Abstract: A device is described for producing a hollow building block from a hydraulically curing, moist building block compound having a mold open on top (1), which comprises core spikes (4) projecting from a mold floor (2) inside mold walls and positioned with lateral spacing to one another to implement hollow chambers of the hollow building block, and having a filling truck (9) movable along a guide (6) above the mold (1), which forms a receptacle chamber (12), delimited by peripheral walls (13), having a screen floor (14) for delivering the received building block compound.

Abstract: An apparatus is described for foaming a slurry made of sand, water and a hydraulic binding medium by adding a foaming agent with a cylindrical vessel (2) for receiving the slurry and an agitator (7) revolving relative to the vessel about the vessel axis. In order to provide simple constructional conditions it is proposed that the agitator (7) comprises agitating units (10) distributed over the cross section of the vessel, which agitating units each consist of a rotor parallel to the vessel axis with agitator rods (14) between retainers (12, 13) on the face side, which rods are distributed over the circumference, are parallel to the axis and can be driven in an alternating manner in opposite directions.