Dispersed-filled composites with a structured nanoscale

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. (paper)