Silica raw materials are widely used in many industries, especially in the manufacture of building materials. Among all rocks with rockforming silica minerals, chemogenic and biogenic sedimentary rocks are highly demanded as active (pozzolanic) mineral additives for composite binders. Raw materials containing amorphous silica are used to obtain composites of the TiO2–SiO2 system with high photocatalytic activity. High sorption properties of silica raw materials are critical in the process of photocatalysis, since these indirectly affect the interaction between respective organic compounds and the photocatalyst surface for their oxidation to the safe compounds of H2O and CO2. Therefore, it seems promising to use silica sedimentary rocks as a photocatalyst carrier in the manufacture of photocatalytic composite materials (PCM) used in cement concrete. This work covers the study of the DIASIL diatomite fine powder and gaize of the Alekseevskoe deposit, as well as PCM obtained on their basis, by the sol-gel deposition of the photocatalytic agent at various precursor/solvent ratios. Preparation of the gaize feed material required disintegration in a jaw crusher and a ball mill to the particle size of –100 μm. The results for the evaluation of the surface acidic properties, the degree of CaO absorption from the lime solution, and the photocatalytic activity of the PCMs synthesized indicate the high efficiency of using the silica raw material studied as a substrate for the TiO2 photocatalyst.The study was carried out with a grant from the Russian Science Foundation (project No. 19-19-00263) using equipment based on the High Technology Center of BSTU named after V. G. Shukhov.

The purpose of this research was to study the influence of multifunctional anatase–silica photocatalytic materials (ASPMs) with various photocatalytic and pozzolanic activities on the properties of white portland cement and fine-grained concrete. ASPMs were synthesized by a sol–gel method, during which the levels of photocatalytic and pozzolanic activity were regulated by a certain amount of solvent. ASPMb, obtained with the use of a smaller amount of solvent, was characterized by increased pozzolanic activity due to the lower degree of coating of the surface of diatomite particles with titanium dioxide and the higher content of an opal–cristobalite–tridymite-phase and Bronsted acid sites. They promoted the reaction of diatomite with portlandite of cement stone and allowed significant decreases in the strength of cement–sand mortar to be avoided when replacing 15% of the cement with ASPMs. This allowed self-cleaning fine-grained concrete to be produced, which, after forced carbonization, simulating the natural aging of the product during operation, retained the ability of self-cleaning without changes. ASPMc, produced with the use of a larger amount of solvent with a more uniform distribution of titanium dioxide on the surface of diatomite, allowed fine-grained concrete with a high self-cleaning ability to be obtained, but with a lesser manifestation of the pozzolanic effect.