The development of modern building materials science involves the process of designing innovative materials that exhibit unique characteristics, such as energy efficiency, environmental friendliness, self-healing ability, and photocatalytic properties. This can be achieved by modifying cement with nano- and fine-dispersed additives that can give the material new properties. Such additives include a number of compounds based on the TiO₂-Bi₂O₃ system. These compounds have photocatalytic activity in the near-UV and visible range of the spectrum, which can serve to create photocatalytic concretes. Here, the purpose of this scientific study was to synthesize compounds based on the TiO₂-Bi₂O₃ system using two methods in order to identify the most optimal variant for creating a composite material and determine its properties. Within the framework of this article, two methods of obtaining a photocatalytically active additive based on the TiO₂-Bi₂O₃ system are considered: the solid-state and citrate-based methods. The photocatalytic, mechanical and structural properties of composites containing the synthesized additive are investigated. In this study, it was found that for the creation of photocatalytic concretes, it is advisable to use cement compositions with a bismuth titanate content of 3–10 wt.%. of the cement content, regardless of the method of obtaining the additive. However, the most optimal composition is one containing 5 wt.% of the synthesized additive. It is noted that compositions containing 5% by weight of bismuth titanate demonstrate photocatalytic activity and also show an increase in strength on the first day of hardening by 10% for the solid-state method and 16% for the citrate method.

Nowadays, mortars are building materials with various properties that can be achieved through the careful selection of components and the introduction of different modifying additives. An additive based on the TiO₂–Bi₂O₃ oxide system can be considered a modifying component with photocatalytic and biocidal properties capable of decomposing organic pollutants, viruses, bacteria, and fungal spores. The purpose of the work was to obtain cement compositions containing the additive, study their physical and mechanical properties, evaluate their photocatalytic activity in accordance with the UNI 11259-2016 standard, and assess their resistance to mold fouling. In this study, samples of cement–sand plaster with the TiO₂–Bi₂O₃ additive synthesized via citrate-based technology at 1.7 and 5.0 wt.% were prepared, and their physical, mechanical, photocatalytic, and biocidal properties were examined. As a result, the authors identified photocatalytic activity in both the UV and visible spectra, achieving 69% after 26 hours of UV irradiation. The samples demonstrated 100% resistance to mold fouling. The compressive strength of the modified samples increased by 32.0–39.0%; bending strength by 33–38.0%; and adhesion strength to the base by 60–70%. The cost calculation also confirmed the feasibility of introducing the additive at 1.7 wt.% into the cement composition. The resulting cement material formula can be recommended for designing fungi-resistant, self-cleaning plasters.

The current stage of the construction industry development implies increased requirements for building materials to maintain and improve global environmental processes. The understanding by ecologists globally of the danger of anthropogenic impact on the global environment has been reflected in the formulation of Sustainable Development Goals (SDGs). Thus, scientists and engineers are turning to safe plant-based raw materials as innovative building materials. Of particular interest for practice is the use of Reynoutria sachalinensis, which may exhibit biocidal properties. The purpose of this study was to obtain a gypsum stone modified with an extract from the green mass of R. sachalinensis, as resistant coating to fouling by microscopic fungi. The results indicated 10% decrease in the required water addition to gypsum paste when using plant extract, a slowdown of the initial and final setting time of the modified gypsum paste samples compared to the control samples by 6 and 7 min, respectively, and a slight decrease in bending and compressive strengths of the samples of 12.5% and 6%. The 100% resistance of the modified samples to fouling by microscopic mould fungi was also revealed.