After cutting, the green cakes are grouped on steam car by crane. The aerated concrete is hardened under steam pressure in special, sealed pressure vessels, the autoclaves, thereby achieving its final strength. The steam pressure is approx. 12 bar, the temperature approx. 192° C. Usually, the hardening time is between 10 and 12 hours. The used steam for the hardening process in the autoclaves is generated in a steam boiler plant.