148 research outputs found
ΠΠ°Π½ΠΎΡΠΈΠ±ΡΠΎΠ±Π΅ΡΠΎΠ½: ΠΌΠ½ΠΎΠ³ΠΎΡΡΠΎΠ²Π½Π΅Π²ΠΎΠ΅ Π°ΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅
Concrete is the most commonly used building material worldwide. One of its main disadvantages is the fragility of fracture and low crack resistance. The use of dispersed reinforcement of concrete composites is a promising direction in solving this type of problem. Dispersed fibers, evenly distributed over the entire volume of the material, create a spatial frame and contribute to the inhibition of developing cracks under the action of destructive forces. In order to increase the fracture toughness of concrete, dispersed fiber reinforcement is increasingly used in practice. The beginning of crack nucleation occurs at the nanoscale in the cement matrix. Thus, the use of nano-reinforcement with dispersed nanofibers can have a positive effect on the crack resistance of the cement composite. It is proposed to consider carbon nanotubes as such nanofibers. The presence of carbon nanofibers changes the microstructure and nanostructure of cement modified with carbon nanotubes. The result of the processes occurring in capillaries and cracks are deformations in the intergranular matrix, the free flow of which is prevented by rigid clinker grains and nanocarbon tubes, which creates a certain stress intensity at the tips of the separation cracks. The working hypothesis is confirmed that the required fracture toughness of structural concrete is provided by multi-level reinforcement: at the level of the crystalline aggregate of cement stone β carbon nanotubes, and at the level of fine-grained concrete β various macro-sized fibers (steel, polymer). Reinforcement of a crystalline joint with carbon nanotubes leads to an increase in the fracture toughness of the matrix (cement stone) by 20 %, compressive strength by 12 %, and tensile strength in bending by 20 %. When reinforcing at the level of fine-grained concrete, we obtain a composite β nanofibre-reinforced concrete with fracture toughness.ΠΠ΅ΡΠΎΠ½ ΡΠ²Π»ΡΠ΅ΡΡΡ Π½Π°ΠΈΠ±ΠΎΠ»Π΅Π΅ ΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½Π΅Π½Π½ΡΠΌ ΡΡΡΠΎΠΈΡΠ΅Π»ΡΠ½ΡΠΌ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠΌ Π²ΠΎ Π²ΡΠ΅ΠΌ ΠΌΠΈΡΠ΅. ΠΡΠ½ΠΎΠ²Π½ΡΠΌΠΈ Π΅Π³ΠΎ Π½Π΅Π΄ΠΎΡΡΠ°ΡΠΊΠ°ΠΌΠΈ ΡΠ²Π»ΡΡΡΡΡ Ρ
ΡΡΠΏΠΊΠΎΡΡΡ ΠΏΡΠΈ ΡΠ°ΡΡΡΠΆΠ΅Π½ΠΈΠΈ ΠΈ Π½ΠΈΠ·ΠΊΠ°Ρ ΡΡΠ΅ΡΠΈΠ½ΠΎΡΡΠΎΠΉΠΊΠΎΡΡΡ. ΠΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ Π΄ΠΈΡΠΏΠ΅ΡΡΠ½ΠΎΠ³ΠΎ Π°ΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π±Π΅ΡΠΎΠ½Π½ΡΡ
ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΎΠ² β ΠΏΠ΅ΡΡΠΏΠ΅ΠΊΡΠΈΠ²Π½ΠΎΠ΅ Π½Π°ΠΏΡΠ°Π²Π»Π΅Π½ΠΈΠ΅ Π² ΡΠ΅ΡΠ΅Π½ΠΈΠΈ ΡΠ°ΠΊΠΎΠ³ΠΎ ΡΠΎΠ΄Π° Π·Π°Π΄Π°Ρ. ΠΠΈΡΠΏΠ΅ΡΡΠ½ΡΠ΅ Π²ΠΎΠ»ΠΎΠΊΠ½Π°, ΡΠ°Π²Π½ΠΎΠΌΠ΅ΡΠ½ΠΎ ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½Π½ΡΠ΅ ΠΏΠΎ Π²ΡΠ΅ΠΌΡ ΠΎΠ±ΡΠ΅ΠΌΡ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π°, ΡΠΎΠ·Π΄Π°ΡΡ ΠΏΡΠΎΡΡΡΠ°Π½ΡΡΠ²Π΅Π½Π½ΡΠΉ ΠΊΠ°ΡΠΊΠ°Ρ ΠΈ ΡΠΏΠΎΡΠΎΠ±ΡΡΠ²ΡΡΡ ΡΠΎΡΠΌΠΎΠΆΠ΅Π½ΠΈΡ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΡΡΠ΅ΡΠΈΠ½ ΠΏΠΎΠ΄ Π΄Π΅ΠΉΡΡΠ²ΠΈΠ΅ΠΌ ΡΠ°Π·ΡΡΡΠ°ΡΡΠΈΡ
ΡΠΈΠ». ΠΠ»Ρ ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΡ ΡΡΠ΅ΡΠΈΠ½ΠΎΡΡΠΎΠΉΠΊΠΎΡΡΠΈ Π±Π΅ΡΠΎΠ½Π° Π½Π° ΠΏΡΠ°ΠΊΡΠΈΠΊΠ΅ Π²ΡΠ΅ ΡΠ°ΡΠ΅ ΠΏΡΠΈΠΌΠ΅Π½ΡΡΡ Π°ΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ Π΄ΠΈΡΠΏΠ΅ΡΡΠ½ΡΠΌΠΈ Π²ΠΎΠ»ΠΎΠΊΠ½Π°ΠΌΠΈ. ΠΠ°ΡΠ°Π»ΠΎ Π·Π°ΡΠΎΠΆΠ΄Π΅Π½ΠΈΡ ΡΡΠ΅ΡΠΈΠ½Ρ ΠΏΡΠΎΠΈΡΡ
ΠΎΠ΄ΠΈΡ Π½Π° Π½Π°Π½ΠΎΡΡΠΎΠ²Π½Π΅ Π² ΡΠ΅ΠΌΠ΅Π½ΡΠ½ΠΎΠΉ ΠΌΠ°ΡΡΠΈΡΠ΅. Π’Π°ΠΊΠΈΠΌ ΠΎΠ±ΡΠ°Π·ΠΎΠΌ, ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ Π½Π°Π½ΠΎΠ°ΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π΄ΠΈΡΠΏΠ΅ΡΡΠ½ΡΠΌΠΈ Π½Π°Π½ΠΎΠ²ΠΎΠ»ΠΎΠΊΠ½Π°ΠΌΠΈ ΠΌΠΎΠΆΠ΅Ρ ΠΏΠΎΠ»ΠΎΠΆΠΈΡΠ΅Π»ΡΠ½ΠΎ ΡΠΊΠ°Π·Π°ΡΡΡΡ Π½Π° ΡΡΠ΅ΡΠΈΠ½ΠΎΡΡΠΎΠΉΠΊΠΎΡΡΠΈ ΡΠ΅ΠΌΠ΅Π½ΡΠ½ΠΎΠ³ΠΎ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠ°. Π ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΡΠ°ΠΊΠΈΡ
Π½Π°Π½ΠΎΠ²ΠΎΠ»ΠΎΠΊΠΎΠ½ ΠΏΡΠ΅Π΄Π»Π°Π³Π°Π΅ΡΡΡ ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡ ΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΠ΅ Π½Π°Π½ΠΎΡΡΡΠ±ΠΊΠΈ. ΠΡΠΈΡΡΡΡΡΠ²ΠΈΠ΅ ΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΡ
Π½Π°Π½ΠΎΠ²ΠΎΠ»ΠΎΠΊΠΎΠ½ ΠΈΠ·ΠΌΠ΅Π½ΡΠ΅Ρ ΠΌΠΈΠΊΡΠΎΡΡΡΡΠΊΡΡΡΡ ΠΈ Π½Π°Π½ΠΎΡΡΡΡΠΊΡΡΡΡ ΡΠ΅ΠΌΠ΅Π½ΡΠ°, ΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΠΌΠΈ Π½Π°Π½ΠΎΡΡΡΠ±ΠΊΠ°ΠΌΠΈ. Π Π΅Π·ΡΠ»ΡΡΠ°ΡΠΎΠΌ ΠΏΡΠΎΡΠ΅ΡΡΠΎΠ², ΠΏΡΠΎΠΈΡΡ
ΠΎΠ΄ΡΡΠΈΡ
Π² ΠΊΠ°ΠΏΠΈΠ»Π»ΡΡΠ°Ρ
ΠΈ ΡΡΠ΅ΡΠΈΠ½Π°Ρ
, ΡΠ²Π»ΡΡΡΡΡΒ Π΄Π΅ΡΠΎΡΠΌΠ°ΡΠΈΠΈ Π² ΠΌΠ΅ΠΆΠ·Π΅ΡΠ½ΠΎΠ²ΠΎΠΉ ΠΌΠ°ΡΡΠΈΡΠ΅, ΡΠ²ΠΎΠ±ΠΎΠ΄Π½ΠΎΠΌΡ ΡΠ΅ΡΠ΅Π½ΠΈΡ ΠΊΠΎΡΠΎΡΡΡ
