Abstract: A building block is disclosed which is intended to be arranged in substantially horizontal layers stacked upon each other without the use of mortar. The upper and lower support surfaces of the blocks are wave-shaped in two perpendicular directions in such a manner that the wave-patterns in both directions have the same amplitude and periodicity and a constant wave section over their entire extension. Disclosed also is apparatus for manufacturing the blocks, comprising at least one mold which has a bottom surface having a wave-shape corresponding to that of the block and an upper edge profile corresponding to the wave-shape of the top of the block in the longitudinal direction of the block. Means is located above the mold for supplying a casting mass to the mold and a rotary and vertically movable roll is located above the mold for levelling out and smoothing the mass at the upper end of the mold.

Abstract: A building block is disclosed which is intended to be arranged in substantially horizontal layers stacked upon each other without the use of mortar. The upper and lower support surfaces of the blocks are wave-shaped in two perpendicular directions in such a manner that the wave-patterns in both directions have the same amplitude and periodicity and a constant wave section over their entire extension. Disclosed are also a method and an apparatus for manufacturing the blocks.