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Том 7 №6

Архив журнала Строительные материалы и изделия Том 7 №6

Field thermal imaging surveys of residential buildings – a prerequisite for the development of energy-efficient external enclosures

https://doi.org/10.58224/2618-7183-2024-7-6-1
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Аннотация
The work involved a full-scale thermal imaging survey of a residential building during a hot period of time, where the effect of solar heating of the building's façade and the inner surface of the outer enclosure was studied, taking into account the orientation of the building and the time of the survey. As a result, it was found that the effect of solar heating on the building’s façade significantly increases the temperature on the façade surface, where, depending on the façade orientation and time, the building’s façade surface is exposed to heating from the east, west and south sides. Thus, the maximum values of the façade surface temperature reach 63.1°C, 57.0°C and 53.4°C, respectively, which is almost twice as high as the initial temperature values. Solar heating also has a significant effect on the temperature of the inner surface of the external enclosure, also depending on the façade orientation. Thus, on the east side in the morning, the surface temperature of the external enclosure increases by 3.8°C, which continues until 16:00. The influence of the sun provokes heating of the inner surface of the external enclosure of the living room on the western side by 4.2°C, and on the southern side the maximum temperature on the surface of the inner enclosure was observed in the period from 12:00 to 16:00, which exceeded the initial one by up to 3.8°C. At that, the influence of heating from the sun on the northern side was not observed. With that, it was found that the influence of solar heating of the building façade provokes deviations in the microclimate of the room, where the deviation in the permissible internal air temperature of the living room is 14.1% during the day, and in the optimal humidity by 13.3% in the afternoon. The findings of this study can be taken into account when designing or developing new energy-efficient external enclosing wall structures, where the criterion of heat resistance must also be taken into account in parallel with the criterion of heat protection in the climatic features of the Republic of Kazakhstan.
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Developing administrative and process-related solutions for the benefit of residential construction projects

https://doi.org/10.58224/2618-7183-2024-7-6-2
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Аннотация
Housing construction is a key segment of economy in any country, as it satisfies the needs of population and ensures safe living conditions.
This segment must take into account the requirements of safety, environmental friendliness, energy efficiency and limited mobility, resulting in high-quality construction products within pre-set deadlines. Due to the fact that many parties are involved in the construction of buildings, numerous processes are underway. As a result, various risk factors may arise. They may cause a failure to meet deadlines and lower quality of work.
The authors propose administrative and process-related solutions aimed at eliminating the most substantial risk factors.
The study solves the following tasks: analyzing the general contractor's activity in residential construction; studying risk factors that affect the building construction period; identifying actions aimed at mitigating risk factors by applying administrative and process-related solutions; developing and implementing a novel method developed on the basis of the research projects.
An expert survey was conducted among the top specialists from the construction industry, and a list of risk factors arising during the construction of residential buildings was made.
As a result, a method is developed that enables the pre-assessment of potential construction risk factors and elimination or minimization of their effect. This method reduces the period of construction, improves the quality of construction facilities and, on the whole, increases labor productivity.
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Application of ash and slag waste from coal combustion in the construction of the earth bed of roads

https://doi.org/10.58224/2618-7183-2024-7-6-3
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Аннотация
More than 1.5 billion tonnes of ash and slag waste from thermal power plants have been accumulated in the RF. The most promising direction of reuse is construction and repair of roads. The most material-intensive direction is the construction of earth bed. The aim of the study is to expand the practice of using ash and slag mixtures from thermal power plants for the construction of roadbeds in continental and polar climate. In order to achieve the goal set in the work the ash and slag mixture from different ash dumps of Irkutsk region was sampled. Ash and slag wastes can be considered as technogenic soils and classified according to GOST 25100 as gravelly sands and dusty sands. Ash and slag mixtures do not possess cohesion, have low values of internal friction angle, high porosity of particles and low specific weight, and small frost heave deformation. To evaluate the efficiency of ash and slag mixtures application in the structures of the roadbed of roads the design and construction of the roadway and the roadbed on the section of the road in the Irkutsk region was carried out. The technology of works on construction of earth bed layers from ash and slag mixtures is similar to the technology of erection of layers from soils. The constructed construction of road with earth bed from ash and slag mixtures has operational characteristics not lower than the construction of the adjacent road section with earth bed from local soils. Ash and slag mixtures can be used for construction of earth bed layers practically without restrictions.
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Development of geopolymer binders

