Ruslan Kudabayev

Given the high energy intensity of the cement grinding process, the development of new and effective intensifiers is a pressing issue. The aim of this work is to develop grinding intensifiers from secondary raw materials produced during carpet manufacturing and gas processing wastes, and to study their effect on the structure and strength of modified cement stone. Methods of physicochemical analysis of raw materials and the obtained grinding intensifier, as well as standard methods for testing cement stone were used in the work. The possibility of obtaining an effective intensifier through the interaction of HYPAN (Hydrolyzed polyacrylonitrile) and diethanolamine was established. The optimal dosage of the grinding intensifier was determined to be 0.1%, which allows increasing the grade strength of modified cement stone by 31.2% and reducing the water consumption by 11%, which is explained by hydration due to the additional effect of reducing the electrokinetic potential between cement particles and increasing the fineness of cement particle grinding. Physicochemical analysis methods established that there is practically no free water in the modified cement stone sample and that the formation of the structure in the cement stone was achieved to a much greater extent. It has been established that, over time, the amount of C-S-H hydration products and calcium sulfoaluminate in the cement matrix of modified cement stone increases, which leads to an increase in the strength of the cement.

This article presents the results of a study exploring the potential use of gas processing waste as a raw material for synthesizing cement grinding intensifiers. Effective raw materials for synthesizing grinding intensifiers were identified: methyldiethanolamine (a gas processing waste) and hydrolyzed polyacrylonitrile (HIPAN) obtained from recycled nitrofiber. The use of alkanolamines as a raw material for synthesizing grinding intensifiers was substantiated. Physicochemical methods demonstrated the effectiveness of the methyldiethanolamine purification method. Optimal conditions for synthesizing grinding intensifiers were determined. Physicochemical analysis of the resulting grinding intensifiers revealed that all compositions exhibit a very strong C=O (amide) peak at 3300 cm⁻¹, a broad N-H elongation peak at 1236 cm⁻¹, and a strong C-N (amide III) elongation, which together confirm the clear presence of the amide group (-CONH-) required for grinding intensifiers. It was determined that the cumulative distribution curve of the product obtained with the addition of 0.25% of the synthesized grinding intensifiers G+M and G+T shifts toward finer grinding due to the unique combination of active components (alkanolamines, HIPAN), which allows them to act synergistically. HIPAN provides increased efficiency due to its high basicity, which reduces the electrostatic attraction between particles, leading to finer grinding and increased productivity.

This paper presents data on the synthesis of cement grinding intensifiers produced from oil and gas processing wastes, namely secondary alkanolamines. The results of physicochemical characterization of the raw materials are reported, including the optimal purification conditions for the wastes and the synthesis parameters of the grinding intensifiers, as well as the physicochemical properties of the obtained products. It was found that the optimal conditions for producing the grinding intensifier involve conducting the reaction at 45°C for 6 hours with a 1:9 component ratio. The effects of the synthesized intensifiers on the cement clinker grinding process were investigated, including their influence on particle size distribution and the mineralogical composition of modified cements. The particles of the modified cement were shown to exhibit a predominantly spherical morphology; the maximum laser diffraction value reached 13.5%, the intensity was 88%, and the particle size was mainly around 2 μm (more than 53.5%), while the fraction of particles within the 100-200 μm range was 4.87%. X-ray diffraction and differential thermal analysis revealed that hydration of the modified cement is accompanied by a slight decrease in the diffraction intensity of calcium silicate phases (C2S and C3S), whereas an increase in the diffraction intensity of calcium hydroxide (Ca(OH)2) was observed. This indicates the formation of calcium hydroxide and calcium silicate hydrate (C-S-H) during cement hydration. The diffraction peaks of these phases were detected within the ranges of 30-33° 2θ and 40-45° 2θ. In addition, the presence of aluminate (C3A) and ferrite (C4AF) phases within 40-45° 2θ corresponds to calcium carbonate (CaCO3) observed in low-intensity regions between 29.4° 2θ and 48.5° 2θ, which is associated with CO2 absorption from the atmosphere. These changes reflect phase transformations during hydration and the formation of phases that are critical for strength development. The optimal dosage of the grinding intensifier in the cement composition was determined to be 0.02 wt.% (based on dry residue).

