A grooved cement floor, say, for a stable, is laid in sections, and the deep part of the grooves is formed by inserting laths in the wet cement, the rounded portion between the grooves being obtained by cutting off with a trowel, before withdrawing the laths, the arrises at the edges of the grooves. After the cutting is done and the laths are withdrawn, the concrete is carefully smoothed with properly shaped moulds. For the proper performance of the work considerable dexterity and skill are required, as the whole operation must be completed before the cement has begun to set.