ANALYSIS OF THE THERMAL INSULATION PROPERTIES OFEXPANDED CLAY CONCRETE WITH MINERAL ADDITIVES

ABSTRACT

This article examines the thermal insulation properties of expanded clay concrete with added mineral admixtures. The purpose of the study is to improve the thermophysical indicators of expanded clay concrete in the production of energy-efficient construction materials. As mineral additives, peroxynite and zola were used, with their amounts in the mixture tested at different percentages. Key parameters such as thermal conductivity coefficient, density, and water absorption were determined and compared with the indicators of ordinary expanded clay concrete. The results showed that the addition of mineral admixtures reduced thermal conductivity by up to 10–20%, while stabilizing the porosity of the concrete.

АННОТАЦИЯ

В данной статье исследованы теплоизоляционные свойства керамзитобетона с добавлением минеральных наполнителей. Цель исследования – улучшение термофизических показателей керамзитобетона при производстве энергоэффективных строительных материалов. В качестве минеральных добавок использовались пероксинит и зола, которые вводились в состав смеси в различных процентных соотношениях. Были определены такие основные параметры, как коэффициент теплопроводности, плотность и водопоглощение, результаты которых сопоставлены с показателями обычного керамзитобетона. Результаты показали, что введение минеральных добавок позволило снизить теплопроводность на 10–20%, при этом пористость бетона стабилизировалась.

Keywords: Expanded clay filler, mineral additive, peroxynite, fly ash, expanded clay concrete, thermal conductivity, density, energy efficiency, thermal insulation.

Ключевые слова: Керамзитовый наполнитель, минеральная добавка, пероксинит, зола, керамзитобетон, теплопроводность, плотность, энергоэффективность, теплоизоляция.

Introduction
In recent years, ensuring energy efficiency and environmental safety in the construction sector has remained one of the urgent issues. In order to reduce heat loss in buildings and decrease operating costs, it is necessary to develop construction materials with high thermal insulation properties. From this point of view, one of the materials with a light and porous structure – expanded clay concrete – is widely used. By adding various mineral additives to the composition, it is possible to further improve its physical-mechanical and thermophysical properties.

In particular, the use of industrial waste and local raw materials today has a twofold significance: on the one hand, it reduces environmental problems, and on the other hand, it ensures economic efficiency. In this study, peroxynite and fly ash (fly-ash cinder) mineral additives were selected.

Literature Review

From international experience it is known that Turkish scientists, having studied mixtures of expanded clay and fly ash, noted that thermal conductivity decreased by 10–15%. In China, however, fly ash and other mineral additives are widely used, light geopolymer concretes have been developed, and their thermophysical properties have been thoroughly analyzed. In Poland and other European countries, by testing lightweight concretes based on perlite and vermiculite, it was possible to reduce thermal conductivity down to 0.20–0.25 W/(m·K). In India, meanwhile, research has been carried out on producing concrete based on lightweight aggregates prepared from fly ash and industrial waste, and on increasing its thermal efficiency.

Research Methodology

The research was carried out using a scientific-experimental method. As mineral additives, peroxynite and fly ash were added in certain percentages to the composition of expanded clay concrete, and their effect on thermal insulation and physical-mechanical properties was studied.

For conducting the research, in order to reduce the cement consumption added to the composition of expanded clay concrete, samples were prepared by adding 0%, 10%, 15%, 20%, and 25% peroxynite and fly ash. The sample sizes were prepared in accordance with the requirements of GOST 7076-99 at 30×30×5 cm, and thermal conductivity and resistance were determined on the XND-2-3030C device.

Experimental Results

The thermal conductivity and thermal resistance of the samples with peroxynite added to expanded clay concrete are presented in Table 1. As shown, the density of the samples increases as the peroxynite content rises, while the thermal conductivity coefficient fluctuates slightly within the range of 0.2462–0.2655 W/(m·K). The best thermal resistance value (0.2030 m²·K/W) was observed at 15% peroxynite content.

Table 1.

Thermal conductivity and thermal resistance of samples with peroxynite added

The results for the samples with fly ash added are given in Table 2. The data demonstrate that, depending on the proportion of fly ash, both density and thermal conductivity vary. A slight reduction in thermal conductivity (down to 0.2458 W/(m·K)) was observed at 25% fly ash, accompanied by the highest thermal resistance value (0.2033 m²·K/W).

Table 2.

Thermal conductivity and thermal resistance of samples with fly ash added

Main Observations:

1. Samples with Peroxynite Added: With the addition of peroxynite, the density of the samples gradually increased (from 4330 kg/m³ to 5012 kg/m³). The thermal conductivity coefficient (λ) slightly rose from 0.2471 W/(m·K) to 0.2655 W/(m·K). Meanwhile, the thermal resistance (R) decreased from 0.2021 m²·K/W to 0.1882 m²·K/W. This indicates that although the addition of peroxynite increased the mechanical density of the concrete, its thermal insulation efficiency relatively declined.

Figure 1. Prepared standard samples

2. Samples with Fly Ash Added: The density increased from 0.964 g/cm³ to 1.092 g/cm³ (here the units are written as g/cm³, i.e., approximately 964–1092 kg/m³). The thermal conductivity coefficient varied: it rose from 0.2474 W/(m·K) (0% additive) to 0.2833 W/(m·K) (15% additive), and then decreased to 0.2458 W/(m·K) at 25%. The thermal resistance (R) remained within the range of 0.2015–0.2033 m²·K/W, in some cases showing slight improvement. Thus, the addition of fly ash, especially at 20–25% ratios, contributed to enhancing the thermal insulation properties.

Figure 2. Peroksinit va uchuvchan kul miqdorini 20 % qo‘shilgan namunalar

Conclusion.

In conclusion, it can be stated that according to the results of the experiments carried out, the addition of waste materials (slag, microsilica, and peroxynite) to the cement mass had a significant effect on the physical and mechanical properties of expanded clay concrete. The highest results were recorded when 15–20% additives were introduced. Thus, the rational use of waste materials not only contributes to environmental protection but also serves to produce energy-efficient, durable, and economically effective construction materials.

References:

1. ГОСТ 7076-99. Материалы теплоизоляционные. Методы определения теплопроводности и термического сопротивления.–М.: Стандартинформ, 2000.
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