| 摘要 |
A primary layer (1) is free of binder, and has a density of 20 - 600 kg cubic metre and a surface weight of 70 -1800 sq. metre. It has a water absorption property which extends to 4 -25 grams per gram of surface material. The loose fibre layer is encompassed by covering and support layers (2, 3) comprising fibres temporarily bound to each other, with a density of 50 -900 km cubic metres. Each covering and support layer has a surface weight of 7 - 1200 grams per square metre, and decays in the ground within 60 days. |
