SYNTHESIS OF FOAM GLASS GRANULES BASED ON LOCAL RAW MATERIALS UNDER THE CONDITIONS OF UZBEKISTAN

ABSTRACT

This study is devoted to the synthesis of foam glass granules based on local raw materials under the conditions of Uzbekistan. The research focuses on the use of secondary glass waste, enriched kaolin, sodium silicate, caustic soda, and glauconite as primary components for producing lightweight and energy-efficient insulating materials. The technological process includes crushing, mixing, granulation, drying, and high-temperature foaming, resulting in a porous structure with enhanced thermal insulation properties. Experimental results show that the obtained foam glass granules have low density (about 780 g/dm³), high porosity (65–70%), low thermal conductivity (0.10–0.12 W/m·K), and high thermal stability (up to 1000 °C). Comparative analysis demonstrates that the properties of locally produced materials are comparable to or exceed those of foreign analogues. The developed material is environmentally friendly, economically efficient, and can serve as an import-substituting product for construction and industrial insulation applications.

АННОТАЦИЯ

Данное исследование посвящено синтезу пеностекольных гранул на основе местного сырья в условиях Узбекистана. В работе рассматривается использование вторичного стекла, обогащённого каолина, жидкого стекла, каустической соды и глауконита в качестве основных компонентов для получения лёгких и энергоэффективных теплоизоляционных материалов. Технологический процесс включает стадии измельчения, смешивания, гранулирования, сушки и высокотемпературного вспенивания, в результате чего формируется пористая структура с высокими теплоизоляционными свойствами. Экспериментальные результаты показали, что полученные гранулы обладают низкой плотностью (около 780 г/дм³), высокой пористостью (65–70%), низкой теплопроводностью (0,10–0,12 Вт/м·К) и высокой термической устойчивостью  (до 1000 °C). Сравнительный анализ подтвердил, что свойства местных материалов соответствуют или превосходят зарубежные аналоги. Разработанный материал является экологически безопасным, экономически эффективным и может быть использован в качестве импортозамещающего продукта в строительстве и промышленной теплоизоляции.

Keywords: foam glass, granules, local raw materials, waste glass, thermal insulation, porous structure, energy efficiency, synthesis, kaolin, import substitution.

Ключевые слова: пеностекло, гранулы, местное сырье, вторичное стекло, теплоизоляция, пористая структура, энергоэффективность, синтез, каолин, импортозамещение.

Introduction

Today, one of the urgent tasks in the construction materials industry is the creation of energy-efficient, environmentally friendly, and high-performance materials. One such material is foam glass granules, which are widely used as a lightweight, heat-retaining, and durable material. Foam glass is primarily produced through the recycling of glass waste, which allows for waste reduction and efficient use of resources [1].

The increasing demand for construction materials in Uzbekistan, as well as the necessity to utilize local raw materials, requires the development of production technologies for foam glass granules. Our republic possesses raw material resources such as glass waste, quartz sand, dolomite, and limestone, which are essential components for the synthesis of foam glass.

The synthesis of foam glass granules is typically carried out by mixing glass powder with gas-forming agents and foaming the mixture at high temperatures. During this process, a porous structure is formed, resulting in a product with superior thermal insulation properties. Scientific research indicates that the raw material composition and technological parameters used in the production process directly influence the physical and mechanical properties of the foam glass [2].

In recent years, scientific research has been conducted on the synthesis of various composite materials based on local raw materials. For instance, studies on the synthesis of materials based on liquid glass and silica demonstrate the possibility of obtaining high-temperature resistant and durable materials [3-4].

At the same time, due to the growing demand for lightweight and energy-efficient materials in the modern construction industry, the local production of foam glass granules is of significant economic importance. This serves not only to create an import-substituting product but also to mitigate environmental problems through waste recycling.

In view of the above, the topic 'Synthesis of foam glass granules based on local raw materials under the conditions of Uzbekistan' is of high scientific and practical relevance.

Methods

Gas-releasing components responsible for the formation of a foamed structure, a matrix based on glass melt, and a specialized thermal treatment technology play an important role in the composition of foam glass granules. Under the influence of high temperatures, gas formation occurs, resulting in the development of a porous structure within the material. This structure ensures the lightweight nature of the granules and provides their thermal insulation properties.

The main advantages of these granules include low density and lightweight characteristics, high thermal and frost resistance performance, chemical stability, resistance to dust formation, and environmental safety. Due to the absence of harmful substances in their composition, the material is considered environmentally friendly. Foam glass granules meet modern global construction and industrial standards and are regarded as an innovative material with high energy efficiency.

Foam Glass Granules Based on Local Raw Materials: Raw Material Base and Availability

The following main raw materials are used in the production of foam glass granules. These components are economically feasible for the local industry and are available based on analytical assessments. They play a significant role in forming the structural and thermo-technical properties of foam glass materials.

