The factors determining the production of fine-grained high-strength concrete are considered. The effect of micro-and complex nanodisperse additives based on natural mineral components, as well as the packing density of the quartz aggregate, on the strength parameters of fine-grained concrete is studied. The compositions of the fine-grained concrete modified by micro-and complex nanodisperse additives have been developed. The dependence of the fine concrete strength on the ratio of the mineral component and the stabilizer in the nanodisperse additive and the time of ultrasonic dispersion and additive storage is analyzed. The stabilization mechanisms of water dispersions of complex nanodisperse additives by various surface active modifiers are considered. The positive role of ultrasonic dispersion in obtaining nanodispersed additives is shown. The application efficiency of the micro-filler improving the density and strength of fine-grained concrete is revealed. The structure of fine-grained concrete is studied. It has been established by scanning electron microscopy that the introduction of the micro-and nanodispersed additives in the concrete leads to a less defective crystalline structure of the material.

The physical and mechanical properties of lightweight constructional heat-insulating concrete (sawdust gypsum concrete) with high-strength gypsum binder, modified by food cotton microcrystalline cellulose and organic fillers of plant origin from the waste wood of coniferous and deciduous species in the form of cavitationly processed pine and birch sawdust have been studied. The dependence of the cavitation extraction time of water-soluble reducing substances (sugars) from sawdust on the strength of sawdust gypsum concrete is established. The changes in microstructure of the gypsum matrix, the mean density, bending tension strength and compression strength, the thermal conductivity coefficient of sawdust gypsum concrete on the basis of the cavitationly processed sawdust with the introduction of microcrystalline cellulose are analyzed. It is proven that microcrystalline cellulose compacts the space between the crystalline hydrates of calcium sulfate dihydrate in the gypsum matrix microstructure and improves the physical and mechanical properties of sawdust gypsum concrete.

The effective highly-dispersed additive on the basis of the natural mineral wollastonite has been developed and studied. It enables obtaining fine concrete with the bending strength of up to 21.6 MPa and the strength of compression of up to 55 MPa, and the content of 0.5% (in terms of dry matter). The additive is a suspension of wollastonite after mechanical, and then ultrasonic processing in the aquatic environment of the anionic stabilizer of naphthalene-formaldehyde type. Due to the laser granulometry it has been ascertained that grinding wollastonite together with the anionic stabilizer leads to a change in the specific surface from 20 400 to 32 600 cm2/cm3 and to forming the particles with a modal diameter of 10.31 μm. After ultrasonic processing in the aquatic stabilizer environment the wollastonite particle size reduces to 0.4 μm. The positive heat and humidity effect on the structure and strength of the concrete with highly-dispersed wollastonite-based additive under the mode 3+4+3 h at the isothermal hardening temperature of 80оС is shown. The application of the developed additive in the fine concrete composition makes it possible to save up to 15% of cement due to the strength increase.

The stabilizer nature effect on the aggregative stability of the modifying concrete additives based on halloysite nanotubes in the aquatic environment is shown. The chemical composition and morphology of halloysite nanotubes and their additives, obtained by ultrasonic dispersion in the aquatic environment of the surfactant, are studied. The influence on the processes of charge stabilization on the outer and inner surface of halloysite nanotubes is determined. The dependence of nanotube sizes and specific surface area on the stabilizer type, the time of ultrasonic dispersion, and additive storage is revealed. The stabilization mechanisms of aqueous dispersions of modifying additives based on halloysite nanotubes with anion-and cation-active substances are considered. It is established that the polynaphthalenesulfonate-based modifier S-3 has got the maximum efficiency as a stabilizer of aqueous dispersions of modifying concrete additives with halloysite nanotubes.

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