Construction of Unique Buildings and Structures

RAR RUS 12001-12001 Kuzminov Oleg Olegovich O-6995-2019 6508103761 0000-0002-1196-8004 Peter the Great St. Petersburg Polytechnic University Vatin Nikolai Ivanovich vatin@mail.ru

St. Petersburg, Russian Federation

Method for evaluating self-healing in cement composites via permeability variation analysis The research object is a novel method for evaluating the self-healing capacity of cementitious composites incorporating cementitious capillary crystalline waterproofing (CCCW) admixtures, specifically using cement paste and concrete specimens with artificially created through-channels simulating cracks. The research method involves preparing cylindrical specimens (26 mm diameter, 140 mm height) with a controlled 0.4 mm diameter axial channel formed by a removable polyamide-6 string, followed by qualitative (visual air bubble observation) and quantitative permeability assessments after 65 days of wet curing, employing the BB-2 vacuum device for air permeability and the UVF-6 installation for water penetration depth under pressure in accordance with GOST 12730.5. The results demonstrate that specimens with the CCCW admixture (Krystaline Add1) exhibited significant self-healing, with specific compositions achieving a water resistance grade of W8 and partial or complete channel sealing. 10.4123/CUBS.120.1 69 Concrete Self-healing Water resistance Crack Waterproofing additive Cementitious composites Testing methods Maintainability Durability https://unistroy.spbstu.ru/article/2025.120.1/ 12001.pdf

RAR RUS 12002-12002 Pankov Pavel Pavlovich Konovalova Nataliya Anatolyevna Shavanov Nikolay Dmitrievich Bespolitov Dmitry Viktorovich Composite materials based on ash and slag waste for thermal insulation of roadbeds The object of research is the ash and slag mixture of the Amazar boiler station (Trans-Baikal Railway), involved in the composition of the composite as an inert filler of the polymer matrix. The aim of this work is to study the methods of utilization of ash and slag mixture in the compositions of composite materials for waterproofing and thermal insulation of the main platform of the railway roadbed. Method. To obtain data on the chemical and phase composition, physical and physicochemical properties, microstructural features of the ash and slag mixture and the composite based on it, modern analytical methods were used (X-ray fluorescence and X-ray phase analysis; differential scanning calorimetry and thermogravimetry; infrared spectroscopy; light, stereo- and scanning electron microscopy; computed X-ray microtomography, etc.). The conditions for the synthesis of the composite matrix, sample preparation modes and their performance characteristics are presented. Scanning electron microscopy and computed X-ray microtomography were used to study the pore space properties of a composite material and establish the mechanism of its cryostructuring. Results. The ash and slag mixture was found to be non-heaving, with the specific effective activity of natural radionuclides meeting the requirements of GOST 30108-94 (295 Bq/kg), allowing its unrestricted use in the construction industry. Based on its hydraulic activity, the ash and slag mixture is classified as an inert material. Infrared spectroscopy, differential scanning calorimetry, and thermogravimetry revealed the presence of organic compounds (coal, semi-coke, and coke residues) in the ash and slag mixture. Scanning electron microscopy revealed the heterogeneity of the ash and slag mixture's pore space, which may facilitate the production of a composite with optimal thermal insulation properties. The resulting composite material is frost-resistant and waterproof (ti not less than 3600 s), characterized by a compressive strength of 6.20 MPa and a thermal conductivity of 0.17 W/(m•K). Cryogenic treatment of the composite material led to a change in the spatial orientation of its microstructural elements. The maximum volume in the composite material structure (13-39 mm3) is occupied by pores with sizes of 0.028-0.084 mm, which account for up to 41 %. The total porosity of the composite was 17.28 %, which determines its thermophysical properties and allows it to be recommended for the installation of hydro- and thermal-insulating protective layers under railway ballast. 10.4123/CUBS.120.2 69 Composite materials Thermal insulation of roadbeds Cryostructuring Polymer matrix Waste disposal Ash and slag mixtures https://unistroy.spbstu.ru/article/2025.120.2/ 12002.pdf

RAR RUS 12003-12003 P-3728-2017 57194112309 0000-0001-6184-2365 Vyatka State University Tyukalov Yury Yakovlevich yutvgu@mail.ru

Kirov, Russian Federation

GMW-6276-2022 0000-0002-3884-874X Vyatka State University Ashikhmin Stanislav Eduardovich ashihminstanislav@gmail.com

Kirov, Russian Federation

Composite reinforcement strength at high temperatures: The influence of preheating The object of research is the composite reinforcement at high temperatures. Method. During the study, 16 specimens with composite rods bonded with epoxy resin on metal tubes were prepared. The specimens were tested using a universal hydraulic machine and pre-heated using a heat gun to heat the reinforcement to various temperatures (20°C, 100°C, 150°C, 250°C, and 300°C). The maximum breaking load was determined for specimens with and without preheating. Results. Test results show that preheating the rods increases the strength of composite rods at elevated temperatures. As the reheating temperature increases, the effect of preheating on the strength of the composite rebar increases. The difference in maximum tensile strength between preheated and unheated rods, tested at 300°C, reaches 50%. 10.4123/CUBS.120.3 69 Fire resistance Quick-erecting connections Composite rods Epoxy adhesive https://unistroy.spbstu.ru/article/2025.120.3/ 12003.pdf

