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ARTICLE INFO
STUDY OF HEAT DISSIPATION PROPERTIES OF CEMENT STONE IN FINE-GRAINED CONCRETE Raximov Shavkat Turdimurotovich
(Associate Professor of Tashkent University of Architecture and Civil Engineering, PhD) Xudoynazarova Qunduz Djumanazarovna, Mustafaqulov Javohir Rahmonqul o'g'li
(Supporting doctoral students of Tashkent University of Architecture
and Civil Engineering) e-mail.: [email protected] https://doi.org/10.5281/zenodo.14833012
ABSTRACT
This article describes the thermal insulation property of cement stone in fine-grained concrete. The water demand of cement stones based on fly-ash and chemical additives is small, therefore, according to the law and depending on the nature of additives, the heat release from cement stone is reduced.
Received: 30th January 2025 Accepted: 06th February 2025 Online: 07th February 2025
KEYWORDS Cement stone, fine-grained concrete, heat dissipation, portland cement, properties, fly-ash, marble waste, water-cement ratio.
The demand for energy resources in the world and the continuous growth of their cost require the introduction of energy-efficient materials and technologies, especially in construction. In this regard, it is important to increase the production volume of concrete used for the construction of buildings and structures in developed countries, including countries such as the USA, Germany, Japan, China, and Russia, to use industrial waste in production, to optimize the composition and properties of fine-grained concrete, to reduce their cost and to increase their efficiency. is gaining importance [1].
The heat release process that occurs during the hardening process of binders in finegrained concrete is of great importance in large-scale concreting works. The heat release properties of cement stone depend primarily on its mineralogical composition, the duration of the hydration process, the softness of the aggregate, the amount of water added for mixing, and the ambient temperature.
The heat release properties of cement stone in fine-grained concrete during the hardening process are characteristic not only of cement, but also of the prepared concrete mixture, and depend on a number of factors: cement consumption, water-cement ratio, concrete mix mobility, hardening temperature, and other factors. The results of research conducted at the Leningrad Polytechnic Institute [1] at the Department of Building Materials show that the heat release from 1 m3 of concrete (cal/g) is linearly dependent on the cement consumption and the mobility of the mixture. Compared to Portland cement-based mixtures with the same mobility, concrete mixtures based on fly ash and plasticizer chemical additives have a lower water requirement, therefore, according to the law and depending on the nature of the additives, the heat release from the mixture decreases. This is also confirmed by the results of research conducted by V.V. Stolnikov on the heat release in Portland cement and fly ash-based concrete
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Ws,
Compositions t/r The content of binders, by mass, % Mixture composition, by mass (binder-marble processing waste) Water/ cement
Portland cement Fly ash MEGAPLAST SC-7 PC-08 (in liquid form)
1 100 - - 1:2 0,39
2 85 15 2 1:2 0,40
3 80 20 2 1:2 0,40
Table 2 (see Figure 1) shows the results of heat release during hydration of Portland cement and cement-ash-additive based binders.
It can be seen that the addition of fly ash to Portland cement used for fine-grained concrete reduced heat release. Increasing the amount of fly ash decreased the heat release index. The hydraulic activity of fly ash-based portland cement has a significant effect on its heat release index [4].
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Figure 1. A sheet of experimental work
In experimental studies, when 20% of Portland cement was replaced with fly ash, the heat release was significantly reduced. However, the hydraulic activity of fly ash did not significantly affect the heat release parameters of Portland cement at a 5-day period. This effect became more noticeable at later stages of the mixture's hardening.
Table 2
During the period of hydration of the binders heat dissipation indicators
Duration of test work, hours 1 gram (cal/g) of binder for compositions, heat release rates of hydration for a given fraction of time
1 2 3
0 - - -
5 36 31 29
15 38 35 31
24 41 38 36
48 52 46 43
72 62 52 48
96 71 59 53
120 75 63 58
144 79 66 61
168 83 70 62
n the research wor k, when the concentration of Ca(OH)2 reached a certain vali
active interaction of fly ash with it occurred, which resulted in the activation of the ash. These particles interacted primarily with Ca(OH)2, which is released during the hydration of clinker
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Ws,
References:
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