| 摘要 |
PCT No. PCT/FI89/00119 Sec. 371 Date Dec. 4, 1990 Sec. 102(e) Date Dec. 4, 1990 PCT Filed Jun. 16, 1989 PCT Pub. No. WO89/12719 PCT Pub. Date Dec. 28, 1989.A field construction for sports or other fields is disclosed which includes a substrate or other surface layer and also a filter layer having a pipe network (2,3). The pipe network (2,3) comprises numerous perforated multi-purpose pipes (3) to dry the field and to lead air through the field. In the filter layer (4), the proportion of fine material or material having a granular size of less than 0.06 mm is less than 5%; most advantageously the proportion is less than 1%, so that the filter layer is highly permeable to air, and the substrate includes so much fine material that is less permeable to air. |
