Keramzit

Keramzit, also known as expanded clay aggregate (ECA) or LECA in some markets, is a lightweight inorganic ceramic aggregate produced by firing natural clays in a rotary kiln at high temperatures. The heating causes the clay minerals to plastically deform and gases generated during firing create a foamed, porous structure. The resulting product consists of hollow or partially hollow spherical pellets that are typically a few millimeters in diameter. Sizes vary to suit different applications.

Production involves preparing raw clay, sometimes blending with additional components, crushing and drying, then feeding the material into a tunnel or rotary kiln where it is heated to approximately 1000–1200°C. The rapid expansion of the material during firing forms lightweight beads with high porosity. After cooling, the pellets are screened into defined size ranges and may be washed or coated for specific uses.

Keramzit has low bulk density and high porosity, giving it good thermal and acoustic insulation properties. It is non-combustible and resistant to decay, with moderate water absorption depending on grade. The material provides reduced dead load in structural elements and can improve drainage and aeration in soil-based systems. Thermal conductivity is relatively low compared with traditional aggregates, contributing to insulating properties in composite materials.

Common applications include lightweight concrete and prefabricated blocks, plaster and backfill fills, drainage layers, and horticultural substrates where improved aeration and moisture management are desired. In horticulture and green roofing, keramzit supports root health and temperature stabilization. The term keramzit is widely used in Russian and some post-Soviet markets; internationally it is frequently referred to as expanded clay aggregate or LECA.