https://doi.org/10.58224/2618-7183-2024-7-6-4
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Аннотация
The scale of consumption of raw materials is large, and to a greater extent, it is the building materials industry that has a detrimental effect on the environment, thereby disturbing the pristine appearance and landscape of nature. Production volumes of Portland cement clinker have exceeded the mark of 5 billion tons per year. But the key dilemma lies in the emission of greenhouse gases, because during the high-temperature processing of raw materials to produce clinker, carbon dioxide, methane and nitrous oxide are released into the atmosphere.
At the same time, slag-alkali and geopolymer binders can be considered as an alternative to resource-intensive Portland cement; they have found practical application in many developed countries of the world. A large backlog of research has allowed the authors of the work to model materials of both technogenic and natural origin “technogenic reaction powder – natural component – alkaline activator” in one binder system. Microanalysis confirmed the effectiveness of the integrated use of sodium silicofluoride and finely dispersed bentonite additives in the binder system, which had a beneficial effect on the pore structure of the stone and the properties of the cement stone.
Using a properly designed binder composition “aspiration dust – finely dispersed bentonite – sodium silicofluoride – alkaline binder”, it is possible to obtain high-quality and durable composites with a low carbon footprint, thereby solving many environmental problems.
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The effect of the introduction of B4C on the adhesive and cohesive properties of self-fluxing coatings

https://doi.org/10.58224/2618-7183-2024-7-6-5
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Аннотация
Wear and tear of technical equipment elements is a serious problem that negatively affects the productivity of production processes. The work analyzed the strength of cohesive and adhesive bonds of wear-resistant coatings obtained by detonation gas-dynamic spraying method based on a self-fluxing alloy, depending on the introduction of B4C particles into the composite composition. The chemical composition of the cohesive bonds of the resulting coatings and the effect of boron-containing elements on their strength were analyzed. The method of transverse scratching of transverse sections of thick coatings is a qualitative assessment of adhesive and cohesive properties and helps to determine the mechanisms of their destruction. The purpose of the work is to study the effect of the introduction of B4C particles on the adhesive and cohesive properties of coatings obtained by detonation gas-dynamic spraying based on self-fluxing NiCrBSi alloy. Methods for studying coating samples obtained by detonation gas-thermal method: scanning electron microscopy, energy dispersive analysis, optical metallographic microscopy, scratch testing. Previously, wear-resistant coatings based on self-fluxing NiCrBSi-B4C alloy have proven their effectiveness as protective coatings for centrifugal beet cutter knives. This study substantiates the feasibility of obtaining a composite based on such coatings with the introduction of boron carbide to improve its strength characteristics.
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Protection of construction sites from unmanned aerial vehicles using mesh fences

https://doi.org/10.58224/2618-7183-2024-7-6-6
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Аннотация
Introduction. During a special military operation, unmanned aerial vehicles (UAVs) are actively used by the enemy to attack industrial and energy facilities of the Russian Federation. One of the most effective ways to protect objects from UAVs is the use of enclosing structures using trapping nets. They make it possible to prevent the UAV from contacting the enclosing structures of a building or structure and minimize the consequences of an explosive charge explosion. Research methods. Calculation methods based on the formulas of M.A. Sadovsky were used to determine the permissible distances from the UAV-trapping grids to the enclosing structures of the object. The deflection of the grids was determined by the calculation method by solving a partial differential equation describing the transverse vibrations of the membrane.
Objective: To determine the possibility of using mesh structures to prevent damage to industrial, energy and civil facilities by damaging explosive explosion factors carried by UAVs. Tasks. Selection and justification of calculation methods for assessing the degree of damage by an explosive charge to the protected object and the magnitude of the deflection of the grids during an attack of the UAV; calculation of the permissible distance from the trapping mesh structures to the enclosing structures of a building or structure; assessment of the deflection of the grids under the dynamic influence of the UAV. Results. Calculations performed within the framework of the study made it possible to determine the permissible distances from the trapping mesh structures to a building or structure with different explosive masses; the deflection values of the grids under the dynamic influence of UAVS on them. Conclusions. The calculations of the distance from the trapping mesh structures to the protected objects made it possible to identify the effectiveness of this method of ensuring security in the event of a UAV attack. The materials of grids and structures of supporting elements used in construction make it possible to implement physical (passive) protection against UAVS in practice.
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The high-tech and effective method of strengthening reinforced concrete structures with CFRP materials with preliminary modification of the cross-section shape

