Ключевые слова: phase composition

Influence of mechanical activation on the characteristics of glass concrete

https://doi.org/10.58224/2618-7183-2025-8-4-4
Аннотация
This work presents the study of effect of mechanical activation on the properties of glass concrete binder, based on mechanically activated glass and calcium oxide. The goal of the study was to identify patterns of changes in the microstructure and phase composition of the material with different durations of grinding and subsequent hydration.
We found that under mechanical activation for 12 minutes, all calcium oxide enters into a chemical reaction with the formation of the mineral combeyite (Na₂Ca₂Si₃O₉). Further hydration of the material leads to the transformation of combeyite into diverite (Na₂Ca₃Si₆O₁₆) and wollastonite (CaSiO₃). The microstructure is characterized by lamellar structures, an increase in strength is provided by a decrease in the particle size and an increase in the chemical interaction of the components.
It is shown that the duration of mechanical activation has a significant effect on the physical and mechanical characteristics of the material. A correlation was established between the duration of grinding and the strength and elastic modulus indices. Thermal and moisture treatment additionally increases the strength of the material, reaching values over 100 MPa.
The obtained results demonstrate the potential of the proposed technology for creating highly efficient building materials with specified physical and technical characteristics, contributing to the savings of traditional cement binders and reducing the pollution of the construction industry.
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Photocatalysts based on Zn-Ti layered double hydroxide and its calcination products for self-cleaning concretes: Structure formation and photocatalytic activity

https://doi.org/10.58224/2618-7183-2025-8-1-2
Аннотация
Currently, the development of highly active photocatalytic additives for self-cleaning cement materials is a topical direction of building materials science. Mixed transition metal oxides are one of the effective types of photocatalysts, because they have improved functional characteristics compared to monometallic compounds. The purpose of this study was to establish the effects of synthesis conditions on the structure parameters and photocatalytic activity of zinc-titanium layered double hydroxide (Zn-Ti LDH) with Zn2+/Ti4+ molar ratio of 2/1, as well as its calcination products in the form of zinc-titanium mixed metal oxides (Zn-Ti MMOs). It was found that the mixing temperature of solutions of precursor salts and precipitators, as well as the temperature of sediment aging, were the main synthesis parameters that had the greatest impact on the phase composition and crystallite size of layered double hydroxide.
The research results showed differences in the kinetics of photodestruction of methylene blue (MB) in solution under UV radiation in the presence of Zn-Ti layered double hydroxide and Zn-Ti mixed metal oxides. The photocatalytic process involving Zn-Ti MMOs, corresponding to a pseudo-first order reaction kinetic, proceeded in a diffusion mode with limiting step in the form of dye adsorption on the surface of photocatalyst. The photodegradation of MB in the presence of Zn-Ti LDH, which was more accurately described by a pseudo-second order model, occurred in a kinetic regime, where the photocatalytic reaction was the limiting stage.
Mixed metal oxides of zinc and titanium had significantly higher functional characteristics compared to their Zn-Ti LDH precursor. The calcination of Zn-Ti layered double hydroxide at 200–500 °C allowed to achieve the highest photocatalytic activity of Zn-Ti MMO, which was due to phase transformations occurring during thermal treatment. The decomposition of Zn-Ti LDH at 200–250 °C resulted in the formation of a crystalline phase of zinc oxide (ZnO), which had a hexagonal wurtzite crystal structure with the ability to effectively absorb radiation from almost the entire UV spectral region. The rise of the Zn-Ti LDH calcination temperature to 500 °C led to an increase in the crystallinity degree of ZnO.
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