EFFECTIVE ADDITIVES FOR THE PRODUCTION OF WALL CERAMICS FROM LOW-GRADE CLAY RAW MATERIALS

In the production of building materials, an important task is to obtain high-quality ceramic high-void porous wall materials with high strength and thermal insulation properties. To solve this problem, with the depletion of high-quality raw material reserves, it is important to involve in production widely available low-quality low-melting clay raw materials, as well as waste from the extraction and processing of non-metallic minerals. In order to improve the properties of low-quality raw materials, various methods of processing and enrichment are used, including modification with technological (powder-forming, fluxing, etc.) additives. This method is effective and economically advantageous, as it allows for targeted regulation of the structure and properties of ceramics, as well as the utilization of certain wastes. The study investigated the effect of additives of zeolite-containing siliceous rock (zeolite content 32%), refractory clay and vermiculite (silicon oxide to aluminum oxide ratio = 3.9:1) to clay raw materials of mineralogical and technological grade 5a (OE = 18-19 mg.eq, Chgl = 9-13 units, H2Oads = 2.9-3.9%, H2Opog = 4.5-7.5%, K = 1.45-2.20, MC = 15-20%) on the physical and mechanical properties of ceramics. It has been established that ceramic laboratory samples obtained from a three-component mixture consisting of 43-51% clay raw materials of mineralogical and technological difference 5a, 42-50% zeolite-containing siliceous rock, and 7-9% expanded vermiculite have a compressive strength 1.6-2.8 times higher than products made from “pure” clay, and their average density is 0.12-0.27 g/cm3 lower. From the raw materials studied, it is possible to predict the production of ceramic wall materials (bricks, stones) with a strength grade of 100 and above with relatively high thermal characteristics. The use of zeolite-containing clay materials, refractory clay, and vermiculite in combination with low-quality clay raw materials contributes to the improvement of the physical and mechanical properties of ceramic products. Increased strength and reduced density of products are achieved through the correct ratio of calcium and silicon oxides in the mixture, which promotes the formation of wollastonite during sintering. Highly dispersed vermiculite, in turn, helps activate the sintering process and increase porosity, which improves the thermal insulation properties of ceramics. Thus, the modification of clay raw materials with the above additives allows the formation of high-quality ceramic materials with high strength and optimal thermal insulation characteristics, which increases the competitiveness of products and production efficiency in the field of building materials.