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Ключевые слова: thermal conductivity

Eco-Friendly Foam Concrete with Improved Physical and Mechanical Properties, Modified with Fly Ash and Reinforced with Coconut Fibers

https://doi.org/10.58224/2618-7183-2025-8-1-1
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Аннотация
The development of new types of environmentally friendly and cost-effective building materials is currently a relevant topic and is actively developing throughout the world. In modern construction materials science, the most popular direction is the development of new concrete compositions using waste of various origins. The objective of this study is to develop new compositions of foam concrete using local waste from the fuel and energy complex and plant natural fibers. To determine the optimal amount of the modifying additive fly ash (FA), 7 experimental concrete compositions with different percentages of cement replacement by FA were made. The content was established as optimal. Foam concrete with 15% FA has the lowest density of 1075 kg/m3 and a minimum thermal conductivity coefficient of 0.248 W/m × °C, as well as increases in compressive and bending strength of 23.3% and 21.7%, respectively. The effect of coconut fiber (CF) was assessed on the composition of foam concrete modified with the optimal amount of FA 15%. The optimal dosage of CF was 0.6%. As a result of FA modification and CF dispersed reinforcement, a complex effect was obtained. The increase in compressive and bending strength was 30.14% and 72.83%, respectively, compared to conventional foam concrete. The density and thermal conductivity coefficient decreased by 9.8% and 8.34%, respectively. The results obtained during the experimental studies prove the effectiveness of the proposed formulation solutions and allow obtaining an energy-efficient foam concrete composite with improved characteristics.
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Analysis of thermal efficiency of external fencing made of innovative ceramic blocks

https://doi.org/10.58224/2618-7183-2024-7-3-1
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Аннотация
The paper presents a comprehensive theoretical study of the external fencing structure made of innovative Porortherm 38 ceramic blocks in comparison with traditional structures made of solid ceramic brick, hollow ceramic brick and gas block. The study was conducted in the climatic conditions of Shymkent city, South Kazakhstan. The middle temperature values of the frostiest 5 days with a provision of 0,92 were adopted as the external temperature. The results of the study of the actual resistance (Rf) of the structures under study showed that all adopted structures meet the condition Rf˃Rreq, while the actual resistance of the new structure is 1.3 times more efficient than traditional ones. The analysis of temperature fields showed that the new structure is 2% more efficient than traditional ones. Moreover, no additional insulation costs are required. The obtained results were also confirmed by computer modeling in the ELCUT software package. The results of calculating the humidity regime showed that a condensation area appears in almost all the structures under consideration. The results of calculating the amount of moisture evaporated from the multicoat structure of the external fencing during the torrefaction period showed that all the accumulated moisture will evaporate during the specified period, the calculation of the condition of inadmissibility of moisture accumulation in the structures of external fencings for an annual period and for the period of moisture accumulation showed that all the considered structures meet the requirement . The results of calculating the air regime of multicoat structures of external fencings also showed that all structures including the new one meet the condition . The result of calculating the value of thermal inertia (D) in the proposed structure is up to three times more efficient than traditional structures, which applies to structures with high inertia (7˂D). The obtained results of the study indicate that the new proposal of a structure made of ceramics is cost-effective, innovative blocks can be proposed as a supplement to the register of materials of existing standards.
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Analysis of the effect of porosity on thermal conductivity with consideration of the internal structure of arbolite

https://doi.org/10.58224/2618-7183-2024-7-3-4
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Аннотация
A theoretical study of the effect of porosity and internal structure of the exterior envelope in the ANSYS and BLENDER software systems has been carried out in the paper. As an example of exterior enclosure structure, an arbolite block with porosity up to 20% and fiber structure in the direction along and across the heat flux, as well as randomly and at an angle of 45° was studied. As a result of the study, it was found that the significant effect of the heat flux dependence on the porosity of the material is the porosity of the block over 10%, which reached up to 5.92%, and with porosity up to 5% showed a difference of 1.3%. At the same time, the fiber structure also showed a significant difference from 8.16% to 15.33% depending on the fiber direction. At the same time, the analysis of the effect of porosity on the thermal conductive value also showed a difference of up to 15.33% for the same value of heat flux. At the same time, the influence of fiber structure shows an additional difference of up to 5.9%. The results of the study showed that the most thermally conductive arbolite blocks are, those in which the direction of fibers are located along (along the X axis) and at 45 ° relative to the structure of fibers across (along the Y axis) and random, the difference of which was up to 1.6%. The obtained results of this study, further excluding the costly experiments to determine the coefficient of thermal conductivity can be used to accurately estimate the coefficient of thermal conductivity of external envelopes made of arbolite blocks, considering porosity and fiber structure in the design of residential buildings.
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