| 摘要 |
<p>The sports surface esp. for tennis comprises an upper porous dressing of crushed material (1), a filtering medium (2) and a drainage foundation (3) laid into a suitably shaped excavation which incorporates a network of drains (5). The material forming the upper dressing is pref. made up of a porous volcanic rock haVing a particle size of class 0-1. The upper dressing pref. contains a filler of the same rock in the proportion of 10 to 30 percent by volume.</p> |
