Leca is initial letters for light expanded clay aggregate.
Expanded clay aggregates are porous ceramic products with a uniform pore structure of fine, closed cells and with a densely sintered, firm external skin. It is manufactured in rotary kilns from raw materials containing clay minerals. The raw material is prepared, moulded and then subjected to a firing process at temperatures of between 1100 and 1200 ºC, resulting in a significant increase in volume due to expansion. The LECA grains internal cellular structure with thousands of air-filled cavities gives thermal and sound insulation properties.