75504 2712-8172 18 5 2025

RAR RUS 13701-13701 Civil Engineering Department, University of Thi-Qar Sekhi Alaa Ahmed aalasekhi@gmail.com

Nasiriyah, Iraq

0000-0002-0951-7394 Civil Engineering Department, University of Thi-Qar Shaia Hussein Abd h.shaia@utq.edu.iq

Nasiriyah, Iraq

Stabilization of sandy soil contaminated with crude-oil utilizing Portland cement The issue of soil pollution has lately gotten worse because of the increase in industrial wastes like heavy metals, liquid hydrocarbons, and petroleum hydrocarbons. Oil is one of the most important sources of industrial pollution, which deteriorates large parts of surface areas and water bodies, and oil or its derivatives spill into surface areas or water bodies, either spontaneously or forcibly. Petroleum-polluted soil has an ordinarily adverse impact on its geotechnical features making it inadequate substance for construction projects. Therefore, there is an urgent need to find suitable techniques for improving such polluted soils. This paper is prepared to show two matters: the first deals with a comparison between the natural sandy soil and sandy soil polluted with 11.8 % of crude oil, while the second deals with an estimation of the mechanical features of polluted soil after being treated with five different proportions of ordinary Portland cement as stabilizer agents. Many experimental tests have been applied depending on the ASTM standards to evaluate several geotechnical features like the consistency limits, compaction parameters, UCS, and direct shear characteristics. The results showed that the existence of crude-oil in sandy soil minimizes the dry density, moisture content, shear stress, friction angle, and effective cohesion. Otherwise, the utilization of Portland cement in polluted sandy soil increases such mechanical features. 10.34910/MCE.137.1 624 soil pollution sandy soil geotechnical stabilizer Portland cement crude-oil effective cohesion shear stress https://engstroy.spbstu.ru/article/2025.137.1/

RAR RUS 13702-13702 The University of Kerbala Haitham Abdullah Samir haitham.a@s.uokerbala.edu.iq

Karbala, Iraq

The University of Kerbala Ali Hameed Naser Almamoori haitham.a@s.uokerbala.edu.iq

Karbala, Iraq

Structural behavior of thin-walled steel short columns filled with recycled aggregate concrete This paper presents an experimental investigation to study the behavior of 12 recycled aggregate concrete-filled steel tubular (RACFST) short columns subjected to concentric axial loading. These columns formed from six different cross-sections involving: triangle, elliptical, and hexagon, whereas the other three sections included traditional forms for control purposes, involving: square, rectangular, and circular. The whole of the RACFST columns sections used is made of mild steel plates. All columns were divided into two groups and filled with recycled aggregate concrete. The steel tube thickness was the only parameter modified to study its effect properly. In addition, the study included the search for the best effective section with regard to the properties of stability and confinement, so these columns were designed so that the cross-sectional areas of steel tubes were approximately equal. Different data have been recorded in the experimental tests, including: the ultimate failure axial load, final failure stress, the reduction in the axial column length, failure patterns, and lateral displacement. Data obtained exhibited of RACFST columns with circular and elliptical sections, respectively, showed better stability, confinement for the concrete, and the ability to withstand greater final failure stress. On the other hand, the arrangement of all RACFST columns with polygonal sections in terms of bearing the ultimate failure stress was as follows: hexagonal (C.H.), square (C.S.), rectangle (C.R.), and triangle (C.T.). The reason for this was the increase in the number of corners of steel plates that formed the model. In another concept, this means that the greater the number of formed sides and the greater the angle between the sides (90° or more), the section can achieve more stability and confinement, respectively. In addition to these, the results showed, when the thickness of the steel tube increases, the concrete contribution ratio value decreases of the specimens examined. 10.34910/MCE.137.2 69 short length column recycled aggregate concrete filled steel tubes RACFST recycled coarse aggregate RCA thin-walled steel tubes axial compression section shape effect https://engstroy.spbstu.ru/article/2025.137.2/

RAR RUS 13703-13703 Ministry of Sciences and Technology Ahmed Sahar as.18.48@grad.uotechnology.edu.iq

Baghdad, Iraq

Peter the Great Saint Petersburg Polytechnic University Sabri Mohanad Muaya mohanad.m.sabri@gmail.com

Polytechnicheskay, 29

Iraqi Atomic Energy Commission, Directorate of Nuclear Applications Saleh Anas anasdaf@yahoo.com

