CC BY
4NEW HEAT STORAGE COMPOSITE MATERIALS FOR ENERGY EFFICIENT
BUILDINGS
Hamidov Adhamjon Inomjonovich Professor of Namangan Engineering Construction Institute E-mail: adxamjon! 954@gmail. com. tel:+998902148822
Abstract. Development of new heat-retaining gypsum composite materials for energy efficiency of buildings and research of their physical and technical properties
Methods. It was conducted in the Laboratory of Construction Materials and Products of the Namangan Institute of Engineering and Construction. In the experiment, crushed travertine waste from "Galaba" LLC in Chust district of Namangan region, crushed marble waste from "Zoirjon Fayz" LLC located in the economic zone of Uchkoprik district of Fergana region were used as test objects. The physical and mechanical properties of the obtained compositions were determined by testing sample sticks prepared according to the requirements of GOST 23789-79.
Results. According to the obtained results, the ratio of water-gypsum is from 0.36 to 0.375, the amount of waste powder is from 6 to 10% in relation to the mass of gypsum. Test results showed that the compressive strength limit of gypsum stone is 19.20 MPa when the amount of marble waste is 10%, and 18.5 MPa for travertine.
Conclusion. Based on the analysis of the obtained results, it can be concluded that the use of industrial waste - travertine in the development of new heat-retaining gypsum composite materials for ensuring the energy efficiency of buildings is effective from an economic and ecological point of view.
Key words. Energy efficiency, heat preservation, industrial waste, gypsum composite materials.
Introduction.
Resolution PQ-4335 of the President of the Republic of Uzbekistan dated May 23, 2019 "On additional measures for the rapid development of the construction materials industry" provides for sustainable growth in the production and export of competitive products in our Republic, as well as modernization of enterprises, technical and technological tasks of systematic work on deepening the structural changes in the construction materials industry aimed at renewal have been defined [1]. Also, the Resolution stipulates the development of proposals for the organization of the production of new types of energy-efficient and ecologically safe construction materials, the introduction of innovations and international standards to the production of construction materials. According to the decision, a loan of 14 million dollars is allocated for the production of 4.4 million square meters of artificial decorative tiles in Andijan, Jizzakh, Navoi, Syrdarya and Tashkent regions. The development of new types of innovative building materials is shown. The role of heat-retaining materials in ensuring the energy efficiency of buildings is incomparable. The use of heat-retaining materials reduces the thickness and weight of wall and fence constructions, and the consumption of basic building materials (cement, metal, brick) is saved. According to the analysis, as a result of the use of heat-retaining materials in the fence structures of panel and frame-panel buildings, compared to buildings without non-heat-retaining materials, the consumption of steel is reduced by 1.5-3 times, cement by 3-4 times, 1 t of mineral wool replaces 7.5 thousand bricks [2].
Reducing the weight of structures is especially relevant in seismic regions, as seismic loads due to the weight of buildings are reduced.When choosing effective heat-retaining materials, attention is paid to their heat-retaining properties, environmental safety, price, production volume in our country, technological features, duration of operation and other factors.
The conducted analyzes show that in the construction of energy-efficient buildings, a comprehensive approach to the selection of effective heat-retaining materials and the use of the
EHM program are recommended.
Their use has economic, social and ecological importance. Therefore, it is very important to research new effective thermal insulation materials, especially materials based on local materials and industrial waste, to ensure the energy efficiency of buildings.
Problem. Uzbekistan has a large reserve of gypsum stone (according to the Decision PQ-4335, 1.8 million tons of gypsum stone is set to be mined in Uzbekistan in 2025), the work of Uzbek scientists in the field of gypsum binders is recognized in foreign countries. Nevertheless, the production and application of gypsum binders and materials based on them is not enough. At the industrial level, mainly low-grade gypsum and a small amount for special purposes - high-strength gypsum and gypsum-cement-putsosol binder are produced. The republic's market of building materials is mainly occupied by expensive gypsum products produced abroad. Therefore, the issue of production of artificial facing plates from competitive composite materials using waste on the basis of low-grade gypsum is very urgent. n order to reduce the consumption of gypsum in production conditions, artificial fillers - slag, perlite, vermiculite, aglyporite, expanded polystyrene, etc. is used. The use of industrial and agricultural waste instead of fillers is economically and environmentally effective [3]. Research.
In order to save gypsum and improve its thermal and acoustic properties, industrial and agricultural waste (marble and travertine powder, hemp fiber, cotton stalks, rice husks, wood waste) and SDj-2 (superplasticizer Djalilova) to increase its plasticity in the preparation of gypsum composite building boards for energy-efficient buildings ) application mechanisms were studied [4].
