Increasing the strength of building ceramics made on the basis of low-melting clays

Abstract

The object of the study is the physical and chemical processes of formation of the structure and properties, intensification of sintering of ceramic masses based on local raw materials (Krynichanska low-melting clay raw materials of the Kyiv region, Ukraine) by regulating the chemical and mineralogical composition and technological regimes. When choosing clay raw materials for specific ceramic technologies, it is necessary to be guided by a comprehensive assessment of the physicochemical properties of clay rock. These can be the granulometric and material composition, including the chemical and mineralogical composition of the clay and impurity components, the presence of amorphous material. The state of order in the structure of clay-forming minerals is also important, the knowledge of which makes it possible to determine the ways of regulating the basic technological properties of clay rock in order to bring them to the required level. Among physical and mechanical parameters, mechanical strength is one of the main criteria for determining the suitability of raw materials for the production of building ceramics. The conducted studies have shown that with an increase in the amount of rotten stone additive introduced from 10 to 20 % of low-melting clay, the mechanical strength of ceramic samples in compression and bending increases. The introduction of rotten stone additive provides an increase in the coefficient of sensitivity to drying low-melting clay raw materials, which has a positive effect on the crack resistance of raw bricks when drying clay rock in order to bring them to the required level. The use of silica materials in the composition of ceramic masses based on low-melting clays as an additive to improve the physical and mechanical characteristics of the finished product has shown its effectiveness. This can be explained by the fact that the nature of the interaction of silica additives, which was used as rotten stone, differs from the interaction of clay minerals present in ceramic raw materials with water. Since silica exists in rotten stone in the form of amorphous silica gel, it helps to improve the structure of clay, makes it monolithic, increasing mechanical strength. The impurities of low-melting oxides, which are part of the rotten stone, contribute to the formation of low-melting eutectic, reducing the refractoriness of amorphous silica and have a positive effect on the sintering process, forming a glass phase.