Abstract. The article describes the new method for producing the asphalt concrete mixture, which has high strength characteristics, minimal water saturation. An attempt was made to theoretically substantiate the mechanism of hardening of the material. Asphalt concrete is a typical dispersed-filled composite material in which mineral particles of different dispersity are used as a filler, and the matrix is a binder-bitumen.To obtain a high-quality composite, it is necessary to ensure continuity of the material matrix. However, the formulations of asphalt-concrete mixtures used do not satisfy this requirement. This is due, on the one hand, to economic considerations, on the other hand, to a decrease in the strength of the material. The proposed method allows to solve this problem. The main consumer of bitumen in the asphalt mix is the smallest filler particles -mineral powder, which consumes up to 95 % of the binder. It is proposed to introduce a binder into the mineral powder by the granulation method by pelletizing. When the material moves in a rotating granulator, two types of forces act on the material particles: tearing off, caused by dynamic factors, and restraining forces caused by intermolecular interaction. Their combined effect makes it possible to form an ordered structure of the material with the finest interlayer layers of the binder between the solid particles realizing the nanoeffect. The structure thus obtained forms a continuous matrix of composite material with a minimum content of bitumen and strength indicators, several times higher than the requirements of GOST. The presence of a continuous matrix minimizes the water saturation of asphalt concrete, ensuring high durability of the road surface. The properties of the binder in the interlayers between the particles of the mineral powder differ significantly from the properties of the bulk bitumen, which prevents it from extruding at an elevated temperature from the structure of the material under the action of external transport loads, resulting in a consequent brittle failure. From the standpoint of the mechanics of a continuous medium, the stress state in liquid interlayers is represented by a set of spherical and deviator tensors, which made it possible to describe the mechanism of hardening of the material. The results of experimental studies are presented, which confirm the possibility of obtaining a qualitatively new asphalt-concrete mixture with characteristics that are substantially higher than the requirements of GOST, which is a worthy alternative to the traditional method of obtaining the material. Keywords. Structured nanomatrix, disperse-filled material, asphalt concrete, asphalt concrete mixture, mineral powder, interphase layer, bulk phase Introduction. In the process of operating a road, its road clothing and primarily asphalt concrete cover experiences increased loads from transport, temperature changes, weather conditions, ramming and other factors that lead to reduced durability, rapid loss of strength and the appearance of var...
The paper presents an analysis of positions, which a theory of a liquid wetting a solid surface is based on, using the sitting drop equilibrium as an example. Certain inconsistencies are indicated in these positions, which is the subject of the discussion. The paper explains why the interfacial tension of solid-gas has no effect on the equilibrium of a drop. It proposes a mechanism to form a liquid-solid interface layer, the tensor of interfacial tensions of which is represented as a pressure tensor. It is established that the surface tension of the interface layer is variable and changes in magnitude and direction depending on the wetting conditions. It is determined that it is not possible to present a range of phenomena accompanying the wetting of a solid surface with a liquid by examining the equilibrium of a three-phase contact line.
The paper discusses the change of phosphogypsum surface state produced by Apatit (Cherepovetsky branch, Vologda region) during calcination at 298-1173 K. The authors have determined the average size of its crystallites and studied the atomic composition of raw materials and finished composites that include crushed rock fraction (5-10 mm), oil bitumen, and polyethylene terephthalate additive (1.0-1.2 wt. %). The compounds present in calcined phosphogypsum have been analyzed by X-ray diffraction. The granulate was obtained by pelletizing phosphogypsum with a mixture of the above components. The paper presents the assessment of its physical and chemical properties. The granulated composites based on the specified samples of calcined phosphogypsum, bitumen, and melted polyethylene terephthalate waste show great promise for construction road works in European countries in summer and winter, as well as countries with tropical climates.
Dynamic quality of machines is one of the dominant factors affecting both the geometric parameters of the accuracy of components, and the physicomechanical characteristics of the treated surface layer. Individually, each machine has a certain dynamic quality, which varies both in the process of operation and when the values of cutting mode parameters are changed. What is important in the manufacture of precision machine-and instrument components making is the assessment of the actual dynamic quality of machines according to the characteristics of vibroacoustic vibrations.
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