RAR RUS 12004-12004 0000-0002-0649-4342 Vdovin Evgeny Anatolievich vdovin007@mail.ru

Kazan, Russian Federation

0000-0001-9680-6698 Kazan State University of Architecture and Engineering Stroganov Victor Fedorovich svf08@mail.ru 0000-0002-0149-8854 Kazan State University of Architecture and Engineering Bulanov Pavel Efimovich pavel.bulanov1991@yandex.ru

Kazan, Russian Federation

Vybornov Daniil Romanovich Technological factors of complex-modified strengthened soils for road construction Comprehensive modification methods for strengthened soils offer a promising approach to mitigating the negative impact of clay minerals and expanding the potential for using clay soils in road pavement construction. Industrial application of comprehensive modification methods for strengthened soils in road construction requires data on the influence of process factors on the physical and mechanical properties of road pavement materials. It has been established that the role of process factors in the comprehensive modification of strengthened soils has not been adequately studied and is a pressing issue when it comes to using complex clay systems in road construction. The study examines the following process factors of comprehensively modified strengthened clay soils that influence changes in the physical and mechanical properties of materials during the construction of pavement layers: the order of component introduction into the soil (water, binder, modifiers), the size of soil aggregates present in the strengthened soil, the compaction coefficient and moisture content, and the duration of the construction process. Graphical and analytical relationships were obtained for the influence of process factors on the compressive strength, flexural tensile strength, and frost resistance coefficient of strengthened soils. It was demonstrated that the use of integrated modification methods enables improved soil strengthened process efficiency. The negative impacts of mixture heterogeneity and insufficient fineness of soil aggregates were reduced, while the efficiency of mechanisms was increased, both during the mixture preparation stage and during subsequent installation of the structural layers of road pavements. 10.4123/CUBS.120.4 69 Reinforced soils technological factors complex modification method road surface physical and mechanical characteristics https://unistroy.spbstu.ru/article/2025.120.4/ 12004.pdf

RAR RUS 12005-12005 0000-0002-0649-4342 Vdovin Evgeny Anatolievich vdovin007@mail.ru

Kazan, Russian Federation

Vybornov Daniil Romanovich Methods for modification of strengthened kaolinite clays in road construction The presence of clay minerals, such as kaolinite, in soils during soil strengthened negatively impacts the physical and mechanical properties and durability of cement-based soils, as well as the increased amount of binder used in road pavement, which is a pressing issue. It has been established that mitigating the negative impact of clay minerals in soils, reducing the binder content in materials, and improving the physical, mechanical, technological, and operational properties of road pavement is possible through the use of methods for modifying strengthened soils. Promising modification methods have been identified, the main ones being: altering the ion-exchange complex, hydrophobization, plasticization, and complex modification (a combination of methods). The effects of modification methods on the physical and mechanical properties of strengthened kaolin clays (compressive strength, tensile strength, and frost resistance coefficient) have been determined. The impact of the complex modification was investigated using the mathematical design of experiments method. Regression equations were obtained in the form of a second-degree polynomial, and response functions were constructed as parametric dependencies. It has been shown that the use of the complex modification method provides the greatest opportunity to level out the negative impact of kaolinite and, as a consequence, to obtain structural layers of road pavement with improved physical and mechanical properties. 10.4123/CUBS.120.5 69 Kaolin clay strengthened soils modification methods physical and mechanical properties road pavement https://unistroy.spbstu.ru/article/2025.120.5/ 12005.pdf

RAR RUS 12006-12006 Arleninov Petr Dmitrievich Short-term and long-term testing of beams made of high-strength concrete with different types of reinforcement The object of research is the nature of deformation of flexural elements made of high-strength concrete, reinforced with classical bar and sheet reinforcement, under long-term loads. The relevance of the work is determined by the lack of data on the deformation characteristics of such structures in regulatory documents and scientific literature; this applies both to short-term loads and especially to long-term ones. Such experiments have not been conducted previously in our country, and they are also rare abroad. Method. Comprehensive experiments were carried out on beam specimens of the same cross-section, reinforced in three different ways – external sheet reinforcement (Type A), classical bar reinforcement designed for the same failure load (Type B), and bar reinforcement for twice the load (Type C). The experiment included short-term tests to failure and long-term tests with step-by-step loading; part of the beam specimens was loaded to 50% of the failure load before the long-term tests. During the testing, beam deflections and the nature of crack formation were investigated. Results. It was found that with the same load-bearing capacity and similar nature of deformation, significantly fewer cracks form in beams with external sheet reinforcement, but with a crack width an order of magnitude greater. Under long-term loading conditions, beams with external sheet reinforcement and initial cracks showed a smaller reduction in stiffness at the reloading stages compared to beams reinforced according to the classical scheme. The work confirmed the applicability of standard calculation methods for the first group of limit states to flexural elements with external sheet reinforcement. To increase crack resistance, the installation of additional structural bar reinforcement is recommended in them. The obtained data reveal the features of deformation of structures with external sheet reinforcement and determine the necessity for further research for other types of cross-sections and classes of concrete. 10.4123/CUBS.120.6 69 Concretes High-strength concrete Cracks Creep Deformation Stiffness Composite steel and concrete beams https://unistroy.spbstu.ru/article/2025.120.6/ 12006.pdf