| 摘要 |
The surface comprises a foundation layer (1), one or more impervious layer (4,7) and a porous top one (8,9). The latter is preferable of very open asphalted concrete and adjacent to a drain gutter (5) connected to the porous layer so as to discharge water from it. The gutter is supported by the impervious layer, typically via a positioning layer of mortar (6) on the latter. There can be a further impervious layer, enclosed by the gutter at the side. Drain holes (12) can be provided in the side of the gutter towards the porous layer, while the impervious layer extends at least to the bottom edges (16) of the holes. The gutter bottom can be below the level of these edges.
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