Microporous materials of the CaO – Al ₂ O ₃ – SiO ₂ system based on gypsum‐lime binders

Abstract

Microporous materials based on the CaO–Al ₂ O ₃ –SiO ₂ system were developed using inexpensive and readily available Ukrainian raw materials, including gypsum, lime, chalk, quartz sand, and alumina. The materials were produced by slip casting of self‐hardening gypsum–lime mixtures into metal molds followed by firing at 1220–1280 °C. The phase composition and physico‐mechanical properties of wollastonite‐ and anorthite‐based materials were investigated. X‐ray diffraction and petrographic analysis confirmed the predominance of pseudowollastonite in compositions without alumina and anorthite in alumina‐containing compositions. The obtained materials exhibited a highly microporous structure with a significant amount of closed pores. Depending on composition, moisture content, and firing temperature, the apparent density varied within 0.87–1.16 g/cm3 and compressive strength within 1.2–7.2 MPa. The use of a combined gypsum–lime binder improved strength characteristics while maintaining low density. The developed materials can be considered promising for multifunctional applications including thermal insulation panels, fire‐resistant screens, and tooling for casting non‐ferrous alloys.