Nebezhko Yu.I.

Postgraduate, Don State Technical University, Department of Construction Materials

Comparison of technological properties of clay raw materials during the tests using plastic and soft methods of brick molding

https://doi.org/10.58224/2618-7183-2026-9-2-7
Abstract
The article presents the results of studies of technological properties of clay raw materials using the example of highly dispersed refractory clays of Vladimirovskoye deposit and low-dispersed fusible loams of Aksayskoye deposit in relation to plastic and soft methods of product molding. Research in this area is being conducted due to the lack of testing methods for clay raw materials in relation to the wet method of product molding, despite the fact that ceramic bricks produced using this production technology are in high demand in modern construction and architecture. In Russia, only a few companies produce bricks using this technology, and many companies have not yet been able to master this technology. Comparative tests on typical water-soaked clay raw materials showed that the existing accepted methods approved by regulatory documents cannot be applied to soft molding technology and that a separate method needs to be developed. Thus, with soft molding, molding materials are characterized by an increased degree of deformation under load, reduced plastic strength and critical compressive stress, as well as increased stickiness. It has been shown that a simple increase in the moisture content of molding materials leads to the deterioration in the basic pre-firing technological properties: air shrinkage, sensitivity to drying, cohesion; and to achieve the required degree of sintering, an increased firing temperature is required. Therefore, increasing the moisture content of molding materials is not a simple solution. Molding materials for soft molding must contain increased amounts of leaners with grain compositions approaching the densest packing and the presence of the required amount of sand fraction particles. Otherwise, obtaining high-quality facing ceramic bricks with high decorative properties becomes extremely problematic from a technological perspective. The results of the conducted research will allow to move closer to the development of a method for selecting raw materials for soft molding of ceramic bricks and, in practical terms, will help in organizing production using this technology.
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Molding properties of clay mixtures in the soft mud brick manufacture

https://doi.org/10.58224/2618-7183-2024-7-1-5
Abstract
The article reveals physical and mechanical characteristics of clay mixtures in the soft mud brick manifacture. Considering that currently Russia has no advisory or regulatory documents on the selection of raw materials for soft mud bricks and requirements for their physical and mechanical properties, this issue is quite relevant. The authors, based on their extensive practical experience, present data on acceptable ranges of clay mixtures deformation and critical compressive stress in the soft mud brick manufacture, as well as the results of studies on the influence of electrolyte additives on these indicators. The findings of how the mineral composition of clay raw materials and moisture con-tent influence the critical compressive stress and stickiness of clay mixtures are also presented. Thus, it has been experimentally established that the critical compressive stress of clay mixtures for soft mud bricks should be in the range of 0.2 – 0.8 kg/cm2, and the deformation degree of raw bricks should be in the range of 3 – 5 units. Moreover, even within such narrow limits, depending on their variation as well as on the method of molding and the composition of clay mixtures, it is possible to obtain differ-ent structures of the brick front surface: granular, tuberculate, grooved, wavy, corrugated, spotted, scaly, and their combinations. The moisture content of clay mixtures, depending on the type of clay raw material, can vary within very wide limits: from 20 to 38 per cent. The data obtained will make it possible to develop methods for selecting raw materials for soft mud bricks, which in turn will con-tribute to the organization of its wide production in various regions.
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