Ключевые слова: particle size distribution

Investigation of the synthesis of a grinding intensifier from secondary raw materials and its influence on the microstructural development of cement stone

https://doi.org/10.58224/2618-7183-2026-9-1-9
Аннотация
This paper presents data on the synthesis of cement grinding intensifiers produced from oil and gas processing wastes, namely secondary alkanolamines. The results of physicochemical characterization of the raw materials are reported, including the optimal purification conditions for the wastes and the synthesis parameters of the grinding intensifiers, as well as the physicochemical properties of the obtained products. It was found that the optimal conditions for producing the grinding intensifier involve conducting the reaction at 45°C for 6 hours with a 1:9 component ratio. The effects of the synthesized intensifiers on the cement clinker grinding process were investigated, including their influence on particle size distribution and the mineralogical composition of modified cements. The particles of the modified cement were shown to exhibit a predominantly spherical morphology; the maximum laser diffraction value reached 13.5%, the intensity was 88%, and the particle size was mainly around 2 μm (more than 53.5%), while the fraction of particles within the 100-200 μm range was 4.87%. X-ray diffraction and differential thermal analysis revealed that hydration of the modified cement is accompanied by a slight decrease in the diffraction intensity of calcium silicate phases (C2S and C3S), whereas an increase in the diffraction intensity of calcium hydroxide (Ca(OH)2) was observed. This indicates the formation of calcium hydroxide and calcium silicate hydrate (C-S-H) during cement hydration. The diffraction peaks of these phases were detected within the ranges of 30-33° 2θ and 40-45° 2θ. In addition, the presence of aluminate (C3A) and ferrite (C4AF) phases within 40-45° 2θ corresponds to calcium carbonate (CaCO3) observed in low-intensity regions between 29.4° 2θ and 48.5° 2θ, which is associated with CO2 absorption from the atmosphere. These changes reflect phase transformations during hydration and the formation of phases that are critical for strength development. The optimal dosage of the grinding intensifier in the cement composition was determined to be 0.02 wt.% (based on dry residue).
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Dust concentration in the air of roadside areas

https://doi.org/10.58224/2618-7183-2025-8-5-7
Аннотация
The article addresses a pressing issue – air pollution in cities with fine dust particles. This study collected 18 dust samples during spring and autumn periods in various parts of Elista city. Based on the analysis results of the selected dust’s dispersed composition, regression equations were developed, where the dependent variable was the concentration of PM10 and PM2.5, and the independent variables were the distance from the sampling site to the highway and the height of the sampling site from the ground. Samples were collected from window sills and other horizontal surfaces where dust settled from atmospheric air. Thus, the study aimed to critically analyze the patterns of dust composition changes in the air influenced by various factors, excluding the impact of industrial production, which is not widespread in this city. Empirical dependencies of fine dust concentrations of PM10 and PM2.5 fractions on the distance from the road and the height of the sampling site were obtained. A general range of values was obtained for the dust mass distribution function by particle diameters during spring and autumn. The study found that the geometry of the building, its relative position to seasonal winds, and the distance from the road play a much more significant role in the dispersed composition than wind speed, humidity level, or season
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Sustainable gypsum composites reinforced with basalt technogenic nanofiber

https://doi.org/10.58224/2618-7183-2025-8-2-2
Аннотация
Sustainable composites based on gypsum man-made stone are produced using a technology that excludes the firing stage. It meets the requirements for resource and energy conservation, does not harm the environment and can be used in the production of a number of biopositive building materials. The use of pure dihydrate gypsum from gypsum mold waste in the composition of sustainable gypsum composites predetermines the expansion of the scope of application of materials and products based on it. These wastes are characterized by stable physicochemical and mechanical properties. However, the features of the mineralogical composition require high costs for their use in the production of fired gypsum binders using classical technologies. Binders based on them have low strength and other physical indicators. Application without firing technology allows for the maximum use of all the unique properties of gypsum – creation of a comfortable environment, high resistance in fire conditions, good insulating characteristics, etc. By introducing highly dispersed basalt dust particles into the composition of stable gypsum composites based on dihydrate gypsum, gypsum stone is reinforced and compacted at the micro- and nanoscale levels. This is facilitated by the optimal values of the pressing force and humidity of the raw mix selected during the study. They are important technological parameters. The resulting high-strength gypsum composite is characterized by a fine-crystalline structure with higher performance indicators than conventional gypsum materials due to the screening of the moisture effect on it.
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