Baghdad, Iraq

University of Technology Al-Adili A.Sh. Aqeeladili@hotmail.com

Baghdad, Iraq

Thermal conductivity reduction and acoustic insulation enhancement in nanosilica-modified lightweight porcelanite concrete This study investigates the thermal and acoustic insulation properties of lightweight concrete modified with nanosilica and porcelanite aggregates. Eight lightweight concrete formulations with varying nanosilica content (0%, 1%, 1.5%, and 2%) and aggregate sizes (4 mm and 5 mm) were developed and tested. The results indicate that incorporating nanosilica significantly enhances both thermal conductivity and acoustic impedance. Concrete samples with 4 mm porcelanite and 1 % nanosilica achieved a thermal conductivity reduction of 24.85 %, while samples with 5 mm porcelanite and 2 % nanosilica demonstrated an 8.42 % increase in acoustic impedance. These findings underline the synergistic effects of nanosilica and aggregate size, providing insights for optimizing lightweight concrete performance in thermal and acoustic insulation applications. 10.34910/MCE.137.3 624 porcelanite nanosilica thermal conductivity acoustic insulation scanning electron microscope https://engstroy.spbstu.ru/article/2025.137.3/

RAR RUS 13704-13704 Al-Muthanna University Al-Gabri Nabaa nabaa.q.husain@mu.edu.iq

Samawah, Al Muthanna Province, Iraq

Al-Muthanna University Shanbara Hayder hayder.shanbara@mu.edu.iq

Samawah, Al Muthanna Province, Iraq

Analytical evaluation of the rutting response under the static loading in flexible pavement In this research, a special model for assessing the impact of static load on flexible pavement behavior is studied, through the use of crawling screening parameters. Relying on previous experiments, the FEM simulation was done using the Abaqus program, which is accurately predicted the behavior of the static load. The results showed that this pregnancy greatly affects the sidewalk response, and thus leads to the accumulation of stress and emotion and their development in asphalt concrete, in the end, it leads to the formation of permanent distortion. The FEM analysis shows an increase in the depth of distortion of the static load result, which means the importance of taking its impact into consideration when designing the sidewalk and maintenance strategies. The research underscores the value of enhanced rutting prediction models to improve pavement performance and support the development of more durable and sustainable road infrastructure. 10.34910/MCE.137.4 69 FEM Abaqus program static load rutting flexible pavement static loading pavement https://engstroy.spbstu.ru/article/2025.137.4/

RAR RUS 13705-13705 Kazan State University of Architecture and Engineering Sabirov Ilshat ilshat-sabirov@bk.ru

Kazan, Russian Federation

Kazan State University of Architecture and Engineering Rakhimova Nailia rahimova.07@list.ru 55530988100 Kazan (Volga region) Federal University Morozov Vladimir Vladimir.Morozov@kpfu.ru

Kazan, Russian Federation

Kazan (Volga region) Federal University Eskin Alexey eskin.aleksey@gmail.com

Kazan, Russian Federation

Exploring the potential of calcined montmorillonite-kaolinite clay with medium percentage of clay minerals for low-carbon cements Expanding the raw material base and diversifying supplementary cementitious materials based on distribution, availability, and competitiveness with traditional materials is a key focus for promoting the production and application of low-carbon cements. This approach is crucial for ensuring the sustainable development of the cement industry. Extensive research and practical experience in recent decades have highlighted the promising potential of using thermally activated clays to create low-emission cements. Calcined clays have now become significant and growing part of the range of reactive aluminosilicates suitable for use as primary or supplementary sources in producing clinker-free or low-clinker cements. This is facilitated by the abundant reserves of clay raw materials and the high reactivity of activated clays. The practical implementation of thermally activated clays followed extensive, long-term studies on the potential use of various types of clays. Research focused on the influence of chemical and mineralogical compositions, activation methods, and other factors on their reactivity. While important parameters for kaolin clays, such as kaolin content, optimal temperature and duration of thermal treatment, and fineness of grinding, are well-defined and included in standards, these aspects are not thoroughly studied for polymineral and montmorillonite clays. This study examines the impact of temperature and duration of calcination on the reactivity of montmorillonite-kaolinic clay with an average clay minerals content and explores its potential in environmentally-oriented low clinker cements. 10.34910/MCE.137.5 691.54 clay montmorillonite kaolinite calcination cement paste https://engstroy.spbstu.ru/article/2025.137.5/