Industrial and agricultural waste:
❖ Marble powder is a powder produced in the production of marble decorative tiles.
❖ Travertine is a powder produced in the production of travertine decorative tiles.
❖ Hemp fiber - waste from the processing of fibrous annual plant branches:
❖ Rice husk - a waste of the rice processing industry, a fiber with a length of 6-8 mm, a width
of 3-4 mm and a thickness of 0.3-0.5 mm;
❖ Fibers 1-2 mm long and 25 |im wide are produced as a result of crushing the cotton stalk;
Wood waste - waste generated during wood processing, fibers 5-10 mm long and 20 |im
wide are produced.
❖
The optimal time of mixing waste with gypsum and plasticizer SDj -2 additive was determined. ITS-1 equipment for determining thermal conductivity was used to determine the thermal-physical properties of artificial facing plates based on new gypsum composite materials prepared by adding these wastes. On the basis of different fillers, 160x160x40 mm plasterboards (according to the tests, G-5 plaster brand was selected) were prepared [5]. 3 samples were prepared for each test. The samples were dried to a constant mass. The test results are given in Table 1.
Table 1. Thermal-physical properties of artificial facing plates based on new gypsum composite
materials.
Sam ple Fillers Density 3 kg/m Thermal conductivity W/(iK Relative heat capacity, kDj/kgK
1 Travertine powder 410 0.068 0.58
2 Marble powder 470 0.078 0.71
3 Hemp fiber 435 0.068 0.59
4 Gozapoya fiber 450 0.078 0.71
5 Rice husk 460 0.086 0.82
6 Wood shavings 490 0.075 0.86
As can be seen from the table, the thermal conductivity of tiles obtained on the basis of travertine powder meets the requirements. The thermal conductivity of the material depends on the density and amount of fillers. It was found that the addition of waste up to 10% is the most optimal (the amount of waste in the experiment was 5, 10, 15%).
In order to increase the heat storage capacity of gypsum concrete products, many studies are being conducted on the use of agricultural waste - straw, rice straw, cotton stalks, and wood waste. However, straw and paddy straw are the main fodder for livestock, and hemp and wood waste are used as fuel for the preparation of bread products and food. Their disposal can cause significant damage to the family budget of villagers.
Therefore, it is advisable to use marble and travertine waste in obtaining gypsum composite material. The physical and mechanical properties of the obtained compositions were determined by testing sample sticks prepared according to the requirements of GOST 23789-79. The ratio of water-gypsum is from 0.36 to 0.375, the amount of waste powder is from 6 to 10% in relation to the mass of gypsum. Test results showed that the compressive strength limit of gypsum stone is 19.20 MPa when the amount of marble waste is 10%, and 18.5 MPa for travertine.
Studies on the solubility and physical mechanical properties of gypsum binder and waste powders can be concluded that intergrowth of calcite and calcium sulfate dihydrate crystals in marble and travertine wastes leads to changes in crystal morphology. This phenomenon is explained by the presence of soluble substances in the waste and their participation in the crystallization process [6].
The acceleration of phase formation processes leads to an increase in the number of new morphologically modified dihydrates in the gypsum system [7].
Thus, the conducted research shows that the increase in physical and mechanical properties of gypsum compositions modified with marble and travertine powders is primarily due to the formation of new phases in the heterogeneous process of gypsum solidification with the chemical participation of soluble minerals of marble and travertine and. it can be concluded that the particles of marble and travertine powder fill the pore space of the binder and ensure the formation of gypsum stone in a more perfect structure [8,9,10,11,12].
Result.
On the basis of gypsum composite building materials, artificial decorative plates can be made in different colors by adding pigments.
According to the results of the tests, the new gypsum composite building boards belong to the category of bio-resistant materials
To determine the fire resistance, 150x60x10mm samples were prepared and their flammability was evaluated according to their fire resistance for 5 minutes. According to the test results, the researched material belongs to difficult combustible materials.
When using SDj-2 additive to increase the plasticity of the new gypsum composite construction material, the plasticity of the material increased (hydration made it possible to reduce the amount of water, the water resistance property of the material increased, and the time of gypsum hardening was significantly slowed down.
When the price of 1 ton of G-5 gypsum is 600,000 soums, the efficiency of production of artificial decorative tiles using 10% industrial or agricultural waste to save gypsum is 60,000 soums (size of tiles 150x200x8 sm).
Conclusion.
It is economically and ecologically effective to use artificial facing plates based on the new gypsum composite building material prepared with the addition of industrial and agricultural waste in energy-efficient buildings. It is recommended to use these plates in barrier (self-supporting) constructions.
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