To smooth out any surface irregularities in the slab, the bottom bed of mortar is laid on using type III standard mortar. A layer of mortar is spread to a thickness of 10 to 30 mm using an adjustable mortar track or sledge that allows type III standard mortar to be laid out precisely. The surface can be leveled with precision. On this layer of mortar blocks acting as a grade course may be set to make up height differences, i.e., base brick.