https://doi.org/10.58224/2618-7183-2024-7-6-7
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Аннотация
It is known that the effectiveness of reinforcement with CFRP composite materials of reinforced concrete structures of round or oval sections is significantly higher than rectangular or square ones due to the uneven distribution of internal limiting pressure in the latter. This study is devoted to the study of the effectiveness of a new method of strengthenet based on a preliminary change in the shape of reinforced concrete and concrete columns of square section. The sharp corners of the columns create a concentrating internal limiting stress in the CFRP composite cage, while the amplification system collapses prematurely, and the amplification efficiency is greatly reduced. To comprehensively solve this problem, the authors have manufactured, strengthened and tested a number of reinforced concrete columns with different variants of CFRP composite reinforcement. For the purity of the experiment, reference racks were also made, not reinforced, and reinforced with CFRP composite clips without rounding. All prototypes were made of the same materials, as well as strengthened and tested using the same techniques. The paper describes the features of traditional and modern methods of composite strengthenet of reinforced concrete columns, analyzes the main disadvantages of existing strengthenet methods and, based on this, presents a new strengthenet method that allows more efficient use of composite materials in the transverse direction. The new strengthenet method is described in detail, the main schemes and procedure for performing strengthenet work are presented. The final stage of the work is the main results of an experimental study, where the characteristics of reference samples were compared with similar structures strengthened in the transverse direction with CFRP composite materials. The experimental results show that the proposed amplification method is highly effective. For the best effect, it is proposed that the material used for rounding has higher strength and less deformability compared to concrete columns.
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Heat transfer from a cylindrical heater to a medium with variable thermophysical characteristics and heat source power

https://doi.org/10.58224/2618-7183-2024-7-6-8
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Аннотация
The formulation and solution of the problem of non-stationary thermal conductivity in a composite material with variable thermophysical characteristics are considered. Density, heat capacity, thermal conductivity, as well as the power of the heat source due to the hydration reactions of the binder components change during the concrete hardening process. The heat transfer problem is formulated for the general case when there are no calculation formulas for thermophysical transfer coefficients. The “microprocess method” was used to calculate the dynamics of the temperature field. According to this method, the space from the outer surface of the heater is modeled by a system of successively located “rings”. When moving from the previous “ring” to the next one, the charge in the transfer coefficients and the power of the volumetric heat source were taken into account. At the same time, the initial and boundary conditions were corrected. The boundary value problems are formulated in the form of a differential equation of non-stationary heat transfer with an arbitrary initial distribution of transfer potentials, Dirichlet boundary conditions, and a heat source in the form Po=f(Fo).The obtained solutions are analyzed for some particular cases. Prospects for further theoretical and experimental research are determined.
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Development of a method to identify the need for capital repairs and renovation of administrative buildings

https://doi.org/10.58224/2618-7183-2024-7-6-9
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Аннотация
Identification of needs for production resources during repairs, restoration and reconstruction strongly relies on administrative and engineering solutions. The scope of problems, addressed by these projects, encompasses limited production and non-production resources, as well as unpredictable external risks, or ambiguous initial information about construction facilities. Today all available decision-making principles, underlying the long-term planning of capital repairs and reconstruction of civil buildings, disregard a great number of production-related and administrative factors. Advanced design software and applications, developed on the basis of various mathematical principles, used to describe construction technologies and processes, facilitate decision making by specialists responsible for the implementation of such projects. In this case, principal factors include optimal labour costs and guaranteed quality. The article outlines basic decision-making principles underlying a program of capital repairs or reconstruction of civil buildings in operation. These principles are based on computing the potential of administrative and engineering solutions. Scientific research, conducted in the process of drafting this article, encompasses the analysis of various production-related factors characteristic of production processes, including capital repairs and reconstruction. These factors are represented as a system of linguistic data flow that specifies term sets and membership functions for each condition. Most significant factors are the technical condition of permanent buildings and structures, the attitude of consumers to the subject of the study, and its operation period starting upon completion of earlier repair or reconstruction, as well as the serviceability of internal and external engineering systems. As a result of scientific research, the authors developed and tested a new method used to identify the need for construction and installation work performed within the framework of capital repairs or renovation. The novel method includes specific requirements that apply to the scope of work and the sequence of its implementation.
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The impact of the visual design of public spaces In the Arabic city

https://doi.org/10.58224/2618-7183-2024-7-6-10
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Аннотация
A good design of public urban spaces considers all the visual and aesthetic determinants dedicated to its formation. In a design of public urban spaces in European cities, it is a studying perception of form in the townscape. In addition, most design focuses on the details of constituent elements to suit the overall consideration to aesthetic form. It has a lack of design study in the Arab cities, where all the considerations are not fully applied. The design neglects the study of the visual dimensions and the cultural identity of the Arab city. Therefore, this research is to fill the knowledge gaps and deficiencies about the formation of the urban spaces in Arab cities. The Methodology of this research is descriptive and analytic. It discusses the design determinants of visual and aesthetic composition of public spaces in the Arab cities. It is also a study on the determinants of visual reading of its components by analyzing their forms and their relationship with the surrounding elements (building masses, street furniture elements) and by using the space syntax assessment technique to identify the foundations and visual access to a graphic and aesthetic design reflecting the Arabic identity.
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