Expanded-clay aggregate, or exclay, is a lightweight ceramic aggregate, for short an LWA, used in construction. Exclay is produced from natural clay and the end product have the shape of round pellets. They clay have been expanded by thermal treatment in a rotating kiln operating at temperatures about 1100 oC. Exclay lightweight aggregates are available in various densities and gradings between 3-32 mm. It is commercialized in sacks of 25-50 liters. The weight of exclay pellets is approximately 350 kg/m3.
More and more contractors are discovering the advantages of using exclay products in their projects. In addition to high durability, the material retains heat and has excellent sound insulating properties. It is also an environmentally friendly product composed of natural clay and has a long life span.
The pellets can be compressed into solid, lightweight blocks of LWA and exclay is the main aggregate used for LECA blocks. LWAs are also frequently used in water filtration systems due to their high surface area.
To make the exclay, toxic residues such as used oils and all kinds of petroleum gas oils are being burned which makes residues detached while mixing with liquids.
Tor Arne, Hammer; Klaas van Breugel, Steinar Helland, Ivar Holand, Magne Maage, Jan P. G. Mijnsbergen, Edda Lilja Sveinsdóttir (2000). "Economic Design and Construction with Structural Lightweight Aggregate Concrete" (PDF). EUROMAT 99 6: 18. DOI:10.1002/3527606211.ch3. Retrieved on 2007-12-17.