ΠΏΡΠ΅ΠΏΡΡΡΡΠ²ΡΡΡ ΠΆΠ΅ΡΡΠΊΠΈΠ΅ Π·Π΅ΡΠ½Π° ΠΊΠ»ΠΈΠ½ΠΊΠ΅ΡΠ° ΠΈ Π½Π°Π½ΠΎΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΠ΅ ΡΡΡΠ±ΠΊΠΈ, ΡΡΠΎ ΡΠΎΠ·Π΄Π°Π΅Ρ Π² Π²Π΅ΡΡΠΈΠ½Π°Ρ
ΡΠ°Π·Π΄Π΅Π»ΠΈΡΠ΅Π»ΡΠ½ΡΡ
ΡΡΠ΅ΡΠΈΠ½ Π½Π΅ΠΊΠΎΡΠΎΡΡΡ ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΡ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΡ. ΠΠΎΠ΄ΡΠ²Π΅ΡΠΆΠ΄Π΅Π½Π° ΡΠ°Π±ΠΎΡΠ°Ρ Π³ΠΈΠΏΠΎΡΠ΅Π·Π°, ΡΡΠΎ ΡΡΠ΅Π±ΡΠ΅ΠΌΠ°Ρ ΡΡΠ΅ΡΠΈΠ½ΠΎΡΡΠΎΠΉΠΊΠΎΡΡΡ ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠΎΠ½Π½ΠΎΠ³ΠΎ Π±Π΅ΡΠΎΠ½Π° ΠΎΠ±Π΅ΡΠΏΠ΅ΡΠΈΠ²Π°Π΅ΡΡΡ ΠΌΠ½ΠΎΠ³ΠΎΡΡΠΎΠ²Π½Π΅Π²ΡΠΌ Π°ΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ: Π½Π° ΡΡΠΎΠ²Π½Π΅ ΠΊΡΠΈΡΡΠ°Π»Π»ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π·Π°ΠΏΠΎΠ»Π½ΠΈΡΠ΅Π»Ρ ΡΠ΅ΠΌΠ΅Π½ΡΠ½ΠΎΠ³ΠΎ ΠΊΠ°ΠΌΠ½Ρ β ΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΠΌΠΈ Π½Π°Π½ΠΎΡΡΡΠ±ΠΊΠ°ΠΌΠΈ, Π½Π° ΡΡΠΎΠ²Π½Π΅ ΠΌΠ΅Π»ΠΊΠΎΠ·Π΅ΡΠ½ΠΈΡΡΠΎΠ³ΠΎ Π±Π΅ΡΠΎΠ½Π° β ΡΠ°Π·Π»ΠΈΡΠ½ΡΠΌΠΈ Π²ΠΈΠ΄Π°ΠΌΠΈ ΠΌΠ°ΠΊΡΠΎΡΠ°Π·ΠΌΠ΅ΡΠ½ΠΎΠΉ ΡΠΈΠ±ΡΡ (ΡΡΠ°Π»ΡΠ½ΡΠ΅, ΠΏΠΎΠ»ΠΈΠΌΠ΅ΡΠ½ΡΠ΅). ΠΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΠΌΠΈ Π½Π°Π½ΠΎΡΡΡΠ±ΠΊΠ°ΠΌΠΈ ΠΊΡΠΈΡΡΠ°Π»Π»ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΡΠΎΡΡΠΊΠ° ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡ ΠΊ ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΡ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»Ρ Π²ΡΠ·ΠΊΠΎΡΡΠΈ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ ΠΌΠ°ΡΡΠΈΡΡ (ΡΠ΅ΠΌΠ΅Π½ΡΠ½ΠΎΠ³ΠΎ ΠΊΠ°ΠΌΠ½Ρ) Π½Π° 20 %, ΠΏΡΠΎΡΠ½ΠΎΡΡΠΈ Π½Π° ΡΠΆΠ°ΡΠΈΠ΅ Π½Π° 12 %, ΠΏΡΠΎΡΠ½ΠΎΡΡΠΈ Π½Π° ΡΠ°ΡΡΡΠΆΠ΅Π½ΠΈΠ΅ ΠΏΡΠΈ ΠΈΠ·Π³ΠΈΠ±Π΅ Π½Π° 20 %. ΠΡΠΈ Π°ΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠΈ Π½Π° ΡΡΠΎΠ²Π½Π΅ ΠΌΠ΅Π»ΠΊΠΎΠ·Π΅ΡΠ½ΠΈΡΡΠΎΠ³ΠΎ Π±Π΅ΡΠΎΠ½Π° ΠΏΠΎΠ»ΡΡΠ°Π΅ΠΌ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡ β Π½Π°Π½ΠΎΡΠΈΠ±ΡΠΎΠ±Π΅ΡΠΎΠ½ Ρ Π²ΡΠ·ΠΊΠΎΡΡΡΡ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ
Nanofiber Concrete: Multi-Level Reinforcement
Concrete is the most commonly used building material worldwide. One of its main disadvantages is the fragility of fracture and low crack resistance. The use of dispersed reinforcement of concrete composites is a promising direction in solving this type of problem. Dispersed fibers, evenly distributed over the entire volume of the material, create a spatial frame and contribute to the inhibition of developing cracks under the action of destructive forces. In order to increase the fracture toughness of concrete, dispersed fiber reinforcement is increasingly used in practice. The beginning of crack nucleation occurs at the nanoscale in the cement matrix. Thus, the use of nano-reinforcement with dispersed nanofibers can have a positive effect on the crack resistance of the cement composite. It is proposed to consider carbon nanotubes as such nanofibers. The presence of carbon nanofibers changes the microstructure and nanostructure of cement modified with carbon nanotubes. The result of the processes occurring in capillaries and cracks are deformations in the intergranular matrix, the free flow of which is prevented by rigid clinker grains and nanocarbon tubes, which creates a certain stress intensity at the tips of the separation cracks. The working hypothesis is confirmed that the required fracture toughness of structural concrete is provided by multilevel reinforcement: at the level of the crystalline aggregate of cement stone β carbon nanotubes, and at the level of fine-grained concrete β various macro-sized fibers (steel, polymer). Reinforcement of a crystalline joint with carbon nanotubes leads to an increase in the fracture toughness of the matrix (cement stone) by 20 %, compressive strength by 12 %, and tensile strength in bending by 20 %. When reinforcing at the level of fine-grained concrete, we obtain a composite β nanofibre-reinforced concrete with fracture toughness
Strength Indicators of Fiber Reinforced Concrete with Carbon Nanomaterials
