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RAR RUS 12101-12101 Qais Qais Abdurrahman Ali Kotlyarevskaya Alena Valerevna Okolnikova Galina Erikovna Al-muradi Yunes Ali Ali Thermo-mechanical evaluation of hybrid basalt fiber aerodrome concrete pavement under dynamic impact The object of research is the thermo-mechanical behaviour of hybrid basalt fibre-reinforced concrete used in aerodrome pavements. The subject of the research is the effect of hybrid fibre composition on impact resistance and thermal durability under dynamic loading. The purpose of the research was to develop and assess a hybrid basalt fibre mix capable of enhancing the mechanical and thermal stability of airfield pavements. Method. Three concrete mixes were selected: a control mix (K, 0% fibre), a micro-fibre mix (2A, 2% micro-fibre), and a macro-fibre mix (2B, 2% macro-fibre). The mechanical properties, specifically the Modulus of Elasticity, were modelled as a function of temperature and using reduction factors based on existing building standards (Eurocode 2: EN 1992-1-2). A linear static analysis was performed for 12 cases (3 mixes, 4 temperatures) using Autodesk Robot Structural Analysis software. The pavement was modelled as a slab with elastic soil supports (Winkler foundation). Two cumulative load cases were applied: a static uniform pressure of over an area and a uniform temperature increase. The primary output parameters were Total Displacement and Maximum Bending Moment. Results. The results indicate that high temperature is the most governing factor in the slab's structural behaviour, causing a varied reduction in material stiffness. This thermal degradation led to a gradual and dramatic increase in maximum vertical displacement, which rose from a baseline of at (Mix K) to at across all three mixes. Crucially, at high temperatures, the reinforcing action of both micro- and macro-basalt fibres was rendered insignificant because the failure mode was completely governed by the thermal degradation of the cement matrix itself. The maximum bending moment exhibited a non-linear relationship with temperature, initially decreasing due to stiffness loss, but then increasing sharply at (to for Mix K) due to significant thermal stresses and warping effects, indicating a state of critical distress. 10.4123/CUBS.121.1 69 Hybrid fibre-reinforced concrete Thermo-mechanical analysis Aerodrome pavements Finite element analysis Elevated temperatures https://unistroy.spbstu.ru/article/2026.121.1/ 12101.pdf

RAR RUS 12102-12102 Chernykh Tamara Nikolaevna Komelkova Maria Vladimirovna Wu Chuangzhou Gorbachevskikh Kirill Alekseevich Gilevich Anton Anatolevich Orlov Aleksandr Anatolevich Shape memory polymer rods for improving crack resistance in reinforced concrete beams The object of research is reinforced concrete beams with combined reinforcement. Improving their crack resistance is essential because crack propagation reduces structural durability, and conventional methods of crack closure are not always effective. Method. The study employs an experimental method involving four-point bending tests on specimens with additional heat-activated polycaprolactone rods. Results. The study found that after heat activation, the crack width in the modified beams was more than halved compared to that in the control specimens, and the deflection decreased by 16%. These results demonstrate the potential of using shape-memory polymer elements to control the deformation state of reinforced concrete structures and thereby improve their performance. 10.4123/CUBS.121.2 69 Reinforced Concrete; Self-healing; Deformation; Bending Tests; Concrete Beams And Girders; Shape Memory Polymers; Reinforcement https://unistroy.spbstu.ru/article/2026.121.2/ 12102.pdf

RAR RUS 12103-12103 Qais Qais Abdurrahman Ali Kotlyarevskaya Alena Valerevna Okolnikova Galina Erikovna Hybrid basalt fiber aerodrome concrete performance evaluation Concrete airport pavements are subjected to severe mechanical and environmental demands, necessitating improved crack resistance, fatigue performance, and durability. The object of research is macro–micro hybrid basalt fiber reinforced concrete (BFRC) as a potential high-performance pavement material. The work aims to evaluate the influence of basalt fiber dosage and hybridization on crack width and depth, fracture toughness, fatigue life, chloride ingress resistance, and structural reliability. Method. Mechanical properties from laboratory tests were integrated with semi-empirical fracture mechanics models, S–N fatigue relationships, Fick’s second-law chloride diffusion analysis, and reliability-based statistical assessment. Results. Results indicate that increasing fiber content reduced predicted crack width and depth, while hybrid systems significantly enhanced fracture parameters. The 1.5A0.5B mix exhibited the highest fracture toughness and durability performance, whereas the 2A1B mix demonstrated superior fatigue life and reliability index. Overall, balanced hybrid basalt fiber systems provided synergistic improvements in cracking resistance, fracture behavior, fatigue performance, and long-term durability for airport pavement applications. 69 Basalt fiber Crack Durability Fatigue Fracture toughness Fiber hybridization https://unistroy.spbstu.ru/article/2026.121.3/ 12103.pdf

