Keyword: «porous structure»

This arcticle presents a hypothetical model of transformation of the porous structure of coals’ organic matter of under the influence of negative temperatures. The model takes into account various scenarios of freezing and thawing of inner water, including either the formation of additional cracks and collectors, or with the «collapse» of micro- and mesopores. The results are presented on experiments related to the study of the effect coals of different genetic types with respect to a degree of vitrinite recovery during single freezing-thawing at different temperatures (-20, -40 and -60 °C) on their mechanical strength. It is shown that for coals of genotype I characterized by high heterogeneity of structure, the processes of freezing-thawing at different temperatures lead to an increase in the mechanical strength, which may be caused by the effect of compaction of organic matter due to the effect of «collapsing» of micro- and mesopores.

This study investigates the effect of polymethylsilsesquioxane aerogel on the water absorption of cement composites. The relevance of this research is driven by the need to enhance the durability of concrete structures exposed to aggressive water saturation and cyclic temperature variations. Concrete cube specimens with a 100 mm edge were fabricated using a constant mixed design, with aerogel added at 0%, 0.2%, 0.375%, and 0.475% by cement mass. Water absorption tests were performed in accordance with GOST 12730.3-2020. The results demonstrate that aerogel incorporation proportionally reduces water absorption. At the maximum dosage (0.475%), water absorption decreased from 5.70% to 3.10%, representing an approximate twofold reduction. These findings confirm the potential of superhydrophobic nanoporous aerogels as effective bulk modifiers for developing a water-repellent cement matrix without significantly increasing the structural mass.

The article discusses the main features of aerated concrete as a modern building material. It provides information on its composition, production technology (autoclave and non-autoclave), and physical and technical properties, depending on its density grade. The article also describes various applications of aerated concrete, including its use for exterior and interior walls, insulation, lintels, frame filling, and in monolithic construction and special cases. The article also highlights the limitations of using this material.