Concrete composites with low defects, dense and homogeneous, with a high degree of adhesion between the cement matrix and aggregates, as well as a high ratio between static tensile and compressive strengths and plasticity have the best crack resistance characteristics. This ratio increases in the case of the use of fiber-reinforced concrete. Modern research in nanotechnology focuses on the management of matter at the nanoscale level, which makes it possible to create materials with new properties. Due to the high aspect ratio, flexibility, high strength and rigidity, carbon nanotubes (CNTs) exhibit reinforcing properties. Due to their nanoscale features, CNTs interact with a complex network of calcium-silicate-hydrate binder (C β S β H), contribute to a decrease in porosity and compaction of the cement stone structure, increase the shear forces of matrix adhesion in the contact zone. Thus, there are all prerequisites to assert that fiber concrete with a cement matrix modified with carbon nanotubes will have the required high strength characteristics and crack resistance due to multilevel dispersed reinforcement and the efficient operation of fiber in a nanomodified concrete matrix. This article presents the results of testing samples made of cement stone, concrete and fiber concrete with carbon nanotubes. The presence of carbon nanotubes in cement stone contributes to an increase in compressive strength by 11 %, tensile strength during bending by 20 %. The test results of samples made of reinforced fiber concrete modified with nanocarbon materials have shown an increase in tensile strength during bending up to 109 %, tensile strength during splitting up to 82 %, axial tensile strength up to 78 %
Brussowvirus SW13 Requires a Cell Surface-Associated Polysaccharide To Recognize Its Streptococcus thermophilus Host
Four bacteriophage-insensitive mutants (BIMs) of the dairy starter bacterium Streptococcus thermophilus UCCSt50 were isolated following challenge with Brussowvirus SW13. The BIMs displayed an altered sedimentation phenotype. Whole-genome sequencing and comparative genomic analysis of the BIMs uncovered mutations within a family 2 glycosyltransferase-encoding gene (orf06955(UCCSt50)) located within the variable region of the cell wall-associated rhamnose-glucose polymer (Rgp) biosynthesis locus (designated the rgp gene cluster here). Complementation of a representative BIM, S. thermophilus B1, with native orf06955(UCCSt50) restored phage sensitivity comparable to that of the parent strain. Detailed bioinformatic analysis of the gene product of orf06955(UCCSt50) identified it as a functional homolog of the Lactococcus lactis polysaccharide pellicle (PSP) initiator WpsA. Biochemical analysis of cell wall fractions of strains UCCSt50 and B1 determined that mutations within orf06955(UCCSt50) result in the loss of the side chain decoration from the Rgp backbone structure. Furthermore, it was demonstrated that the intact Rgp structure incorporating the side chain structure is essential for phage binding through fluorescence labeling studies. Overall, this study confirms that the rgp gene cluster of S. thermophilus encodes the biosynthetic machinery for a cell surface-associated polysaccharide that is essential for binding and subsequent infection by Brussowviruses, thus enhancing our understanding of S. thermophilus phage-host dynamics.IMPORTANCE Streptococcus thermophilus is an important starter culture bacterium in global dairy fermentation processes, where it is used for the production of various cheeses and yogurt. Bacteriophage predation of the species can result in substandard product quality and, in rare cases, complete fermentation collapse. To mitigate these risks, it is necessary to understand the phage-host interaction process, which commences with the recognition of, and adsorption to, specific host-encoded cell surface receptors by bacteriophage(s). As new groups of S. thermophilus phages are being discovered, the importance of underpinning the genomic elements that specify the surface receptor(s) is apparent. Our research identifies a single gene that is critical for the biosynthesis of a saccharidic moiety required for phage adsorption to its S. thermophilus host. The acquired knowledge provides novel insights into phage-host interactions for this economically important starter species
ΠΠ½ΠΎΠ³ΠΎΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠ°Ρ ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠ° ΠΎΡΠ΅Π½ΠΊΠΈ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»Π΅ΠΉ ΠΊΠ°ΡΠ΅ΡΡΠ²Π° Π½Π°Π½ΠΎΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΡΠΈΠ±ΡΠΎΠ±Π΅ΡΠΎΠ½Π° Π΄Π»Ρ ΡΡΡΠΎΠΈΡΠ΅Π»ΡΠ½ΠΎΠΉ ΠΏΠ»ΠΎΡΠ°Π΄ΠΊΠΈ