RAR RUS 12104-12104 0000-0002-4590-8552 Ehsani Armin 0000-0001-5939-3257 Nasimi Shahin Shambina Svetlana Lvovna 0000-0002-7168-5786 Gebre Tesfaldet Hadgembes Bond strength between concrete and steel rebar in circular sections The object of research is the bond behavior between concrete and steel reinforcing bars (rebars) in circular sections, including force-transmission mechanisms and the influence of key design parameters such as embedment length, concrete cover (sample diameter), and 28‑day compressive strength of concrete. This work aims to evaluate how these parameters affect bond strength experimentally and to provide practical solutions to improve the performance of reinforced concrete structures with circular cross‑sections. Method. The pull-out test is one of several tests used to determine the adherence between concrete and steel. This work used the pull-out test in three configurations to examine the effects of the length of rebar buried in concrete, the amount of concrete coating on the rebar, and the 28-day compressive strength of concrete on adhesion between concrete and steel. A total of 12 pull‑out test specimens were prepared with cylindrical concrete samples (diameter 59.2 mm to 192 mm, length 100 mm to 300 mm). Three series of tests were conducted: (1) variable embedment length (100–300 mm) at fixed diameter (120 mm) and fixed compressive strength (25 N/mm²); (2) variable sample diameter (59.2–192 mm) at fixed embedment length (200 mm) and fixed compressive strength (25 N/mm²); (3) variable 28‑day compressive strength (15–30 N/mm²) at fixed Diameter (120 mm) and fixed embedment length (200 mm). The pull‑out force and slip were recorded, and the average maximum adhesion stress was calculated. Results. As the reinforcement length inside the concrete sample increased, no noticeable change was observed in the average maximum adhesion stress. According to several experimental studies on the bond strength of concrete and rebar in circular sections, the average maximum adhesion stress rises with the concrete sample's diameter. Additionally, the average maximum adhesive stress increases with 28-day compressive strength. 10.4123/CUBS.121.4 69 Compressive strength Adhesion strength Pull-out test Adhesion between steel and concrete Reinforced concrete https://unistroy.spbstu.ru/article/2026.121.4/ 12104.pdf

RAR RUS 12105-12105 0000-0003-0032-7989 Voronezh State Technical University Kotova Kristina Sergeevna kottova-k@yandex.ru

Voronezh, Russian Federation

Shvedova Mariia Aleksandrovna marishwedowa@mail.ru Yurov Pavel Yuryevich Glukhov Sergey Alekseevich Ovcharov Ruslan Romanovich The effect of photoluminescent powder on the rheological properties of architectural cement composites for 3D printing The object of research is 3D-printable decorative concrete with added photoluminescent powder. This work aims to obtain cement composite mixtures with photoluminescent properties for construction 3D printing with specified technological properties by varying their component composition in terms of the type of cement matrix, the type of cement, and the dispersion of the photoluminescent powder. Method. The technological characteristics of the resulting mixtures were determined using compression rheometry. The setting kinetics of the mixtures were controlled by the plastic strength indicator, which was determined using a conical plastometer of the author's design. The fluidity of the mixtures was evaluated by the diameter of the mixture flow using the standard method of mechanical creep using the Hegemann cone. The criteria for the plasticity and shape stability of the studied mixtures were determined based on the results of compression tests conducted at a constant deformation rate and a constant loading rate. Results. The dependence of the setting processes of the studied mixtures on the type of cement matrix (micro-grained, fine-grained), the type of cement used (white, gray), and the dispersion of the photoluminescent powder has been established. The setting process is more intense in micro-grained systems with limestone flour. At the same time, systems with white cement have higher plastic strength and lower spread diameter than systems with gray cement, regardless of the type of filler and aggregate. All studied systems show increased plastic strength when photoluminescent powders are added, regardless of particle size. Based on the obtained values of the criteria characteristics of plasticity and form stability, all studied systems are suitable for the 3D-printing process. However, mixtures with the addition of photoluminescent powder PLP2 do not meet the requirements of the 3D-printing process in terms of preserving properties over time, as they are characterized by a rapid increase in plastic strength over time, and mixtures based on gray cement do not meet the requirements for decorative properties. Therefore, it is recommended to use white-cement mixtures with quartz sand and a photoluminescent powder additive (particle size 10.4123/CUBS.121.5 69 Translucent 3D printed composites Photoluminescent powders Decorative products https://unistroy.spbstu.ru/article/2026.121.5/ 12105.pdf