Perlite is a white or light gray aggregate, produced in the process of expanding from mineral raw materials of volcanic origin. This process involves roasting the raw material at a temperature of 950 ° C to 1100 ° C, which results in a 20-fold increase in grain volume. The chemical composition of perlite is mainly silicon oxides, aluminum, punishment, potassium, calcium, magnesium and iron. The grains are spherical in shape with a diameter below 0,32 mm (do 90% volume). The bulk density of the perlite is from 50-200 kg/m3. The aggregate is resistant to high temperatures (melting point from 950 ° C to 1300 ° C). The thermal conductivity is 0,045-0,050 W / mK. Perlite is used as concrete admixtures, insulating mortars and fittings, it is also used to perform thermal and sound insulation.