PROPERTIES OF ECO-FRIENDLY CERAMIC MATERIALS BASED ON FLY ASH AND RICE HUSK

Abstract

This study examines the feasibility of producing sustainable ceramic materials from locally available loess-like loam, fly ash from a thermal power plant, liquid glass, and ground rice husk. The work is motivated by two parallel challenges: the need to reduce the consumption of high-quality clay in traditional ceramic production and the need to valorize industrial and agricultural wastes that are otherwise landfilled, stockpiled, or openly burned. In the proposed system, loess-like loam serves as the basic aluminosilicate matrix, fly ash acts as a fine mineral component rich in silica and alumina, liquid glass functions as a fluxing and structure-promoting additive, and rice husk plays a dual role as an internal fuel and a silica-bearing pore-forming modifier during firing. The investigated raw mixes contained 40.0–53.5 wt.% loess-like loam, 42.0–52.0 wt.% fly ash, 4.0–6.0 wt.% liquid glass, and 0.5–2.0 wt.% ground rice husk. Samples were prepared by semi-dry pressing and fired at 900–1000 °C. According to the reported experimental results, the developed compositions achieved compressive strengths in the range of 28–35 MPa, water absorption of 15–18%, and frost resistance up to 62 freeze–thaw cycles. Compared with the reference composition, the modified ceramic system showed a broader high-strength range, lower water absorption, and better frost durability. SEM observations revealed a denser microstructure in the modified compositions, while XRD analysis confirmed the formation of quartz, cristobalite, mullite, anorthite, and hematite phases. The results demonstrate that the combined use of fly ash and rice husk contributes to matrix densification, improved durability characteristics, and effective utilization of industrial and agricultural waste in ceramic production.