The term Leca is derived from “light expanded clay aggregate,” meaning expanded lightweight clay granules. These granules are produced by expanding clay in rotary kilns at a temperature of around 1200°C. Leca lightweight granules (industrial Leca) are almost spherical in shape with a rough and uneven surface. The external microscopic surface of the granules has fine pores and is brown in color, while the internal structure of the granules has a black cellular texture. They possess a range of notable features, including low weight, low thermal conductivity, good sound absorption, fire resistance, durability, and chemical stability.