| 摘要 |
<p>A tubular tree shelter is formed of paper mill sludge with various additives such as binders, fillers, u.v. blockers and foaming agents. The material is introduced into a mould with retractable pins to form apertures in its wall. The apertures may be larger at the top end of the tree shelter than at the bottom, and the top end may be moulded with an internal curve to prevent damage to an emerging tree.</p> |