Nanomodified fiber-reinforced concrete is a building material for which the required characteristics of fracture toughness are a distinctive feature. Determination of the stress intensity factor of fiber-reinforced concrete makes it possible to correctly assess the resistance of the material during the formation and development of cracks. The proposed multi-parameter methodology for assessing the quality indicators of nanomodified fiber-reinforced concrete makes it possible to evaluate the quality of a fiber-reinforced concrete structure in construction and laboratory conditions. To carry out control at the construction site, modern and long-used methods of non-destructive testing are used: ultrasonic sounding, ultrasonic tomography, elastic rebound, separation with chipping. For laboratory studies, the technique provides for the manufacture of prism samples that can be molded or cut from the body of the structure. This methodology makes it possible to obtain in laboratory conditions such material parameters as tensile strength in bending, tensile strength in splitting, critical stress intensity factor for normal separation, critical stress intensity factor for transverse shear, energy consumption for individual stages of deformation and destruction of the sample, as well as to evaluate the uniformity of distribution fibers. Moreover, it is provided to obtain all the parameters on one sample from the series, which eliminates errors and inaccuracies in the quality indicators of the material associated with different conditions of hardening, molding, inaccuracies in duplicating the composition.ΠΠ°Π½ΠΎΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΡΠΉ ΡΠΈΠ±ΡΠΎΠ±Π΅ΡΠΎΠ½ β ΡΡΠΎ ΡΡΡΠΎΠΈΡΠ΅Π»ΡΠ½ΡΠΉ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π», ΠΎΡΠ»ΠΈΡΠΈΡΠ΅Π»ΡΠ½ΠΎΠΉ ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΡΡ ΠΊΠΎΡΠΎΡΠΎΠ³ΠΎ ΡΠ²Π»ΡΡΡΡΡ ΡΡΠ΅Π±ΡΠ΅ΠΌΡΠ΅ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠΈ ΡΡΠ΅ΡΠΈΠ½ΠΎΡΡΠΎΠΉΠΊΠΎΡΡΠΈ. ΠΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΠ΅ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠ° ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΠΈ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΠΉ ΡΠΈΠ±ΡΠΎΠ±Π΅ΡΠΎΠ½Π° Π΄Π°Π΅Ρ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΡ ΠΏΡΠ°Π²ΠΈΠ»ΡΠ½ΠΎ ΠΎΡΠ΅Π½ΠΈΡΡ ΡΠΎΠΏΡΠΎΡΠΈΠ²Π»Π΅Π½ΠΈΠ΅ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π° ΠΏΡΠΈ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΠΈ ΠΈ ΡΠ°Π·Π²ΠΈΡΠΈΠΈ ΡΡΠ΅ΡΠΈΠ½. ΠΡΠ΅Π΄Π»Π°Π³Π°Π΅ΠΌΠ°Ρ ΠΌΠ½ΠΎΠ³ΠΎΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠ°Ρ ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠ° ΠΎΡΠ΅Π½ΠΊΠΈ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»Π΅ΠΉ ΠΊΠ°ΡΠ΅ΡΡΠ²Π° Π½Π°Π½ΠΎΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΡΠΈΠ±ΡΠΎΠ±Π΅ΡΠΎΠ½Π° ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΠΎΡΠ΅Π½ΠΈΡΡ ΠΊΠ°ΡΠ΅ΡΡΠ²ΠΎ ΡΠΈΠ±ΡΠΎΠ±Π΅ΡΠΎΠ½Π½ΠΎΠΉ ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠΈ Π² ΡΡΡΠΎΠΈΡΠ΅Π»ΡΠ½ΡΡ
ΠΈ Π»Π°Π±ΠΎΡΠ°ΡΠΎΡΠ½ΡΡ
ΡΡΠ»ΠΎΠ²ΠΈΡΡ
. ΠΠ»Ρ ΠΎΡΡΡΠ΅ΡΡΠ²Π»Π΅Π½ΠΈΡ ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ Π½Π° ΡΡΡΠΎΠΈΡΠ΅Π»ΡΠ½ΠΎΠΉ ΠΏΠ»ΠΎΡΠ°Π΄ΠΊΠ΅ ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΡΡ ΡΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΡΠ΅ ΠΈ Π΄Π°Π²Π½ΠΎ ΠΏΡΠΈΠΌΠ΅Π½ΡΠ΅ΠΌΡΠ΅ ΠΌΠ΅ΡΠΎΠ΄Ρ Π½Π΅ΡΠ°Π·ΡΡΡΠ°ΡΡΠ΅Π³ΠΎ ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ: ΡΠ»ΡΡΡΠ°Π·Π²ΡΠΊΠΎΠ²ΠΎΠ΅ Π·ΠΎΠ½Π΄ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅, ΡΠ»ΡΡΡΠ°Π·Π²ΡΠΊΠΎΠ²ΡΡ ΡΠΎΠΌΠΎΠ³ΡΠ°ΡΠΈΡ, ΡΠΏΡΡΠ³ΠΈΠΉ ΠΎΡΡΠΊΠΎΠΊ, ΠΎΡΡΡΠ² ΡΠΎ ΡΠΊΠ°Π»ΡΠ²Π°Π½ΠΈΠ΅ΠΌ. ΠΠ»Ρ Π»Π°Π±ΠΎΡΠ°ΡΠΎΡΠ½ΡΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠ° ΠΏΡΠ΅Π΄ΡΡΠΌΠ°ΡΡΠΈΠ²Π°Π΅Ρ ΠΈΠ·Π³ΠΎΡΠΎΠ²Π»Π΅Π½ΠΈΠ΅ ΠΏΡΠΈΠ·ΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΎΠ±ΡΠ°Π·ΡΠΎΠ², ΠΊΠΎΡΠΎΡΡΠ΅ ΠΌΠΎΠ³ΡΡ Π±ΡΡΡ ΠΎΡΠ»ΠΈΡΡ Π² ΡΠΎΡΠΌΡ ΠΈΠ»ΠΈ Π²ΡΡΠ΅Π·Π°Π½Ρ ΠΈΠ· ΡΠ΅Π»Π° ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠΈ. ΠΡΠ° ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠ° ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΠΏΠΎΠ»ΡΡΠΈΡΡ Π² Π»Π°Π±ΠΎΡΠ°ΡΠΎΡΠ½ΡΡ
ΡΡΠ»ΠΎΠ²ΠΈΡΡ
ΡΠ°ΠΊΠΈΠ΅ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π°, ΠΊΠ°ΠΊ ΠΏΡΠΎΡΠ½ΠΎΡΡΡ Π½Π° ΠΈΠ·Π³ΠΈΠ±, ΠΏΡΠΎΡΠ½ΠΎΡΡΡ ΠΏΡΠΈ ΡΠ°ΡΡΡΠΆΠ΅Π½ΠΈΠΈ Π½Π° ΡΠ°ΡΠΊΠ°Π»ΡΠ²Π°Π½ΠΈΠ΅, ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½Ρ ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΠΈ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΠΉ ΠΏΡΠΈ Π½ΠΎΡΠΌΠ°Π»ΡΠ½ΠΎΠΌ ΠΎΡΡΡΠ²Π΅, ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½Ρ ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΠΈ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΠΉ ΠΏΡΠΈ ΠΏΠΎΠΏΠ΅ΡΠ΅ΡΠ½ΠΎΠΌ ΡΠ΄Π²ΠΈΠ³Π΅, ΡΠ½Π΅ΡΠ³ΠΎΠ·Π°ΡΡΠ°ΡΡ Π½Π° ΠΎΡΠ΄Π΅Π»ΡΠ½ΡΠ΅ ΡΡΠ°Π΄ΠΈΠΈ Π΄Π΅ΡΠΎΡΠΌΠ°ΡΠΈΠΈ ΠΈ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ ΠΎΠ±ΡΠ°Π·ΡΠ°, Π° ΡΠ°ΠΊΠΆΠ΅ ΠΎΡΠ΅Π½ΠΈΡΡ ΡΠ°Π²Π½ΠΎΠΌΠ΅ΡΠ½ΠΎΡΡΡ ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ Π²ΠΎΠ»ΠΎΠΊΠΎΠ½. ΠΠΎΠ»Π΅Π΅ ΡΠΎΠ³ΠΎ, ΠΏΡΠ΅Π΄ΡΡΠΌΠΎΡΡΠ΅Π½ΠΎ ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΈΠ΅ Π²ΡΠ΅Ρ
ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² Π½Π° ΠΎΠ΄Π½ΠΎΠΌ ΠΎΠ±ΡΠ°Π·ΡΠ΅ ΠΈΠ· ΡΠ΅ΡΠΈΠΈ, ΡΡΠΎ ΠΈΡΠΊΠ»ΡΡΠ°Π΅Ρ ΠΎΡΠΈΠ±ΠΊΠΈ ΠΈ Π½Π΅ΡΠΎΡΠ½ΠΎΡΡΠΈ Π² ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»ΡΡ
ΠΊΠ°ΡΠ΅ΡΡΠ²Π° ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π°, ΡΠ²ΡΠ·Π°Π½Π½ΡΠ΅ Ρ ΡΠ°Π·Π»ΠΈΡΠ½ΡΠΌΠΈ ΡΡΠ»ΠΎΠ²ΠΈΡΠΌΠΈ ΡΠ²Π΅ΡΠ΄Π΅Π½ΠΈΡ, ΡΠΎΡΠΌΠΎΠ²Π°Π½ΠΈΡ, ΠΏΠΎΠ³ΡΠ΅ΡΠ½ΠΎΡΡΡΠΌΠΈ ΠΏΡΠΈ Π΄ΡΠ±Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΠΈ ΡΠΎΡΡΠ°Π²Π°
Multi-Parameter Methodology for Assessing Quality Indicators of Nanomodified Fiber-Reinforced Concrete for Construction Site
Nanomodified fiber-reinforced concrete is a building material for which the required characteristics of fracture toughness are a distinctive feature. Determination of the stress intensity factor of fiber-reinforced concrete makes it possible to correctly assess the resistance of the material during the formation and development of cracks. The proposed multi-parameter methodology for assessing the quality indicators of nanomodified fiber-reinforced concrete makes it possible to evaluate the quality of a fiber-reinforced concrete structure in construction and laboratory conditions. To carry out control at the construction site, modern and long-used methods of non-destructive testing are used: ultrasonic sounding, ultrasonic tomography, elastic rebound, separation with chipping. For laboratory studies, the technique provides for the manufacture of prism samples that can be molded or cut from the body of the structure. This methodology makes it possible to obtain in laboratory conditions such material parameters as tensile strength in bending, tensile strength in splitting, critical stress intensity factor for normal separation, critical stress intensity factor for transverse shear, energy consumption for individual stages of deformation and destruction of the sample, as well as to evaluate the uniformity of distribution fibers. Moreover, it is provided to obtain all the parameters on one sample from the series, which eliminates errors and inaccuracies in the quality indicators of the material associated with different conditions of hardening, molding, inaccuracies in duplicating the composition
ΠΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΡ ΡΠΎΡΡΠ°Π²Π° Π½Π°Π½ΠΎΡΠΈΠ±ΡΠΎΠ±Π΅ΡΠΎΠ½Π° ΠΏΠΎ Π²ΡΠ·ΠΊΠΎΡΡΠΈ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ ΠΌΠΎΠ΄ΠΈΡΠΈΠΊΠ°ΡΠΈΠ΅ΠΉ ΠΌΠ°ΡΡΠΈΡΡ
Concrete is a quasi-brittle building material that has low tensile strength. The process of its destruction under loading is inhomogeneous, due to the nature of the concrete structure mass, consisting of components with different physical and mechanical properties. Gradual deformation and destruction can be characterized as a process of formation and development of microcracks. The presence of different-sized components in concrete makes it possible to consider its structure as a multi-level system. In this system, each level is a matrix with its own structural inclusions, which play both a structure-forming role and the role of stress concentrators under the action of mechanical loads. The critical stress intensity factor is a good indicator of the crack resistance (fracture toughness) of a material. Nanoconcrete, from the point of view of a multilevel system, is a concrete composite with crack propagation inhibitors at the level of the cementing substance (carbon nanotubes are consi-dered as inhibitors). The presence of fiber fibers at subsequent scale levels allows us to consider concrete as a composite with multi-level dispersed reinforcement (nanofiber concrete). The paper discusses the change of concrete fracture toughness indicator (crack resistance) with dispersed reinforcement of the matrix at different structural levels. TheΒ presented for normal separation of notched cubes under eccentric compression with the determination of the stress intensity factor for concrete modified with carbon nanotubes acting as crack propagation inhibitors at the level of cementing substance (nanoconcrete), as well as for nanofiber concrete with dispersed reinforcement at the level of fine-grained concrete. Based on experimental studies by non-equilibrium methods of fracture mechanics, compositions of nanofiber-reinforced concrete of maximum crack resistance (fracture toughness) with different fiber concentrations and several types of matrices modified with nanocarbon additives are proposed in the paper.ΠΠ΅ΡΠΎΠ½ β ΠΊΠ²Π°Π·ΠΈΡ
