The possibility of obtaining effective highly dispersed additives from natural wollastonite is substantiated and their influence on the properties of fine-grained concrete is investigated. On the basis of wollastonite, a complex micro-filler with particle sizes up to 100 microns was developed, obtained by joint grinding with quartz sand in a 3:1 ratio in a ball mill in the presence of an anionic surfactant naphthalene-formaldehyde type C-3 and a calcium stearate hydrophobizer technical C-17. A suspension of wollastonite with a modal particle diameter of 405 nm was obtained by pre-grinding wollastonite and anionic surfactant in a ball mill, with their further ultrasonic treatment in a bath-type activator. Mathematical models of the dependence of compression and bending strength on the content of the initial components are developed. It is established that the complex microfill leads to an increase in the strength of fine-grained concrete in bending by 2 times, in compression by 1.7 times with its content in the composition of fine-grained concrete in the amount of 10% by weight of cement. Wollastonite suspension increases the bending strength of fine-grained concrete to 3.1 MPa, compression to 57.8 MPa. The results of qualitative x-ray phase analysis showed that the total intensity of diffraction maxima of not fully hydrated alite C3S, belite C2S grains and their aggregates in cement stone with wollastonite decreases by 1.5-2 times compared to the control composition. This is most likely due to the amorphous nature of the wollastonite surface after grinding in a ball mill and ultrasonic dispersion in a bath-type activator. In addition, such particles are the centers of crystallization. Their needle-like shape contributes to the reinforcement of the structure by crystallizing new formations of cement stone.

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 article considers the optimization of the content of the components of the additive of stabilized highly dispersed wollastonite using a developed and patented computer algorithm for finding extreme coordinates of the dependencies of the mechanical characteristics of fine-grained concrete Extr.sce and Interp.sce based on the Scilab engineering and scientific computing environment. The developed programs allow determining the best combination of components and technological parameters for obtaining an additive to identify the optimal value of the desired indicator of the final characteristics of fine-grained concrete. The search for the maximum value of the strength indicators of fine-grained concrete is performed depending on the combination of the initial components of the modifier based on highly dispersed wollastonite, as well as the time of their ultrasonic dispersion with the output of visual data processing models in the form of contour and 3d graphs of the interpolation surface. As a result of the simulation, it is found that the additive shows the most effective result with a wollastonite content of 5 g/l, in which a modifier M with a concentration of 2.1 ml/l is used as a suspension stabilizer, while the ultrasonic dispersion time is 5 minutes. The developed additive of optimal composition contributes to the production of modified fine–grained concrete with a bending strength of 6.8 MPa and compression strength of 58.5 MPa