THE EFFECT OF ALKALINE MODIFICATION ON THE PROPERTIES OF CLAY-BASED CERAMICS

TThis study investigates the low plasticity of clay raw materials from the Sannikovskoye deposit (Republic of Sakha (Yakutia)), which limits their application in the production of building ceramics. This study explores alkaline treatment of clay from the Sannikovskoye deposit using aqueous sodium carbonate solutions to enhance its properties for use in building materials. This deposit is a promising raw material source due to its favorable composition and location. The authors have previously investigated three prominent clay deposits near Yakutsk. Although these deposits have large reserves, their mineral and chemical compositions are markedly different. A unifying characteristic is the low plasticity of the clays, which causes manufacturing issues in ceramic production. In this study additional analytical methods were employed, including an assessment of the electrochemical properties of the raw materials and their suspensions, along with an evaluation of their adsorption characteristics. The results indicate that the raw material is characterized by a high content of framework aluminosilicates (plagioclase and potassium feldspars) and the presence of hydromica-type clay minerals (illite and chlorite), which accounts for its low adsorption capacity and plasticity. The effect of sodium carbonate on the electrochemical properties of clay suspensions was studied, and an increase in the negative zeta potential and pH with increasing Na₂CO₃ concentration was observed, which is attributed to ion exchange processes and enhanced stability of the dispersed system. Ceramic samples fired at 950 °C were tested for water absorption and flexural strength. The maximum flexural strength (8.50 MPa) was achieved with the addition of a 10% sodium carbonate solution, while the lowest water absorption (10.51%) was observed at a 15% concentration, demonstrating the complex influence of alkaline modification on ceramic body structure formation and highlighting the importance of selecting an optimal modifier concentration depending on the intended application of the ceramic material