ΡΡΠΏΠΊΠΈΠΉ ΡΡΡΠΎΠΈΡΠ΅Π»ΡΠ½ΡΠΉ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π», ΠΊΠΎΡΠΎΡΡΠΉ ΠΈΠΌΠ΅Π΅Ρ Π½ΠΈΠ·ΠΊΡΡ ΠΏΡΠΎΡΠ½ΠΎΡΡΡ ΠΏΡΠΈ ΡΠ°ΡΡΡΠΆΠ΅Π½ΠΈΠΈ. ΠΡΠΎΡΠ΅ΡΡ Π΅Π³ΠΎ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ ΠΏΡΠΈ Π½Π°Π³ΡΡΠΆΠ΅Π½ΠΈΠΈ Π½ΠΎΡΠΈΡ Π½Π΅ΠΎΠ΄Π½ΠΎΡΠΎΠ΄Π½ΡΠΉ Ρ
Π°ΡΠ°ΠΊΡΠ΅Ρ, ΠΎΠ±ΡΡΠ»ΠΎΠ²Π»Π΅Π½Π½ΡΠΉ ΡΡΡΠ½ΠΎΡΡΡΡ ΡΡΡΡΠΊΡΡΡΡ Π±Π΅ΡΠΎΠ½Π½ΠΎΠΉ ΠΌΠ°ΡΡΡ, ΡΠΎΡΡΠΎΡΡΠ΅ΠΉ ΠΈΠ· ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΠΎΠ² Ρ ΡΠ°Π·Π»ΠΈΡΠ½ΡΠΌΠΈ ΡΠΈΠ·ΠΈΠΊΠΎ-ΠΌΠ΅Ρ
Π°Π½ΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΡΠ²ΠΎΠΉΡΡΠ²Π°ΠΌΠΈ. ΠΠΎΡΡΠ΅ΠΏΠ΅Π½Π½ΠΎΠ΅ Π΄Π΅ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΠΈ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΠ΅ ΠΌΠΎΠΆΠ½ΠΎ ΠΎΡ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΠ·ΠΎΠ²Π°ΡΡ ΠΊΠ°ΠΊ ΠΏΡΠΎΡΠ΅ΡΡ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ ΠΈ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΌΠΈΠΊΡΠΎΡΡΠ΅ΡΠΈΠ½. ΠΠ°Π»ΠΈΡΠΈΠ΅ Π² Π±Π΅ΡΠΎΠ½Π΅ ΡΠ°Π·Π½ΡΡ
ΠΏΠΎ ΡΠ°Π·ΠΌΠ΅ΡΡ ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΠΎΠ² ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡ Π΅Π³ΠΎ ΡΡΡΠΎΠ΅Π½ΠΈΠ΅ ΠΊΠ°ΠΊ ΠΌΠ½ΠΎΠ³ΠΎΡΡΠΎΠ²Π½Π΅Π²ΡΡ ΡΠΈΡΡΠ΅ΠΌΡ. Π ΡΡΠΎΠΉ ΡΠΈΡΡΠ΅ΠΌΠ΅ ΠΊΠ°ΠΆΠ΄ΡΠΉ ΡΡΠΎΠ²Π΅Π½Ρ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»ΡΠ΅Ρ ΡΠΎΠ±ΠΎΠΉ ΠΌΠ°ΡΡΠΈΡΡ ΡΠΎ ΡΠ²ΠΎΠΈΠΌΠΈ ΡΡΡΡΠΊΡΡΡΠ½ΡΠΌΠΈ Π²ΠΊΠ»ΡΡΠ΅Π½ΠΈΡΠΌΠΈ, ΠΊΠΎΡΠΎΡΡΠ΅ ΠΈΠ³ΡΠ°ΡΡ ΠΊΠ°ΠΊ ΡΡΡΡΠΊΡΡΡΠΎΠΎΠ±ΡΠ°Π·ΡΡΡΡΡ ΡΠΎΠ»Ρ, ΡΠ°ΠΊ ΠΈ ΡΠΎΠ»Ρ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΎΡΠΎΠ² Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΠΉ ΠΏΡΠΈ Π΄Π΅ΠΉΡΡΠ²ΠΈΠΈ ΠΌΠ΅Ρ
Π°Π½ΠΈΡΠ΅ΡΠΊΠΈΡ
Π½Π°Π³ΡΡΠ·ΠΎΠΊ. ΠΡΠΈΡΠΈΡΠ΅ΡΠΊΠΈΠΉ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½Ρ ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΠΈ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΠΉ ΡΠ²Π»ΡΠ΅ΡΡΡ Ρ
ΠΎΡΠΎΡΠΈΠΌ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»Π΅ΠΌ ΡΡΠ΅ΡΠΈΠ½ΠΎΡΡΠΎΠΉΠΊΠΎΡΡΠΈ (Π²ΡΠ·ΠΊΠΎΡΡΠΈ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ) ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π°. ΠΠ°Π½ΠΎΠ±Π΅ΡΠΎΠ½, Ρ ΡΠΎΡΠΊΠΈ Π·ΡΠ΅Π½ΠΈΡ ΠΌΠ½ΠΎΠ³ΠΎΡΡΠΎΠ²Π½Π΅Π²ΠΎΠΉ ΡΠΈΡΡΠ΅ΠΌΡ, ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»ΡΠ΅Ρ ΡΠΎΠ±ΠΎΠΉ Π±Π΅ΡΠΎΠ½Π½ΡΠΉ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡ Ρ ΠΈΠ½Π³ΠΈΠ±ΠΈΡΠΎΡΠ°ΠΌΠΈ ΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½Π΅Π½ΠΈΡ ΡΡΠ΅ΡΠΈΠ½ Π½Π° ΡΡΠΎΠ²Π½Π΅ ΡΠ΅ΠΌΠ΅Π½ΡΠΈΡΡΡΡΠ΅Π³ΠΎ Π²Π΅ΡΠ΅ΡΡΠ²Π° (Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΠΈΠ½Π³ΠΈΠ±ΠΈΡΠΎΡΠΎΠ² ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡΡΡ ΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΠ΅ Π½Π°Π½ΠΎΡΡΡΠ±ΠΊΠΈ). ΠΡΠΈΡΡΡΡΡΠ²ΠΈΠ΅ ΡΠΈΠ±ΡΠΎΠ²ΡΡ
Π²ΠΎΠ»ΠΎΠΊΠΎΠ½ Π½Π° ΠΏΠΎΡΠ»Π΅Π΄ΡΡΡΠΈΡ
ΠΌΠ°ΡΡΡΠ°Π±Π½ΡΡ
ΡΡΠΎΠ²Π½ΡΡ
ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡ Π±Π΅ΡΠΎΠ½ ΠΊΠ°ΠΊ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡ Ρ ΠΌΠ½ΠΎΠ³ΠΎΡΡΠΎΠ²Π½Π΅Π²ΡΠΌ Π΄ΠΈΡΠΏΠ΅ΡΡΠ½ΡΠΌ Π°ΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ (Π½Π°Π½ΠΎΡΠΈΠ±ΡΠΎΠ±Π΅ΡΠΎΠ½). Π ΡΡΠ°ΡΡΠ΅ ΡΠ°ΡΡΠΌΠΎΡΡΠ΅Π½ΠΎ ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»Ρ Π²ΡΠ·ΠΊΠΎΡΡΠΈ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ (ΡΡΠ΅ΡΠΈΠ½ΠΎΡΡΠΎΠΉΠΊΠΎΡΡΠΈ) Π±Π΅ΡΠΎΠ½Π° ΠΏΡΠΈ Π΄ΠΈΡΠΏΠ΅ΡΡΠ½ΠΎΠΌ Π°ΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠΈ ΠΌΠ°ΡΡΠΈΡΡ Π½Π° ΡΠ°Π·Π½ΡΡ
ΡΡΡΡΠΊΡΡΡΠ½ΡΡ
ΡΡΠΎΠ²Π½ΡΡ
. ΠΡΠΈΠ²Π΅Π΄Π΅Π½Ρ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΈΡΠΏΡΡΠ°Π½ΠΈΠΉ Π½Π° Π½ΠΎΡΠΌΠ°Π»ΡΠ½ΡΠΉ ΠΎΡΡΡΠ² ΠΎΠ±ΡΠ°Π·ΡΠΎΠ²-ΠΊΡΠ±ΠΎΠ² Ρ Π½Π°Π΄ΡΠ΅Π·Π°ΠΌΠΈ ΠΏΡΠΈ Π²Π½Π΅ΡΠ΅Π½ΡΡΠ΅Π½Π½ΠΎΠΌ ΡΠΆΠ°ΡΠΈΠΈ Ρ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΠ΅ΠΌ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠ° ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΠΈ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΠΉ Π΄Π»Ρ Π±Π΅ΡΠΎΠ½Π°, ΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΠΌΠΈ Π½Π°Π½ΠΎΡΡΡΠ±ΠΊΠ°ΠΌΠΈ, Π²ΡΡΡΡΠΏΠ°ΡΡΠΈΠΌΠΈ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΠΈΠ½Π³ΠΈΠ±ΠΈΡΠΎΡΠΎΠ² ΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½Π΅Π½ΠΈΡ ΡΡΠ΅ΡΠΈΠ½ Π½Π° ΡΡΠΎΠ²Π½Π΅ ΡΠ΅ΠΌΠ΅Π½ΡΠΈΡΡΡΡΠ΅Π³ΠΎ Π²Π΅ΡΠ΅ΡΡΠ²Π° (Π½Π°Π½ΠΎΠ±Π΅ΡΠΎΠ½), Π° ΡΠ°ΠΊΠΆΠ΅ Π΄Π»Ρ Π½Π°Π½ΠΎΡΠΈΠ±ΡΠΎΠ±Π΅ΡΠΎΠ½ΠΎΠ² Ρ Π΄ΠΈΡΠΏΠ΅ΡΡΠ½ΡΠΌ Π°ΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ Π½Π° ΡΡΠΎΠ²Π½Π΅ ΠΌΠ΅Π»ΠΊΠΎΠ·Π΅ΡΠ½ΠΈΡΡΠΎΠ³ΠΎ Π±Π΅ΡΠΎΠ½Π°. ΠΠ° ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠΈ ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΡΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ Π½Π΅ΡΠ°Π²Π½ΠΎΠ²Π΅ΡΠ½ΡΠΌΠΈ ΠΌΠ΅ΡΠΎΠ΄Π°ΠΌΠΈ ΠΌΠ΅Ρ