RAR RUS 13706-13706 Dalian University of Technology Nie Feng 1007159549@qq.com

Dalian, China

China Railway 11th Bureau Group Ltd. Zhou Xuhui 251357091@qq.com

Wuhan City, China

Dalian University of Technology Wang Huili wanghuili@dlut.edu.cn

Dalian, China

Dalian University of Technology Zhang Chenbo 18636289345@163.com

Dalian, China

Contact of swivel construction spherical hinge In this paper, the contact stress of the spherical hinge is analyzed. By comparing the finite element model with the calculation results of the related contact theory, it is found that the distribution mode of the contact stress of the spherical hinge is similar to that of the vertical compressive stress distribution model of the spherical hinge, while Hertz contact theory is not suitable for analyzing the contact problem of the spherical hinge. In addition, the existence of unbalanced weight and inadequate contact between the upper and lower spherical hinges are studied in this paper. The results show that for a 30,000-ton swivel bridge, when the unbalanced moment is 0.5×104 KN·m~2.0×104 KN·m, the contact stress in the middle area of the spherical hinge increases, and the contact stress difference between the two sides also increases gradually, up to 16.97 % of the maximum contact stress. When the non-contact area of the middle of the spherical hinge is 10 %, 20 % and 40 %, the maximum contact stress and friction force at the edge of the spherical hinge increase by 9.41 % and 16.16 % respectively compared with the normal situation, but the total friction torque hardly changes. 10.34910/MCE.137.6 69 contact theory inadequate contact spherical hinge swivel construction unbalanced weight https://engstroy.spbstu.ru/article/2025.137.6/

RAR RUS 13707-13707 57196066346 0000-0002-8051-5914 National Research Moscow State Civil Engineering University Denisov Aleksandr den-al-v@inbox.ru

Moscow, Russia

Prediction of radiation changes in concrete and mortars under the influence of gamma radiation The present research was carried out due to the insufficient study of the effect of gamma radiation on concrete and mortar. The research took into account the availability of developed and experimentally tested methods for the analytical determination of radiation, thermal, and radiation-thermal changes in concrete and its components under neutron irradiation and heating, as well as radiation changes in the aggregates and hardened cement paste (HCP) under the influence of gamma radiation. The aim of the work was to establish the possibility of using these existing analytical methods to predict radiation changes in concrete and mortar under the influence of gamma radiation. In this case, the existing experimental results of the influence of gamma irradiation on 7 different concretes and 11 cement mortars were used. The studies performed have shown the possibility of using existing analytical methods to predict radiation changes in the dimensions of concrete under the influence of gamma radiation. The results of the studies of predicting radiation changes in the strength of concrete and mortars under the action of gamma radiation showed significant differences between the calculated and experimental changes when using the existing analytical methods applied under neutron irradiation and heating without their correction. It is assumed that this is due to differences in the processes of acceleration of hydration and carbonization of HCP under the action of gamma radiation under neutron irradiation-heating and under gamma irradiation. It is proposed to take into account these differences in the values of one of the parameters of the method for analytical determination of strength changes in early age HCP and to introduce an additional correction factor that takes into account the effect of aragonite and vaterite formation during carbonization of mature HCP under the action of gamma radiation. The values of this parameter and its dependence on the change in the volume of early age HCP under the action of gamma radiation are established. The values of the additional coefficient taking into account the effect of aragonite and vaterite formation for the considered mature concretes and its dependence on the absorbed dose and the estimated amount of carbonates are determined. It is shown that by using the adjusted parameter for early age concrete and an additional coefficient for mature concrete, the existing analytical methods can be used to predict radiation-induced changes in the strength of concrete and cement mortars under the influence of gamma radiation. 10.34910/MCE.137.7 691:699.887 concrete mortar aggregates hardened cement paste influence of gamma radiation and heating radiation and radiation-thermal changes and damage changes in linear dimensions volume strength forecasting https://engstroy.spbstu.ru/article/2025.137.7/

RAR RUS 13708-13708 0000-0003-2533-9732 National Research Moscow State Civil Engineering University Samarin Oleg samarin-oleg@mail.ru Non-stationary thermal mode of a room at integrated regulation of split systems Due to the non-linearity of the propagation of temperature waves in massive fences, one of the most difficult control objects is an air-conditioned room equipped with automated microclimate systems, especially if complex algorithms are used for regulation. Therefore, the task of studying the non-stationary thermal regime of such a room still remains actual, despite the presence of a number of solutions describing the behavior of the air temperature in it with changes in heat supply. On the other hand, such objects are regularly found in the decision-making process to ensure an internal microclimate, so the results obtained can be used for a wide class of tasks. The proposed work presents a variant of a simplified mathematical formulation and solution of the task of calculating changes in internal temperature in a room in which a local split-system type cooling system is provided for the assimilation of heat surpluses, regulated by an integral law, in conditions when general exchange ventilation performs only sanitary and hygienic functions. The basic differential equation of the room thermal balance for this case is formulated, and it is shown that with the introduction of a fixed layer thickness of sharp temperature fluctuations over the considered time interval, this equation with feedback describing the action of the regulator is linear of the second order and is solved in elementary functions in the form of a damped sine wave. Using this solution, calculations were performed for a characteristic room and its validity and formal compliance with the classical results of the automatic control theory were proved by comparing the results with data from field measurements carried out in the same room, as well as with the results obtained for similar tasks by other authors. The obtained formulas are proposed to be used for estimated calculations of the indoor air temperature behavior in an air-conditioned room with the assimilation of heat supply by split systems regulated by an integral law, and for solving identification problems to determine the actual parameters of the room and the controller. 10.34910/MCE.137.8 697.1 : 628.8 microclimate temperature thermal balance heat gain regulation integral law transmission coefficient civil engineering building construction industry https://engstroy.spbstu.ru/article/2025.137.8/

