bimetallic particles synthesized using the electric explosion of copper–tungsten wires in argon. The effects of the sintering temperature on the structure and hardness of the fabricated composites was studied. In terms of the structure of the samples, tungsten particles of predominantly spherical shapes with sizes ranging from submicrons to 80–90 µm were uniformly distributed throughout the copper matrix. Based on the analysis, the volume fractions of tungsten and copper were approximately equal. The calculated average phase compositions for all the samples were 58.9 wt% for W, 27.3 wt% for Cu, and 13.8 wt% WO2. When the annealing temperature increased from 1100 °C to 1250 °C, the wetting of tungsten by molten copper improved, which resulted in the porosity of the copper matrix being at the minimum, as observed in the contact zone. Due to good wetting and a decrease in the viscosity of copper, rearrangement of the solid phase of the tungsten in the bulk of the composites improved, and the density and hardness of the pseudo-alloy increased. The formation of coarse tungsten grains is caused by the fact that submicron and micron particles are growing in size and merging into agglomerates during the course of liquid-phase sintering, and this happens because of the high surface activity of ultrafine particles. Further research will be devoted to solving the discovered problems.

Introduction.Silicon oxide film coatings have unique properties and are widely used in various industries, including construction.This paper presents the results on the preparation of polyalkylhydroxysiloxane liquid film in the presence of nanoscale particles of metallic bismuth.Methods and materials.Laser ablation method of metallic bismuth in aqueous medium was used to obtain bismuth nanoparticles.The surface of the target was treated with a laser beam at the workstation of an ytterbium pulsed fiber laser are discussed.The particle size and electrokinetic properties of colloidal bismuth sols were determined method by dynamic light scattering.After drying, Bi powder was added to polyalkylhydroxysiloxane liquid.Thin films cured under different heat treatment modes are applied to glass substrates by dipping.The resulting films were characterized by SEM, X-ray phase analysis, and FTIR spectroscopy.Results.In this work, the electrokinetic properties of colloidal bismuth sols are discussed.Laser ablation of a bismuth substrate leads to an increase in electrical conductivity and the appearance of a double electric layer in colloidal sols.The effect of the curing temperature on the properties of the coating is shown.It was found that the content of bismuth nanoparticles in the polyalkylhydroxysiloxane coating (3 wt.%) does not lead to the formation of crystalline phases.At the same time, the composition of the film and the mode of heat treatment affect the short-range order of molecular bonds.Increasing the content of bismuth nanoparticles in the coating of more than 10 wt.% leads to the appearance of microcrystalline phases of bismuth silicates in the system.Conclusion.The results obtained in the course of the study supplement the information about the production of bismuth nanoparticles by laser ablation and are of great importance in the practice of creating composite films.

Ultra-fine filler or mineral powder is the main mineral component responsible for structure formation in the bitumen-mineral system, therefore mineral and chemical composition, chemical reactivity, surface area, fineness, particle shape, porosity and density are the crucial parameters for structure formation of the composite. This work studied the effect of fineness and chemical and mineral composition of fillers on the structure of asphalt binder. It was demonstrated that an increase in surface area boosts porosity, and void content of the filler, but reduces the porous size. For carbonate fillers such as limestone and chalk with high fineness it was investigated that compaction applied to asphalt binder specimens showed very low water saturation. This can be explained by the film effect of water impermeable bitumen in the matrix and by small porous size with mostly close pores. An increase in surface area of silicate fillers improves the compaction of structure but cannot reach the same level of compaction degree demonstrated by the specimens with carbonate fillers. SEM analysis of microstructural characteristics for the asphalt binder showed that the incorporation of fine-fractioned chalk filler resulted in the formation of asphalt binder with high density and micro-and nanoporous matrix.

Nowadays, the researchers of materials sciences area, use direct and indirect methods such as microscopy, porosimetry, etc. for studying structural characteristics of materials. X-ray computed tomography is among one of the modern and widely used research analytical methods that provides 3D images of solid materials without any preliminary preparation, such as crashing of sample, and violation of its structural integrity. To demonstrate the potential possibilities of X-ray computed tomography, in this research matrices with cellular structure using portland cement-based cellular concrete was studied as an example. The study showed that the pore structure of cellular concrete is dominated by capillary pores with a diameter of up to 200 um. The majority of pores did not exceed 1.6 mm in diameter, that formed during the foaming process. The calculated average size of the volumetric distribution of air voids was 0.95 mm. About 80% of large pores of a cellular concrete specimen with an average size of about 1 mm determines high porosity of the composite which is consistent with its average density values. The study of interpore structure partition using X-ray computed tomography allows for evaluation the difference in thickness from 10 um to 0.6 mm in the zones of “confluence” of large pores. The porosity of cement matrix, including individual pores with sizes from -30 to 250 um, was about 16.5%. The cement matrix is dominated by the products of cement hydration with capillary and “gel” pores. There are few nonreacted cement particles that are evenly distributed throughout the volume of the composite. To obtain more complete information about the structure of cellular concrete or any other composite, it is necessary to perform complex studies applying not only X-ray computer tomography technique, also scanning electron microscopy for evaluation of chemical analysis to identify mineral phases present and correlate them with absorption intensity of X-ray radiation on tomographic images.

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.