Π°Π½ΠΈΠΊΠΈ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½Ρ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΈΠΈ Π½Π°Π½ΠΎΡΠΈΠ±ΡΠΎΠ±Π΅ΡΠΎΠ½Π° ΠΌΠ°ΠΊΡΠΈΠΌΠ°Π»ΡΠ½ΠΎΠΉ ΡΡΠ΅ΡΠΈΠ½ΠΎΡΡΠΎΠΉΠΊΠΎΡΡΠΈ (Π²ΡΠ·ΠΊΠΎΡΡΠΈ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ) Ρ ΡΠ°Π·Π»ΠΈΡΠ½ΠΎΠΉ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΠ΅ΠΉ ΡΠΈΠ±ΡΡ ΠΈ Π½Π΅ΡΠΊΠΎΠ»ΡΠΊΠΈΠΌΠΈ ΡΠΈΠΏΠ°ΠΌΠΈ ΠΌΠ°ΡΡΠΈΡ, ΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
Π½Π°Π½ΠΎΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΠΌΠΈ Π΄ΠΎΠ±Π°Π²ΠΊΠ°ΠΌΠΈ
ΠΠ°ΡΠ΅ΡΠΈΠ°Π»Ρ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΡΠ΅ΠΌΠ΅Π½ΡΠ°, ΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΡΠ΅ Π½Π°Π½ΠΎΡΠ°Π·ΠΌΠ΅ΡΠ½ΡΠΌΠΈ Π΄ΠΎΠ±Π°Π²ΠΊΠ°ΠΌΠΈ
The most common and reliable material without which modern construction is indispensable is concrete. The development of construction production is pushing for new solutions to improve the quality of concrete mix and concrete. The most demanded and significant indicators of a concrete mixture are the compressive strength and mobility of the concrete mixture. Every year, the volume of research on nanomaterials as modifying components of concrete is significantly increasing, and the results indicate the prospects for their use. Nanoparticles with a large specific surface are distinguished by chemical activity, can accelerate hydration and increase strength characteristics due to nucleation and subsequent formation of CβSβH and compaction of the material microstructure. Sol of nanosilica, which can be used instead of microsilica from industrial enterprises, and carbon nanomaterial have a wide reproduction base. This paper presents studies of these types of nanomaterials and the results of their application in cement concrete. Studies have shown that the effect is also observed with the introduction of an additive containing only one type of nanoparticles. The dependence of the obtained characteristics of cement concretes on the content of these nanomaterials has been established. It has been found that the best results were obtained with an additive in which the above-mentioned nanomaterials were used together. Compressive strength ofΒ heavy concrete samples, improved by the complex nanodispersed system, was 78.7 MPa, which exceeds the strength of the sample containing the CNT additive in a pair with a super-plasticizer by 37 %. Β The paper proposes the mechanism for Β action of the presented complex additive.Π‘Π°ΠΌΡΠΌ ΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½Π΅Π½Π½ΡΠΌ ΠΈ Π½Π°Π΄Π΅ΠΆΠ½ΡΠΌ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠΌ, Π±Π΅Π· ΠΊΠΎΡΠΎΡΠΎΠ³ΠΎ Π½Π΅ ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΡΡΡ ΡΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΠΎΠ΅ ΡΡΡΠΎΠΈΡΠ΅Π»ΡΡΡΠ²ΠΎ, ΡΠ²Π»ΡΠ΅ΡΡΡ Π±Π΅ΡΠΎΠ½. Π Π°Π·Π²ΠΈΡΠΈΠ΅ ΡΡΡΠΎΠΈΡΠ΅Π»ΡΠ½ΠΎΠ³ΠΎ ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄ΡΡΠ²Π° ΠΏΠΎΠ΄ΡΠ°Π»ΠΊΠΈΠ²Π°Π΅Ρ ΠΊ Π½ΠΎΠ²ΡΠΌ ΡΠ΅ΡΠ΅Π½ΠΈΡΠΌ Π² ΡΠ»ΡΡΡΠ΅Π½ΠΈΠΈ ΠΊΠ°ΡΠ΅ΡΡΠ²Π° Π±Π΅ΡΠΎΠ½Π½ΠΎΠΉ ΡΠΌΠ΅ΡΠΈ ΠΈ Π±Π΅ΡΠΎΠ½Π°. ΠΠ°ΠΈΠ±ΠΎΠ»Π΅Π΅ Π²ΠΎΡΡΡΠ΅Π±ΠΎΠ²Π°Π½Π½ΡΠ΅ ΠΈ Π·Π½Π°ΡΠΈΠΌΡΠ΅ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»ΠΈ Π±Π΅ΡΠΎΠ½Π½ΠΎΠΉ ΡΠΌΠ΅ΡΠΈ β ΠΏΡΠΎΡΠ½ΠΎΡΡΡ ΠΏΡΠΈ ΡΠΆΠ°ΡΠΈΠΈ ΠΈ ΠΏΠΎΠ΄Π²ΠΈΠΆΠ½ΠΎΡΡΡ Π±Π΅ΡΠΎΠ½Π½ΠΎΠΉ ΡΠΌΠ΅ΡΠΈ. Π‘ ΠΊΠ°ΠΆΠ΄ΡΠΌ Π³ΠΎΠ΄ΠΎΠΌ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ Π½Π°Π½ΠΎΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠ² Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΡΡΡΠΈΡ
ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΠΎΠ² Π±Π΅ΡΠΎΠ½Π° ΡΡΠ°Π½ΠΎΠ²ΠΈΡΡΡ Π±ΠΎΠ»ΡΡΠ΅, Π° ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΡΠΊΠ°Π·ΡΠ²Π°ΡΡ Π½Π° ΠΏΠ΅ΡΡΠΏΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΠΈΡ
ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΡ. ΠΠ°Π½ΠΎΡΠ°ΡΡΠΈΡΡ, ΠΎΠ±Π»Π°Π΄Π°ΡΡΠΈΠ΅ Π±ΠΎΠ»ΡΡΠΎΠΉ ΡΠ΄Π΅Π»ΡΠ½ΠΎΠΉ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΡΡ, ΠΎΡΠ»ΠΈΡΠ°ΡΡΡΡ Ρ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΎΠΉ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡΡ, ΠΌΠΎΠ³ΡΡ ΡΡΠΊΠΎΡΡΡΡ Π³ΠΈΠ΄ΡΠ°ΡΠ°ΡΠΈΡ ΠΈ ΠΏΠΎΠ²ΡΡΠ°ΡΡ ΠΏΡΠΎΡΠ½ΠΎΡΡΠ½ΡΠ΅ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»ΠΈ Π·Π° ΡΡΠ΅Ρ Π·Π°ΡΠΎΠ΄ΡΡΠ΅ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ ΠΈ ΠΏΠΎΡΠ»Π΅Π΄ΡΡΡΠ΅Π³ΠΎ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ CβSβH, ΡΠΏΠ»ΠΎΡΠ½Π΅Π½ΠΈΡ ΠΌΠΈΠΊΡΠΎΡΡΡΡΠΊΡΡΡΡ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π°. Π¨ΠΈΡΠΎΠΊΡΡ Π±Π°Π·Ρ Π²ΠΎΡΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄ΡΡΠ²Π° ΠΈΠΌΠ΅ΡΡ Π·ΠΎΠ»Ρ Π½Π°Π½ΠΎΠΊΡΠ΅ΠΌΠ½Π΅Π·Π΅ΠΌΠ°, ΠΊΠΎΡΠΎΡΡΠΉ ΠΌΠΎΠΆΠ΅Ρ Π±ΡΡΡ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ Π²Π·Π°ΠΌΠ΅Π½ ΠΌΠΈΠΊΡΠΎΠΊΡΠ΅ΠΌΠ½Π΅Π·Π΅ΠΌΠ° Ρ ΠΈΠ½Π΄ΡΡΡΡΠΈΠ°Π»ΡΠ½ΡΡ
