| 摘要 |
<p>The machine is for the erosion of localised areas of concrete paving slabs by the application of water jets. Voids of various plan shapes may be formed, and a mobile template with a cut out is used to delineate the earea to be removed. The erosion takes place prior to the pressing of the slab unit, and with the slab disposed on a horizontal bed. The template is displaced vertically to bear on the slab, and the active edges of the cut out are provided with sealing beads of rubber or similar. The beads may be of a wedge section and curve inwardly towards the visible concrete surface when at repose.</p> |
