Русский Русский

Bektursunova A.K.

Doctor of Philosophy (PhD), Senior Lecturer, M. Auezov South Kazakhstan University, Department of Technology and Design of Textile Materials

Investigation of the synthesis of a grinding intensifier from secondary raw materials and its influence on the microstructural development of cement stone

https://doi.org/10.58224/2618-7183-2026-9-1-9
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Аннотация
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).
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Analysis of the influence of temperature loads on the stress-strain state of a pre-stressed cylindrical shell

https://doi.org/10.58224/2618-7183-2025-8-4-5
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Аннотация
The progressiveness of the idea of prestressing consists, on the one hand, in the possibility to regulate the stress state in accordance with the peculiarity of the structure operation, and on the other hand, in the expansion of the economically advantageous range of application of high- and high-strength steels. Such strengthening is also relevant for cylindrical shells, the throughput or storage volumes of which are directly proportional to the operating pressure. The most effective type of prestressing in this case is considered to be winding on the shell body at an angle to the longitudinal axis or in the annular direction without tilting the high-strength profile. In this regard, in this work, a theoretical study of the influence of temperature loads on the stress state of the combined shell was carried out. As a result of the study, an analytical evaluation method was developed that takes into account the mechanical, geometric values of the wall and wrapping material, as well as the parameters of the prestress, taking into account temperature effects. The developed method also found that the established ring stresses in the shell wall increase with an increase in the temperature gradient, and the stresses in the wrapping decrease. At a temperature gradient of 70°C, the ring stresses increased by 1.8 times, and the stresses in the wrapping decreased by 1.3 times. At the same time, the change in operating temperature has a noticeable effect on the distribution of stresses in the wall of the shell and wrapping. Thus, calculations of a main pipeline pre-stressed with steel wire showed that at a temperature gradient of ΔΤ=30°C, the achieved level of prestressing can decrease by 10-12% compared to the initial one, and at ΔΤ=50°C, the pre-stressed wrapping does not affect the stress state of the shell wall. The obtained results of the study indicate that, taking into account the temperature loads on the structure, it is possible to adopt the necessary design parameters for further design of steel shells even more accurately.
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