| 摘要 |
<p>The concrete in plastic state is poured over a flexible plastics sheet with sufficient flexibility to form creases and folds in the shape taken up by the concrete, the sheet being placed on a load-bearing and rigid structure. A plasticiser is used during the mixing of the concrete. The concrete is vibrated in the mould for 2-4 minutes to ensure that the concrete occupies all the creases in the mould. It is allowed to set for 24-36 hours and then removed from the mould, giving a totally compact part with a brilliant surface.</p> |
