| 摘要 |
<p>A composite cover 10 for a manhole or other opening comprises an upper 12 and lower 14 skin of glass reinforced plastics material. The upper and lower skins are bonded to one another about the edges 18 and spaced apart from one another therebetween to define a space 16 containing reinforcing walls 20 extending between the upper 12 and lower 14 skins. The reinforcing walls 20 are preferably formed from a corrugated sheet of glass fibre reinforced plastics material. The cover of the invention is as strong as conventional cast iron covers but is lighter and cheaper to manufacture.</p> |