RAR RUS 13709-13709 57191530761 0000-0002-4765-5819 Moscow State University of Civil Engineering (National Research University) Alekseytsev Anatoly aalexw@mail.ru

Moscow, Russia

Bryansk State University of Engineering and Technology Kurchenko Natalia inserpik@gmail.com Evaluating the structural safety of steel frames using a probabilistic robustness index During the design of buildings and structures with steel frames, the issue of ensuring their mechanical safety under accidental actions arises. A number of such actions are not accounted for in the normal operating conditions of buildings and are therefore classified as emergency events. To assess the degree of resistance of load-bearing structures to these actions, the concept of structural robustness has been introduced in modern scientific literature. However, due to the insufficient study of the problem, there are relatively few works devoted to the quantitative assessment of robustness in the form of specific indicators, and those that do exist are primarily focused on reinforced concrete structures. This paper proposes a method for evaluating a probabilistic robustness index for steel frame structural systems. Its calculation uses a modified form of classical reliability theory equations, based on the premise that the failure of a frame system occurs through the formation of a mechanism with the minimum number of plastic hinges. When determining the probability of failure, the deformation behavior of frame elements is considered, with their sequential or parallel inclusion in the failure mechanism scheme, analogous to electrical circuits with series or parallel connections. To evaluate the dispersion of random variables, the statistical simulation method (Monte Carlo) and experimentally observed data are used. Examples of robustness index calculation are provided for various accident scenario types. The specific practical implementation of the method demonstrated its applicability, allowing conclusions to be drawn about the mechanical safety of structures with steel frame systems that are subject to heightened responsibility levels or other special requirements for resistance to progressive collapse. 10.34910/MCE.137.9 621.3.019.32 steel structures robustness mechanical safety deformations accident scenario progressive collapse reliability failure probability failure https://engstroy.spbstu.ru/article/2025.137.9/

RAR RUS 13710-13710 0000-0002-5019-3598 Al-Muthanna University, College of Engineering Al-Adhadh Ahmed ahmad_al_iraqi2000@mu.edu.iq

Al-Muthanna, Iraq

The effect of a sustainable material as partially replacement of cement on the geotechnical properties of sandy soil The deserts in Iraq need to be utilized due to the population growing and cities expansion. More than one third of Iraq's land covered with deserts. Deserts soils have some issues that makes their improvement mandatory. Examples of the issues of soils of deserts are the low bearing capacity, high permeability, high collapsibility potential, and low durability. These issues are because of the uniform particles size distributions of these soils and the lack of edges of the particles. For that, soil improvement is required to modify and fix these issues. Cement is considered one of the most efficient additive to be used for soil stabilization. However, it has some environment issues since it is considered one of the most CO2 emissions sources and energy consumption and also it changes the behavior of soil to be more brittle. In this study, a supplementary cementitious material, calcined shale, is used as partially replacement of cement to improve the geotechnical properties of sandy soil as a more sustainable material. The maximum dry density of cement treated soil reduced by approximately 2.6 % when calcined shale content increased from 0 to 70 %. The unconfined compressive strength increased when calcined shale is added and reached the maximum increasing rate, 12 %, when 30 % of cement is partially replaced with calcined shale and then drops by 49 % when calcined shale increased to 70 %. For the durability, the samples treated with calcined shale exhibit slightly lower performance compared to the samples treated solely with cement. However, these samples successfully completed the 12 cycles of wetting and drying. The results revealed that the calcined shale has the most effect on the unconfined compressive strength of cement stabilized sandy soil when 30 % is used as partially replacement. 10.34910/MCE.137.10 624 unconfined compression strength durability cement sandy soil calcined shale https://engstroy.spbstu.ru/article/2025.137.10/