A theoretical study of the porosity influence on external building enclosures was conducted using ANSYS and Blender software packages. A foam concrete block with porosity up to 15% was investigated as an example of an external enclosure design. Pore content was analyzed from 1.5% to 15%. The percentage analysis of pores revealed that the thermal flow value shows a significant difference at 15% porosity, reaching up to 11.3 W/m², while porosity up to 10% indicates 12.2 W/m². Furthermore, with a difference of 1.31 times, the thermal flow value reaches 15 W/m² at 1.5% porosity. Additionally, the increase in porosity positively affects the effective thermal conductivity of the foam concrete structure and its thermal resistance. The obtained research results can be used to eliminate costly experiments and provide an accurate assessment of the thermal conductivity coefficient for external enclosures made of foam concrete blocks, taking porosity into account during residential building design

This article considers the possibility of using technogenic waste from the mechanical processing of Sastobe carbonate rocks as coarse and fine aggregates in the production of heavy concrete. X-ray diffractometric analysis CaCO3 d = (3.849-3.14-2.49-2.277-2.088-1.912-1.869 A0) and the endothermic peak in the temperature interval of 800-850°C in the differential-thermal analysis curve technogenic residues formed during mechanical processing of Sastobe carbonate rocks showed that it mainly consists of calcium carbonate. Studies have shown that fine and coarse aggregates based on carbonate rocks have a rough surface, which increases their specific surface area and ensures a strong bond with the cement stone. At the same time, technogenic waste contains 2-3% powder fraction up to 0.16 mm, this fraction serves as an active mineral mixture. As a result of research, the use of these wastes as fillers can reduce the consumption of traditional crushed stone and sand by 50% without reducing the physical and mechanical properties of concrete, replacing 50% of traditional fillers with technogenic fillers based on carbonate rocks, increasing the density of concrete (2490kg/m3), reducing its water absorption (0.66 %), strength (49.8 MPa) and frost resistance (F400) indicators made it possible to obtain concrete that is the same as the control sample and to reduce its cost without reducing the physical and mechanical properties of concrete and to improve the environmental conditions of the region.

Shrinkage has a great influence on the operation of the heat accumulator design, therefore, when developing structures with heat storage materials, it becomes necessary to determine the pressure in a non-expanding (closed) storage structure from the compressibility coefficient of the material, which can be considered an operational characteristic of the material. The article presents data on shrinkage (and expansion) of the investigated heat-storage materials and a method for estimating the pressure that can develop in sealed battery structures completely filled with heat-storage materials in a crystalline state. It has been determined that, for the normal operation of structures with heat storage material, it is necessary either to create conditions in it that allow avoiding an increase in pressure, or when filling the structures of the accumulator of heat storage material, take into account the shrinkage of the material, or use heat storage material with melting temperatures lower than is required when working at atmospheric pressure. pressure.

This paper proposes a mathematical model and a procedure for calculating the thermal state of the enclosing structure of the building, which includes an energy-active panel that accumulates solar radiation due to the phase transition of the heat-accumulating material. The mathematical model is based on a two-dimensional non-stationary nonlinear equation of thermal conductivity, which describes the process of heat transfer in the bearing layer of the enclosing structure and the energy-active panel. The model also includes equations describing radiant heat transfer between opaque and translucent bodies. To correctly describe solar insolation, the ASHRAE 2009 model was used in conjunction with the daily change in the position of the Sun in the sky. To solve the system of equations that make up the mathematical model, an iterative procedure has been developed, which involves alternating solution at each time step of the two-dimensional equation of thermal conductivity and a set of algebraic equations of convective and radiant heat transfer. The study’s result established that the amount of accumulated energy in the heat-accumulating material of the phase transition during daylight hours increases significantly, from 15 to 35 %. At night, the surface temperature of the heat-accumulating element in structures using a material with a phase transition is greater than in the case of heat accumulation only in the bearing layer. As a result, it is possible to select from 70 to 120 % more accumulated heat while the presence of high-thermal partitions in a heat-accumulating material with a phase transition contributes to an increase in accumulated heat and usable heat

Development of the engineering procedure for the thermotechnical calculation of a building envelope with air chambers and a heat­reflecting coating