1. Secondary glass — This raw material is obtained from recyclable glass waste and forms the primary silicate matrix of foam glass granules. Under the conditions of Uzbekistan, the annual amount of glass waste is approximately 408,000 tons, which provides a sufficient raw material base for recycling and foam glass production. Glass is an amorphous material that melts at high temperatures and serves as the main silicate source for creating a porous structure.
2. Enriched kaolin — An aluminosilicate mineral used as an additional raw material to improve the mechanical strength and thermal stability of foam glass granules. Kaolin reserves in Uzbekistan amount to millions of tons, and the possibility of beneficiation and industrial-scale production has been confirmed. When enriched kaolin is combined with impregnating agents and gas-forming substances, it helps control the porous structure and increases the thermal stability of the granules.
3. Liquid glass / Na₂SiO₃ (sodium silicate) — This reagent performs dissolving and foaming functions in foam glass technology. The addition of sodium silicate to raw materials facilitates the melting of glass particles and promotes bubble formation necessary for creating a porous structure. Under the conditions of Uzbekistan, liquid glass-forming substances such as sodium silicate are either imported or prepared through the chemical industry.
4. Caustic soda, NaOH (sodium hydroxide) — A substance that accelerates bubble formation and enhances the reactivity of raw materials during the synthesis of foam glass granules. It typically releases gas when interacting with acidic and slag-containing materials, thereby strengthening the porous structure. The supply of reagents such as caustic soda is available through Uzbekistan’s domestic market and chemical industry.
5. Additional minerals: Glauconite — An iron-potassium silicate mineral that can be used as an additional component or secondary phase-forming material in foam glass or other ceramic materials. Glauconite reserves are available in Uzbekistan, particularly in deposits such as Changi, Krantaus, Kofrun, and Tagarasay, and are considered promising industrial raw materials.

This mineral may provide an additional phase effect in foam glass granule production, enhance thermal stability, and enrich the glass matrix through chemical modification.

Technological Scheme for Obtaining Foam Glass Granules

Technological Scheme (Sequence)

Raw materials → Crushing → Mixing → Granulation → Foaming in furnace → Cooling → Classification → Finished product

Table 1.

Main Technical Characteristics

Discussion

Based on the experimental results, a 1 kg sample of granulated foam glass was obtained under laboratory conditions, and its physicochemical properties were evaluated according to industry guidelines and technical specifications. Secondary glass, enriched kaolin, liquid glass (Na₂SiO₃), caustic soda (NaOH), glauconite and water were used as the main raw materials in the production process.

Initially, the raw materials were mixed according to measured proportions and converted into a homogeneous paste. The mixture was then formed into granules with diameters ranging from 0.6 to 12 mm. The prepared granules were dried in a drying cabinet at a temperature of 110–115 °C to remove excess moisture. After drying, the granules were subjected to thermal treatment (foaming) at temperatures of 800–1000 °C, during which gas bubbles formed by caustic soda created a closed porous structure.

Table 2.

Physicochemical Properties of Granulated Foam Glass Sample

The density, porosity, thermal conductivity, abrasion resistance, and other physicochemical properties of the prepared granules were determined through laboratory testing. The results confirmed compliance with technical specifications and demonstrated that the material possesses high strength, stability, and suitability for effective use in construction and industrial applications.

Figure 1. Granulated foam glass sample obtained during laboratory testing

Table 3.

Comparison of Physicochemical Properties of Local and Foreign Foam Glass Granules

As seen from the analysis of Table 3, foam glass granules produced in Uzbekistan demonstrate physicochemical properties comparable to or superior to foreign analogues. Local granules with diameters ranging from 0.6–12 mm provide high insulation efficiency due to their density (780 g/dm³) and porosity (65–70%).

Additionally, firing losses are minimal (3–5%), while thermal conductivity (0.10–0.12 W/m·K) and abrasion resistance (70%) are comparable to or better than foreign analogues. Chemical and thermal stability indicators also comply with technical specifications, ensuring stability in the temperature range of 800–1000 °C.

These results indicate that foam glass granules produced from local raw materials (secondary glass, enriched kaolin, caustic soda, and glauconite) can be effectively used as high-quality insulating materials under local economic conditions. Furthermore, they contribute to reducing dependence on imported materials and support the development of domestic production.

Conclusions

Based on the conducted laboratory experiments, it was confirmed that granulated foam glass samples obtained from local raw materials — secondary glass, enriched kaolin, and glauconite mineral — demonstrate physicochemical properties comparable to foreign analogues, particularly low density (780 g/dm³), high porosity (65–70%), and thermal stability (≥ 1000 °C).

This innovative material fully meets modern standards of energy efficiency and fire safety and is recommended for use as an environmentally friendly, economically beneficial, and import-substituting insulating material in construction and industrial applications.

References:

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