ΠΏΡΠ΅Π΄ΠΏΡΠΈΡΡΠΈΠΉ, ΠΈ ΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΠΉ Π½Π°Π½ΠΎΠΌΠ°ΡΠ΅ΡΠΈΠ°Π». Π ΡΡΠ°ΡΡΠ΅ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Ρ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ Π΄Π°Π½Π½ΡΡ
Π²ΠΈΠ΄ΠΎΠ² Π½Π°Π½ΠΎΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠ² ΠΈ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΈΡ
ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΡ Π² ΡΠ΅ΠΌΠ΅Π½ΡΠ½ΡΡ
Π±Π΅ΡΠΎΠ½Π°Ρ
. ΠΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΠΏΠΎΠΊΠ°Π·Π°Π»ΠΈ, ΡΡΠΎ ΡΡΡΠ΅ΠΊΡ Π½Π°Π±Π»ΡΠ΄Π°Π΅ΡΡΡ ΡΠ°ΠΊΠΆΠ΅ ΠΏΡΠΈ Π²Π²Π΅Π΄Π΅Π½ΠΈΠΈ Π΄ΠΎΠ±Π°Π²ΠΊΠΈ, ΡΠΎΠ΄Π΅ΡΠΆΠ°ΡΠ΅ΠΉ ΡΠΎΠ»ΡΠΊΠΎ ΠΎΠ΄ΠΈΠ½ Π²ΠΈΠ΄ Π½Π°Π½ΠΎΡΠ°ΡΡΠΈΡ. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Π° Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΡ ΠΏΠΎΠ»ΡΡΠ°Π΅ΠΌΡΡ
Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊ ΡΠ΅ΠΌΠ΅Π½ΡΠ½ΡΡ
Π±Π΅ΡΠΎΠ½ΠΎΠ² ΠΎΡ ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²Π° Π΄Π°Π½Π½ΡΡ
Π½Π°Π½ΠΎΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠ². ΠΡΡΠ²Π»Π΅Π½ΠΎ, ΡΡΠΎ Π½Π°ΠΈΠ»ΡΡΡΠΈΠ΅ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ Π±ΡΠ»ΠΈ ΠΏΠΎΠ»ΡΡΠ΅Π½Ρ Ρ Π΄ΠΎΠ±Π°Π²ΠΊΠΎΠΉ, Π² ΠΊΠΎΡΠΎΡΠΎΠΉ ΡΠΎΠ²ΠΌΠ΅ΡΡΠ½ΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π»ΠΈΡΡ Π²ΡΡΠ΅ΠΏΠ΅ΡΠ΅ΡΠΈΡΠ»Π΅Π½Π½ΡΠ΅ Π½Π°Π½ΠΎΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Ρ. ΠΡΠΎΡΠ½ΠΎΡΡΡ Π½Π° ΡΠΆΠ°ΡΠΈΠ΅ ΠΎΠ±ΡΠ°Π·ΡΠΎΠ² ΡΡΠΆΠ΅Π»ΠΎΠ³ΠΎ Π±Π΅ΡΠΎΠ½Π°, ΡΠ»ΡΡΡΠ΅Π½Π½Π°Ρ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΠΎΠΉ Π½Π°Π½ΠΎΠ΄ΠΈΡΠΏΠ΅ΡΡΠ½ΠΎΠΉ ΡΠΈΡΡΠ΅ΠΌΠΎΠΉ, ΡΠΎΡΡΠ°Π²ΠΈΠ»Π° 78,7 ΠΠΠ°, ΡΡΠΎ ΠΏΡΠ΅Π²ΡΡΠ°Π΅Ρ ΠΏΡΠΎΡΠ½ΠΎΡΡΡ ΠΎΠ±ΡΠ°Π·ΡΠ°, ΡΠΎΠ΄Π΅ΡΠΆΠ°ΡΠ΅Π³ΠΎ Π΄ΠΎΠ±Π°Π²ΠΊΡ ΡΠ³Π»Π΅ΡΠΎΠ΄Π½ΡΡ
Π½Π°Π½ΠΎΡΡΡΠ±ΠΎΠΊ Π² ΠΏΠ°ΡΠ΅ Ρ ΡΡΠΏΠ΅ΡΠΏΠ»Π°ΡΡΠΈΡΠΈΠΊΠ°ΡΠΎΡΠΎΠΌ, Π½Π° 37 %. ΠΠ·ΡΡΠ΅Π½ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌ Π΄Π΅ΠΉΡΡΠ²ΠΈΡ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Π½ΠΎΠΉ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΠΎΠΉ Π΄ΠΎΠ±Π°Π²ΠΊΠΈ
Oxygen transport in Pr nickelates: Elucidation of atomic-scale features
Pr2NiO4+Ξ΄ oxide with a layered RuddlesdenβPopper structure is a promising material for SOFC cathodes and oxygen separation membranes due to a high oxygen mobility provided by the cooperative mechanism of oxygen migration involving both interstitial oxygen species and apical oxygen of the NiO6 octahedra. Doping by Ca improves thermodynamic stability and increases electronic conductivity of Pr2 β xCaxNiO4+Ξ΄, but decreases oxygen mobility due to decreasing the oxygen excess and appearing of 1β2 additional slow diffusion channels at x β₯ 0.4, probably, due to hampering of cooperative mechanism of migration. However, atomic-scale features of these materials determining oxygen migration require further studies. In this work characteristics of oxygen diffusion in Pr2 β xCaxNiO4+Ξ΄ (x = 0β0.6) are compared with results of the surface analysis by X-ray photoelectron spectroscopy and modeling of the interstitial oxygen migration by the plane-wave density functional theory calculations. According to the X-ray photoelectron spectroscopy data, the surface is enriched by Pr for undoped sample and by Ca for doped ones. The O1s peak at ~531 eV corresponding to a weakly bound form of surface oxygen located at Pr cations disappears at ~500 Β°C. Migration of interstitial oxygen was modeled for a I4/mmm phase of Pr2NiO4+Ξ΄. The interstitial oxygen anion repulses the apical one in the NiO6 octahedra pushing it into the tetrahedral site between Pr cations. The calculated activation barrier of this migration is equal to 0.585 eV, which reasonably agrees with the experimental value of 0.83 eV obtained by the oxygen isotope exchange method. At the same time, for the model compound Ca2NiO4+Ξ΄, obtained by isomorphic substitution of Pr by Ca in Pr2NiO4+Ξ΄, calculations implied formation of the peroxide ion comprised of interstitial and lattice oxygen species not revealed in the case of incomplete substitution (up to PrCaNiO4+Ξ΄ composition). Hence, calculations in the framework of the plane-wave density functional theory provide a realistic estimation of specificity of oxygen migration features in Pr2NiO4+Ξ΄ doped by alkaline-earth metals. Β© 2019 Elsevier B.V.Russian Science Foundation,Β RSF: 16-13-00112Support by Russian Science Foundation (Project 16-13-00112 ) is gratefully acknowledged
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