Приведены результаты экспериментальных и теоретических исследований по распространению и приему в подводных звуковых каналах широкополосных импульсных сигналов на основе псевдослучайных последовательностей. Анализ экспериментально полученных импульсных характеристик указывает на наличие предпосылок для повышения помехоустойчивости приема навигационных и командных сигналов, а также увеличения дальности действия при неизменной мощности излучения. Цель специально выполненных экспериментальных работ заключалась в получении исходных данных для повышения эффективности навигационных систем дальнего радиуса действия путем оптимизации характеристик излучаемых сигналов. Исследованы особенности формирования импульсных откликов при приеме сигналов с различной частотной полосой и длительностью символов, а также динамика структуры откликов при смещениях глубины приёмного гидрофона относительно оси подводных звуковых каналов. На основе лучевых представлений осуществлена физическая интерпретация полученных экспериментальных результатов для практического применения в решении актуальных задач гидроакустики и океанологии.

The 3D printing technologies have appeared for a long time and are successfully used in a number of industries. The activities of many leading companies in the creation of layouts, models and prototypes of units, assemblies, products are practically not carried out without the use of 3D printing. The following are batch production technologies with high productivity combined with low cost, comparable to traditional methods of manufacturing products. The production of various products from silicate masses in an additive manner is seriously constrained by a number of issues due to the specifics of the material itself. One of them - achieving high physical and mechanical characteristics is possible only after hydration (for cements) or heat treatment (ceramic masses) of the product. Significant influence is exerted by the method of manufacturing the product. The most convenient and least energy-consuming method (in comparison with the powder 3D printing methods using laser sintering) is layer-by-layer slip casting or plastic extrusion, however, there are some unresolved problems. This paper highlights the key problems of using the additive method of manufacturing structural products on ceramic and hydration bonds using plastic and rigid masses in combination with vibration effects.

The results of experimental studies on the features of propagation and reception of broadband pulsed signals in an underwater sound channel (USC) at a distance of 300 km from the source are discussed. The characteristics of the formation of the pulse responses by reception of the phase-shift keyed signals with different frequency bands and durations of symbols are studied. From the point of view of the ray theory of sound propagation in a deep-ocean waveguide, a physical interpretation of the results is presented and practical conclusions are drawn for solving the problems of positioning of autonomous underwater platforms.

The results of experimental and theoretical studies on the propagation and reception of broadband pulsed signals based on pseudorandom sequences are discussed. The features of impulse response functions for reception of signals with different frequency bands and durations of symbols are investigated. Separation of acoustic energy arrivals in the cross-correlation function of the received and emitted signals is investigated in the framework of the normal mode theory for a deep-sea waveguides. The study concluded that a combination of navigation signals with different symbols duration must be used for solving practical problems of autonomous underwater vehicles positioning.

The article studies the toxicological characteristics and behavior of geopolymer samples GB-1 and GB-2 based on fly ash from thermal power plants. Cement paste also was used to provide comprehensive comparative analysis. Aerated tap water was used as a reference medium. The toxicity of the studied materials was determined by applying standard biotesting methods using such aquatic organisms as Scenedesmus quadricauda microalgae and cladocerans Daphnia magna. Based on the obtained experimental and analytical data, it was found that the most favorable environment for algae is sample GB-2. Different behavior is observed in crustaceans. In this case, the most favorable medium for acute and chronic toxicity is a cement paste. The highest toxic effect is observed in the GB-1 sample medium vs. the others studied samples for all considered parameters of toxicity, including chronic one: the decrease in the concentration of algae is 30-35 %; the death of daphnia is 50-80 %. Chronic toxicity, which was determined by the value of the total fertility of daphnia in GB-1 medium, is 5-18 times less compared to the Reference sample.

a promising direction in solving the problem of obtaining high-quality asphalt concrete is the use of mineral fillers, including from industrial waste. The article considers the use of OEMK slag as a mineral powder in the asphalt concrete mix. The influence of hydrophobization of mineral powder by GF Preparation on moisture absorption and its structuring ability to change the maximum shear stress from the content of mineral powder before and after hydrophobization was studied. It is established that the treatment of the filler provides the necessary hydrophobicity of the mineral material, reduces the bituminous capacity, water saturation, porosity of the asphalt binder, and increases its strength and water resistance. The results of studies of the main characteristics of asphalt concrete on the example of a mixture of type G III of the brand showed that as a result of hydrophobization, the strength, water resistance, water saturation, and swelling of the composite significantly increase

Coal power plants represent the large source of environmental pollution in soils, ground and surface water by leaching out toxic compounds from open landfilled and impounded coal combustion residuals (CCR) such as fly ash. The use of fly ash as a main component in geopolymer binder (GB) systems is one of the effective methods of CCR beneficial utilization. The toxicity assessment as well as leachability of harden geopolymers were tested in aqueous media where oat seeds were used as affected test objects. Bio-resistance of the developed geopolymers was evaluated by the resistance to mold fungi growth. The developed geopolymers demonstrated a very low toxicity and leachability to the biota based on the low effect to germinating ability and growth retardation of the exposed oat seeds. Therefore, the studied fly ash products were proved to be environmentally safe when used in GB systems. The absence of fungi growth observed on the surface of geopolymer samples demonstrates high bio-resistance.