Abstract: A process for the production of building units from an afterhardening mixture containing cement and/or lime as binding material includes the following steps. The raw material is continuously fed and pressed by stamping into a die with CO.sub.2 gas at a pressure higher than atmospheric being passed through the raw mixture in the die space. Through an instantaneous reaction of carbonation, the material is hardened to a formed body. The CO.sub.2 is prevented from escaping by a gastight seal in the vicinity of the inlet port of the die. Further towards the outlet port, the pressure of the CO.sub.2 gas is decreased. In the vicinity of the outlet port only as much CO.sub.2 gas is fed as is necessary for the completing of the chemical reaction. Thus, any loss of gas will be minimized. The continuously discharged body is cut to size by using a saw.